License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 17:07:57 +03:00
// SPDX-License-Identifier: GPL-2.0
2005-04-17 02:20:36 +04:00
/*
* linux / fs / super . c
*
* Copyright ( C ) 1991 , 1992 Linus Torvalds
*
* super . c contains code to handle : - mount structures
* - super - block tables
* - filesystem drivers list
* - mount system call
* - umount system call
* - ustat system call
*
* GK 2 / 5 / 95 - Changed to support mounting the root fs via NFS
*
* Added kerneld support : Jacques Gelinas and Bjorn Ekwall
* Added change_root : Werner Almesberger & Hans Lermen , Feb ' 96
* Added options to / proc / mounts :
2007-10-20 01:21:04 +04:00
* Torbjörn Lindh ( torbjorn . lindh @ gopta . se ) , April 14 , 1996.
2005-04-17 02:20:36 +04:00
* Added devfs support : Richard Gooch < rgooch @ atnf . csiro . au > , 13 - JAN - 1998
* Heavily rewritten for ' one fs - one tree ' dcache architecture . AV , Mar 2000
*/
2011-11-17 08:57:37 +04:00
# include <linux/export.h>
2005-04-17 02:20:36 +04:00
# include <linux/slab.h>
# include <linux/blkdev.h>
# include <linux/mount.h>
# include <linux/security.h>
# include <linux/writeback.h> /* for the emergency remount stuff */
# include <linux/idr.h>
2006-03-26 13:37:12 +04:00
# include <linux/mutex.h>
2010-04-29 22:33:35 +04:00
# include <linux/backing-dev.h>
2011-01-07 09:50:05 +03:00
# include <linux/rculist_bl.h>
2011-05-26 20:01:43 +04:00
# include <linux/cleancache.h>
fscrypt: add FS_IOC_ADD_ENCRYPTION_KEY ioctl
Add a new fscrypt ioctl, FS_IOC_ADD_ENCRYPTION_KEY. This ioctl adds an
encryption key to the filesystem's fscrypt keyring ->s_master_keys,
making any files encrypted with that key appear "unlocked".
Why we need this
~~~~~~~~~~~~~~~~
The main problem is that the "locked/unlocked" (ciphertext/plaintext)
status of encrypted files is global, but the fscrypt keys are not.
fscrypt only looks for keys in the keyring(s) the process accessing the
filesystem is subscribed to: the thread keyring, process keyring, and
session keyring, where the session keyring may contain the user keyring.
Therefore, userspace has to put fscrypt keys in the keyrings for
individual users or sessions. But this means that when a process with a
different keyring tries to access encrypted files, whether they appear
"unlocked" or not is nondeterministic. This is because it depends on
whether the files are currently present in the inode cache.
Fixing this by consistently providing each process its own view of the
filesystem depending on whether it has the key or not isn't feasible due
to how the VFS caches work. Furthermore, while sometimes users expect
this behavior, it is misguided for two reasons. First, it would be an
OS-level access control mechanism largely redundant with existing access
control mechanisms such as UNIX file permissions, ACLs, LSMs, etc.
Encryption is actually for protecting the data at rest.
Second, almost all users of fscrypt actually do need the keys to be
global. The largest users of fscrypt, Android and Chromium OS, achieve
this by having PID 1 create a "session keyring" that is inherited by
every process. This works, but it isn't scalable because it prevents
session keyrings from being used for any other purpose.
On general-purpose Linux distros, the 'fscrypt' userspace tool [1] can't
similarly abuse the session keyring, so to make 'sudo' work on all
systems it has to link all the user keyrings into root's user keyring
[2]. This is ugly and raises security concerns. Moreover it can't make
the keys available to system services, such as sshd trying to access the
user's '~/.ssh' directory (see [3], [4]) or NetworkManager trying to
read certificates from the user's home directory (see [5]); or to Docker
containers (see [6], [7]).
By having an API to add a key to the *filesystem* we'll be able to fix
the above bugs, remove userspace workarounds, and clearly express the
intended semantics: the locked/unlocked status of an encrypted directory
is global, and encryption is orthogonal to OS-level access control.
Why not use the add_key() syscall
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We use an ioctl for this API rather than the existing add_key() system
call because the ioctl gives us the flexibility needed to implement
fscrypt-specific semantics that will be introduced in later patches:
- Supporting key removal with the semantics such that the secret is
removed immediately and any unused inodes using the key are evicted;
also, the eviction of any in-use inodes can be retried.
- Calculating a key-dependent cryptographic identifier and returning it
to userspace.
- Allowing keys to be added and removed by non-root users, but only keys
for v2 encryption policies; and to prevent denial-of-service attacks,
users can only remove keys they themselves have added, and a key is
only really removed after all users who added it have removed it.
Trying to shoehorn these semantics into the keyrings syscalls would be
very difficult, whereas the ioctls make things much easier.
However, to reuse code the implementation still uses the keyrings
service internally. Thus we get lockless RCU-mode key lookups without
having to re-implement it, and the keys automatically show up in
/proc/keys for debugging purposes.
References:
[1] https://github.com/google/fscrypt
[2] https://goo.gl/55cCrI#heading=h.vf09isp98isb
[3] https://github.com/google/fscrypt/issues/111#issuecomment-444347939
[4] https://github.com/google/fscrypt/issues/116
[5] https://bugs.launchpad.net/ubuntu/+source/fscrypt/+bug/1770715
[6] https://github.com/google/fscrypt/issues/128
[7] https://askubuntu.com/questions/1130306/cannot-run-docker-on-an-encrypted-filesystem
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Eric Biggers <ebiggers@google.com>
2019-08-05 05:35:46 +03:00
# include <linux/fscrypt.h>
2012-02-13 07:58:52 +04:00
# include <linux/fsnotify.h>
2012-06-12 18:20:34 +04:00
# include <linux/lockdep.h>
2016-05-24 17:29:01 +03:00
# include <linux/user_namespace.h>
2018-11-04 11:19:03 +03:00
# include <linux/fs_context.h>
2018-11-02 02:07:23 +03:00
# include <uapi/linux/mount.h>
2008-03-22 22:48:17 +03:00
# include "internal.h"
2005-04-17 02:20:36 +04:00
2017-10-03 19:17:41 +03:00
static int thaw_super_locked ( struct super_block * sb ) ;
2005-04-17 02:20:36 +04:00
2015-02-02 20:07:59 +03:00
static LIST_HEAD ( super_blocks ) ;
static DEFINE_SPINLOCK ( sb_lock ) ;
2005-04-17 02:20:36 +04:00
2012-06-12 18:20:34 +04:00
static char * sb_writers_name [ SB_FREEZE_LEVELS ] = {
" sb_writers " ,
" sb_pagefaults " ,
" sb_internal " ,
} ;
2011-07-08 08:14:42 +04:00
/*
* One thing we have to be careful of with a per - sb shrinker is that we don ' t
* drop the last active reference to the superblock from within the shrinker .
* If that happens we could trigger unregistering the shrinker from within the
* shrinker path and that leads to deadlock on the shrinker_rwsem . Hence we
* take a passive reference to the superblock to avoid this from occurring .
*/
2013-08-28 04:17:57 +04:00
static unsigned long super_cache_scan ( struct shrinker * shrink ,
struct shrink_control * sc )
2011-07-08 08:14:42 +04:00
{
struct super_block * sb ;
2013-08-28 04:17:57 +04:00
long fs_objects = 0 ;
long total_objects ;
long freed = 0 ;
long dentries ;
long inodes ;
2011-07-08 08:14:42 +04:00
sb = container_of ( shrink , struct super_block , s_shrink ) ;
/*
* Deadlock avoidance . We may hold various FS locks , and we don ' t want
* to recurse into the FS that called us in clear_inode ( ) and friends . .
*/
2013-08-28 04:17:57 +04:00
if ( ! ( sc - > gfp_mask & __GFP_FS ) )
return SHRINK_STOP ;
2011-07-08 08:14:42 +04:00
2015-02-19 20:19:35 +03:00
if ( ! trylock_super ( sb ) )
2013-08-28 04:17:57 +04:00
return SHRINK_STOP ;
2011-07-08 08:14:42 +04:00
2013-07-19 21:12:31 +04:00
if ( sb - > s_op - > nr_cached_objects )
2015-02-13 01:58:51 +03:00
fs_objects = sb - > s_op - > nr_cached_objects ( sb , sc ) ;
2011-07-08 08:14:44 +04:00
list_lru: introduce list_lru_shrink_{count,walk}
Kmem accounting of memcg is unusable now, because it lacks slab shrinker
support. That means when we hit the limit we will get ENOMEM w/o any
chance to recover. What we should do then is to call shrink_slab, which
would reclaim old inode/dentry caches from this cgroup. This is what
this patch set is intended to do.
Basically, it does two things. First, it introduces the notion of
per-memcg slab shrinker. A shrinker that wants to reclaim objects per
cgroup should mark itself as SHRINKER_MEMCG_AWARE. Then it will be
passed the memory cgroup to scan from in shrink_control->memcg. For
such shrinkers shrink_slab iterates over the whole cgroup subtree under
the target cgroup and calls the shrinker for each kmem-active memory
cgroup.
Secondly, this patch set makes the list_lru structure per-memcg. It's
done transparently to list_lru users - everything they have to do is to
tell list_lru_init that they want memcg-aware list_lru. Then the
list_lru will automatically distribute objects among per-memcg lists
basing on which cgroup the object is accounted to. This way to make FS
shrinkers (icache, dcache) memcg-aware we only need to make them use
memcg-aware list_lru, and this is what this patch set does.
As before, this patch set only enables per-memcg kmem reclaim when the
pressure goes from memory.limit, not from memory.kmem.limit. Handling
memory.kmem.limit is going to be tricky due to GFP_NOFS allocations, and
it is still unclear whether we will have this knob in the unified
hierarchy.
This patch (of 9):
NUMA aware slab shrinkers use the list_lru structure to distribute
objects coming from different NUMA nodes to different lists. Whenever
such a shrinker needs to count or scan objects from a particular node,
it issues commands like this:
count = list_lru_count_node(lru, sc->nid);
freed = list_lru_walk_node(lru, sc->nid, isolate_func,
isolate_arg, &sc->nr_to_scan);
where sc is an instance of the shrink_control structure passed to it
from vmscan.
To simplify this, let's add special list_lru functions to be used by
shrinkers, list_lru_shrink_count() and list_lru_shrink_walk(), which
consolidate the nid and nr_to_scan arguments in the shrink_control
structure.
This will also allow us to avoid patching shrinkers that use list_lru
when we make shrink_slab() per-memcg - all we will have to do is extend
the shrink_control structure to include the target memcg and make
list_lru_shrink_{count,walk} handle this appropriately.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Suggested-by: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-13 01:58:47 +03:00
inodes = list_lru_shrink_count ( & sb - > s_inode_lru , sc ) ;
dentries = list_lru_shrink_count ( & sb - > s_dentry_lru , sc ) ;
2013-08-28 04:18:00 +04:00
total_objects = dentries + inodes + fs_objects + 1 ;
2014-05-17 15:56:38 +04:00
if ( ! total_objects )
total_objects = 1 ;
2011-07-08 08:14:44 +04:00
2013-08-28 04:17:57 +04:00
/* proportion the scan between the caches */
2013-08-28 04:18:00 +04:00
dentries = mult_frac ( sc - > nr_to_scan , dentries , total_objects ) ;
2013-08-28 04:17:58 +04:00
inodes = mult_frac ( sc - > nr_to_scan , inodes , total_objects ) ;
list_lru: introduce list_lru_shrink_{count,walk}
Kmem accounting of memcg is unusable now, because it lacks slab shrinker
support. That means when we hit the limit we will get ENOMEM w/o any
chance to recover. What we should do then is to call shrink_slab, which
would reclaim old inode/dentry caches from this cgroup. This is what
this patch set is intended to do.
Basically, it does two things. First, it introduces the notion of
per-memcg slab shrinker. A shrinker that wants to reclaim objects per
cgroup should mark itself as SHRINKER_MEMCG_AWARE. Then it will be
passed the memory cgroup to scan from in shrink_control->memcg. For
such shrinkers shrink_slab iterates over the whole cgroup subtree under
the target cgroup and calls the shrinker for each kmem-active memory
cgroup.
Secondly, this patch set makes the list_lru structure per-memcg. It's
done transparently to list_lru users - everything they have to do is to
tell list_lru_init that they want memcg-aware list_lru. Then the
list_lru will automatically distribute objects among per-memcg lists
basing on which cgroup the object is accounted to. This way to make FS
shrinkers (icache, dcache) memcg-aware we only need to make them use
memcg-aware list_lru, and this is what this patch set does.
As before, this patch set only enables per-memcg kmem reclaim when the
pressure goes from memory.limit, not from memory.kmem.limit. Handling
memory.kmem.limit is going to be tricky due to GFP_NOFS allocations, and
it is still unclear whether we will have this knob in the unified
hierarchy.
This patch (of 9):
NUMA aware slab shrinkers use the list_lru structure to distribute
objects coming from different NUMA nodes to different lists. Whenever
such a shrinker needs to count or scan objects from a particular node,
it issues commands like this:
count = list_lru_count_node(lru, sc->nid);
freed = list_lru_walk_node(lru, sc->nid, isolate_func,
isolate_arg, &sc->nr_to_scan);
where sc is an instance of the shrink_control structure passed to it
from vmscan.
To simplify this, let's add special list_lru functions to be used by
shrinkers, list_lru_shrink_count() and list_lru_shrink_walk(), which
consolidate the nid and nr_to_scan arguments in the shrink_control
structure.
This will also allow us to avoid patching shrinkers that use list_lru
when we make shrink_slab() per-memcg - all we will have to do is extend
the shrink_control structure to include the target memcg and make
list_lru_shrink_{count,walk} handle this appropriately.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Suggested-by: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-13 01:58:47 +03:00
fs_objects = mult_frac ( sc - > nr_to_scan , fs_objects , total_objects ) ;
2011-07-08 08:14:42 +04:00
2013-08-28 04:17:57 +04:00
/*
* prune the dcache first as the icache is pinned by it , then
* prune the icache , followed by the filesystem specific caches
2015-02-13 01:59:17 +03:00
*
* Ensure that we always scan at least one object - memcg kmem
* accounting uses this to fully empty the caches .
2013-08-28 04:17:57 +04:00
*/
2015-02-13 01:59:17 +03:00
sc - > nr_to_scan = dentries + 1 ;
list_lru: introduce list_lru_shrink_{count,walk}
Kmem accounting of memcg is unusable now, because it lacks slab shrinker
support. That means when we hit the limit we will get ENOMEM w/o any
chance to recover. What we should do then is to call shrink_slab, which
would reclaim old inode/dentry caches from this cgroup. This is what
this patch set is intended to do.
Basically, it does two things. First, it introduces the notion of
per-memcg slab shrinker. A shrinker that wants to reclaim objects per
cgroup should mark itself as SHRINKER_MEMCG_AWARE. Then it will be
passed the memory cgroup to scan from in shrink_control->memcg. For
such shrinkers shrink_slab iterates over the whole cgroup subtree under
the target cgroup and calls the shrinker for each kmem-active memory
cgroup.
Secondly, this patch set makes the list_lru structure per-memcg. It's
done transparently to list_lru users - everything they have to do is to
tell list_lru_init that they want memcg-aware list_lru. Then the
list_lru will automatically distribute objects among per-memcg lists
basing on which cgroup the object is accounted to. This way to make FS
shrinkers (icache, dcache) memcg-aware we only need to make them use
memcg-aware list_lru, and this is what this patch set does.
As before, this patch set only enables per-memcg kmem reclaim when the
pressure goes from memory.limit, not from memory.kmem.limit. Handling
memory.kmem.limit is going to be tricky due to GFP_NOFS allocations, and
it is still unclear whether we will have this knob in the unified
hierarchy.
This patch (of 9):
NUMA aware slab shrinkers use the list_lru structure to distribute
objects coming from different NUMA nodes to different lists. Whenever
such a shrinker needs to count or scan objects from a particular node,
it issues commands like this:
count = list_lru_count_node(lru, sc->nid);
freed = list_lru_walk_node(lru, sc->nid, isolate_func,
isolate_arg, &sc->nr_to_scan);
where sc is an instance of the shrink_control structure passed to it
from vmscan.
To simplify this, let's add special list_lru functions to be used by
shrinkers, list_lru_shrink_count() and list_lru_shrink_walk(), which
consolidate the nid and nr_to_scan arguments in the shrink_control
structure.
This will also allow us to avoid patching shrinkers that use list_lru
when we make shrink_slab() per-memcg - all we will have to do is extend
the shrink_control structure to include the target memcg and make
list_lru_shrink_{count,walk} handle this appropriately.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Suggested-by: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-13 01:58:47 +03:00
freed = prune_dcache_sb ( sb , sc ) ;
2015-02-13 01:59:17 +03:00
sc - > nr_to_scan = inodes + 1 ;
list_lru: introduce list_lru_shrink_{count,walk}
Kmem accounting of memcg is unusable now, because it lacks slab shrinker
support. That means when we hit the limit we will get ENOMEM w/o any
chance to recover. What we should do then is to call shrink_slab, which
would reclaim old inode/dentry caches from this cgroup. This is what
this patch set is intended to do.
Basically, it does two things. First, it introduces the notion of
per-memcg slab shrinker. A shrinker that wants to reclaim objects per
cgroup should mark itself as SHRINKER_MEMCG_AWARE. Then it will be
passed the memory cgroup to scan from in shrink_control->memcg. For
such shrinkers shrink_slab iterates over the whole cgroup subtree under
the target cgroup and calls the shrinker for each kmem-active memory
cgroup.
Secondly, this patch set makes the list_lru structure per-memcg. It's
done transparently to list_lru users - everything they have to do is to
tell list_lru_init that they want memcg-aware list_lru. Then the
list_lru will automatically distribute objects among per-memcg lists
basing on which cgroup the object is accounted to. This way to make FS
shrinkers (icache, dcache) memcg-aware we only need to make them use
memcg-aware list_lru, and this is what this patch set does.
As before, this patch set only enables per-memcg kmem reclaim when the
pressure goes from memory.limit, not from memory.kmem.limit. Handling
memory.kmem.limit is going to be tricky due to GFP_NOFS allocations, and
it is still unclear whether we will have this knob in the unified
hierarchy.
This patch (of 9):
NUMA aware slab shrinkers use the list_lru structure to distribute
objects coming from different NUMA nodes to different lists. Whenever
such a shrinker needs to count or scan objects from a particular node,
it issues commands like this:
count = list_lru_count_node(lru, sc->nid);
freed = list_lru_walk_node(lru, sc->nid, isolate_func,
isolate_arg, &sc->nr_to_scan);
where sc is an instance of the shrink_control structure passed to it
from vmscan.
To simplify this, let's add special list_lru functions to be used by
shrinkers, list_lru_shrink_count() and list_lru_shrink_walk(), which
consolidate the nid and nr_to_scan arguments in the shrink_control
structure.
This will also allow us to avoid patching shrinkers that use list_lru
when we make shrink_slab() per-memcg - all we will have to do is extend
the shrink_control structure to include the target memcg and make
list_lru_shrink_{count,walk} handle this appropriately.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Suggested-by: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-13 01:58:47 +03:00
freed + = prune_icache_sb ( sb , sc ) ;
2013-08-28 04:17:57 +04:00
if ( fs_objects ) {
2015-02-13 01:59:17 +03:00
sc - > nr_to_scan = fs_objects + 1 ;
2015-02-13 01:58:51 +03:00
freed + = sb - > s_op - > free_cached_objects ( sb , sc ) ;
2011-07-08 08:14:42 +04:00
}
2015-02-19 20:19:35 +03:00
up_read ( & sb - > s_umount ) ;
2013-08-28 04:17:57 +04:00
return freed ;
}
static unsigned long super_cache_count ( struct shrinker * shrink ,
struct shrink_control * sc )
{
struct super_block * sb ;
long total_objects = 0 ;
sb = container_of ( shrink , struct super_block , s_shrink ) ;
2014-06-05 03:10:47 +04:00
/*
2018-05-11 04:20:57 +03:00
* We don ' t call trylock_super ( ) here as it is a scalability bottleneck ,
* so we ' re exposed to partial setup state . The shrinker rwsem does not
* protect filesystem operations backing list_lru_shrink_count ( ) or
* s_op - > nr_cached_objects ( ) . Counts can change between
* super_cache_count and super_cache_scan , so we really don ' t need locks
* here .
*
* However , if we are currently mounting the superblock , the underlying
* filesystem might be in a state of partial construction and hence it
* is dangerous to access it . trylock_super ( ) uses a SB_BORN check to
* avoid this situation , so do the same here . The memory barrier is
* matched with the one in mount_fs ( ) as we don ' t hold locks here .
2014-06-05 03:10:47 +04:00
*/
2018-05-11 04:20:57 +03:00
if ( ! ( sb - > s_flags & SB_BORN ) )
return 0 ;
smp_rmb ( ) ;
2013-08-28 04:17:57 +04:00
if ( sb - > s_op & & sb - > s_op - > nr_cached_objects )
2015-02-13 01:58:51 +03:00
total_objects = sb - > s_op - > nr_cached_objects ( sb , sc ) ;
2013-08-28 04:17:57 +04:00
list_lru: introduce list_lru_shrink_{count,walk}
Kmem accounting of memcg is unusable now, because it lacks slab shrinker
support. That means when we hit the limit we will get ENOMEM w/o any
chance to recover. What we should do then is to call shrink_slab, which
would reclaim old inode/dentry caches from this cgroup. This is what
this patch set is intended to do.
Basically, it does two things. First, it introduces the notion of
per-memcg slab shrinker. A shrinker that wants to reclaim objects per
cgroup should mark itself as SHRINKER_MEMCG_AWARE. Then it will be
passed the memory cgroup to scan from in shrink_control->memcg. For
such shrinkers shrink_slab iterates over the whole cgroup subtree under
the target cgroup and calls the shrinker for each kmem-active memory
cgroup.
Secondly, this patch set makes the list_lru structure per-memcg. It's
done transparently to list_lru users - everything they have to do is to
tell list_lru_init that they want memcg-aware list_lru. Then the
list_lru will automatically distribute objects among per-memcg lists
basing on which cgroup the object is accounted to. This way to make FS
shrinkers (icache, dcache) memcg-aware we only need to make them use
memcg-aware list_lru, and this is what this patch set does.
As before, this patch set only enables per-memcg kmem reclaim when the
pressure goes from memory.limit, not from memory.kmem.limit. Handling
memory.kmem.limit is going to be tricky due to GFP_NOFS allocations, and
it is still unclear whether we will have this knob in the unified
hierarchy.
This patch (of 9):
NUMA aware slab shrinkers use the list_lru structure to distribute
objects coming from different NUMA nodes to different lists. Whenever
such a shrinker needs to count or scan objects from a particular node,
it issues commands like this:
count = list_lru_count_node(lru, sc->nid);
freed = list_lru_walk_node(lru, sc->nid, isolate_func,
isolate_arg, &sc->nr_to_scan);
where sc is an instance of the shrink_control structure passed to it
from vmscan.
To simplify this, let's add special list_lru functions to be used by
shrinkers, list_lru_shrink_count() and list_lru_shrink_walk(), which
consolidate the nid and nr_to_scan arguments in the shrink_control
structure.
This will also allow us to avoid patching shrinkers that use list_lru
when we make shrink_slab() per-memcg - all we will have to do is extend
the shrink_control structure to include the target memcg and make
list_lru_shrink_{count,walk} handle this appropriately.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Suggested-by: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-13 01:58:47 +03:00
total_objects + = list_lru_shrink_count ( & sb - > s_dentry_lru , sc ) ;
total_objects + = list_lru_shrink_count ( & sb - > s_inode_lru , sc ) ;
2013-08-28 04:17:57 +04:00
2018-08-18 01:48:21 +03:00
if ( ! total_objects )
return SHRINK_EMPTY ;
2013-08-28 04:17:53 +04:00
total_objects = vfs_pressure_ratio ( total_objects ) ;
2011-07-08 08:14:44 +04:00
return total_objects ;
2011-07-08 08:14:42 +04:00
}
2015-07-22 21:21:13 +03:00
static void destroy_super_work ( struct work_struct * work )
{
struct super_block * s = container_of ( work , struct super_block ,
destroy_work ) ;
int i ;
for ( i = 0 ; i < SB_FREEZE_LEVELS ; i + + )
2015-08-11 18:05:04 +03:00
percpu_free_rwsem ( & s - > s_writers . rw_sem [ i ] ) ;
2015-07-22 21:21:13 +03:00
kfree ( s ) ;
}
static void destroy_super_rcu ( struct rcu_head * head )
{
struct super_block * s = container_of ( head , struct super_block , rcu ) ;
INIT_WORK ( & s - > destroy_work , destroy_super_work ) ;
schedule_work ( & s - > destroy_work ) ;
}
2017-10-11 20:48:55 +03:00
/* Free a superblock that has never been seen by anyone */
static void destroy_unused_super ( struct super_block * s )
2012-06-12 18:20:34 +04:00
{
2017-10-11 20:48:55 +03:00
if ( ! s )
return ;
up_write ( & s - > s_umount ) ;
2013-10-01 23:09:58 +04:00
list_lru_destroy ( & s - > s_dentry_lru ) ;
list_lru_destroy ( & s - > s_inode_lru ) ;
security_sb_free ( s ) ;
2016-05-24 17:29:01 +03:00
put_user_ns ( s - > s_user_ns ) ;
2013-10-01 23:09:58 +04:00
kfree ( s - > s_subtype ) ;
2018-04-04 13:53:07 +03:00
free_prealloced_shrinker ( & s - > s_shrink ) ;
2017-10-11 20:48:55 +03:00
/* no delays needed */
destroy_super_work ( & s - > destroy_work ) ;
2012-06-12 18:20:34 +04:00
}
2005-04-17 02:20:36 +04:00
/**
* alloc_super - create new superblock
2006-09-06 11:03:41 +04:00
* @ type : filesystem type superblock should belong to
2012-06-25 15:55:37 +04:00
* @ flags : the mount flags
2016-05-24 17:29:01 +03:00
* @ user_ns : User namespace for the super_block
2005-04-17 02:20:36 +04:00
*
* Allocates and initializes a new & struct super_block . alloc_super ( )
* returns a pointer new superblock or % NULL if allocation had failed .
*/
2016-05-24 17:29:01 +03:00
static struct super_block * alloc_super ( struct file_system_type * type , int flags ,
struct user_namespace * user_ns )
2005-04-17 02:20:36 +04:00
{
2006-03-25 14:08:13 +03:00
struct super_block * s = kzalloc ( sizeof ( struct super_block ) , GFP_USER ) ;
2009-09-22 04:01:09 +04:00
static const struct super_operations default_op ;
2013-10-01 23:09:58 +04:00
int i ;
if ( ! s )
return NULL ;
2005-04-17 02:20:36 +04:00
2014-01-22 03:48:45 +04:00
INIT_LIST_HEAD ( & s - > s_mounts ) ;
2016-05-24 17:29:01 +03:00
s - > s_user_ns = get_user_ns ( user_ns ) ;
2017-12-05 17:32:25 +03:00
init_rwsem ( & s - > s_umount ) ;
lockdep_set_class ( & s - > s_umount , & type - > s_umount_key ) ;
/*
* sget ( ) can have s_umount recursion .
*
* When it cannot find a suitable sb , it allocates a new
* one ( this one ) , and tries again to find a suitable old
* one .
*
* In case that succeeds , it will acquire the s_umount
* lock of the old one . Since these are clearly distrinct
* locks , and this object isn ' t exposed yet , there ' s no
* risk of deadlocks .
*
* Annotate this by putting this lock in a different
* subclass .
*/
down_write_nested ( & s - > s_umount , SINGLE_DEPTH_NESTING ) ;
2014-01-22 03:48:45 +04:00
2013-10-01 23:09:58 +04:00
if ( security_sb_alloc ( s ) )
goto fail ;
2013-09-04 17:04:39 +04:00
2013-10-01 23:09:58 +04:00
for ( i = 0 ; i < SB_FREEZE_LEVELS ; i + + ) {
2015-08-11 18:05:04 +03:00
if ( __percpu_init_rwsem ( & s - > s_writers . rw_sem [ i ] ,
sb_writers_name [ i ] ,
& type - > s_writers_key [ i ] ) )
2013-10-01 23:09:58 +04:00
goto fail ;
2005-04-17 02:20:36 +04:00
}
2013-10-01 23:09:58 +04:00
init_waitqueue_head ( & s - > s_writers . wait_unfrozen ) ;
2015-01-14 12:42:41 +03:00
s - > s_bdi = & noop_backing_dev_info ;
2013-10-01 23:09:58 +04:00
s - > s_flags = flags ;
2016-06-09 23:44:48 +03:00
if ( s - > s_user_ns ! = & init_user_ns )
2016-05-18 21:50:06 +03:00
s - > s_iflags | = SB_I_NODEV ;
2013-10-01 23:09:58 +04:00
INIT_HLIST_NODE ( & s - > s_instances ) ;
VFS: don't keep disconnected dentries on d_anon
The original purpose of the per-superblock d_anon list was to
keep disconnected dentries in the cache between consecutive
requests to the NFS server. Dentries can be disconnected if
a client holds a file open and repeatedly performs IO on it,
and if the server drops the dentry, whether due to memory
pressure, server restart, or "echo 3 > /proc/sys/vm/drop_caches".
This purpose was thwarted by commit 75a6f82a0d10 ("freeing unlinked
file indefinitely delayed") which caused disconnected dentries
to be freed as soon as their refcount reached zero.
This means that, when a dentry being used by nfsd gets disconnected, a
new one needs to be allocated for every request (unless requests
overlap). As the dentry has no name, no parent, and no children,
there is little of value to cache. As small memory allocations are
typically fast (from per-cpu free lists) this likely has little cost.
This means that the original purpose of s_anon is no longer relevant:
there is no longer any need to keep disconnected dentries on a list so
they appear to be hashed.
However, s_anon now has a new use. When you mount an NFS filesystem,
the dentry stored in s_root is just a placebo. The "real" root dentry
is allocated using d_obtain_root() and so it kept on the s_anon list.
I don't know the reason for this, but suspect it related to NFSv4
where a mount of "server:/some/path" require NFS to look up the root
filehandle on the server, then walk down "/some" and "/path" to get
the filehandle to mount.
Whatever the reason, NFS depends on the s_anon list and on
shrink_dcache_for_umount() pruning all dentries on this list. So we
cannot simply remove s_anon.
We could just leave the code unchanged, but apart from that being
potentially confusing, the (unfair) bit-spin-lock which protects
s_anon can become a bottle neck when lots of disconnected dentries are
being created.
So this patch renames s_anon to s_roots, and stops storing
disconnected dentries on the list. Only dentries obtained with
d_obtain_root() are now stored on this list. There are many fewer of
these (only NFS and NILFS2 use the call, and only during filesystem
mount) so contention on the bit-lock will not be a problem.
Possibly an alternate solution should be found for NFS and NILFS2, but
that would require understanding their needs first.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-12-21 01:45:40 +03:00
INIT_HLIST_BL_HEAD ( & s - > s_roots ) ;
2015-03-04 21:40:00 +03:00
mutex_init ( & s - > s_sync_lock ) ;
2013-10-01 23:09:58 +04:00
INIT_LIST_HEAD ( & s - > s_inodes ) ;
2015-03-04 20:37:22 +03:00
spin_lock_init ( & s - > s_inode_list_lock ) ;
2016-07-27 01:21:50 +03:00
INIT_LIST_HEAD ( & s - > s_inodes_wb ) ;
spin_lock_init ( & s - > s_inode_wblist_lock ) ;
2013-10-01 23:09:58 +04:00
s - > s_count = 1 ;
atomic_set ( & s - > s_active , 1 ) ;
mutex_init ( & s - > s_vfs_rename_mutex ) ;
lockdep_set_class ( & s - > s_vfs_rename_mutex , & type - > s_vfs_rename_key ) ;
2017-06-08 15:39:48 +03:00
init_rwsem ( & s - > s_dquot . dqio_sem ) ;
2013-10-01 23:09:58 +04:00
s - > s_maxbytes = MAX_NON_LFS ;
s - > s_op = & default_op ;
s - > s_time_gran = 1000000000 ;
2018-01-22 05:04:23 +03:00
s - > s_time_min = TIME64_MIN ;
s - > s_time_max = TIME64_MAX ;
2015-04-15 01:46:48 +03:00
s - > cleancache_poolid = CLEANCACHE_NO_POOL ;
2013-10-01 23:09:58 +04:00
s - > s_shrink . seeks = DEFAULT_SEEKS ;
s - > s_shrink . scan_objects = super_cache_scan ;
s - > s_shrink . count_objects = super_cache_count ;
s - > s_shrink . batch = 1024 ;
2015-02-13 01:59:14 +03:00
s - > s_shrink . flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE ;
2018-04-04 13:53:07 +03:00
if ( prealloc_shrinker ( & s - > s_shrink ) )
goto fail ;
2018-08-18 01:47:50 +03:00
if ( list_lru_init_memcg ( & s - > s_dentry_lru , & s - > s_shrink ) )
2018-08-18 01:47:45 +03:00
goto fail ;
2018-08-18 01:47:50 +03:00
if ( list_lru_init_memcg ( & s - > s_inode_lru , & s - > s_shrink ) )
2018-08-18 01:47:45 +03:00
goto fail ;
2005-04-17 02:20:36 +04:00
return s ;
2013-08-28 04:18:18 +04:00
2013-10-01 23:09:58 +04:00
fail :
2017-10-11 20:48:55 +03:00
destroy_unused_super ( s ) ;
2013-10-01 23:09:58 +04:00
return NULL ;
2005-04-17 02:20:36 +04:00
}
/* Superblock refcounting */
/*
2010-03-23 04:13:53 +03:00
* Drop a superblock ' s refcount . The caller must hold sb_lock .
2005-04-17 02:20:36 +04:00
*/
2017-10-11 20:48:55 +03:00
static void __put_super ( struct super_block * s )
2005-04-17 02:20:36 +04:00
{
2017-10-11 20:48:55 +03:00
if ( ! - - s - > s_count ) {
list_del_init ( & s - > s_list ) ;
WARN_ON ( s - > s_dentry_lru . node ) ;
WARN_ON ( s - > s_inode_lru . node ) ;
WARN_ON ( ! list_empty ( & s - > s_mounts ) ) ;
security_sb_free ( s ) ;
fscrypt: add FS_IOC_ADD_ENCRYPTION_KEY ioctl
Add a new fscrypt ioctl, FS_IOC_ADD_ENCRYPTION_KEY. This ioctl adds an
encryption key to the filesystem's fscrypt keyring ->s_master_keys,
making any files encrypted with that key appear "unlocked".
Why we need this
~~~~~~~~~~~~~~~~
The main problem is that the "locked/unlocked" (ciphertext/plaintext)
status of encrypted files is global, but the fscrypt keys are not.
fscrypt only looks for keys in the keyring(s) the process accessing the
filesystem is subscribed to: the thread keyring, process keyring, and
session keyring, where the session keyring may contain the user keyring.
Therefore, userspace has to put fscrypt keys in the keyrings for
individual users or sessions. But this means that when a process with a
different keyring tries to access encrypted files, whether they appear
"unlocked" or not is nondeterministic. This is because it depends on
whether the files are currently present in the inode cache.
Fixing this by consistently providing each process its own view of the
filesystem depending on whether it has the key or not isn't feasible due
to how the VFS caches work. Furthermore, while sometimes users expect
this behavior, it is misguided for two reasons. First, it would be an
OS-level access control mechanism largely redundant with existing access
control mechanisms such as UNIX file permissions, ACLs, LSMs, etc.
Encryption is actually for protecting the data at rest.
Second, almost all users of fscrypt actually do need the keys to be
global. The largest users of fscrypt, Android and Chromium OS, achieve
this by having PID 1 create a "session keyring" that is inherited by
every process. This works, but it isn't scalable because it prevents
session keyrings from being used for any other purpose.
On general-purpose Linux distros, the 'fscrypt' userspace tool [1] can't
similarly abuse the session keyring, so to make 'sudo' work on all
systems it has to link all the user keyrings into root's user keyring
[2]. This is ugly and raises security concerns. Moreover it can't make
the keys available to system services, such as sshd trying to access the
user's '~/.ssh' directory (see [3], [4]) or NetworkManager trying to
read certificates from the user's home directory (see [5]); or to Docker
containers (see [6], [7]).
By having an API to add a key to the *filesystem* we'll be able to fix
the above bugs, remove userspace workarounds, and clearly express the
intended semantics: the locked/unlocked status of an encrypted directory
is global, and encryption is orthogonal to OS-level access control.
Why not use the add_key() syscall
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We use an ioctl for this API rather than the existing add_key() system
call because the ioctl gives us the flexibility needed to implement
fscrypt-specific semantics that will be introduced in later patches:
- Supporting key removal with the semantics such that the secret is
removed immediately and any unused inodes using the key are evicted;
also, the eviction of any in-use inodes can be retried.
- Calculating a key-dependent cryptographic identifier and returning it
to userspace.
- Allowing keys to be added and removed by non-root users, but only keys
for v2 encryption policies; and to prevent denial-of-service attacks,
users can only remove keys they themselves have added, and a key is
only really removed after all users who added it have removed it.
Trying to shoehorn these semantics into the keyrings syscalls would be
very difficult, whereas the ioctls make things much easier.
However, to reuse code the implementation still uses the keyrings
service internally. Thus we get lockless RCU-mode key lookups without
having to re-implement it, and the keys automatically show up in
/proc/keys for debugging purposes.
References:
[1] https://github.com/google/fscrypt
[2] https://goo.gl/55cCrI#heading=h.vf09isp98isb
[3] https://github.com/google/fscrypt/issues/111#issuecomment-444347939
[4] https://github.com/google/fscrypt/issues/116
[5] https://bugs.launchpad.net/ubuntu/+source/fscrypt/+bug/1770715
[6] https://github.com/google/fscrypt/issues/128
[7] https://askubuntu.com/questions/1130306/cannot-run-docker-on-an-encrypted-filesystem
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Eric Biggers <ebiggers@google.com>
2019-08-05 05:35:46 +03:00
fscrypt_sb_free ( s ) ;
2017-10-11 20:48:55 +03:00
put_user_ns ( s - > s_user_ns ) ;
kfree ( s - > s_subtype ) ;
call_rcu ( & s - > rcu , destroy_super_rcu ) ;
2005-04-17 02:20:36 +04:00
}
}
/**
* put_super - drop a temporary reference to superblock
* @ sb : superblock in question
*
* Drops a temporary reference , frees superblock if there ' s no
* references left .
*/
2020-11-16 17:21:18 +03:00
void put_super ( struct super_block * sb )
2005-04-17 02:20:36 +04:00
{
spin_lock ( & sb_lock ) ;
__put_super ( sb ) ;
spin_unlock ( & sb_lock ) ;
}
/**
2010-03-22 22:22:31 +03:00
* deactivate_locked_super - drop an active reference to superblock
2005-04-17 02:20:36 +04:00
* @ s : superblock to deactivate
*
2016-02-02 16:31:06 +03:00
* Drops an active reference to superblock , converting it into a temporary
2010-03-22 22:22:31 +03:00
* one if there is no other active references left . In that case we
2005-04-17 02:20:36 +04:00
* tell fs driver to shut it down and drop the temporary reference we
* had just acquired .
2010-03-22 22:22:31 +03:00
*
* Caller holds exclusive lock on superblock ; that lock is released .
2005-04-17 02:20:36 +04:00
*/
2010-03-22 22:22:31 +03:00
void deactivate_locked_super ( struct super_block * s )
2005-04-17 02:20:36 +04:00
{
struct file_system_type * fs = s - > s_type ;
2010-03-22 15:53:19 +03:00
if ( atomic_dec_and_test ( & s - > s_active ) ) {
2011-09-21 19:56:28 +04:00
cleancache_invalidate_fs ( s ) ;
2011-07-08 08:14:42 +04:00
unregister_shrinker ( & s - > s_shrink ) ;
2014-06-05 03:10:46 +04:00
fs - > kill_sb ( s ) ;
2013-08-28 04:18:18 +04:00
2015-02-13 01:59:07 +03:00
/*
* Since list_lru_destroy ( ) may sleep , we cannot call it from
* put_super ( ) , where we hold the sb_lock . Therefore we destroy
* the lru lists right now .
*/
list_lru_destroy ( & s - > s_dentry_lru ) ;
list_lru_destroy ( & s - > s_inode_lru ) ;
2005-04-17 02:20:36 +04:00
put_filesystem ( fs ) ;
put_super ( s ) ;
2010-03-22 22:22:31 +03:00
} else {
up_write ( & s - > s_umount ) ;
2005-04-17 02:20:36 +04:00
}
}
2010-03-22 22:22:31 +03:00
EXPORT_SYMBOL ( deactivate_locked_super ) ;
2005-04-17 02:20:36 +04:00
2009-05-06 09:07:50 +04:00
/**
2010-03-22 22:22:31 +03:00
* deactivate_super - drop an active reference to superblock
2009-05-06 09:07:50 +04:00
* @ s : superblock to deactivate
*
2010-03-22 22:22:31 +03:00
* Variant of deactivate_locked_super ( ) , except that superblock is * not *
* locked by caller . If we are going to drop the final active reference ,
* lock will be acquired prior to that .
2009-05-06 09:07:50 +04:00
*/
2010-03-22 22:22:31 +03:00
void deactivate_super ( struct super_block * s )
2009-05-06 09:07:50 +04:00
{
2020-03-05 11:06:39 +03:00
if ( ! atomic_add_unless ( & s - > s_active , - 1 , 1 ) ) {
2010-03-22 22:22:31 +03:00
down_write ( & s - > s_umount ) ;
deactivate_locked_super ( s ) ;
2009-05-06 09:07:50 +04:00
}
}
2010-03-22 22:22:31 +03:00
EXPORT_SYMBOL ( deactivate_super ) ;
2009-05-06 09:07:50 +04:00
2005-04-17 02:20:36 +04:00
/**
* grab_super - acquire an active reference
* @ s : reference we are trying to make active
*
* Tries to acquire an active reference . grab_super ( ) is used when we
* had just found a superblock in super_blocks or fs_type - > fs_supers
* and want to turn it into a full - blown active reference . grab_super ( )
* is called with sb_lock held and drops it . Returns 1 in case of
* success , 0 if we had failed ( superblock contents was already dead or
livelock avoidance in sget()
Eric Sandeen has found a nasty livelock in sget() - take a mount(2) about
to fail. The superblock is on ->fs_supers, ->s_umount is held exclusive,
->s_active is 1. Along comes two more processes, trying to mount the same
thing; sget() in each is picking that superblock, bumping ->s_count and
trying to grab ->s_umount. ->s_active is 3 now. Original mount(2)
finally gets to deactivate_locked_super() on failure; ->s_active is 2,
superblock is still ->fs_supers because shutdown will *not* happen until
->s_active hits 0. ->s_umount is dropped and now we have two processes
chasing each other:
s_active = 2, A acquired ->s_umount, B blocked
A sees that the damn thing is stillborn, does deactivate_locked_super()
s_active = 1, A drops ->s_umount, B gets it
A restarts the search and finds the same superblock. And bumps it ->s_active.
s_active = 2, B holds ->s_umount, A blocked on trying to get it
... and we are in the earlier situation with A and B switched places.
The root cause, of course, is that ->s_active should not grow until we'd
got MS_BORN. Then failing ->mount() will have deactivate_locked_super()
shut the damn thing down. Fortunately, it's easy to do - the key point
is that grab_super() is called only for superblocks currently on ->fs_supers,
so it can bump ->s_count and grab ->s_umount first, then check MS_BORN and
bump ->s_active; we must never increment ->s_count for superblocks past
->kill_sb(), but grab_super() is never called for those.
The bug is pretty old; we would've caught it by now, if not for accidental
exclusion between sget() for block filesystems; the things like cgroup or
e.g. mtd-based filesystems don't have anything of that sort, so they get
bitten. The right way to deal with that is obviously to fix sget()...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-07-20 03:13:55 +04:00
* dying when grab_super ( ) had been called ) . Note that this is only
* called for superblocks not in rundown mode ( = = ones still on - > fs_supers
* of their type ) , so increment of - > s_count is OK here .
2005-04-17 02:20:36 +04:00
*/
2006-09-29 12:59:29 +04:00
static int grab_super ( struct super_block * s ) __releases ( sb_lock )
2005-04-17 02:20:36 +04:00
{
s - > s_count + + ;
spin_unlock ( & sb_lock ) ;
down_write ( & s - > s_umount ) ;
2017-07-17 10:45:35 +03:00
if ( ( s - > s_flags & SB_BORN ) & & atomic_inc_not_zero ( & s - > s_active ) ) {
livelock avoidance in sget()
Eric Sandeen has found a nasty livelock in sget() - take a mount(2) about
to fail. The superblock is on ->fs_supers, ->s_umount is held exclusive,
->s_active is 1. Along comes two more processes, trying to mount the same
thing; sget() in each is picking that superblock, bumping ->s_count and
trying to grab ->s_umount. ->s_active is 3 now. Original mount(2)
finally gets to deactivate_locked_super() on failure; ->s_active is 2,
superblock is still ->fs_supers because shutdown will *not* happen until
->s_active hits 0. ->s_umount is dropped and now we have two processes
chasing each other:
s_active = 2, A acquired ->s_umount, B blocked
A sees that the damn thing is stillborn, does deactivate_locked_super()
s_active = 1, A drops ->s_umount, B gets it
A restarts the search and finds the same superblock. And bumps it ->s_active.
s_active = 2, B holds ->s_umount, A blocked on trying to get it
... and we are in the earlier situation with A and B switched places.
The root cause, of course, is that ->s_active should not grow until we'd
got MS_BORN. Then failing ->mount() will have deactivate_locked_super()
shut the damn thing down. Fortunately, it's easy to do - the key point
is that grab_super() is called only for superblocks currently on ->fs_supers,
so it can bump ->s_count and grab ->s_umount first, then check MS_BORN and
bump ->s_active; we must never increment ->s_count for superblocks past
->kill_sb(), but grab_super() is never called for those.
The bug is pretty old; we would've caught it by now, if not for accidental
exclusion between sget() for block filesystems; the things like cgroup or
e.g. mtd-based filesystems don't have anything of that sort, so they get
bitten. The right way to deal with that is obviously to fix sget()...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-07-20 03:13:55 +04:00
put_super ( s ) ;
return 1 ;
}
2005-04-17 02:20:36 +04:00
up_write ( & s - > s_umount ) ;
put_super ( s ) ;
return 0 ;
}
2011-07-08 08:14:41 +04:00
/*
2015-02-19 20:19:35 +03:00
* trylock_super - try to grab - > s_umount shared
2012-06-09 07:10:55 +04:00
* @ sb : reference we are trying to grab
2011-07-08 08:14:41 +04:00
*
2015-02-19 20:19:35 +03:00
* Try to prevent fs shutdown . This is used in places where we
2011-07-08 08:14:41 +04:00
* cannot take an active reference but we need to ensure that the
2015-02-19 20:19:35 +03:00
* filesystem is not shut down while we are working on it . It returns
* false if we cannot acquire s_umount or if we lose the race and
* filesystem already got into shutdown , and returns true with the s_umount
* lock held in read mode in case of success . On successful return ,
* the caller must drop the s_umount lock when done .
*
* Note that unlike get_super ( ) et . al . this one does * not * bump - > s_count .
* The reason why it ' s safe is that we are OK with doing trylock instead
* of down_read ( ) . There ' s a couple of places that are OK with that , but
* it ' s very much not a general - purpose interface .
2011-07-08 08:14:41 +04:00
*/
2015-02-19 20:19:35 +03:00
bool trylock_super ( struct super_block * sb )
2011-07-08 08:14:41 +04:00
{
if ( down_read_trylock ( & sb - > s_umount ) ) {
2015-02-19 20:19:35 +03:00
if ( ! hlist_unhashed ( & sb - > s_instances ) & &
2017-07-17 10:45:35 +03:00
sb - > s_root & & ( sb - > s_flags & SB_BORN ) )
2011-07-08 08:14:41 +04:00
return true ;
up_read ( & sb - > s_umount ) ;
}
return false ;
}
2005-04-17 02:20:36 +04:00
/**
* generic_shutdown_super - common helper for - > kill_sb ( )
* @ sb : superblock to kill
*
* generic_shutdown_super ( ) does all fs - independent work on superblock
* shutdown . Typical - > kill_sb ( ) should pick all fs - specific objects
* that need destruction out of superblock , call generic_shutdown_super ( )
* and release aforementioned objects . Note : dentries and inodes _are_
* taken care of and do not need specific handling .
2006-10-11 12:22:19 +04:00
*
* Upon calling this function , the filesystem may no longer alter or
* rearrange the set of dentries belonging to this super_block , nor may it
* change the attachments of dentries to inodes .
2005-04-17 02:20:36 +04:00
*/
void generic_shutdown_super ( struct super_block * sb )
{
2007-02-12 11:55:41 +03:00
const struct super_operations * sop = sb - > s_op ;
2005-04-17 02:20:36 +04:00
2006-10-11 12:22:19 +04:00
if ( sb - > s_root ) {
shrink_dcache_for_umount ( sb ) ;
2009-04-27 18:43:53 +04:00
sync_filesystem ( sb ) ;
2017-07-17 10:45:35 +03:00
sb - > s_flags & = ~ SB_ACTIVE ;
2009-01-06 18:20:54 +03:00
2016-03-01 02:28:53 +03:00
cgroup_writeback_umount ( ) ;
2010-10-26 04:49:35 +04:00
2019-12-06 19:55:59 +03:00
/* evict all inodes with zero refcount */
2010-10-26 04:49:35 +04:00
evict_inodes ( sb ) ;
2019-12-06 19:55:59 +03:00
/* only nonzero refcount inodes can have marks */
fsnotify_sb_delete ( sb ) ;
2021-04-22 18:41:16 +03:00
security_sb_delete ( sb ) ;
2005-04-17 02:20:36 +04:00
2013-09-04 17:04:39 +04:00
if ( sb - > s_dio_done_wq ) {
destroy_workqueue ( sb - > s_dio_done_wq ) ;
sb - > s_dio_done_wq = NULL ;
}
2005-04-17 02:20:36 +04:00
if ( sop - > put_super )
sop - > put_super ( sb ) ;
2010-10-26 04:49:35 +04:00
if ( ! list_empty ( & sb - > s_inodes ) ) {
2006-02-07 23:58:48 +03:00
printk ( " VFS: Busy inodes after unmount of %s. "
" Self-destruct in 5 seconds. Have a nice day... \n " ,
sb - > s_id ) ;
2005-04-17 02:20:36 +04:00
}
}
spin_lock ( & sb_lock ) ;
/* should be initialized for __put_super_and_need_restart() */
2011-12-13 07:53:00 +04:00
hlist_del_init ( & sb - > s_instances ) ;
2005-04-17 02:20:36 +04:00
spin_unlock ( & sb_lock ) ;
up_write ( & sb - > s_umount ) ;
2017-04-12 13:24:47 +03:00
if ( sb - > s_bdi ! = & noop_backing_dev_info ) {
2021-11-05 23:36:58 +03:00
if ( sb - > s_iflags & SB_I_PERSB_BDI )
bdi_unregister ( sb - > s_bdi ) ;
2017-04-12 13:24:28 +03:00
bdi_put ( sb - > s_bdi ) ;
sb - > s_bdi = & noop_backing_dev_info ;
}
2005-04-17 02:20:36 +04:00
}
EXPORT_SYMBOL ( generic_shutdown_super ) ;
2019-05-13 00:31:45 +03:00
bool mount_capable ( struct fs_context * fc )
2019-05-12 22:42:48 +03:00
{
2019-05-13 00:31:45 +03:00
if ( ! ( fc - > fs_type - > fs_flags & FS_USERNS_MOUNT ) )
2019-05-12 22:42:48 +03:00
return capable ( CAP_SYS_ADMIN ) ;
else
2019-07-27 15:29:57 +03:00
return ns_capable ( fc - > user_ns , CAP_SYS_ADMIN ) ;
2019-05-12 22:42:48 +03:00
}
2018-12-24 01:25:47 +03:00
/**
* sget_fc - Find or create a superblock
* @ fc : Filesystem context .
* @ test : Comparison callback
* @ set : Setup callback
*
* Find or create a superblock using the parameters stored in the filesystem
* context and the two callback functions .
*
* If an extant superblock is matched , then that will be returned with an
* elevated reference count that the caller must transfer or discard .
*
* If no match is made , a new superblock will be allocated and basic
* initialisation will be performed ( s_type , s_fs_info and s_id will be set and
* the set ( ) callback will be invoked ) , the superblock will be published and it
* will be returned in a partially constructed state with SB_BORN and SB_ACTIVE
* as yet unset .
*/
struct super_block * sget_fc ( struct fs_context * fc ,
int ( * test ) ( struct super_block * , struct fs_context * ) ,
int ( * set ) ( struct super_block * , struct fs_context * ) )
{
struct super_block * s = NULL ;
struct super_block * old ;
struct user_namespace * user_ns = fc - > global ? & init_user_ns : fc - > user_ns ;
int err ;
retry :
spin_lock ( & sb_lock ) ;
if ( test ) {
hlist_for_each_entry ( old , & fc - > fs_type - > fs_supers , s_instances ) {
if ( test ( old , fc ) )
goto share_extant_sb ;
}
}
if ( ! s ) {
spin_unlock ( & sb_lock ) ;
s = alloc_super ( fc - > fs_type , fc - > sb_flags , user_ns ) ;
if ( ! s )
return ERR_PTR ( - ENOMEM ) ;
goto retry ;
}
s - > s_fs_info = fc - > s_fs_info ;
err = set ( s , fc ) ;
if ( err ) {
s - > s_fs_info = NULL ;
spin_unlock ( & sb_lock ) ;
destroy_unused_super ( s ) ;
return ERR_PTR ( err ) ;
}
fc - > s_fs_info = NULL ;
s - > s_type = fc - > fs_type ;
2019-03-25 19:38:23 +03:00
s - > s_iflags | = fc - > s_iflags ;
2018-12-24 01:25:47 +03:00
strlcpy ( s - > s_id , s - > s_type - > name , sizeof ( s - > s_id ) ) ;
list_add_tail ( & s - > s_list , & super_blocks ) ;
hlist_add_head ( & s - > s_instances , & s - > s_type - > fs_supers ) ;
spin_unlock ( & sb_lock ) ;
get_filesystem ( s - > s_type ) ;
register_shrinker_prepared ( & s - > s_shrink ) ;
return s ;
share_extant_sb :
if ( user_ns ! = old - > s_user_ns ) {
spin_unlock ( & sb_lock ) ;
destroy_unused_super ( s ) ;
return ERR_PTR ( - EBUSY ) ;
}
if ( ! grab_super ( old ) )
goto retry ;
destroy_unused_super ( s ) ;
return old ;
}
EXPORT_SYMBOL ( sget_fc ) ;
2005-04-17 02:20:36 +04:00
/**
2019-03-25 19:38:28 +03:00
* sget - find or create a superblock
* @ type : filesystem type superblock should belong to
* @ test : comparison callback
* @ set : setup callback
* @ flags : mount flags
* @ data : argument to each of them
2005-04-17 02:20:36 +04:00
*/
2019-03-25 19:38:28 +03:00
struct super_block * sget ( struct file_system_type * type ,
2005-04-17 02:20:36 +04:00
int ( * test ) ( struct super_block * , void * ) ,
int ( * set ) ( struct super_block * , void * ) ,
2019-03-25 19:38:28 +03:00
int flags ,
2005-04-17 02:20:36 +04:00
void * data )
{
2019-03-25 19:38:28 +03:00
struct user_namespace * user_ns = current_user_ns ( ) ;
2005-04-17 02:20:36 +04:00
struct super_block * s = NULL ;
2007-10-19 10:39:57 +04:00
struct super_block * old ;
2005-04-17 02:20:36 +04:00
int err ;
2019-03-25 19:38:28 +03:00
/* We don't yet pass the user namespace of the parent
* mount through to here so always use & init_user_ns
* until that changes .
*/
if ( flags & SB_SUBMOUNT )
user_ns = & init_user_ns ;
2005-04-17 02:20:36 +04:00
retry :
spin_lock ( & sb_lock ) ;
2007-10-19 10:39:57 +04:00
if ( test ) {
hlist: drop the node parameter from iterators
I'm not sure why, but the hlist for each entry iterators were conceived
list_for_each_entry(pos, head, member)
The hlist ones were greedy and wanted an extra parameter:
hlist_for_each_entry(tpos, pos, head, member)
Why did they need an extra pos parameter? I'm not quite sure. Not only
they don't really need it, it also prevents the iterator from looking
exactly like the list iterator, which is unfortunate.
Besides the semantic patch, there was some manual work required:
- Fix up the actual hlist iterators in linux/list.h
- Fix up the declaration of other iterators based on the hlist ones.
- A very small amount of places were using the 'node' parameter, this
was modified to use 'obj->member' instead.
- Coccinelle didn't handle the hlist_for_each_entry_safe iterator
properly, so those had to be fixed up manually.
The semantic patch which is mostly the work of Peter Senna Tschudin is here:
@@
iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host;
type T;
expression a,c,d,e;
identifier b;
statement S;
@@
-T b;
<+... when != b
(
hlist_for_each_entry(a,
- b,
c, d) S
|
hlist_for_each_entry_continue(a,
- b,
c) S
|
hlist_for_each_entry_from(a,
- b,
c) S
|
hlist_for_each_entry_rcu(a,
- b,
c, d) S
|
hlist_for_each_entry_rcu_bh(a,
- b,
c, d) S
|
hlist_for_each_entry_continue_rcu_bh(a,
- b,
c) S
|
for_each_busy_worker(a, c,
- b,
d) S
|
ax25_uid_for_each(a,
- b,
c) S
|
ax25_for_each(a,
- b,
c) S
|
inet_bind_bucket_for_each(a,
- b,
c) S
|
sctp_for_each_hentry(a,
- b,
c) S
|
sk_for_each(a,
- b,
c) S
|
sk_for_each_rcu(a,
- b,
c) S
|
sk_for_each_from
-(a, b)
+(a)
S
+ sk_for_each_from(a) S
|
sk_for_each_safe(a,
- b,
c, d) S
|
sk_for_each_bound(a,
- b,
c) S
|
hlist_for_each_entry_safe(a,
- b,
c, d, e) S
|
hlist_for_each_entry_continue_rcu(a,
- b,
c) S
|
nr_neigh_for_each(a,
- b,
c) S
|
nr_neigh_for_each_safe(a,
- b,
c, d) S
|
nr_node_for_each(a,
- b,
c) S
|
nr_node_for_each_safe(a,
- b,
c, d) S
|
- for_each_gfn_sp(a, c, d, b) S
+ for_each_gfn_sp(a, c, d) S
|
- for_each_gfn_indirect_valid_sp(a, c, d, b) S
+ for_each_gfn_indirect_valid_sp(a, c, d) S
|
for_each_host(a,
- b,
c) S
|
for_each_host_safe(a,
- b,
c, d) S
|
for_each_mesh_entry(a,
- b,
c, d) S
)
...+>
[akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c]
[akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c]
[akpm@linux-foundation.org: checkpatch fixes]
[akpm@linux-foundation.org: fix warnings]
[akpm@linux-foudnation.org: redo intrusive kvm changes]
Tested-by: Peter Senna Tschudin <peter.senna@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-28 05:06:00 +04:00
hlist_for_each_entry ( old , & type - > fs_supers , s_instances ) {
2007-10-19 10:39:57 +04:00
if ( ! test ( old , data ) )
continue ;
2016-05-24 17:29:01 +03:00
if ( user_ns ! = old - > s_user_ns ) {
spin_unlock ( & sb_lock ) ;
2017-10-11 20:48:55 +03:00
destroy_unused_super ( s ) ;
2016-05-24 17:29:01 +03:00
return ERR_PTR ( - EBUSY ) ;
}
2007-10-19 10:39:57 +04:00
if ( ! grab_super ( old ) )
goto retry ;
2017-10-11 20:48:55 +03:00
destroy_unused_super ( s ) ;
2007-10-19 10:39:57 +04:00
return old ;
}
2005-04-17 02:20:36 +04:00
}
if ( ! s ) {
spin_unlock ( & sb_lock ) ;
2017-07-17 10:45:35 +03:00
s = alloc_super ( type , ( flags & ~ SB_SUBMOUNT ) , user_ns ) ;
2005-04-17 02:20:36 +04:00
if ( ! s )
return ERR_PTR ( - ENOMEM ) ;
goto retry ;
}
2017-07-04 19:25:09 +03:00
2005-04-17 02:20:36 +04:00
err = set ( s , data ) ;
if ( err ) {
spin_unlock ( & sb_lock ) ;
2017-10-11 20:48:55 +03:00
destroy_unused_super ( s ) ;
2005-04-17 02:20:36 +04:00
return ERR_PTR ( err ) ;
}
s - > s_type = type ;
strlcpy ( s - > s_id , type - > name , sizeof ( s - > s_id ) ) ;
list_add_tail ( & s - > s_list , & super_blocks ) ;
2011-12-13 07:53:00 +04:00
hlist_add_head ( & s - > s_instances , & type - > fs_supers ) ;
2005-04-17 02:20:36 +04:00
spin_unlock ( & sb_lock ) ;
get_filesystem ( type ) ;
2018-04-04 13:53:07 +03:00
register_shrinker_prepared ( & s - > s_shrink ) ;
2005-04-17 02:20:36 +04:00
return s ;
}
EXPORT_SYMBOL ( sget ) ;
void drop_super ( struct super_block * sb )
{
up_read ( & sb - > s_umount ) ;
put_super ( sb ) ;
}
EXPORT_SYMBOL ( drop_super ) ;
2016-11-23 14:53:00 +03:00
void drop_super_exclusive ( struct super_block * sb )
{
up_write ( & sb - > s_umount ) ;
put_super ( sb ) ;
}
EXPORT_SYMBOL ( drop_super_exclusive ) ;
2017-10-03 19:17:40 +03:00
static void __iterate_supers ( void ( * f ) ( struct super_block * ) )
{
struct super_block * sb , * p = NULL ;
spin_lock ( & sb_lock ) ;
list_for_each_entry ( sb , & super_blocks , s_list ) {
if ( hlist_unhashed ( & sb - > s_instances ) )
continue ;
sb - > s_count + + ;
spin_unlock ( & sb_lock ) ;
f ( sb ) ;
spin_lock ( & sb_lock ) ;
if ( p )
__put_super ( p ) ;
p = sb ;
}
if ( p )
__put_super ( p ) ;
spin_unlock ( & sb_lock ) ;
}
2010-03-23 13:06:58 +03:00
/**
* iterate_supers - call function for all active superblocks
* @ f : function to call
* @ arg : argument to pass to it
*
* Scans the superblock list and calls given function , passing it
* locked superblock and given argument .
*/
void iterate_supers ( void ( * f ) ( struct super_block * , void * ) , void * arg )
{
2010-07-25 02:31:46 +04:00
struct super_block * sb , * p = NULL ;
2010-03-23 13:06:58 +03:00
spin_lock ( & sb_lock ) ;
2010-07-25 02:31:46 +04:00
list_for_each_entry ( sb , & super_blocks , s_list ) {
2011-12-13 07:53:00 +04:00
if ( hlist_unhashed ( & sb - > s_instances ) )
2010-03-23 13:06:58 +03:00
continue ;
sb - > s_count + + ;
spin_unlock ( & sb_lock ) ;
down_read ( & sb - > s_umount ) ;
2017-07-17 10:45:35 +03:00
if ( sb - > s_root & & ( sb - > s_flags & SB_BORN ) )
2010-03-23 13:06:58 +03:00
f ( sb , arg ) ;
up_read ( & sb - > s_umount ) ;
spin_lock ( & sb_lock ) ;
2010-07-25 02:31:46 +04:00
if ( p )
__put_super ( p ) ;
p = sb ;
2010-03-23 13:06:58 +03:00
}
2010-07-25 02:31:46 +04:00
if ( p )
__put_super ( p ) ;
2010-03-23 13:06:58 +03:00
spin_unlock ( & sb_lock ) ;
}
2011-06-04 04:16:57 +04:00
/**
* iterate_supers_type - call function for superblocks of given type
* @ type : fs type
* @ f : function to call
* @ arg : argument to pass to it
*
* Scans the superblock list and calls given function , passing it
* locked superblock and given argument .
*/
void iterate_supers_type ( struct file_system_type * type ,
void ( * f ) ( struct super_block * , void * ) , void * arg )
{
struct super_block * sb , * p = NULL ;
spin_lock ( & sb_lock ) ;
hlist: drop the node parameter from iterators
I'm not sure why, but the hlist for each entry iterators were conceived
list_for_each_entry(pos, head, member)
The hlist ones were greedy and wanted an extra parameter:
hlist_for_each_entry(tpos, pos, head, member)
Why did they need an extra pos parameter? I'm not quite sure. Not only
they don't really need it, it also prevents the iterator from looking
exactly like the list iterator, which is unfortunate.
Besides the semantic patch, there was some manual work required:
- Fix up the actual hlist iterators in linux/list.h
- Fix up the declaration of other iterators based on the hlist ones.
- A very small amount of places were using the 'node' parameter, this
was modified to use 'obj->member' instead.
- Coccinelle didn't handle the hlist_for_each_entry_safe iterator
properly, so those had to be fixed up manually.
The semantic patch which is mostly the work of Peter Senna Tschudin is here:
@@
iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host;
type T;
expression a,c,d,e;
identifier b;
statement S;
@@
-T b;
<+... when != b
(
hlist_for_each_entry(a,
- b,
c, d) S
|
hlist_for_each_entry_continue(a,
- b,
c) S
|
hlist_for_each_entry_from(a,
- b,
c) S
|
hlist_for_each_entry_rcu(a,
- b,
c, d) S
|
hlist_for_each_entry_rcu_bh(a,
- b,
c, d) S
|
hlist_for_each_entry_continue_rcu_bh(a,
- b,
c) S
|
for_each_busy_worker(a, c,
- b,
d) S
|
ax25_uid_for_each(a,
- b,
c) S
|
ax25_for_each(a,
- b,
c) S
|
inet_bind_bucket_for_each(a,
- b,
c) S
|
sctp_for_each_hentry(a,
- b,
c) S
|
sk_for_each(a,
- b,
c) S
|
sk_for_each_rcu(a,
- b,
c) S
|
sk_for_each_from
-(a, b)
+(a)
S
+ sk_for_each_from(a) S
|
sk_for_each_safe(a,
- b,
c, d) S
|
sk_for_each_bound(a,
- b,
c) S
|
hlist_for_each_entry_safe(a,
- b,
c, d, e) S
|
hlist_for_each_entry_continue_rcu(a,
- b,
c) S
|
nr_neigh_for_each(a,
- b,
c) S
|
nr_neigh_for_each_safe(a,
- b,
c, d) S
|
nr_node_for_each(a,
- b,
c) S
|
nr_node_for_each_safe(a,
- b,
c, d) S
|
- for_each_gfn_sp(a, c, d, b) S
+ for_each_gfn_sp(a, c, d) S
|
- for_each_gfn_indirect_valid_sp(a, c, d, b) S
+ for_each_gfn_indirect_valid_sp(a, c, d) S
|
for_each_host(a,
- b,
c) S
|
for_each_host_safe(a,
- b,
c, d) S
|
for_each_mesh_entry(a,
- b,
c, d) S
)
...+>
[akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c]
[akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c]
[akpm@linux-foundation.org: checkpatch fixes]
[akpm@linux-foundation.org: fix warnings]
[akpm@linux-foudnation.org: redo intrusive kvm changes]
Tested-by: Peter Senna Tschudin <peter.senna@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-28 05:06:00 +04:00
hlist_for_each_entry ( sb , & type - > fs_supers , s_instances ) {
2011-06-04 04:16:57 +04:00
sb - > s_count + + ;
spin_unlock ( & sb_lock ) ;
down_read ( & sb - > s_umount ) ;
2017-07-17 10:45:35 +03:00
if ( sb - > s_root & & ( sb - > s_flags & SB_BORN ) )
2011-06-04 04:16:57 +04:00
f ( sb , arg ) ;
up_read ( & sb - > s_umount ) ;
spin_lock ( & sb_lock ) ;
if ( p )
__put_super ( p ) ;
p = sb ;
}
if ( p )
__put_super ( p ) ;
spin_unlock ( & sb_lock ) ;
}
EXPORT_SYMBOL ( iterate_supers_type ) ;
2020-11-23 15:38:40 +03:00
/**
* get_super - get the superblock of a device
* @ bdev : device to get the superblock for
*
* Scans the superblock list and finds the superblock of the file system
* mounted on the device given . % NULL is returned if no match is found .
*/
struct super_block * get_super ( struct block_device * bdev )
2005-04-17 02:20:36 +04:00
{
2005-06-23 11:09:54 +04:00
struct super_block * sb ;
2005-04-17 02:20:36 +04:00
if ( ! bdev )
return NULL ;
2005-06-23 11:09:54 +04:00
2005-04-17 02:20:36 +04:00
spin_lock ( & sb_lock ) ;
2005-06-23 11:09:54 +04:00
rescan :
list_for_each_entry ( sb , & super_blocks , s_list ) {
2011-12-13 07:53:00 +04:00
if ( hlist_unhashed ( & sb - > s_instances ) )
2010-03-23 02:36:35 +03:00
continue ;
2005-06-23 11:09:54 +04:00
if ( sb - > s_bdev = = bdev ) {
sb - > s_count + + ;
2005-04-17 02:20:36 +04:00
spin_unlock ( & sb_lock ) ;
2020-11-23 15:38:40 +03:00
down_read ( & sb - > s_umount ) ;
2010-03-23 03:23:25 +03:00
/* still alive? */
2017-07-17 10:45:35 +03:00
if ( sb - > s_root & & ( sb - > s_flags & SB_BORN ) )
2005-06-23 11:09:54 +04:00
return sb ;
2020-11-23 15:38:40 +03:00
up_read ( & sb - > s_umount ) ;
2010-03-23 03:23:25 +03:00
/* nope, got unmounted */
2005-06-23 11:09:54 +04:00
spin_lock ( & sb_lock ) ;
2010-03-23 03:23:25 +03:00
__put_super ( sb ) ;
goto rescan ;
2005-04-17 02:20:36 +04:00
}
}
spin_unlock ( & sb_lock ) ;
return NULL ;
}
2009-08-04 01:28:35 +04:00
/**
* get_active_super - get an active reference to the superblock of a device
* @ bdev : device to get the superblock for
*
* Scans the superblock list and finds the superblock of the file system
* mounted on the device given . Returns the superblock with an active
2010-03-23 18:11:05 +03:00
* reference or % NULL if none was found .
2009-08-04 01:28:35 +04:00
*/
struct super_block * get_active_super ( struct block_device * bdev )
{
struct super_block * sb ;
if ( ! bdev )
return NULL ;
2010-03-23 03:15:33 +03:00
restart :
2009-08-04 01:28:35 +04:00
spin_lock ( & sb_lock ) ;
list_for_each_entry ( sb , & super_blocks , s_list ) {
2011-12-13 07:53:00 +04:00
if ( hlist_unhashed ( & sb - > s_instances ) )
2010-03-23 02:36:35 +03:00
continue ;
2010-03-23 03:15:33 +03:00
if ( sb - > s_bdev = = bdev ) {
livelock avoidance in sget()
Eric Sandeen has found a nasty livelock in sget() - take a mount(2) about
to fail. The superblock is on ->fs_supers, ->s_umount is held exclusive,
->s_active is 1. Along comes two more processes, trying to mount the same
thing; sget() in each is picking that superblock, bumping ->s_count and
trying to grab ->s_umount. ->s_active is 3 now. Original mount(2)
finally gets to deactivate_locked_super() on failure; ->s_active is 2,
superblock is still ->fs_supers because shutdown will *not* happen until
->s_active hits 0. ->s_umount is dropped and now we have two processes
chasing each other:
s_active = 2, A acquired ->s_umount, B blocked
A sees that the damn thing is stillborn, does deactivate_locked_super()
s_active = 1, A drops ->s_umount, B gets it
A restarts the search and finds the same superblock. And bumps it ->s_active.
s_active = 2, B holds ->s_umount, A blocked on trying to get it
... and we are in the earlier situation with A and B switched places.
The root cause, of course, is that ->s_active should not grow until we'd
got MS_BORN. Then failing ->mount() will have deactivate_locked_super()
shut the damn thing down. Fortunately, it's easy to do - the key point
is that grab_super() is called only for superblocks currently on ->fs_supers,
so it can bump ->s_count and grab ->s_umount first, then check MS_BORN and
bump ->s_active; we must never increment ->s_count for superblocks past
->kill_sb(), but grab_super() is never called for those.
The bug is pretty old; we would've caught it by now, if not for accidental
exclusion between sget() for block filesystems; the things like cgroup or
e.g. mtd-based filesystems don't have anything of that sort, so they get
bitten. The right way to deal with that is obviously to fix sget()...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-07-20 03:13:55 +04:00
if ( ! grab_super ( sb ) )
2010-03-23 03:15:33 +03:00
goto restart ;
livelock avoidance in sget()
Eric Sandeen has found a nasty livelock in sget() - take a mount(2) about
to fail. The superblock is on ->fs_supers, ->s_umount is held exclusive,
->s_active is 1. Along comes two more processes, trying to mount the same
thing; sget() in each is picking that superblock, bumping ->s_count and
trying to grab ->s_umount. ->s_active is 3 now. Original mount(2)
finally gets to deactivate_locked_super() on failure; ->s_active is 2,
superblock is still ->fs_supers because shutdown will *not* happen until
->s_active hits 0. ->s_umount is dropped and now we have two processes
chasing each other:
s_active = 2, A acquired ->s_umount, B blocked
A sees that the damn thing is stillborn, does deactivate_locked_super()
s_active = 1, A drops ->s_umount, B gets it
A restarts the search and finds the same superblock. And bumps it ->s_active.
s_active = 2, B holds ->s_umount, A blocked on trying to get it
... and we are in the earlier situation with A and B switched places.
The root cause, of course, is that ->s_active should not grow until we'd
got MS_BORN. Then failing ->mount() will have deactivate_locked_super()
shut the damn thing down. Fortunately, it's easy to do - the key point
is that grab_super() is called only for superblocks currently on ->fs_supers,
so it can bump ->s_count and grab ->s_umount first, then check MS_BORN and
bump ->s_active; we must never increment ->s_count for superblocks past
->kill_sb(), but grab_super() is never called for those.
The bug is pretty old; we would've caught it by now, if not for accidental
exclusion between sget() for block filesystems; the things like cgroup or
e.g. mtd-based filesystems don't have anything of that sort, so they get
bitten. The right way to deal with that is obviously to fix sget()...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-07-20 03:13:55 +04:00
up_write ( & sb - > s_umount ) ;
return sb ;
2010-03-23 03:15:33 +03:00
}
2009-08-04 01:28:35 +04:00
}
spin_unlock ( & sb_lock ) ;
return NULL ;
}
2017-07-04 19:25:09 +03:00
2020-11-23 15:38:40 +03:00
struct super_block * user_get_super ( dev_t dev , bool excl )
2005-04-17 02:20:36 +04:00
{
2005-06-23 11:09:54 +04:00
struct super_block * sb ;
2005-04-17 02:20:36 +04:00
spin_lock ( & sb_lock ) ;
2005-06-23 11:09:54 +04:00
rescan :
list_for_each_entry ( sb , & super_blocks , s_list ) {
2011-12-13 07:53:00 +04:00
if ( hlist_unhashed ( & sb - > s_instances ) )
2010-03-23 02:36:35 +03:00
continue ;
2005-06-23 11:09:54 +04:00
if ( sb - > s_dev = = dev ) {
sb - > s_count + + ;
2005-04-17 02:20:36 +04:00
spin_unlock ( & sb_lock ) ;
2020-11-23 15:38:40 +03:00
if ( excl )
down_write ( & sb - > s_umount ) ;
else
down_read ( & sb - > s_umount ) ;
2010-03-23 03:23:25 +03:00
/* still alive? */
2017-07-17 10:45:35 +03:00
if ( sb - > s_root & & ( sb - > s_flags & SB_BORN ) )
2005-06-23 11:09:54 +04:00
return sb ;
2020-11-23 15:38:40 +03:00
if ( excl )
up_write ( & sb - > s_umount ) ;
else
up_read ( & sb - > s_umount ) ;
2010-03-23 03:23:25 +03:00
/* nope, got unmounted */
2005-06-23 11:09:54 +04:00
spin_lock ( & sb_lock ) ;
2010-03-23 03:23:25 +03:00
__put_super ( sb ) ;
goto rescan ;
2005-04-17 02:20:36 +04:00
}
}
spin_unlock ( & sb_lock ) ;
return NULL ;
}
/**
2018-11-04 17:28:36 +03:00
* reconfigure_super - asks filesystem to change superblock parameters
* @ fc : The superblock and configuration
2005-04-17 02:20:36 +04:00
*
2018-11-04 17:28:36 +03:00
* Alters the configuration parameters of a live superblock .
2005-04-17 02:20:36 +04:00
*/
2018-11-04 17:28:36 +03:00
int reconfigure_super ( struct fs_context * fc )
2005-04-17 02:20:36 +04:00
{
2018-11-04 17:28:36 +03:00
struct super_block * sb = fc - > root - > d_sb ;
2005-04-17 02:20:36 +04:00
int retval ;
2018-11-04 17:28:36 +03:00
bool remount_ro = false ;
bool force = fc - > sb_flags & SB_FORCE ;
2009-08-04 01:28:35 +04:00
2018-11-04 17:28:36 +03:00
if ( fc - > sb_flags_mask & ~ MS_RMT_MASK )
return - EINVAL ;
2012-06-12 18:20:34 +04:00
if ( sb - > s_writers . frozen ! = SB_UNFROZEN )
2009-08-04 01:28:35 +04:00
return - EBUSY ;
2018-11-04 17:28:36 +03:00
retval = security_sb_remount ( sb , fc - > security ) ;
if ( retval )
return retval ;
if ( fc - > sb_flags_mask & SB_RDONLY ) {
[PATCH] BLOCK: Make it possible to disable the block layer [try #6]
Make it possible to disable the block layer. Not all embedded devices require
it, some can make do with just JFFS2, NFS, ramfs, etc - none of which require
the block layer to be present.
This patch does the following:
(*) Introduces CONFIG_BLOCK to disable the block layer, buffering and blockdev
support.
(*) Adds dependencies on CONFIG_BLOCK to any configuration item that controls
an item that uses the block layer. This includes:
(*) Block I/O tracing.
(*) Disk partition code.
(*) All filesystems that are block based, eg: Ext3, ReiserFS, ISOFS.
(*) The SCSI layer. As far as I can tell, even SCSI chardevs use the
block layer to do scheduling. Some drivers that use SCSI facilities -
such as USB storage - end up disabled indirectly from this.
(*) Various block-based device drivers, such as IDE and the old CDROM
drivers.
(*) MTD blockdev handling and FTL.
(*) JFFS - which uses set_bdev_super(), something it could avoid doing by
taking a leaf out of JFFS2's book.
(*) Makes most of the contents of linux/blkdev.h, linux/buffer_head.h and
linux/elevator.h contingent on CONFIG_BLOCK being set. sector_div() is,
however, still used in places, and so is still available.
(*) Also made contingent are the contents of linux/mpage.h, linux/genhd.h and
parts of linux/fs.h.
(*) Makes a number of files in fs/ contingent on CONFIG_BLOCK.
(*) Makes mm/bounce.c (bounce buffering) contingent on CONFIG_BLOCK.
(*) set_page_dirty() doesn't call __set_page_dirty_buffers() if CONFIG_BLOCK
is not enabled.
(*) fs/no-block.c is created to hold out-of-line stubs and things that are
required when CONFIG_BLOCK is not set:
(*) Default blockdev file operations (to give error ENODEV on opening).
(*) Makes some /proc changes:
(*) /proc/devices does not list any blockdevs.
(*) /proc/diskstats and /proc/partitions are contingent on CONFIG_BLOCK.
(*) Makes some compat ioctl handling contingent on CONFIG_BLOCK.
(*) If CONFIG_BLOCK is not defined, makes sys_quotactl() return -ENODEV if
given command other than Q_SYNC or if a special device is specified.
(*) In init/do_mounts.c, no reference is made to the blockdev routines if
CONFIG_BLOCK is not defined. This does not prohibit NFS roots or JFFS2.
(*) The bdflush, ioprio_set and ioprio_get syscalls can now be absent (return
error ENOSYS by way of cond_syscall if so).
(*) The seclvl_bd_claim() and seclvl_bd_release() security calls do nothing if
CONFIG_BLOCK is not set, since they can't then happen.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2006-09-30 22:45:40 +04:00
# ifdef CONFIG_BLOCK
2021-01-09 13:42:50 +03:00
if ( ! ( fc - > sb_flags & SB_RDONLY ) & & sb - > s_bdev & &
bdev_read_only ( sb - > s_bdev ) )
2018-11-04 17:28:36 +03:00
return - EACCES ;
[PATCH] BLOCK: Make it possible to disable the block layer [try #6]
Make it possible to disable the block layer. Not all embedded devices require
it, some can make do with just JFFS2, NFS, ramfs, etc - none of which require
the block layer to be present.
This patch does the following:
(*) Introduces CONFIG_BLOCK to disable the block layer, buffering and blockdev
support.
(*) Adds dependencies on CONFIG_BLOCK to any configuration item that controls
an item that uses the block layer. This includes:
(*) Block I/O tracing.
(*) Disk partition code.
(*) All filesystems that are block based, eg: Ext3, ReiserFS, ISOFS.
(*) The SCSI layer. As far as I can tell, even SCSI chardevs use the
block layer to do scheduling. Some drivers that use SCSI facilities -
such as USB storage - end up disabled indirectly from this.
(*) Various block-based device drivers, such as IDE and the old CDROM
drivers.
(*) MTD blockdev handling and FTL.
(*) JFFS - which uses set_bdev_super(), something it could avoid doing by
taking a leaf out of JFFS2's book.
(*) Makes most of the contents of linux/blkdev.h, linux/buffer_head.h and
linux/elevator.h contingent on CONFIG_BLOCK being set. sector_div() is,
however, still used in places, and so is still available.
(*) Also made contingent are the contents of linux/mpage.h, linux/genhd.h and
parts of linux/fs.h.
(*) Makes a number of files in fs/ contingent on CONFIG_BLOCK.
(*) Makes mm/bounce.c (bounce buffering) contingent on CONFIG_BLOCK.
(*) set_page_dirty() doesn't call __set_page_dirty_buffers() if CONFIG_BLOCK
is not enabled.
(*) fs/no-block.c is created to hold out-of-line stubs and things that are
required when CONFIG_BLOCK is not set:
(*) Default blockdev file operations (to give error ENODEV on opening).
(*) Makes some /proc changes:
(*) /proc/devices does not list any blockdevs.
(*) /proc/diskstats and /proc/partitions are contingent on CONFIG_BLOCK.
(*) Makes some compat ioctl handling contingent on CONFIG_BLOCK.
(*) If CONFIG_BLOCK is not defined, makes sys_quotactl() return -ENODEV if
given command other than Q_SYNC or if a special device is specified.
(*) In init/do_mounts.c, no reference is made to the blockdev routines if
CONFIG_BLOCK is not defined. This does not prohibit NFS roots or JFFS2.
(*) The bdflush, ioprio_set and ioprio_get syscalls can now be absent (return
error ENOSYS by way of cond_syscall if so).
(*) The seclvl_bd_claim() and seclvl_bd_release() security calls do nothing if
CONFIG_BLOCK is not set, since they can't then happen.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2006-09-30 22:45:40 +04:00
# endif
2009-08-04 01:28:35 +04:00
2018-11-04 17:28:36 +03:00
remount_ro = ( fc - > sb_flags & SB_RDONLY ) & & ! sb_rdonly ( sb ) ;
}
2009-12-22 03:28:53 +03:00
2014-08-07 15:32:06 +04:00
if ( remount_ro ) {
2015-01-11 18:57:27 +03:00
if ( ! hlist_empty ( & sb - > s_pins ) ) {
2014-08-07 15:32:06 +04:00
up_write ( & sb - > s_umount ) ;
2015-01-11 18:57:27 +03:00
group_pin_kill ( & sb - > s_pins ) ;
2014-08-07 15:32:06 +04:00
down_write ( & sb - > s_umount ) ;
if ( ! sb - > s_root )
return 0 ;
if ( sb - > s_writers . frozen ! = SB_UNFROZEN )
return - EBUSY ;
2018-11-04 17:28:36 +03:00
remount_ro = ! sb_rdonly ( sb ) ;
2014-08-07 15:32:06 +04:00
}
}
shrink_dcache_sb ( sb ) ;
2018-11-04 17:28:36 +03:00
/* If we are reconfiguring to RDONLY and current sb is read/write,
* make sure there are no files open for writing .
*/
2009-12-22 03:28:53 +03:00
if ( remount_ro ) {
2011-11-21 15:11:31 +04:00
if ( force ) {
2013-10-04 19:06:42 +04:00
sb - > s_readonly_remount = 1 ;
smp_wmb ( ) ;
2011-11-21 15:11:31 +04:00
} else {
retval = sb_prepare_remount_readonly ( sb ) ;
if ( retval )
return retval ;
}
2005-04-17 02:20:36 +04:00
}
2018-12-24 02:55:56 +03:00
if ( fc - > ops - > reconfigure ) {
retval = fc - > ops - > reconfigure ( fc ) ;
if ( retval ) {
if ( ! force )
goto cancel_readonly ;
/* If forced remount, go ahead despite any errors */
WARN ( 1 , " forced remount of a %s fs returned %i \n " ,
sb - > s_type - > name , retval ) ;
}
2005-04-17 02:20:36 +04:00
}
2018-11-04 17:28:36 +03:00
WRITE_ONCE ( sb - > s_flags , ( ( sb - > s_flags & ~ fc - > sb_flags_mask ) |
( fc - > sb_flags & fc - > sb_flags_mask ) ) ) ;
2011-11-21 15:11:31 +04:00
/* Needs to be ordered wrt mnt_is_readonly() */
smp_wmb ( ) ;
sb - > s_readonly_remount = 0 ;
2010-05-19 15:16:40 +04:00
2009-12-22 03:28:53 +03:00
/*
* Some filesystems modify their metadata via some other path than the
* bdev buffer cache ( eg . use a private mapping , or directories in
* pagecache , etc ) . Also file data modifications go via their own
* mappings . So If we try to mount readonly then copy the filesystem
* from bdev , we could get stale data , so invalidate it to give a best
* effort at coherency .
*/
if ( remount_ro & & sb - > s_bdev )
invalidate_bdev ( sb - > s_bdev ) ;
2005-04-17 02:20:36 +04:00
return 0 ;
2011-11-21 15:11:31 +04:00
cancel_readonly :
sb - > s_readonly_remount = 0 ;
return retval ;
2005-04-17 02:20:36 +04:00
}
2017-10-03 19:17:40 +03:00
static void do_emergency_remount_callback ( struct super_block * sb )
2005-04-17 02:20:36 +04:00
{
2017-10-03 19:17:40 +03:00
down_write ( & sb - > s_umount ) ;
if ( sb - > s_root & & sb - > s_bdev & & ( sb - > s_flags & SB_BORN ) & &
! sb_rdonly ( sb ) ) {
2018-11-04 17:28:36 +03:00
struct fs_context * fc ;
fc = fs_context_for_reconfigure ( sb - > s_root ,
SB_RDONLY | SB_FORCE , SB_RDONLY ) ;
if ( ! IS_ERR ( fc ) ) {
if ( parse_monolithic_mount_data ( fc , NULL ) = = 0 )
( void ) reconfigure_super ( fc ) ;
put_fs_context ( fc ) ;
}
2005-04-17 02:20:36 +04:00
}
2017-10-03 19:17:40 +03:00
up_write ( & sb - > s_umount ) ;
}
static void do_emergency_remount ( struct work_struct * work )
{
__iterate_supers ( do_emergency_remount_callback ) ;
2009-03-17 11:38:40 +03:00
kfree ( work ) ;
2005-04-17 02:20:36 +04:00
printk ( " Emergency Remount complete \n " ) ;
}
void emergency_remount ( void )
{
2009-03-17 11:38:40 +03:00
struct work_struct * work ;
work = kmalloc ( sizeof ( * work ) , GFP_ATOMIC ) ;
if ( work ) {
INIT_WORK ( work , do_emergency_remount ) ;
schedule_work ( work ) ;
}
2005-04-17 02:20:36 +04:00
}
2017-10-03 19:17:41 +03:00
static void do_thaw_all_callback ( struct super_block * sb )
{
down_write ( & sb - > s_umount ) ;
2018-05-10 22:09:41 +03:00
if ( sb - > s_root & & sb - > s_flags & SB_BORN ) {
2017-10-03 19:17:41 +03:00
emergency_thaw_bdev ( sb ) ;
thaw_super_locked ( sb ) ;
} else {
up_write ( & sb - > s_umount ) ;
}
}
static void do_thaw_all ( struct work_struct * work )
{
__iterate_supers ( do_thaw_all_callback ) ;
kfree ( work ) ;
printk ( KERN_WARNING " Emergency Thaw complete \n " ) ;
}
/**
* emergency_thaw_all - - forcibly thaw every frozen filesystem
*
* Used for emergency unfreeze of all filesystems via SysRq
*/
void emergency_thaw_all ( void )
{
struct work_struct * work ;
work = kmalloc ( sizeof ( * work ) , GFP_ATOMIC ) ;
if ( work ) {
INIT_WORK ( work , do_thaw_all ) ;
schedule_work ( work ) ;
}
}
2008-08-28 06:26:23 +04:00
static DEFINE_IDA ( unnamed_dev_ida ) ;
2005-04-17 02:20:36 +04:00
2018-06-11 19:03:31 +03:00
/**
* get_anon_bdev - Allocate a block device for filesystems which don ' t have one .
* @ p : Pointer to a dev_t .
*
* Filesystems which don ' t use real block devices can call this function
* to allocate a virtual block device .
*
* Context : Any context . Frequently called while holding sb_lock .
* Return : 0 on success , - EMFILE if there are no anonymous bdevs left
* or - ENOMEM if memory allocation failed .
*/
2011-07-07 23:44:25 +04:00
int get_anon_bdev ( dev_t * p )
2005-04-17 02:20:36 +04:00
{
int dev ;
2018-06-11 19:03:31 +03:00
/*
* Many userspace utilities consider an FSID of 0 invalid .
* Always return at least 1 from get_anon_bdev .
*/
dev = ida_alloc_range ( & unnamed_dev_ida , 1 , ( 1 < < MINORBITS ) - 1 ,
GFP_ATOMIC ) ;
if ( dev = = - ENOSPC )
dev = - EMFILE ;
if ( dev < 0 )
return dev ;
* p = MKDEV ( 0 , dev ) ;
2005-04-17 02:20:36 +04:00
return 0 ;
}
2011-07-07 23:44:25 +04:00
EXPORT_SYMBOL ( get_anon_bdev ) ;
2005-04-17 02:20:36 +04:00
2011-07-07 23:44:25 +04:00
void free_anon_bdev ( dev_t dev )
2005-04-17 02:20:36 +04:00
{
2018-06-11 19:03:31 +03:00
ida_free ( & unnamed_dev_ida , MINOR ( dev ) ) ;
2005-04-17 02:20:36 +04:00
}
2011-07-07 23:44:25 +04:00
EXPORT_SYMBOL ( free_anon_bdev ) ;
int set_anon_super ( struct super_block * s , void * data )
{
2015-01-14 12:42:41 +03:00
return get_anon_bdev ( & s - > s_dev ) ;
2011-07-07 23:44:25 +04:00
}
EXPORT_SYMBOL ( set_anon_super ) ;
void kill_anon_super ( struct super_block * sb )
{
dev_t dev = sb - > s_dev ;
generic_shutdown_super ( sb ) ;
free_anon_bdev ( dev ) ;
}
2005-04-17 02:20:36 +04:00
EXPORT_SYMBOL ( kill_anon_super ) ;
void kill_litter_super ( struct super_block * sb )
{
if ( sb - > s_root )
d_genocide ( sb - > s_root ) ;
kill_anon_super ( sb ) ;
}
EXPORT_SYMBOL ( kill_litter_super ) ;
2018-12-24 01:25:47 +03:00
int set_anon_super_fc ( struct super_block * sb , struct fs_context * fc )
{
return set_anon_super ( sb , NULL ) ;
}
EXPORT_SYMBOL ( set_anon_super_fc ) ;
static int test_keyed_super ( struct super_block * sb , struct fs_context * fc )
{
return sb - > s_fs_info = = fc - > s_fs_info ;
}
static int test_single_super ( struct super_block * s , struct fs_context * fc )
{
return 1 ;
}
/**
* vfs_get_super - Get a superblock with a search key set in s_fs_info .
* @ fc : The filesystem context holding the parameters
* @ keying : How to distinguish superblocks
* @ fill_super : Helper to initialise a new superblock
*
* Search for a superblock and create a new one if not found . The search
* criterion is controlled by @ keying . If the search fails , a new superblock
* is created and @ fill_super ( ) is called to initialise it .
*
* @ keying can take one of a number of values :
*
* ( 1 ) vfs_get_single_super - Only one superblock of this type may exist on the
* system . This is typically used for special system filesystems .
*
* ( 2 ) vfs_get_keyed_super - Multiple superblocks may exist , but they must have
* distinct keys ( where the key is in s_fs_info ) . Searching for the same
* key again will turn up the superblock for that key .
*
* ( 3 ) vfs_get_independent_super - Multiple superblocks may exist and are
* unkeyed . Each call will get a new superblock .
*
* A permissions check is made by sget_fc ( ) unless we ' re getting a superblock
* for a kernel - internal mount or a submount .
*/
int vfs_get_super ( struct fs_context * fc ,
enum vfs_get_super_keying keying ,
int ( * fill_super ) ( struct super_block * sb ,
struct fs_context * fc ) )
{
int ( * test ) ( struct super_block * , struct fs_context * ) ;
struct super_block * sb ;
2019-03-21 12:22:36 +03:00
int err ;
2018-12-24 01:25:47 +03:00
switch ( keying ) {
case vfs_get_single_super :
2019-03-21 12:22:36 +03:00
case vfs_get_single_reconf_super :
2018-12-24 01:25:47 +03:00
test = test_single_super ;
break ;
case vfs_get_keyed_super :
test = test_keyed_super ;
break ;
case vfs_get_independent_super :
test = NULL ;
break ;
default :
BUG ( ) ;
}
sb = sget_fc ( fc , test , set_anon_super_fc ) ;
if ( IS_ERR ( sb ) )
return PTR_ERR ( sb ) ;
if ( ! sb - > s_root ) {
2019-03-21 12:22:36 +03:00
err = fill_super ( sb , fc ) ;
if ( err )
goto error ;
2018-12-24 01:25:47 +03:00
sb - > s_flags | = SB_ACTIVE ;
2019-03-21 12:22:36 +03:00
fc - > root = dget ( sb - > s_root ) ;
} else {
fc - > root = dget ( sb - > s_root ) ;
if ( keying = = vfs_get_single_reconf_super ) {
err = reconfigure_super ( fc ) ;
if ( err < 0 ) {
dput ( fc - > root ) ;
fc - > root = NULL ;
goto error ;
}
}
2018-12-24 01:25:47 +03:00
}
return 0 ;
2019-03-21 12:22:36 +03:00
error :
deactivate_locked_super ( sb ) ;
return err ;
2018-12-24 01:25:47 +03:00
}
EXPORT_SYMBOL ( vfs_get_super ) ;
2019-06-02 03:48:55 +03:00
int get_tree_nodev ( struct fs_context * fc ,
int ( * fill_super ) ( struct super_block * sb ,
struct fs_context * fc ) )
{
return vfs_get_super ( fc , vfs_get_independent_super , fill_super ) ;
}
EXPORT_SYMBOL ( get_tree_nodev ) ;
2019-05-23 04:23:39 +03:00
int get_tree_single ( struct fs_context * fc ,
int ( * fill_super ) ( struct super_block * sb ,
struct fs_context * fc ) )
{
return vfs_get_super ( fc , vfs_get_single_super , fill_super ) ;
}
EXPORT_SYMBOL ( get_tree_single ) ;
2019-03-21 12:22:36 +03:00
int get_tree_single_reconf ( struct fs_context * fc ,
int ( * fill_super ) ( struct super_block * sb ,
struct fs_context * fc ) )
{
return vfs_get_super ( fc , vfs_get_single_reconf_super , fill_super ) ;
}
EXPORT_SYMBOL ( get_tree_single_reconf ) ;
2019-09-04 02:05:48 +03:00
int get_tree_keyed ( struct fs_context * fc ,
int ( * fill_super ) ( struct super_block * sb ,
struct fs_context * fc ) ,
void * key )
{
fc - > s_fs_info = key ;
return vfs_get_super ( fc , vfs_get_keyed_super , fill_super ) ;
}
EXPORT_SYMBOL ( get_tree_keyed ) ;
[PATCH] BLOCK: Make it possible to disable the block layer [try #6]
Make it possible to disable the block layer. Not all embedded devices require
it, some can make do with just JFFS2, NFS, ramfs, etc - none of which require
the block layer to be present.
This patch does the following:
(*) Introduces CONFIG_BLOCK to disable the block layer, buffering and blockdev
support.
(*) Adds dependencies on CONFIG_BLOCK to any configuration item that controls
an item that uses the block layer. This includes:
(*) Block I/O tracing.
(*) Disk partition code.
(*) All filesystems that are block based, eg: Ext3, ReiserFS, ISOFS.
(*) The SCSI layer. As far as I can tell, even SCSI chardevs use the
block layer to do scheduling. Some drivers that use SCSI facilities -
such as USB storage - end up disabled indirectly from this.
(*) Various block-based device drivers, such as IDE and the old CDROM
drivers.
(*) MTD blockdev handling and FTL.
(*) JFFS - which uses set_bdev_super(), something it could avoid doing by
taking a leaf out of JFFS2's book.
(*) Makes most of the contents of linux/blkdev.h, linux/buffer_head.h and
linux/elevator.h contingent on CONFIG_BLOCK being set. sector_div() is,
however, still used in places, and so is still available.
(*) Also made contingent are the contents of linux/mpage.h, linux/genhd.h and
parts of linux/fs.h.
(*) Makes a number of files in fs/ contingent on CONFIG_BLOCK.
(*) Makes mm/bounce.c (bounce buffering) contingent on CONFIG_BLOCK.
(*) set_page_dirty() doesn't call __set_page_dirty_buffers() if CONFIG_BLOCK
is not enabled.
(*) fs/no-block.c is created to hold out-of-line stubs and things that are
required when CONFIG_BLOCK is not set:
(*) Default blockdev file operations (to give error ENODEV on opening).
(*) Makes some /proc changes:
(*) /proc/devices does not list any blockdevs.
(*) /proc/diskstats and /proc/partitions are contingent on CONFIG_BLOCK.
(*) Makes some compat ioctl handling contingent on CONFIG_BLOCK.
(*) If CONFIG_BLOCK is not defined, makes sys_quotactl() return -ENODEV if
given command other than Q_SYNC or if a special device is specified.
(*) In init/do_mounts.c, no reference is made to the blockdev routines if
CONFIG_BLOCK is not defined. This does not prohibit NFS roots or JFFS2.
(*) The bdflush, ioprio_set and ioprio_get syscalls can now be absent (return
error ENOSYS by way of cond_syscall if so).
(*) The seclvl_bd_claim() and seclvl_bd_release() security calls do nothing if
CONFIG_BLOCK is not set, since they can't then happen.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2006-09-30 22:45:40 +04:00
# ifdef CONFIG_BLOCK
2019-03-27 17:15:16 +03:00
2005-04-17 02:20:36 +04:00
static int set_bdev_super ( struct super_block * s , void * data )
{
s - > s_bdev = data ;
s - > s_dev = s - > s_bdev - > bd_dev ;
2021-08-09 17:17:44 +03:00
s - > s_bdi = bdi_get ( s - > s_bdev - > bd_disk - > bdi ) ;
2009-09-16 17:02:33 +04:00
2020-09-24 09:51:38 +03:00
if ( blk_queue_stable_writes ( s - > s_bdev - > bd_disk - > queue ) )
s - > s_iflags | = SB_I_STABLE_WRITES ;
2005-04-17 02:20:36 +04:00
return 0 ;
}
2019-03-27 17:15:16 +03:00
static int set_bdev_super_fc ( struct super_block * s , struct fs_context * fc )
{
return set_bdev_super ( s , fc - > sget_key ) ;
}
static int test_bdev_super_fc ( struct super_block * s , struct fs_context * fc )
{
return s - > s_bdev = = fc - > sget_key ;
}
/**
* get_tree_bdev - Get a superblock based on a single block device
* @ fc : The filesystem context holding the parameters
* @ fill_super : Helper to initialise a new superblock
*/
int get_tree_bdev ( struct fs_context * fc ,
int ( * fill_super ) ( struct super_block * ,
struct fs_context * ) )
{
struct block_device * bdev ;
struct super_block * s ;
fmode_t mode = FMODE_READ | FMODE_EXCL ;
int error = 0 ;
if ( ! ( fc - > sb_flags & SB_RDONLY ) )
mode | = FMODE_WRITE ;
if ( ! fc - > source )
return invalf ( fc , " No source specified " ) ;
bdev = blkdev_get_by_path ( fc - > source , mode , fc - > fs_type ) ;
if ( IS_ERR ( bdev ) ) {
errorf ( fc , " %s: Can't open blockdev " , fc - > source ) ;
return PTR_ERR ( bdev ) ;
}
/* Once the superblock is inserted into the list by sget_fc(), s_umount
* will protect the lockfs code from trying to start a snapshot while
* we are mounting
*/
mutex_lock ( & bdev - > bd_fsfreeze_mutex ) ;
if ( bdev - > bd_fsfreeze_count > 0 ) {
mutex_unlock ( & bdev - > bd_fsfreeze_mutex ) ;
warnf ( fc , " %pg: Can't mount, blockdev is frozen " , bdev ) ;
2020-04-28 23:27:48 +03:00
blkdev_put ( bdev , mode ) ;
2019-03-27 17:15:16 +03:00
return - EBUSY ;
}
fc - > sb_flags | = SB_NOSEC ;
fc - > sget_key = bdev ;
s = sget_fc ( fc , test_bdev_super_fc , set_bdev_super_fc ) ;
mutex_unlock ( & bdev - > bd_fsfreeze_mutex ) ;
2019-10-02 12:56:33 +03:00
if ( IS_ERR ( s ) ) {
blkdev_put ( bdev , mode ) ;
2019-03-27 17:15:16 +03:00
return PTR_ERR ( s ) ;
2019-10-02 12:56:33 +03:00
}
2019-03-27 17:15:16 +03:00
if ( s - > s_root ) {
/* Don't summarily change the RO/RW state. */
if ( ( fc - > sb_flags ^ s - > s_flags ) & SB_RDONLY ) {
warnf ( fc , " %pg: Can't mount, would change RO state " , bdev ) ;
deactivate_locked_super ( s ) ;
blkdev_put ( bdev , mode ) ;
return - EBUSY ;
}
/*
2021-05-25 09:12:56 +03:00
* s_umount nests inside open_mutex during
2019-03-27 17:15:16 +03:00
* __invalidate_device ( ) . blkdev_put ( ) acquires
2021-05-25 09:12:56 +03:00
* open_mutex and can ' t be called under s_umount . Drop
2019-03-27 17:15:16 +03:00
* s_umount temporarily . This is safe as we ' re
* holding an active reference .
*/
up_write ( & s - > s_umount ) ;
blkdev_put ( bdev , mode ) ;
down_write ( & s - > s_umount ) ;
} else {
s - > s_mode = mode ;
snprintf ( s - > s_id , sizeof ( s - > s_id ) , " %pg " , bdev ) ;
sb_set_blocksize ( s , block_size ( bdev ) ) ;
error = fill_super ( s , fc ) ;
if ( error ) {
deactivate_locked_super ( s ) ;
return error ;
}
s - > s_flags | = SB_ACTIVE ;
bdev - > bd_super = s ;
}
BUG_ON ( fc - > root ) ;
fc - > root = dget ( s - > s_root ) ;
return 0 ;
}
EXPORT_SYMBOL ( get_tree_bdev ) ;
2005-04-17 02:20:36 +04:00
static int test_bdev_super ( struct super_block * s , void * data )
{
return ( void * ) s - > s_bdev = = data ;
}
2010-07-25 00:46:55 +04:00
struct dentry * mount_bdev ( struct file_system_type * fs_type ,
2005-04-17 02:20:36 +04:00
int flags , const char * dev_name , void * data ,
2010-07-25 00:46:55 +04:00
int ( * fill_super ) ( struct super_block * , void * , int ) )
2005-04-17 02:20:36 +04:00
{
struct block_device * bdev ;
struct super_block * s ;
2010-11-13 13:55:18 +03:00
fmode_t mode = FMODE_READ | FMODE_EXCL ;
2005-04-17 02:20:36 +04:00
int error = 0 ;
2017-07-17 10:45:35 +03:00
if ( ! ( flags & SB_RDONLY ) )
2008-02-23 03:50:45 +03:00
mode | = FMODE_WRITE ;
2010-11-13 13:55:18 +03:00
bdev = blkdev_get_by_path ( dev_name , mode , fs_type ) ;
2005-04-17 02:20:36 +04:00
if ( IS_ERR ( bdev ) )
2010-07-25 00:46:55 +04:00
return ERR_CAST ( bdev ) ;
2005-04-17 02:20:36 +04:00
/*
* once the super is inserted into the list by sget , s_umount
* will protect the lockfs code from trying to start a snapshot
* while we are mounting
*/
2009-08-04 01:28:06 +04:00
mutex_lock ( & bdev - > bd_fsfreeze_mutex ) ;
if ( bdev - > bd_fsfreeze_count > 0 ) {
mutex_unlock ( & bdev - > bd_fsfreeze_mutex ) ;
error = - EBUSY ;
goto error_bdev ;
}
2017-07-17 10:45:35 +03:00
s = sget ( fs_type , test_bdev_super , set_bdev_super , flags | SB_NOSEC ,
2012-06-25 15:55:37 +04:00
bdev ) ;
2009-08-04 01:28:06 +04:00
mutex_unlock ( & bdev - > bd_fsfreeze_mutex ) ;
2005-04-17 02:20:36 +04:00
if ( IS_ERR ( s ) )
[PATCH] VFS: Permit filesystem to override root dentry on mount
Extend the get_sb() filesystem operation to take an extra argument that
permits the VFS to pass in the target vfsmount that defines the mountpoint.
The filesystem is then required to manually set the superblock and root dentry
pointers. For most filesystems, this should be done with simple_set_mnt()
which will set the superblock pointer and then set the root dentry to the
superblock's s_root (as per the old default behaviour).
The get_sb() op now returns an integer as there's now no need to return the
superblock pointer.
This patch permits a superblock to be implicitly shared amongst several mount
points, such as can be done with NFS to avoid potential inode aliasing. In
such a case, simple_set_mnt() would not be called, and instead the mnt_root
and mnt_sb would be set directly.
The patch also makes the following changes:
(*) the get_sb_*() convenience functions in the core kernel now take a vfsmount
pointer argument and return an integer, so most filesystems have to change
very little.
(*) If one of the convenience function is not used, then get_sb() should
normally call simple_set_mnt() to instantiate the vfsmount. This will
always return 0, and so can be tail-called from get_sb().
(*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the
dcache upon superblock destruction rather than shrink_dcache_anon().
This is required because the superblock may now have multiple trees that
aren't actually bound to s_root, but that still need to be cleaned up. The
currently called functions assume that the whole tree is rooted at s_root,
and that anonymous dentries are not the roots of trees which results in
dentries being left unculled.
However, with the way NFS superblock sharing are currently set to be
implemented, these assumptions are violated: the root of the filesystem is
simply a dummy dentry and inode (the real inode for '/' may well be
inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries
with child trees.
[*] Anonymous until discovered from another tree.
(*) The documentation has been adjusted, including the additional bit of
changing ext2_* into foo_* in the documentation.
[akpm@osdl.org: convert ipath_fs, do other stuff]
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Nathan Scott <nathans@sgi.com>
Cc: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 13:02:57 +04:00
goto error_s ;
2005-04-17 02:20:36 +04:00
if ( s - > s_root ) {
2017-07-17 10:45:35 +03:00
if ( ( flags ^ s - > s_flags ) & SB_RDONLY ) {
2009-05-06 09:07:50 +04:00
deactivate_locked_super ( s ) ;
[PATCH] VFS: Permit filesystem to override root dentry on mount
Extend the get_sb() filesystem operation to take an extra argument that
permits the VFS to pass in the target vfsmount that defines the mountpoint.
The filesystem is then required to manually set the superblock and root dentry
pointers. For most filesystems, this should be done with simple_set_mnt()
which will set the superblock pointer and then set the root dentry to the
superblock's s_root (as per the old default behaviour).
The get_sb() op now returns an integer as there's now no need to return the
superblock pointer.
This patch permits a superblock to be implicitly shared amongst several mount
points, such as can be done with NFS to avoid potential inode aliasing. In
such a case, simple_set_mnt() would not be called, and instead the mnt_root
and mnt_sb would be set directly.
The patch also makes the following changes:
(*) the get_sb_*() convenience functions in the core kernel now take a vfsmount
pointer argument and return an integer, so most filesystems have to change
very little.
(*) If one of the convenience function is not used, then get_sb() should
normally call simple_set_mnt() to instantiate the vfsmount. This will
always return 0, and so can be tail-called from get_sb().
(*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the
dcache upon superblock destruction rather than shrink_dcache_anon().
This is required because the superblock may now have multiple trees that
aren't actually bound to s_root, but that still need to be cleaned up. The
currently called functions assume that the whole tree is rooted at s_root,
and that anonymous dentries are not the roots of trees which results in
dentries being left unculled.
However, with the way NFS superblock sharing are currently set to be
implemented, these assumptions are violated: the root of the filesystem is
simply a dummy dentry and inode (the real inode for '/' may well be
inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries
with child trees.
[*] Anonymous until discovered from another tree.
(*) The documentation has been adjusted, including the additional bit of
changing ext2_* into foo_* in the documentation.
[akpm@osdl.org: convert ipath_fs, do other stuff]
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Nathan Scott <nathans@sgi.com>
Cc: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 13:02:57 +04:00
error = - EBUSY ;
goto error_bdev ;
2005-04-17 02:20:36 +04:00
}
[PATCH] VFS: Permit filesystem to override root dentry on mount
Extend the get_sb() filesystem operation to take an extra argument that
permits the VFS to pass in the target vfsmount that defines the mountpoint.
The filesystem is then required to manually set the superblock and root dentry
pointers. For most filesystems, this should be done with simple_set_mnt()
which will set the superblock pointer and then set the root dentry to the
superblock's s_root (as per the old default behaviour).
The get_sb() op now returns an integer as there's now no need to return the
superblock pointer.
This patch permits a superblock to be implicitly shared amongst several mount
points, such as can be done with NFS to avoid potential inode aliasing. In
such a case, simple_set_mnt() would not be called, and instead the mnt_root
and mnt_sb would be set directly.
The patch also makes the following changes:
(*) the get_sb_*() convenience functions in the core kernel now take a vfsmount
pointer argument and return an integer, so most filesystems have to change
very little.
(*) If one of the convenience function is not used, then get_sb() should
normally call simple_set_mnt() to instantiate the vfsmount. This will
always return 0, and so can be tail-called from get_sb().
(*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the
dcache upon superblock destruction rather than shrink_dcache_anon().
This is required because the superblock may now have multiple trees that
aren't actually bound to s_root, but that still need to be cleaned up. The
currently called functions assume that the whole tree is rooted at s_root,
and that anonymous dentries are not the roots of trees which results in
dentries being left unculled.
However, with the way NFS superblock sharing are currently set to be
implemented, these assumptions are violated: the root of the filesystem is
simply a dummy dentry and inode (the real inode for '/' may well be
inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries
with child trees.
[*] Anonymous until discovered from another tree.
(*) The documentation has been adjusted, including the additional bit of
changing ext2_* into foo_* in the documentation.
[akpm@osdl.org: convert ipath_fs, do other stuff]
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Nathan Scott <nathans@sgi.com>
Cc: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 13:02:57 +04:00
2010-07-21 02:18:07 +04:00
/*
2021-05-25 09:12:56 +03:00
* s_umount nests inside open_mutex during
block: make blkdev_get/put() handle exclusive access
Over time, block layer has accumulated a set of APIs dealing with bdev
open, close, claim and release.
* blkdev_get/put() are the primary open and close functions.
* bd_claim/release() deal with exclusive open.
* open/close_bdev_exclusive() are combination of open and claim and
the other way around, respectively.
* bd_link/unlink_disk_holder() to create and remove holder/slave
symlinks.
* open_by_devnum() wraps bdget() + blkdev_get().
The interface is a bit confusing and the decoupling of open and claim
makes it impossible to properly guarantee exclusive access as
in-kernel open + claim sequence can disturb the existing exclusive
open even before the block layer knows the current open if for another
exclusive access. Reorganize the interface such that,
* blkdev_get() is extended to include exclusive access management.
@holder argument is added and, if is @FMODE_EXCL specified, it will
gain exclusive access atomically w.r.t. other exclusive accesses.
* blkdev_put() is similarly extended. It now takes @mode argument and
if @FMODE_EXCL is set, it releases an exclusive access. Also, when
the last exclusive claim is released, the holder/slave symlinks are
removed automatically.
* bd_claim/release() and close_bdev_exclusive() are no longer
necessary and either made static or removed.
* bd_link_disk_holder() remains the same but bd_unlink_disk_holder()
is no longer necessary and removed.
* open_bdev_exclusive() becomes a simple wrapper around lookup_bdev()
and blkdev_get(). It also has an unexpected extra bdev_read_only()
test which probably should be moved into blkdev_get().
* open_by_devnum() is modified to take @holder argument and pass it to
blkdev_get().
Most of bdev open/close operations are unified into blkdev_get/put()
and most exclusive accesses are tested atomically at the open time (as
it should). This cleans up code and removes some, both valid and
invalid, but unnecessary all the same, corner cases.
open_bdev_exclusive() and open_by_devnum() can use further cleanup -
rename to blkdev_get_by_path() and blkdev_get_by_devt() and drop
special features. Well, let's leave them for another day.
Most conversions are straight-forward. drbd conversion is a bit more
involved as there was some reordering, but the logic should stay the
same.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Neil Brown <neilb@suse.de>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Peter Osterlund <petero2@telia.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <joel.becker@oracle.com>
Cc: Alex Elder <aelder@sgi.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: dm-devel@redhat.com
Cc: drbd-dev@lists.linbit.com
Cc: Leo Chen <leochen@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Joern Engel <joern@logfs.org>
Cc: reiserfs-devel@vger.kernel.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
2010-11-13 13:55:17 +03:00
* __invalidate_device ( ) . blkdev_put ( ) acquires
2021-05-25 09:12:56 +03:00
* open_mutex and can ' t be called under s_umount . Drop
block: make blkdev_get/put() handle exclusive access
Over time, block layer has accumulated a set of APIs dealing with bdev
open, close, claim and release.
* blkdev_get/put() are the primary open and close functions.
* bd_claim/release() deal with exclusive open.
* open/close_bdev_exclusive() are combination of open and claim and
the other way around, respectively.
* bd_link/unlink_disk_holder() to create and remove holder/slave
symlinks.
* open_by_devnum() wraps bdget() + blkdev_get().
The interface is a bit confusing and the decoupling of open and claim
makes it impossible to properly guarantee exclusive access as
in-kernel open + claim sequence can disturb the existing exclusive
open even before the block layer knows the current open if for another
exclusive access. Reorganize the interface such that,
* blkdev_get() is extended to include exclusive access management.
@holder argument is added and, if is @FMODE_EXCL specified, it will
gain exclusive access atomically w.r.t. other exclusive accesses.
* blkdev_put() is similarly extended. It now takes @mode argument and
if @FMODE_EXCL is set, it releases an exclusive access. Also, when
the last exclusive claim is released, the holder/slave symlinks are
removed automatically.
* bd_claim/release() and close_bdev_exclusive() are no longer
necessary and either made static or removed.
* bd_link_disk_holder() remains the same but bd_unlink_disk_holder()
is no longer necessary and removed.
* open_bdev_exclusive() becomes a simple wrapper around lookup_bdev()
and blkdev_get(). It also has an unexpected extra bdev_read_only()
test which probably should be moved into blkdev_get().
* open_by_devnum() is modified to take @holder argument and pass it to
blkdev_get().
Most of bdev open/close operations are unified into blkdev_get/put()
and most exclusive accesses are tested atomically at the open time (as
it should). This cleans up code and removes some, both valid and
invalid, but unnecessary all the same, corner cases.
open_bdev_exclusive() and open_by_devnum() can use further cleanup -
rename to blkdev_get_by_path() and blkdev_get_by_devt() and drop
special features. Well, let's leave them for another day.
Most conversions are straight-forward. drbd conversion is a bit more
involved as there was some reordering, but the logic should stay the
same.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Neil Brown <neilb@suse.de>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Peter Osterlund <petero2@telia.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <joel.becker@oracle.com>
Cc: Alex Elder <aelder@sgi.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: dm-devel@redhat.com
Cc: drbd-dev@lists.linbit.com
Cc: Leo Chen <leochen@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Joern Engel <joern@logfs.org>
Cc: reiserfs-devel@vger.kernel.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
2010-11-13 13:55:17 +03:00
* s_umount temporarily . This is safe as we ' re
* holding an active reference .
2010-07-21 02:18:07 +04:00
*/
up_write ( & s - > s_umount ) ;
2010-11-13 13:55:18 +03:00
blkdev_put ( bdev , mode ) ;
2010-07-21 02:18:07 +04:00
down_write ( & s - > s_umount ) ;
2005-04-17 02:20:36 +04:00
} else {
2008-02-23 03:50:45 +03:00
s - > s_mode = mode ;
2015-04-13 15:31:37 +03:00
snprintf ( s - > s_id , sizeof ( s - > s_id ) , " %pg " , bdev ) ;
2006-01-08 12:03:39 +03:00
sb_set_blocksize ( s , block_size ( bdev ) ) ;
2017-07-17 10:45:35 +03:00
error = fill_super ( s , data , flags & SB_SILENT ? 1 : 0 ) ;
2005-04-17 02:20:36 +04:00
if ( error ) {
2009-05-06 09:07:50 +04:00
deactivate_locked_super ( s ) ;
[PATCH] VFS: Permit filesystem to override root dentry on mount
Extend the get_sb() filesystem operation to take an extra argument that
permits the VFS to pass in the target vfsmount that defines the mountpoint.
The filesystem is then required to manually set the superblock and root dentry
pointers. For most filesystems, this should be done with simple_set_mnt()
which will set the superblock pointer and then set the root dentry to the
superblock's s_root (as per the old default behaviour).
The get_sb() op now returns an integer as there's now no need to return the
superblock pointer.
This patch permits a superblock to be implicitly shared amongst several mount
points, such as can be done with NFS to avoid potential inode aliasing. In
such a case, simple_set_mnt() would not be called, and instead the mnt_root
and mnt_sb would be set directly.
The patch also makes the following changes:
(*) the get_sb_*() convenience functions in the core kernel now take a vfsmount
pointer argument and return an integer, so most filesystems have to change
very little.
(*) If one of the convenience function is not used, then get_sb() should
normally call simple_set_mnt() to instantiate the vfsmount. This will
always return 0, and so can be tail-called from get_sb().
(*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the
dcache upon superblock destruction rather than shrink_dcache_anon().
This is required because the superblock may now have multiple trees that
aren't actually bound to s_root, but that still need to be cleaned up. The
currently called functions assume that the whole tree is rooted at s_root,
and that anonymous dentries are not the roots of trees which results in
dentries being left unculled.
However, with the way NFS superblock sharing are currently set to be
implemented, these assumptions are violated: the root of the filesystem is
simply a dummy dentry and inode (the real inode for '/' may well be
inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries
with child trees.
[*] Anonymous until discovered from another tree.
(*) The documentation has been adjusted, including the additional bit of
changing ext2_* into foo_* in the documentation.
[akpm@osdl.org: convert ipath_fs, do other stuff]
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Nathan Scott <nathans@sgi.com>
Cc: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 13:02:57 +04:00
goto error ;
2006-02-22 20:39:02 +03:00
}
[PATCH] VFS: Permit filesystem to override root dentry on mount
Extend the get_sb() filesystem operation to take an extra argument that
permits the VFS to pass in the target vfsmount that defines the mountpoint.
The filesystem is then required to manually set the superblock and root dentry
pointers. For most filesystems, this should be done with simple_set_mnt()
which will set the superblock pointer and then set the root dentry to the
superblock's s_root (as per the old default behaviour).
The get_sb() op now returns an integer as there's now no need to return the
superblock pointer.
This patch permits a superblock to be implicitly shared amongst several mount
points, such as can be done with NFS to avoid potential inode aliasing. In
such a case, simple_set_mnt() would not be called, and instead the mnt_root
and mnt_sb would be set directly.
The patch also makes the following changes:
(*) the get_sb_*() convenience functions in the core kernel now take a vfsmount
pointer argument and return an integer, so most filesystems have to change
very little.
(*) If one of the convenience function is not used, then get_sb() should
normally call simple_set_mnt() to instantiate the vfsmount. This will
always return 0, and so can be tail-called from get_sb().
(*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the
dcache upon superblock destruction rather than shrink_dcache_anon().
This is required because the superblock may now have multiple trees that
aren't actually bound to s_root, but that still need to be cleaned up. The
currently called functions assume that the whole tree is rooted at s_root,
and that anonymous dentries are not the roots of trees which results in
dentries being left unculled.
However, with the way NFS superblock sharing are currently set to be
implemented, these assumptions are violated: the root of the filesystem is
simply a dummy dentry and inode (the real inode for '/' may well be
inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries
with child trees.
[*] Anonymous until discovered from another tree.
(*) The documentation has been adjusted, including the additional bit of
changing ext2_* into foo_* in the documentation.
[akpm@osdl.org: convert ipath_fs, do other stuff]
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Nathan Scott <nathans@sgi.com>
Cc: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 13:02:57 +04:00
2017-07-17 10:45:35 +03:00
s - > s_flags | = SB_ACTIVE ;
2009-01-03 17:47:09 +03:00
bdev - > bd_super = s ;
2005-04-17 02:20:36 +04:00
}
2010-07-25 00:46:55 +04:00
return dget ( s - > s_root ) ;
2005-04-17 02:20:36 +04:00
[PATCH] VFS: Permit filesystem to override root dentry on mount
Extend the get_sb() filesystem operation to take an extra argument that
permits the VFS to pass in the target vfsmount that defines the mountpoint.
The filesystem is then required to manually set the superblock and root dentry
pointers. For most filesystems, this should be done with simple_set_mnt()
which will set the superblock pointer and then set the root dentry to the
superblock's s_root (as per the old default behaviour).
The get_sb() op now returns an integer as there's now no need to return the
superblock pointer.
This patch permits a superblock to be implicitly shared amongst several mount
points, such as can be done with NFS to avoid potential inode aliasing. In
such a case, simple_set_mnt() would not be called, and instead the mnt_root
and mnt_sb would be set directly.
The patch also makes the following changes:
(*) the get_sb_*() convenience functions in the core kernel now take a vfsmount
pointer argument and return an integer, so most filesystems have to change
very little.
(*) If one of the convenience function is not used, then get_sb() should
normally call simple_set_mnt() to instantiate the vfsmount. This will
always return 0, and so can be tail-called from get_sb().
(*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the
dcache upon superblock destruction rather than shrink_dcache_anon().
This is required because the superblock may now have multiple trees that
aren't actually bound to s_root, but that still need to be cleaned up. The
currently called functions assume that the whole tree is rooted at s_root,
and that anonymous dentries are not the roots of trees which results in
dentries being left unculled.
However, with the way NFS superblock sharing are currently set to be
implemented, these assumptions are violated: the root of the filesystem is
simply a dummy dentry and inode (the real inode for '/' may well be
inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries
with child trees.
[*] Anonymous until discovered from another tree.
(*) The documentation has been adjusted, including the additional bit of
changing ext2_* into foo_* in the documentation.
[akpm@osdl.org: convert ipath_fs, do other stuff]
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Nathan Scott <nathans@sgi.com>
Cc: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 13:02:57 +04:00
error_s :
error = PTR_ERR ( s ) ;
error_bdev :
2010-11-13 13:55:18 +03:00
blkdev_put ( bdev , mode ) ;
[PATCH] VFS: Permit filesystem to override root dentry on mount
Extend the get_sb() filesystem operation to take an extra argument that
permits the VFS to pass in the target vfsmount that defines the mountpoint.
The filesystem is then required to manually set the superblock and root dentry
pointers. For most filesystems, this should be done with simple_set_mnt()
which will set the superblock pointer and then set the root dentry to the
superblock's s_root (as per the old default behaviour).
The get_sb() op now returns an integer as there's now no need to return the
superblock pointer.
This patch permits a superblock to be implicitly shared amongst several mount
points, such as can be done with NFS to avoid potential inode aliasing. In
such a case, simple_set_mnt() would not be called, and instead the mnt_root
and mnt_sb would be set directly.
The patch also makes the following changes:
(*) the get_sb_*() convenience functions in the core kernel now take a vfsmount
pointer argument and return an integer, so most filesystems have to change
very little.
(*) If one of the convenience function is not used, then get_sb() should
normally call simple_set_mnt() to instantiate the vfsmount. This will
always return 0, and so can be tail-called from get_sb().
(*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the
dcache upon superblock destruction rather than shrink_dcache_anon().
This is required because the superblock may now have multiple trees that
aren't actually bound to s_root, but that still need to be cleaned up. The
currently called functions assume that the whole tree is rooted at s_root,
and that anonymous dentries are not the roots of trees which results in
dentries being left unculled.
However, with the way NFS superblock sharing are currently set to be
implemented, these assumptions are violated: the root of the filesystem is
simply a dummy dentry and inode (the real inode for '/' may well be
inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries
with child trees.
[*] Anonymous until discovered from another tree.
(*) The documentation has been adjusted, including the additional bit of
changing ext2_* into foo_* in the documentation.
[akpm@osdl.org: convert ipath_fs, do other stuff]
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Nathan Scott <nathans@sgi.com>
Cc: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 13:02:57 +04:00
error :
2010-07-25 00:46:55 +04:00
return ERR_PTR ( error ) ;
}
EXPORT_SYMBOL ( mount_bdev ) ;
2005-04-17 02:20:36 +04:00
void kill_block_super ( struct super_block * sb )
{
struct block_device * bdev = sb - > s_bdev ;
2008-02-23 03:50:45 +03:00
fmode_t mode = sb - > s_mode ;
2005-04-17 02:20:36 +04:00
2009-04-30 04:14:57 +04:00
bdev - > bd_super = NULL ;
2005-04-17 02:20:36 +04:00
generic_shutdown_super ( sb ) ;
sync_blockdev ( bdev ) ;
2010-11-13 13:55:18 +03:00
WARN_ON_ONCE ( ! ( mode & FMODE_EXCL ) ) ;
block: make blkdev_get/put() handle exclusive access
Over time, block layer has accumulated a set of APIs dealing with bdev
open, close, claim and release.
* blkdev_get/put() are the primary open and close functions.
* bd_claim/release() deal with exclusive open.
* open/close_bdev_exclusive() are combination of open and claim and
the other way around, respectively.
* bd_link/unlink_disk_holder() to create and remove holder/slave
symlinks.
* open_by_devnum() wraps bdget() + blkdev_get().
The interface is a bit confusing and the decoupling of open and claim
makes it impossible to properly guarantee exclusive access as
in-kernel open + claim sequence can disturb the existing exclusive
open even before the block layer knows the current open if for another
exclusive access. Reorganize the interface such that,
* blkdev_get() is extended to include exclusive access management.
@holder argument is added and, if is @FMODE_EXCL specified, it will
gain exclusive access atomically w.r.t. other exclusive accesses.
* blkdev_put() is similarly extended. It now takes @mode argument and
if @FMODE_EXCL is set, it releases an exclusive access. Also, when
the last exclusive claim is released, the holder/slave symlinks are
removed automatically.
* bd_claim/release() and close_bdev_exclusive() are no longer
necessary and either made static or removed.
* bd_link_disk_holder() remains the same but bd_unlink_disk_holder()
is no longer necessary and removed.
* open_bdev_exclusive() becomes a simple wrapper around lookup_bdev()
and blkdev_get(). It also has an unexpected extra bdev_read_only()
test which probably should be moved into blkdev_get().
* open_by_devnum() is modified to take @holder argument and pass it to
blkdev_get().
Most of bdev open/close operations are unified into blkdev_get/put()
and most exclusive accesses are tested atomically at the open time (as
it should). This cleans up code and removes some, both valid and
invalid, but unnecessary all the same, corner cases.
open_bdev_exclusive() and open_by_devnum() can use further cleanup -
rename to blkdev_get_by_path() and blkdev_get_by_devt() and drop
special features. Well, let's leave them for another day.
Most conversions are straight-forward. drbd conversion is a bit more
involved as there was some reordering, but the logic should stay the
same.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Neil Brown <neilb@suse.de>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Peter Osterlund <petero2@telia.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <joel.becker@oracle.com>
Cc: Alex Elder <aelder@sgi.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: dm-devel@redhat.com
Cc: drbd-dev@lists.linbit.com
Cc: Leo Chen <leochen@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Joern Engel <joern@logfs.org>
Cc: reiserfs-devel@vger.kernel.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
2010-11-13 13:55:17 +03:00
blkdev_put ( bdev , mode | FMODE_EXCL ) ;
2005-04-17 02:20:36 +04:00
}
EXPORT_SYMBOL ( kill_block_super ) ;
[PATCH] BLOCK: Make it possible to disable the block layer [try #6]
Make it possible to disable the block layer. Not all embedded devices require
it, some can make do with just JFFS2, NFS, ramfs, etc - none of which require
the block layer to be present.
This patch does the following:
(*) Introduces CONFIG_BLOCK to disable the block layer, buffering and blockdev
support.
(*) Adds dependencies on CONFIG_BLOCK to any configuration item that controls
an item that uses the block layer. This includes:
(*) Block I/O tracing.
(*) Disk partition code.
(*) All filesystems that are block based, eg: Ext3, ReiserFS, ISOFS.
(*) The SCSI layer. As far as I can tell, even SCSI chardevs use the
block layer to do scheduling. Some drivers that use SCSI facilities -
such as USB storage - end up disabled indirectly from this.
(*) Various block-based device drivers, such as IDE and the old CDROM
drivers.
(*) MTD blockdev handling and FTL.
(*) JFFS - which uses set_bdev_super(), something it could avoid doing by
taking a leaf out of JFFS2's book.
(*) Makes most of the contents of linux/blkdev.h, linux/buffer_head.h and
linux/elevator.h contingent on CONFIG_BLOCK being set. sector_div() is,
however, still used in places, and so is still available.
(*) Also made contingent are the contents of linux/mpage.h, linux/genhd.h and
parts of linux/fs.h.
(*) Makes a number of files in fs/ contingent on CONFIG_BLOCK.
(*) Makes mm/bounce.c (bounce buffering) contingent on CONFIG_BLOCK.
(*) set_page_dirty() doesn't call __set_page_dirty_buffers() if CONFIG_BLOCK
is not enabled.
(*) fs/no-block.c is created to hold out-of-line stubs and things that are
required when CONFIG_BLOCK is not set:
(*) Default blockdev file operations (to give error ENODEV on opening).
(*) Makes some /proc changes:
(*) /proc/devices does not list any blockdevs.
(*) /proc/diskstats and /proc/partitions are contingent on CONFIG_BLOCK.
(*) Makes some compat ioctl handling contingent on CONFIG_BLOCK.
(*) If CONFIG_BLOCK is not defined, makes sys_quotactl() return -ENODEV if
given command other than Q_SYNC or if a special device is specified.
(*) In init/do_mounts.c, no reference is made to the blockdev routines if
CONFIG_BLOCK is not defined. This does not prohibit NFS roots or JFFS2.
(*) The bdflush, ioprio_set and ioprio_get syscalls can now be absent (return
error ENOSYS by way of cond_syscall if so).
(*) The seclvl_bd_claim() and seclvl_bd_release() security calls do nothing if
CONFIG_BLOCK is not set, since they can't then happen.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2006-09-30 22:45:40 +04:00
# endif
2005-04-17 02:20:36 +04:00
2010-07-25 11:46:36 +04:00
struct dentry * mount_nodev ( struct file_system_type * fs_type ,
2005-04-17 02:20:36 +04:00
int flags , void * data ,
2010-07-25 11:46:36 +04:00
int ( * fill_super ) ( struct super_block * , void * , int ) )
2005-04-17 02:20:36 +04:00
{
int error ;
2012-06-25 15:55:37 +04:00
struct super_block * s = sget ( fs_type , NULL , set_anon_super , flags , NULL ) ;
2005-04-17 02:20:36 +04:00
if ( IS_ERR ( s ) )
2010-07-25 11:46:36 +04:00
return ERR_CAST ( s ) ;
2005-04-17 02:20:36 +04:00
2017-07-17 10:45:35 +03:00
error = fill_super ( s , data , flags & SB_SILENT ? 1 : 0 ) ;
2005-04-17 02:20:36 +04:00
if ( error ) {
2009-05-06 09:07:50 +04:00
deactivate_locked_super ( s ) ;
2010-07-25 11:46:36 +04:00
return ERR_PTR ( error ) ;
2005-04-17 02:20:36 +04:00
}
2017-07-17 10:45:35 +03:00
s - > s_flags | = SB_ACTIVE ;
2010-07-25 11:46:36 +04:00
return dget ( s - > s_root ) ;
2005-04-17 02:20:36 +04:00
}
2010-07-25 11:46:36 +04:00
EXPORT_SYMBOL ( mount_nodev ) ;
2018-11-04 17:28:36 +03:00
static int reconfigure_single ( struct super_block * s ,
int flags , void * data )
{
struct fs_context * fc ;
int ret ;
/* The caller really need to be passing fc down into mount_single(),
* then a chunk of this can be removed . [ Bollocks - - AV ]
* Better yet , reconfiguration shouldn ' t happen , but rather the second
* mount should be rejected if the parameters are not compatible .
*/
fc = fs_context_for_reconfigure ( s - > s_root , flags , MS_RMT_MASK ) ;
if ( IS_ERR ( fc ) )
return PTR_ERR ( fc ) ;
ret = parse_monolithic_mount_data ( fc , data ) ;
if ( ret < 0 )
goto out ;
ret = reconfigure_super ( fc ) ;
out :
put_fs_context ( fc ) ;
return ret ;
}
2005-04-17 02:20:36 +04:00
static int compare_single ( struct super_block * s , void * p )
{
return 1 ;
}
2010-07-25 01:48:30 +04:00
struct dentry * mount_single ( struct file_system_type * fs_type ,
2005-04-17 02:20:36 +04:00
int flags , void * data ,
2010-07-25 01:48:30 +04:00
int ( * fill_super ) ( struct super_block * , void * , int ) )
2005-04-17 02:20:36 +04:00
{
struct super_block * s ;
int error ;
2012-06-25 15:55:37 +04:00
s = sget ( fs_type , compare_single , set_anon_super , flags , NULL ) ;
2005-04-17 02:20:36 +04:00
if ( IS_ERR ( s ) )
2010-07-25 01:48:30 +04:00
return ERR_CAST ( s ) ;
2005-04-17 02:20:36 +04:00
if ( ! s - > s_root ) {
2017-07-17 10:45:35 +03:00
error = fill_super ( s , data , flags & SB_SILENT ? 1 : 0 ) ;
2018-11-04 17:28:36 +03:00
if ( ! error )
s - > s_flags | = SB_ACTIVE ;
2009-12-18 23:18:15 +03:00
} else {
2018-11-04 17:28:36 +03:00
error = reconfigure_single ( s , flags , data ) ;
}
if ( unlikely ( error ) ) {
deactivate_locked_super ( s ) ;
return ERR_PTR ( error ) ;
2005-04-17 02:20:36 +04:00
}
2010-07-25 01:48:30 +04:00
return dget ( s - > s_root ) ;
}
EXPORT_SYMBOL ( mount_single ) ;
2018-11-04 11:19:03 +03:00
/**
* vfs_get_tree - Get the mountable root
* @ fc : The superblock configuration context .
*
* The filesystem is invoked to get or create a superblock which can then later
* be used for mounting . The filesystem places a pointer to the root to be
* used for mounting in @ fc - > root .
*/
int vfs_get_tree ( struct fs_context * fc )
2005-04-17 02:20:36 +04:00
{
2011-03-18 05:08:28 +03:00
struct super_block * sb ;
2018-11-04 11:19:03 +03:00
int error ;
2010-02-05 17:30:46 +03:00
2018-12-24 02:55:56 +03:00
if ( fc - > root )
return - EBUSY ;
/* Get the mountable root in fc->root, with a ref on the root and a ref
* on the superblock .
*/
error = fc - > ops - > get_tree ( fc ) ;
2018-11-04 11:19:03 +03:00
if ( error < 0 )
return error ;
2005-04-17 02:20:36 +04:00
2018-12-24 02:55:56 +03:00
if ( ! fc - > root ) {
pr_err ( " Filesystem %s get_tree() didn't set fc->root \n " ,
fc - > fs_type - > name ) ;
/* We don't know what the locking state of the superblock is -
* if there is a superblock .
*/
BUG ( ) ;
}
2018-11-04 11:19:03 +03:00
sb = fc - > root - > d_sb ;
2011-03-18 05:08:28 +03:00
WARN_ON ( ! sb - > s_bdi ) ;
2018-05-11 04:20:57 +03:00
/*
* Write barrier is for super_cache_count ( ) . We place it before setting
* SB_BORN as the data dependency between the two functions is the
* superblock structure contents that we just set up , not the SB_BORN
* flag .
*/
smp_wmb ( ) ;
2017-07-17 10:45:35 +03:00
sb - > s_flags | = SB_BORN ;
[PATCH] VFS: Permit filesystem to override root dentry on mount
Extend the get_sb() filesystem operation to take an extra argument that
permits the VFS to pass in the target vfsmount that defines the mountpoint.
The filesystem is then required to manually set the superblock and root dentry
pointers. For most filesystems, this should be done with simple_set_mnt()
which will set the superblock pointer and then set the root dentry to the
superblock's s_root (as per the old default behaviour).
The get_sb() op now returns an integer as there's now no need to return the
superblock pointer.
This patch permits a superblock to be implicitly shared amongst several mount
points, such as can be done with NFS to avoid potential inode aliasing. In
such a case, simple_set_mnt() would not be called, and instead the mnt_root
and mnt_sb would be set directly.
The patch also makes the following changes:
(*) the get_sb_*() convenience functions in the core kernel now take a vfsmount
pointer argument and return an integer, so most filesystems have to change
very little.
(*) If one of the convenience function is not used, then get_sb() should
normally call simple_set_mnt() to instantiate the vfsmount. This will
always return 0, and so can be tail-called from get_sb().
(*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the
dcache upon superblock destruction rather than shrink_dcache_anon().
This is required because the superblock may now have multiple trees that
aren't actually bound to s_root, but that still need to be cleaned up. The
currently called functions assume that the whole tree is rooted at s_root,
and that anonymous dentries are not the roots of trees which results in
dentries being left unculled.
However, with the way NFS superblock sharing are currently set to be
implemented, these assumptions are violated: the root of the filesystem is
simply a dummy dentry and inode (the real inode for '/' may well be
inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries
with child trees.
[*] Anonymous until discovered from another tree.
(*) The documentation has been adjusted, including the additional bit of
changing ext2_* into foo_* in the documentation.
[akpm@osdl.org: convert ipath_fs, do other stuff]
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Nathan Scott <nathans@sgi.com>
Cc: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 13:02:57 +04:00
2018-11-04 11:19:03 +03:00
error = security_sb_set_mnt_opts ( sb , fc - > security , 0 , NULL ) ;
2018-12-20 23:04:50 +03:00
if ( unlikely ( error ) ) {
fc_drop_locked ( fc ) ;
return error ;
2018-12-05 19:58:35 +03:00
}
2009-09-19 00:05:53 +04:00
/*
* filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE
* but s_maxbytes was an unsigned long long for many releases . Throw
* this warning for a little while to try and catch filesystems that
2011-03-29 17:33:31 +04:00
* violate this rule .
2009-09-19 00:05:53 +04:00
*/
2011-03-18 05:08:28 +03:00
WARN ( ( sb - > s_maxbytes < 0 ) , " %s set sb->s_maxbytes to "
2018-11-04 11:19:03 +03:00
" negative value (%lld) \n " , fc - > fs_type - > name , sb - > s_maxbytes ) ;
2009-09-19 00:05:53 +04:00
2018-11-04 11:19:03 +03:00
return 0 ;
2005-04-17 02:20:36 +04:00
}
2018-11-04 11:19:03 +03:00
EXPORT_SYMBOL ( vfs_get_tree ) ;
2005-04-17 02:20:36 +04:00
2017-04-12 13:24:28 +03:00
/*
* Setup private BDI for given superblock . It gets automatically cleaned up
* in generic_shutdown_super ( ) .
*/
int super_setup_bdi_name ( struct super_block * sb , char * fmt , . . . )
{
struct backing_dev_info * bdi ;
int err ;
va_list args ;
2020-05-04 15:48:00 +03:00
bdi = bdi_alloc ( NUMA_NO_NODE ) ;
2017-04-12 13:24:28 +03:00
if ( ! bdi )
return - ENOMEM ;
va_start ( args , fmt ) ;
2017-04-12 13:24:49 +03:00
err = bdi_register_va ( bdi , fmt , args ) ;
2017-04-12 13:24:28 +03:00
va_end ( args ) ;
if ( err ) {
bdi_put ( bdi ) ;
return err ;
}
WARN_ON ( sb - > s_bdi ! = & noop_backing_dev_info ) ;
sb - > s_bdi = bdi ;
2021-11-05 23:36:58 +03:00
sb - > s_iflags | = SB_I_PERSB_BDI ;
2017-04-12 13:24:28 +03:00
return 0 ;
}
EXPORT_SYMBOL ( super_setup_bdi_name ) ;
/*
* Setup private BDI for given superblock . I gets automatically cleaned up
* in generic_shutdown_super ( ) .
*/
int super_setup_bdi ( struct super_block * sb )
{
static atomic_long_t bdi_seq = ATOMIC_LONG_INIT ( 0 ) ;
return super_setup_bdi_name ( sb , " %.28s-%ld " , sb - > s_type - > name ,
atomic_long_inc_return ( & bdi_seq ) ) ;
}
EXPORT_SYMBOL ( super_setup_bdi ) ;
2012-06-12 18:20:34 +04:00
/**
* sb_wait_write - wait until all writers to given file system finish
* @ sb : the super for which we wait
* @ level : type of writers we wait for ( normal vs page fault )
*
* This function waits until there are no writers of given type to given file
2015-08-11 18:05:04 +03:00
* system .
2012-06-12 18:20:34 +04:00
*/
static void sb_wait_write ( struct super_block * sb , int level )
{
2015-08-11 18:05:04 +03:00
percpu_down_write ( sb - > s_writers . rw_sem + level - 1 ) ;
}
2012-06-12 18:20:34 +04:00
2016-09-26 19:55:25 +03:00
/*
* We are going to return to userspace and forget about these locks , the
* ownership goes to the caller of thaw_super ( ) which does unlock ( ) .
*/
static void lockdep_sb_freeze_release ( struct super_block * sb )
{
int level ;
for ( level = SB_FREEZE_LEVELS - 1 ; level > = 0 ; level - - )
percpu_rwsem_release ( sb - > s_writers . rw_sem + level , 0 , _THIS_IP_ ) ;
}
/*
* Tell lockdep we are holding these locks before we call - > unfreeze_fs ( sb ) .
*/
static void lockdep_sb_freeze_acquire ( struct super_block * sb )
2015-08-11 18:05:04 +03:00
{
int level ;
2012-06-12 18:20:34 +04:00
2015-08-11 18:05:04 +03:00
for ( level = 0 ; level < SB_FREEZE_LEVELS ; + + level )
percpu_rwsem_acquire ( sb - > s_writers . rw_sem + level , 0 , _THIS_IP_ ) ;
2016-09-26 19:55:25 +03:00
}
static void sb_freeze_unlock ( struct super_block * sb )
{
int level ;
2012-06-12 18:20:34 +04:00
2015-08-11 18:05:04 +03:00
for ( level = SB_FREEZE_LEVELS - 1 ; level > = 0 ; level - - )
percpu_up_write ( sb - > s_writers . rw_sem + level ) ;
2012-06-12 18:20:34 +04:00
}
2010-03-23 17:34:56 +03:00
/**
2010-05-25 09:22:34 +04:00
* freeze_super - lock the filesystem and force it into a consistent state
* @ sb : the super to lock
2010-03-23 17:34:56 +03:00
*
* Syncs the super to make sure the filesystem is consistent and calls the fs ' s
* freeze_fs . Subsequent calls to this without first thawing the fs will return
* - EBUSY .
2012-06-12 18:20:34 +04:00
*
* During this function , sb - > s_writers . frozen goes through these values :
*
* SB_UNFROZEN : File system is normal , all writes progress as usual .
*
* SB_FREEZE_WRITE : The file system is in the process of being frozen . New
* writes should be blocked , though page faults are still allowed . We wait for
* all writes to complete and then proceed to the next stage .
*
* SB_FREEZE_PAGEFAULT : Freezing continues . Now also page faults are blocked
* but internal fs threads can still modify the filesystem ( although they
* should not dirty new pages or inodes ) , writeback can run etc . After waiting
* for all running page faults we sync the filesystem which will clean all
* dirty pages and inodes ( no new dirty pages or inodes can be created when
* sync is running ) .
*
* SB_FREEZE_FS : The file system is frozen . Now all internal sources of fs
* modification are blocked ( e . g . XFS preallocation truncation on inode
* reclaim ) . This is usually implemented by blocking new transactions for
* filesystems that have them and need this additional guard . After all
* internal writers are finished we call - > freeze_fs ( ) to finish filesystem
* freezing . Then we transition to SB_FREEZE_COMPLETE state . This state is
* mostly auxiliary for filesystems to verify they do not modify frozen fs .
*
* sb - > s_writers . frozen is protected by sb - > s_umount .
2010-03-23 17:34:56 +03:00
*/
int freeze_super ( struct super_block * sb )
{
int ret ;
atomic_inc ( & sb - > s_active ) ;
down_write ( & sb - > s_umount ) ;
2012-06-12 18:20:34 +04:00
if ( sb - > s_writers . frozen ! = SB_UNFROZEN ) {
2010-03-23 17:34:56 +03:00
deactivate_locked_super ( sb ) ;
return - EBUSY ;
}
2017-07-17 10:45:35 +03:00
if ( ! ( sb - > s_flags & SB_BORN ) ) {
2012-01-04 06:01:29 +04:00
up_write ( & sb - > s_umount ) ;
return 0 ; /* sic - it's "nothing to do" */
}
2017-07-17 10:45:34 +03:00
if ( sb_rdonly ( sb ) ) {
2012-06-12 18:20:34 +04:00
/* Nothing to do really... */
sb - > s_writers . frozen = SB_FREEZE_COMPLETE ;
2010-03-23 17:34:56 +03:00
up_write ( & sb - > s_umount ) ;
return 0 ;
}
2012-06-12 18:20:34 +04:00
sb - > s_writers . frozen = SB_FREEZE_WRITE ;
/* Release s_umount to preserve sb_start_write -> s_umount ordering */
up_write ( & sb - > s_umount ) ;
sb_wait_write ( sb , SB_FREEZE_WRITE ) ;
2015-08-11 18:05:04 +03:00
down_write ( & sb - > s_umount ) ;
2012-06-12 18:20:34 +04:00
/* Now we go and block page faults... */
sb - > s_writers . frozen = SB_FREEZE_PAGEFAULT ;
sb_wait_write ( sb , SB_FREEZE_PAGEFAULT ) ;
/* All writers are done so after syncing there won't be dirty data */
2010-03-23 17:34:56 +03:00
sync_filesystem ( sb ) ;
2012-06-12 18:20:34 +04:00
/* Now wait for internal filesystem counter */
sb - > s_writers . frozen = SB_FREEZE_FS ;
sb_wait_write ( sb , SB_FREEZE_FS ) ;
2010-03-23 17:34:56 +03:00
if ( sb - > s_op - > freeze_fs ) {
ret = sb - > s_op - > freeze_fs ( sb ) ;
if ( ret ) {
printk ( KERN_ERR
" VFS:Filesystem freeze failed \n " ) ;
2012-06-12 18:20:34 +04:00
sb - > s_writers . frozen = SB_UNFROZEN ;
2015-08-11 18:05:04 +03:00
sb_freeze_unlock ( sb ) ;
2012-06-12 18:20:34 +04:00
wake_up ( & sb - > s_writers . wait_unfrozen ) ;
2010-03-23 17:34:56 +03:00
deactivate_locked_super ( sb ) ;
return ret ;
}
}
2012-06-12 18:20:34 +04:00
/*
2016-09-26 19:07:48 +03:00
* For debugging purposes so that fs can warn if it sees write activity
* when frozen is set to SB_FREEZE_COMPLETE , and for thaw_super ( ) .
2012-06-12 18:20:34 +04:00
*/
sb - > s_writers . frozen = SB_FREEZE_COMPLETE ;
2016-09-26 19:55:25 +03:00
lockdep_sb_freeze_release ( sb ) ;
2010-03-23 17:34:56 +03:00
up_write ( & sb - > s_umount ) ;
return 0 ;
}
EXPORT_SYMBOL ( freeze_super ) ;
2017-10-03 19:17:41 +03:00
static int thaw_super_locked ( struct super_block * sb )
2010-03-23 17:34:56 +03:00
{
int error ;
2016-09-26 19:07:48 +03:00
if ( sb - > s_writers . frozen ! = SB_FREEZE_COMPLETE ) {
2010-03-23 17:34:56 +03:00
up_write ( & sb - > s_umount ) ;
return - EINVAL ;
}
2017-07-17 10:45:34 +03:00
if ( sb_rdonly ( sb ) ) {
2015-08-11 18:05:04 +03:00
sb - > s_writers . frozen = SB_UNFROZEN ;
2010-03-23 17:34:56 +03:00
goto out ;
2015-08-11 18:05:04 +03:00
}
2010-03-23 17:34:56 +03:00
2016-09-26 19:55:25 +03:00
lockdep_sb_freeze_acquire ( sb ) ;
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if ( sb - > s_op - > unfreeze_fs ) {
error = sb - > s_op - > unfreeze_fs ( sb ) ;
if ( error ) {
printk ( KERN_ERR
" VFS:Filesystem thaw failed \n " ) ;
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lockdep_sb_freeze_release ( sb ) ;
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up_write ( & sb - > s_umount ) ;
return error ;
}
}
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sb - > s_writers . frozen = SB_UNFROZEN ;
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sb_freeze_unlock ( sb ) ;
out :
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wake_up ( & sb - > s_writers . wait_unfrozen ) ;
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deactivate_locked_super ( sb ) ;
return 0 ;
}
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/**
* thaw_super - - unlock filesystem
* @ sb : the super to thaw
*
* Unlocks the filesystem and marks it writeable again after freeze_super ( ) .
*/
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int thaw_super ( struct super_block * sb )
{
down_write ( & sb - > s_umount ) ;
return thaw_super_locked ( sb ) ;
}
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EXPORT_SYMBOL ( thaw_super ) ;