Commit Graph

1762 Commits

Author SHA1 Message Date
Linus Torvalds
38da32ee70 bd_inode series
Replacement of bdev->bd_inode with sane(r) set of primitives.
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Merge tag 'pull-bd_inode-1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull bdev bd_inode updates from Al Viro:
 "Replacement of bdev->bd_inode with sane(r) set of primitives by me and
  Yu Kuai"

* tag 'pull-bd_inode-1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  RIP ->bd_inode
  dasd_format(): killing the last remaining user of ->bd_inode
  nilfs_attach_log_writer(): use ->bd_mapping->host instead of ->bd_inode
  block/bdev.c: use the knowledge of inode/bdev coallocation
  gfs2: more obvious initializations of mapping->host
  fs/buffer.c: massage the remaining users of ->bd_inode to ->bd_mapping
  blk_ioctl_{discard,zeroout}(): we only want ->bd_inode->i_mapping here...
  grow_dev_folio(): we only want ->bd_inode->i_mapping there
  use ->bd_mapping instead of ->bd_inode->i_mapping
  block_device: add a pointer to struct address_space (page cache of bdev)
  missing helpers: bdev_unhash(), bdev_drop()
  block: move two helpers into bdev.c
  block2mtd: prevent direct access of bd_inode
  dm-vdo: use bdev_nr_bytes(bdev) instead of i_size_read(bdev->bd_inode)
  blkdev_write_iter(): saner way to get inode and bdev
  bcachefs: remove dead function bdev_sectors()
  ext4: remove block_device_ejected()
  erofs_buf: store address_space instead of inode
  erofs: switch erofs_bread() to passing offset instead of block number
2024-05-21 09:51:42 -07:00
Matthew Wilcox (Oracle)
bc00965dbf btrfs: count super block write errors in device instead of tracking folio error state
Currently the error status of super block write is tracked in page/folio
status bit Error. For that we need to keep the reference for the whole
duration of write and wait.

Count the number of superblock writeback errors in the btrfs_device.
That means we don't need the folio to stay around until it's waited for,
and can avoid the extra call to folio_get/put.

Also remove a mention of PageError in a comment as it's the last mention
of the page Error state.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-05-07 21:31:11 +02:00
Matthew Wilcox (Oracle)
617fb10ea8 btrfs: use the folio iterator in btrfs_end_super_write()
Iterate over folios instead of bvecs.  Switch the order of unlock and put
to be the usual order; we know this folio can't be put until it's been
waited for, but that's fragile.  Remove the calls to ClearPageUptodate /
SetPageUptodate -- if PAGE_SIZE is larger than BTRFS_SUPER_INFO_SIZE,
we'd be marking the entire folio uptodate without having actually
initialised all the bytes in the page.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-05-07 21:31:10 +02:00
Matthew Wilcox (Oracle)
f93ee0df51 btrfs: convert super block writes to folio in write_dev_supers()
This is a direct conversion from pages to folios, assuming single page
folio. Also removes some calls to obsolete APIs and some hidden calls to
compound_head().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-05-07 21:31:10 +02:00
Matthew Wilcox (Oracle)
c94b7349b8 btrfs: convert super block writes to folio in wait_dev_supers()
This is a direct conversion from pages to folios, assuming single page
folio.  Also removes a few calls to compound_head() and calls to
obsolete APIs.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-05-07 21:31:10 +02:00
David Sterba
fef998d1a0 btrfs: use btrfs_is_testing() everywhere
There are open coded tests of BTRFS_FS_STATE_DUMMY_FS_INFO and we have a
wrapper for that that's a compile-time constant when self-tests are not
built in. As this is only for development we can save some bytes and
conditions on release configs by using the helper in the remaining
cases.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-05-07 21:31:07 +02:00
Filipe Manana
905a95f3dd btrfs: initialize delayed inodes xarray without GFP_ATOMIC
There's no need to initialize the delayed inodes xarray with a GFP_ATOMIC
flag because that actually does nothing on the xarray operations. That was
needed for radix trees, but for xarrays the allocation flags are passed as
the last argument to xa_store() (which we are using correctly).

So initialize the delayed inodes xarray with a simple xa_init().

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-05-07 21:31:07 +02:00
Filipe Manana
f1d97e7691 btrfs: add a global per cpu counter to track number of used extent maps
Add a per cpu counter that tracks the total number of extent maps that are
in extent trees of inodes that belong to fs trees. This is going to be
used in an upcoming change that adds a shrinker for extent maps. Only
extent maps for fs trees are considered, because for special trees such as
the data relocation tree we don't want to evict their extent maps which
are critical for the relocation to work, and since those are limited, it's
not a concern to have them in memory during the relocation of a block
group. Another case are extent maps for free space cache inodes, which
must always remain in memory, but those are limited (there's only one per
free space cache inode, which means one per block group).

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-05-07 21:31:06 +02:00
Josef Bacik
e094f48040 btrfs: change root->root_key.objectid to btrfs_root_id()
A comment from Filipe on one of my previous cleanups brought my
attention to a new helper we have for getting the root id of a root,
which makes it easier to read in the code.

The changes where made with the following Coccinelle semantic patch:

// <smpl>
@@
expression E,E1;
@@
(
 E->root_key.objectid = E1
|
- E->root_key.objectid
+ btrfs_root_id(E)
)
// </smpl>

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minor style fixups ]
Signed-off-by: David Sterba <dsterba@suse.com>
2024-05-07 21:31:06 +02:00
Filipe Manana
606a1c5de1 btrfs: remove list_empty() check at warn_about_uncommitted_trans()
At warn_about_uncommitted_trans(), there's no need to check if the list
is empty and return, because list_for_each_entry_safe() is safe to call
for an empty list, it simply does nothing. So remove the check.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-05-07 21:31:03 +02:00
Boris Burkov
5f2fb819f6 btrfs: free PERTRANS at the end of cleanup_transaction()
Some of the operations after the free might convert more PERTRANS
metadata. Do the freeing as late as possible to eliminate a source of
leaked PERTRANS metadata.

This helps with the pass rate of generic/269 and generic/475.

Reviewed-by: Qu Wenruo <qwu@suse.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-05-07 21:31:02 +02:00
Al Viro
224941e837 use ->bd_mapping instead of ->bd_inode->i_mapping
Just the low-hanging fruit...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/r/20240411145346.2516848-2-viro@zeniv.linux.org.uk
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-05-03 02:36:51 -04:00
David Sterba
5a8a57f9a4 btrfs: merge btrfs_del_delalloc_inode() helpers
The helpers btrfs_del_delalloc_inode() and __btrfs_del_delalloc_inode()
don't follow the pattern when the "__" helper does a special case and
are in fact reversed regarding the naming. We can merge them into one as
there's only one place that needs to be open coded.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-03-04 16:24:54 +01:00
Filipe Manana
f5169f12d7 btrfs: stop passing root argument to __btrfs_del_delalloc_inode()
There's no need to pass a root argument to __btrfs_del_delalloc_inode()
and btrfs_del_delalloc_inode(), we can just pass the inode since the root
is always the root associated to that inode. Some remove the root argument
from these functions.

Reviewed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-03-04 16:24:49 +01:00
David Sterba
41044b41ad btrfs: add helper to get fs_info from struct inode pointer
Add a convenience helper to get a fs_info from a VFS inode pointer
instead of open coding the chain or using btrfs_sb() that in some cases
does one more pointer hop.  This is implemented as a macro (still with
type checking) so we don't need full definitions of struct btrfs_inode,
btrfs_root or btrfs_fs_info.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-03-04 16:24:49 +01:00
David Sterba
b33d2e535f btrfs: add helpers to get fs_info from page/folio pointers
Add convenience helpers to get a fs_info from a page or folio pointer
instead of open coding the chain or using btrfs_sb() that in some cases
does one more pointer hop.  This is implemented as a macro (still with
type checking) so we don't need full definitions of struct page, folio,
btrfs_root and btrfs_fs_info. The latter can't be static inlines as this
would create loop between ctree.h <-> fs.h, or the headers would have to
be restructured.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-03-04 16:24:49 +01:00
David Sterba
c8293894af btrfs: add helpers to get inode from page/folio pointers
Add convenience helpers to get a struct btrfs_inode from a page or folio
pointer instead of open coding the chain or intermediate BTRFS_I. This
is implemented as a macro (still with type checking) so we don't need
full definitions of struct page or address_space.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-03-04 16:24:49 +01:00
David Sterba
2467d0fead btrfs: change BUG_ON to assertion in btrfs_read_roots()
There's one caller of btrfs_read_roots() and that already uses the
tree_root pointer, it's pointless to BUG_ON on it. As it's an assumption
of the initialization helpers make it an assert instead.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-03-04 16:24:48 +01:00
David Sterba
a67242907b btrfs: handle invalid root reference found in btrfs_init_root_free_objectid()
The btrfs_init_root_free_objectid() looks up a root by a key, allowing
to do an inexact search when key->offset is -1.  It's never expected to
find such item, as it would break the allowed range of a root id.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-03-04 16:24:47 +01:00
David Sterba
2b712e3bb2 btrfs: remove unused included headers
With help of neovim, LSP and clangd we can identify header files that
are not actually needed to be included in the .c files. This is focused
only on removal (with minor fixups), further cleanups are possible but
will require doing the header files properly with forward declarations,
minimized includes and include-what-you-use care.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-03-04 16:24:46 +01:00
David Sterba
4e00422ee6 btrfs: replace sb::s_blocksize by fs_info::sectorsize
The block size stored in the super block is used by subsystems outside
of btrfs and it's a copy of fs_info::sectorsize. Unify that to always
use our sectorsize, with the exception of mount where we first need to
use fixed values (4K) until we read the super block and can set the
sectorsize.

Replace all uses, in most cases it's fewer pointer indirections.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-03-04 16:24:46 +01:00
Josef Bacik
8fd2b12e6a btrfs: WARN_ON_ONCE() in our leak detection code
fstests looks for WARN_ON's in dmesg.  Add WARN_ON_ONCE() to our leak
detection code (enabled only in debug builds) so that fstests will fail
if these things trip at all.  This will allow us to easily catch
problems with our reference counting that may otherwise go unnoticed.

Reviewed-by: Neal Gompa <neal@gompa.dev>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-03-04 16:24:45 +01:00
Qu Wenruo
84cda1a608 btrfs: cache folio size and shift in extent_buffer
After the conversion to folio interfaces (but without the patch to
enable larger folio allocation), there is an LTP report about observable
performance drop on metadata heavy operations.

https://lore.kernel.org/linux-btrfs/202312221750.571925bd-oliver.sang@intel.com/

This drop is caused by the extra code of calculating the
folio_size()/folio_shift(), instead of the old hard coded
PAGE_SIZE/PAGE_SHIFT.

To slightly reduce the overhead, just cache both folio_size and
folio_shift in extent_buffer.

The two new members (u32 folio_size and u8 folio_shift) are stored
inside the holes of extent_buffer. folio_size is shared with len, which
is reduced to u32. The size of eb does not change.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-03-04 16:24:45 +01:00
Filipe Manana
e2b54eaf28 btrfs: fix double free of anonymous device after snapshot creation failure
When creating a snapshot we may do a double free of an anonymous device
in case there's an error committing the transaction. The second free may
result in freeing an anonymous device number that was allocated by some
other subsystem in the kernel or another btrfs filesystem.

The steps that lead to this:

1) At ioctl.c:create_snapshot() we allocate an anonymous device number
   and assign it to pending_snapshot->anon_dev;

2) Then we call btrfs_commit_transaction() and end up at
   transaction.c:create_pending_snapshot();

3) There we call btrfs_get_new_fs_root() and pass it the anonymous device
   number stored in pending_snapshot->anon_dev;

4) btrfs_get_new_fs_root() frees that anonymous device number because
   btrfs_lookup_fs_root() returned a root - someone else did a lookup
   of the new root already, which could some task doing backref walking;

5) After that some error happens in the transaction commit path, and at
   ioctl.c:create_snapshot() we jump to the 'fail' label, and after
   that we free again the same anonymous device number, which in the
   meanwhile may have been reallocated somewhere else, because
   pending_snapshot->anon_dev still has the same value as in step 1.

Recently syzbot ran into this and reported the following trace:

  ------------[ cut here ]------------
  ida_free called for id=51 which is not allocated.
  WARNING: CPU: 1 PID: 31038 at lib/idr.c:525 ida_free+0x370/0x420 lib/idr.c:525
  Modules linked in:
  CPU: 1 PID: 31038 Comm: syz-executor.2 Not tainted 6.8.0-rc4-syzkaller-00410-gc02197fc9076 #0
  Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
  RIP: 0010:ida_free+0x370/0x420 lib/idr.c:525
  Code: 10 42 80 3c 28 (...)
  RSP: 0018:ffffc90015a67300 EFLAGS: 00010246
  RAX: be5130472f5dd000 RBX: 0000000000000033 RCX: 0000000000040000
  RDX: ffffc90009a7a000 RSI: 000000000003ffff RDI: 0000000000040000
  RBP: ffffc90015a673f0 R08: ffffffff81577992 R09: 1ffff92002b4cdb4
  R10: dffffc0000000000 R11: fffff52002b4cdb5 R12: 0000000000000246
  R13: dffffc0000000000 R14: ffffffff8e256b80 R15: 0000000000000246
  FS:  00007fca3f4b46c0(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007f167a17b978 CR3: 000000001ed26000 CR4: 0000000000350ef0
  Call Trace:
   <TASK>
   btrfs_get_root_ref+0xa48/0xaf0 fs/btrfs/disk-io.c:1346
   create_pending_snapshot+0xff2/0x2bc0 fs/btrfs/transaction.c:1837
   create_pending_snapshots+0x195/0x1d0 fs/btrfs/transaction.c:1931
   btrfs_commit_transaction+0xf1c/0x3740 fs/btrfs/transaction.c:2404
   create_snapshot+0x507/0x880 fs/btrfs/ioctl.c:848
   btrfs_mksubvol+0x5d0/0x750 fs/btrfs/ioctl.c:998
   btrfs_mksnapshot+0xb5/0xf0 fs/btrfs/ioctl.c:1044
   __btrfs_ioctl_snap_create+0x387/0x4b0 fs/btrfs/ioctl.c:1306
   btrfs_ioctl_snap_create_v2+0x1ca/0x400 fs/btrfs/ioctl.c:1393
   btrfs_ioctl+0xa74/0xd40
   vfs_ioctl fs/ioctl.c:51 [inline]
   __do_sys_ioctl fs/ioctl.c:871 [inline]
   __se_sys_ioctl+0xfe/0x170 fs/ioctl.c:857
   do_syscall_64+0xfb/0x240
   entry_SYSCALL_64_after_hwframe+0x6f/0x77
  RIP: 0033:0x7fca3e67dda9
  Code: 28 00 00 00 (...)
  RSP: 002b:00007fca3f4b40c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
  RAX: ffffffffffffffda RBX: 00007fca3e7abf80 RCX: 00007fca3e67dda9
  RDX: 00000000200005c0 RSI: 0000000050009417 RDI: 0000000000000003
  RBP: 00007fca3e6ca47a R08: 0000000000000000 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
  R13: 000000000000000b R14: 00007fca3e7abf80 R15: 00007fff6bf95658
   </TASK>

Where we get an explicit message where we attempt to free an anonymous
device number that is not currently allocated. It happens in a different
code path from the example below, at btrfs_get_root_ref(), so this change
may not fix the case triggered by syzbot.

To fix at least the code path from the example above, change
btrfs_get_root_ref() and its callers to receive a dev_t pointer argument
for the anonymous device number, so that in case it frees the number, it
also resets it to 0, so that up in the call chain we don't attempt to do
the double free.

CC: stable@vger.kernel.org # 5.10+
Link: https://lore.kernel.org/linux-btrfs/000000000000f673a1061202f630@google.com/
Fixes: e03ee2fe87 ("btrfs: do not ASSERT() if the newly created subvolume already got read")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-02-29 22:34:11 +01:00
Qu Wenruo
e03ee2fe87 btrfs: do not ASSERT() if the newly created subvolume already got read
[BUG]
There is a syzbot crash, triggered by the ASSERT() during subvolume
creation:

 assertion failed: !anon_dev, in fs/btrfs/disk-io.c:1319
 ------------[ cut here ]------------
 kernel BUG at fs/btrfs/disk-io.c:1319!
 invalid opcode: 0000 [#1] PREEMPT SMP KASAN
 RIP: 0010:btrfs_get_root_ref.part.0+0x9aa/0xa60
  <TASK>
  btrfs_get_new_fs_root+0xd3/0xf0
  create_subvol+0xd02/0x1650
  btrfs_mksubvol+0xe95/0x12b0
  __btrfs_ioctl_snap_create+0x2f9/0x4f0
  btrfs_ioctl_snap_create+0x16b/0x200
  btrfs_ioctl+0x35f0/0x5cf0
  __x64_sys_ioctl+0x19d/0x210
  do_syscall_64+0x3f/0xe0
  entry_SYSCALL_64_after_hwframe+0x63/0x6b
 ---[ end trace 0000000000000000 ]---

[CAUSE]
During create_subvol(), after inserting root item for the newly created
subvolume, we would trigger btrfs_get_new_fs_root() to get the
btrfs_root of that subvolume.

The idea here is, we have preallocated an anonymous device number for
the subvolume, thus we can assign it to the new subvolume.

But there is really nothing preventing things like backref walk to read
the new subvolume.
If that happens before we call btrfs_get_new_fs_root(), the subvolume
would be read out, with a new anonymous device number assigned already.

In that case, we would trigger ASSERT(), as we really expect no one to
read out that subvolume (which is not yet accessible from the fs).
But things like backref walk is still possible to trigger the read on
the subvolume.

Thus our assumption on the ASSERT() is not correct in the first place.

[FIX]
Fix it by removing the ASSERT(), and just free the @anon_dev, reset it
to 0, and continue.

If the subvolume tree is read out by something else, it should have
already get a new anon_dev assigned thus we only need to free the
preallocated one.

Reported-by: Chenyuan Yang <chenyuan0y@gmail.com>
Fixes: 2dfb1e43f5 ("btrfs: preallocate anon block device at first phase of snapshot creation")
CC: stable@vger.kernel.org # 5.15+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-01-31 08:42:53 +01:00
Qu Wenruo
96c36eaa77 btrfs: migrate btrfs_repair_io_failure() to folio interfaces
[BUG]
Test case btrfs/124 failed if larger metadata folio is enabled, the
dying message looks like this:

 BTRFS error (device dm-2): bad tree block start, mirror 2 want 31686656 have 0
 BTRFS info (device dm-2): read error corrected: ino 0 off 31686656 (dev /dev/mapper/test-scratch2 sector 20928)
 BUG: kernel NULL pointer dereference, address: 0000000000000020
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 CPU: 6 PID: 350881 Comm: btrfs Tainted: G           OE      6.7.0-rc3-custom+ #128
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 2/2/2022
 RIP: 0010:btrfs_read_extent_buffer+0x106/0x180 [btrfs]
 PKRU: 55555554
 Call Trace:
  <TASK>
  read_tree_block+0x33/0xb0 [btrfs]
  read_block_for_search+0x23e/0x340 [btrfs]
  btrfs_search_slot+0x2f9/0xe60 [btrfs]
  btrfs_lookup_csum+0x75/0x160 [btrfs]
  btrfs_lookup_bio_sums+0x21a/0x560 [btrfs]
  btrfs_submit_chunk+0x152/0x680 [btrfs]
  btrfs_submit_bio+0x1c/0x50 [btrfs]
  submit_one_bio+0x40/0x80 [btrfs]
  submit_extent_page+0x158/0x390 [btrfs]
  btrfs_do_readpage+0x330/0x740 [btrfs]
  extent_readahead+0x38d/0x6c0 [btrfs]
  read_pages+0x94/0x2c0
  page_cache_ra_unbounded+0x12d/0x190
  relocate_file_extent_cluster+0x7c1/0x9d0 [btrfs]
  relocate_block_group+0x2d3/0x560 [btrfs]
  btrfs_relocate_block_group+0x2c7/0x4b0 [btrfs]
  btrfs_relocate_chunk+0x4c/0x1a0 [btrfs]
  btrfs_balance+0x925/0x13c0 [btrfs]
  btrfs_ioctl+0x19f1/0x25d0 [btrfs]
  __x64_sys_ioctl+0x90/0xd0
  do_syscall_64+0x3f/0xf0
  entry_SYSCALL_64_after_hwframe+0x6e/0x76

[CAUSE]
The dying line is at btrfs_repair_io_failure() call inside
btrfs_repair_eb_io_failure().

The function is still relying on the extent buffer using page sized
folios.
When the extent buffer is using larger folio, we go into the 2nd slot of
folios[], and triggered the NULL pointer dereference.

[FIX]
Migrate btrfs_repair_io_failure() to folio interfaces.

So that when we hit a larger folio, we just submit the whole folio in
one go.

This also affects data repair path through btrfs_end_repair_bio(),
thankfully data is still fully page based, we can just add an
ASSERT(), and use page_folio() to convert the page to folio.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15 23:03:58 +01:00
Qu Wenruo
55151ea9ec btrfs: migrate subpage code to folio interfaces
Although subpage itself is conflicting with higher folio, since subpage
(sectorsize < PAGE_SIZE and nodesize < PAGE_SIZE) means we will never
need higher order folio, there is a hidden pitfall:

- btrfs_page_*() helpers

Those helpers are an abstraction to handle both subpage and non-subpage
cases, which means we're going to pass pages pointers to those helpers.

And since those helpers are shared between data and metadata paths, it's
unavoidable to let them to handle folios, including higher order
folios).

Meanwhile for true subpage case, we should only have a single page
backed folios anyway, thus add a new ASSERT() for btrfs_subpage_assert()
to ensure that.

Also since those helpers are shared between both data and metadata, add
some extra ASSERT()s for data path to make sure we only get single page
backed folio for now.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15 23:03:58 +01:00
Qu Wenruo
8d99361835 btrfs: migrate get_eb_page_index() and get_eb_offset_in_page() to folios
These two functions are still using the old page based code, which is
not going to handle larger folios at all.

The migration itself is going to involve the following changes:

- PAGE_SIZE -> folio_size()
- PAGE_SHIFT -> folio_shift()
- get_eb_page_index() -> get_eb_folio_index()
- get_eb_offset_in_page() -> get_eb_offset_in_folio()

And since we're going to support larger folios, although above straight
conversion is good enough, this patch would add extra comments in the
involved functions to explain why the same single line code can now
cover 3 cases:

- folio_size == PAGE_SIZE, sectorsize == PAGE_SIZE, nodesize >= PAGE_SIZE
  The common, non-subpage case with per-page folio.

- folio_size > PAGE_SIZE, sectorsize == PAGE_SIZE, nodesize >= PAGE_SIZE
  The incoming larger folio, non-subpage case.

- folio_size == PAGE_SIZE, sectorsize < PAGE_SIZE, nodesize < PAGE_SIZE
  The existing subpage case, we won't larger folio anyway.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15 23:03:58 +01:00
Qu Wenruo
13df3775ef btrfs: cleanup metadata page pointer usage
Although we have migrated extent_buffer::pages[] to folios[], we're
still mostly using the folio_page() help to grab the page.

This patch would do the following cleanups for metadata:

- Introduce num_extent_folios() helper
  This is to replace most num_extent_pages() callers.

- Use num_extent_folios() to iterate future large folios
  This allows us to use things like
  bio_add_folio()/bio_add_folio_nofail(), and only set the needed flags
  for the folio (aka the leading/tailing page), which reduces the loop
  iteration to 1 for large folios.

- Change metadata related functions to use folio pointers
  Including their function name, involving:
  * attach_extent_buffer_page()
  * detach_extent_buffer_page()
  * page_range_has_eb()
  * btrfs_release_extent_buffer_pages()
  * btree_clear_page_dirty()
  * btrfs_page_inc_eb_refs()
  * btrfs_page_dec_eb_refs()

- Change btrfs_is_subpage() to accept an address_space pointer
  This is to allow both page->mapping and folio->mapping to be utilized.
  As data is still using the old per-page code, and may keep so for a
  while.

- Special corner case place holder for future order mismatches between
  extent buffer and inode filemap
  For now it's  just a block of comments and a dead ASSERT(), no real
  handling yet.

The subpage code would still go page, just because subpage and large
folio are conflicting conditions, thus we don't need to bother subpage
with higher order folios at all. Just folio_page(folio, 0) would be
enough.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minor styling tweaks ]
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15 23:01:04 +01:00
Qu Wenruo
082d5bb9b3 btrfs: migrate extent_buffer::pages[] to folio
For now extent_buffer::pages[] are still only accepting single page
pointer, thus we can migrate to folios pretty easily.

As for single page, page and folio are 1:1 mapped, including their page
flags.

This patch would just do the conversion from struct page to struct
folio, providing the first step to higher order folio in the future.

This conversion is pretty simple:

- extent_buffer::pages[] -> extent_buffer::folios[]

- page_address(eb->pages[i]) -> folio_address(eb->pages[i])

- eb->pages[i] -> folio_page(eb->folios[i], 0)

There would be more specific cleanups preparing for the incoming higher
order folio support.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15 23:01:04 +01:00
David Sterba
6140ba8a0a btrfs: switch btrfs_root::delayed_nodes_tree to xarray from radix-tree
The radix-tree has been superseded by the xarray
(https://lwn.net/Articles/745073), this patch converts the
btrfs_root::delayed_nodes, the APIs are used in a simple way.

First idea is to do xa_insert() but this would require GFP_ATOMIC
allocation which we want to avoid if possible. The preload mechanism of
radix-tree can be emulated within the xarray API.

- xa_reserve() with GFP_NOFS outside of the lock, the reserved entry
  is inserted atomically at most once

- xa_store() under a lock, in case something races in we can detect that
  and xa_load() returns a valid pointer

All uses of xa_load() must check for a valid pointer in case they manage
to get between the xa_reserve() and xa_store(), this is handled in
btrfs_get_delayed_node().

Otherwise the functionality is equivalent, xarray implements the
radix-tree and there should be no performance difference.

The patch continues the efforts started in 253bf57555 ("btrfs: turn
delayed_nodes_tree into an XArray") and fixes the problems with locking
and GFP flags 088aea3b97 ("Revert "btrfs: turn delayed_nodes_tree
into an XArray"").

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15 23:01:03 +01:00
Josef Bacik
9fb3b1a7fe btrfs: set clear_cache if we use usebackuproot
We're currently setting this when we try to load the roots and we see
that usebackuproot is set.  Instead set this at mount option parsing
time.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15 20:27:05 +01:00
Josef Bacik
83e3a40a69 btrfs: move one shot mount option clearing to super.c
There's no reason this has to happen in open_ctree, and in fact in the
old mount API we had to call this from remount.  Move this to super.c,
unexport it, and call it from both mount and reconfigure.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15 20:27:04 +01:00
Josef Bacik
41d46b290e btrfs: move the device specific mount options to super.c
We add these mount options based on the fs_devices settings, which can
be set once we've opened the fs_devices.  Move these into their own
helper and call it from get_tree_super.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15 20:27:04 +01:00
Josef Bacik
ad21f15b0f btrfs: switch to the new mount API
Now that we have all of the parts in place to use the new mount API,
switch our fs_type to use the new callbacks.

There are a few things that have to be done at the same time because of
the order of operations changes that come along with the new mount API.
These must be done in the same patch otherwise things will go wrong.

1. Export and use btrfs_check_options in open_ctree().  This is because
   the options are done ahead of time, and we need to check them once we
   have the feature flags loaded.

2. Update the free space cache settings.  Since we're coming in with the
   options already set we need to make sure we don't undo what the user
   has asked for.

3. Set our sb_flags at init_fs_context time, the fs_context stuff is
   trying to manage the sb_flagss itself, so move that into
   init_fs_context and out of the fill super part.

Additionally I've marked the unused functions with __maybe_unused and
will remove them in a future patch.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15 20:27:04 +01:00
Josef Bacik
2496bff6e5 btrfs: add a NOSPACECACHE mount option flag
With the old mount API we'd pre-populate the mount options with the
space cache settings of the file system, and then the user toggled them
on or off with the mount options.  When we switch to the new mount API
the mount options will be set before we get into opening the file
system, so we need a flag to indicate that the user explicitly asked for
-o nospace_cache so we can make the appropriate changes after the fact.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15 20:27:04 +01:00
Josef Bacik
272efa308f btrfs: do not allow free space tree rebuild on extent tree v2
We currently don't allow these options to be set if we're extent tree v2
via the mount option parsing.  However when we switch to the new mount
API we'll no longer have the super block loaded, so won't be able to
make this distinction at mount option parsing time.  Address this by
checking for extent tree v2 at the point where we make the decision to
rebuild the free space tree.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15 20:27:03 +01:00
Josef Bacik
a6a8f22a4a btrfs: move space cache settings into open_ctree
Currently we pre-load the space cache settings in btrfs_parse_options,
however when we switch to the new mount API the mount option parsing
will happen before we have the super block loaded.  Add a helper to set
the appropriate options based on the fs settings, this will allow us to
have consistent free space cache settings.

This also folds in the space cache related decisions we make for subpage
sectorsize support, so all of this is done in one place.

Since this was being called by parse options it looks like we're
changing the behavior of remount, but in fact we aren't.  The
pre-loading of the free space cache settings is done because we want to
handle the case of users not using any space_cache options, we'll derive
the appropriate mount option based on the on disk state.  On remount
this wouldn't reset anything as we'll have cleared the v1 cache
generation if we mounted -o nospace_cache.  Similarly it's impossible to
turn off the free space tree without specifically saying -o
nospace_cache,clear_cache, which will delete the free space tree and
clear the compat_ro option.  Again in this case calling this code in
remount wouldn't result in any change.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15 20:27:03 +01:00
Josef Bacik
6207c9e3c2 btrfs: set default compress type at btrfs_init_fs_info time
With the new mount API we'll be setting our compression well before we
call open_ctree.  We don't want to overwrite our settings, so set the
default in btrfs_init_fs_info instead of open_ctree.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15 20:27:03 +01:00
Qu Wenruo
397239ed6a btrfs: allow extent buffer helpers to skip cross-page handling
Currently btrfs extent buffer helpers are doing all the cross-page
handling, as there is no guarantee that all those eb pages are
contiguous.

However on systems with enough memory, there is a very high chance the
page cache for btree_inode are allocated with physically contiguous
pages.

In that case, we can skip all the complex cross-page handling, thus
speeding up the code.

This patch adds a new member, extent_buffer::addr, which is only set to
non-NULL if all the extent buffer pages are physically contiguous.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15 20:27:03 +01:00
Johannes Thumshirn
aa6313e6ff btrfs: zoned: don't clear dirty flag of extent buffer
One a zoned filesystem, never clear the dirty flag of an extent buffer,
but instead mark it as zeroout.

On writeout, when encountering a marked extent_buffer, zero it out.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15 20:27:02 +01:00
Johannes Thumshirn
cbf44cd93d btrfs: rename EXTENT_BUFFER_NO_CHECK to EXTENT_BUFFER_ZONED_ZEROOUT
EXTENT_BUFFER_ZONED_ZEROOUT better describes the state of the extent buffer,
namely it is written as all zeros. This is needed in zoned mode, to
preserve I/O ordering.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15 20:27:02 +01:00
Filipe Manana
7dc66abb5a btrfs: use a dedicated data structure for chunk maps
Currently we abuse the extent_map structure for two purposes:

1) To actually represent extents for inodes;
2) To represent chunk mappings.

This is odd and has several disadvantages:

1) To create a chunk map, we need to do two memory allocations: one for
   an extent_map structure and another one for a map_lookup structure, so
   more potential for an allocation failure and more complicated code to
   manage and link two structures;

2) For a chunk map we actually only use 3 fields (24 bytes) of the
   respective extent map structure: the 'start' field to have the logical
   start address of the chunk, the 'len' field to have the chunk's size,
   and the 'orig_block_len' field to contain the chunk's stripe size.

   Besides wasting a memory, it's also odd and not intuitive at all to
   have the stripe size in a field named 'orig_block_len'.

   We are also using 'block_len' of the extent_map structure to contain
   the chunk size, so we have 2 fields for the same value, 'len' and
   'block_len', which is pointless;

3) When an extent map is associated to a chunk mapping, we set the bit
   EXTENT_FLAG_FS_MAPPING on its flags and then make its member named
   'map_lookup' point to the associated map_lookup structure. This means
   that for an extent map associated to an inode extent, we are not using
   this 'map_lookup' pointer, so wasting 8 bytes (on a 64 bits platform);

4) Extent maps associated to a chunk mapping are never merged or split so
   it's pointless to use the existing extent map infrastructure.

So add a dedicated data structure named 'btrfs_chunk_map' to represent
chunk mappings, this is basically the existing map_lookup structure with
some extra fields:

1) 'start' to contain the chunk logical address;
2) 'chunk_len' to contain the chunk's length;
3) 'stripe_size' for the stripe size;
4) 'rb_node' for insertion into a rb tree;
5) 'refs' for reference counting.

This way we do a single memory allocation for chunk mappings and we don't
waste memory for them with unused/unnecessary fields from an extent_map.

We also save 8 bytes from the extent_map structure by removing the
'map_lookup' pointer, so the size of struct extent_map is reduced from
144 bytes down to 136 bytes, and we can now have 30 extents map per 4K
page instead of 28.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15 20:27:02 +01:00
Filipe Manana
6000d9313f btrfs: remove log_extents_lock and logged_list from struct btrfs_root
The logged_list[2] and log_extents_lock[2] members of struct btrfs_root
are no longer used, their last use was removed in commit 5636cf7d6d
("btrfs: remove the logged extents infrastructure"). So remove these
fields. This reduces the size of struct btrfs_root, on a release kernel,
from 1392 bytes down to 1352 bytes.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15 20:27:00 +01:00
Boris Burkov
b321a52cce btrfs: free qgroup pertrans reserve on transaction abort
If we abort a transaction, we never run the code that frees the pertrans
qgroup reservation. This results in warnings on unmount as that
reservation has been leaked. The leak isn't a huge issue since the fs is
read-only, but it's better to clean it up when we know we can/should. Do
it during the cleanup_transaction step of aborting.

CC: stable@vger.kernel.org # 5.15+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-06 22:32:49 +01:00
Qu Wenruo
2db313205f btrfs: add dmesg output for first mount and last unmount of a filesystem
There is a feature request to add dmesg output when unmounting a btrfs.
There are several alternative methods to do the same thing, but with
their own problems:

- Use eBPF to watch btrfs_put_super()/open_ctree()
  Not end user friendly, they have to dip their head into the source
  code.

- Watch for directory /sys/fs/<uuid>/
  This is way more simple, but still requires some simple device -> uuid
  lookups.  And a script needs to use inotify to watch /sys/fs/.

Compared to all these, directly outputting the information into dmesg
would be the most simple one, with both device and UUID included.

And since we're here, also add the output when mounting a filesystem for
the first time for parity. A more fine grained monitoring of subvolume
mounts should be done by another layer, like audit.

Now mounting a btrfs with all default mkfs options would look like this:

  [81.906566] BTRFS info (device dm-8): first mount of filesystem 633b5c16-afe3-4b79-b195-138fe145e4f2
  [81.907494] BTRFS info (device dm-8): using crc32c (crc32c-intel) checksum algorithm
  [81.908258] BTRFS info (device dm-8): using free space tree
  [81.912644] BTRFS info (device dm-8): auto enabling async discard
  [81.913277] BTRFS info (device dm-8): checking UUID tree
  [91.668256] BTRFS info (device dm-8): last unmount of filesystem 633b5c16-afe3-4b79-b195-138fe145e4f2

CC: stable@vger.kernel.org # 5.4+
Link: https://github.com/kdave/btrfs-progs/issues/689
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
2023-11-23 22:27:26 +01:00
Filipe Manana
0124855ff1 btrfs: add and use helpers for reading and writing last_trans_committed
Currently the last_trans_committed field of struct btrfs_fs_info is
modified and read without any locking or other protection. For example
early in the fsync path, skip_inode_logging() is called which reads
fs_info->last_trans_committed, but at the same time we can have a
transaction commit completing and updating that field.

In the case of an fsync this is harmless and any data race should be
rare and at most cause an unnecessary logging of an inode.

To avoid data race warnings from tools like KCSAN and other issues such
as load and store tearing (amongst others, see [1]), create helpers to
access the last_trans_committed field of struct btrfs_fs_info using
READ_ONCE() and WRITE_ONCE(), and use these helpers everywhere.

[1] https://lwn.net/Articles/793253/

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12 16:44:17 +02:00
Filipe Manana
6008859b6c btrfs: add and use helpers for reading and writing log_transid
Currently the log_transid field of a root is always modified while holding
the root's log_mutex locked. Most readers of a root's log_transid are also
holding the root's log_mutex locked, however there is one exception which
is btrfs_set_inode_last_trans() where we don't take the lock to avoid
blocking several operations if log syncing is happening in parallel.

Any races here should be harmless, and in the worst case they may cause a
fsync to log an inode when it's not really needed, so nothing bad from a
functional perspective.

To avoid data race warnings from tools like KCSAN and other issues such
as load and store tearing (amongst others, see [1]), create helpers to
access the log_transid field of a root using READ_ONCE() and WRITE_ONCE(),
and use these helpers where needed.

[1] https://lwn.net/Articles/793253/

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12 16:44:17 +02:00
Filipe Manana
f985078796 btrfs: add and use helpers for reading and writing last_log_commit
Currently, the last_log_commit of a root can be accessed concurrently
without any lock protection. Readers can be calling btrfs_inode_in_log()
early in a fsync call, which reads a root's last_log_commit, while a
writer can change the last_log_commit while a log tree if being synced,
at btrfs_sync_log(). Any races here should be harmless, and in the worst
case they may cause a fsync to log an inode when it's not really needed,
so nothing bad from a functional perspective.

To avoid data race warnings from tools like KCSAN and other issues such
as load and store tearing (amongst others, see [1]), create helpers to
access the last_log_commit field of a root using READ_ONCE() and
WRITE_ONCE(), and use these helpers everywhere.

[1] https://lwn.net/Articles/793253/

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12 16:44:17 +02:00
Anand Jain
a5b8a5f9f8 btrfs: support cloned-device mount capability
Guilherme's previous work [1] aimed at the mounting of cloned devices
using a superblock flag SINGLE_DEV during mkfs.
 [1] https://lore.kernel.org/linux-btrfs/20230831001544.3379273-1-gpiccoli@igalia.com/

Building upon this work, here is in memory only approach. As it mounts
we determine if the same fsid is already mounted if then we generate a
random temp fsid which shall be used the mount, in memory only not
written to the disk. We distinguish devices by devt.

Example:
  $ fallocate -l 300m ./disk1.img
  $ mkfs.btrfs -f ./disk1.img
  $ cp ./disk1.img ./disk2.img
  $ cp ./disk1.img ./disk3.img
  $ mount -o loop ./disk1.img /btrfs
  $ mount -o ./disk2.img /btrfs1
  $ mount -o ./disk3.img /btrfs2

  $ btrfs fi show -m
  Label: none  uuid: 4a212b48-1bec-46a5-938a-783c8c1f0b02
	Total devices 1 FS bytes used 144.00KiB
	devid    1 size 300.00MiB used 88.00MiB path /dev/loop0

  Label: none  uuid: adabf2fe-5515-4ad0-95b4-7b1609218c16
	Total devices 1 FS bytes used 144.00KiB
	devid    1 size 300.00MiB used 88.00MiB path /dev/loop1

  Label: none  uuid: 1d77d0df-7d92-439e-adbd-20b9b86fdedb
	Total devices 1 FS bytes used 144.00KiB
	devid    1 size 300.00MiB used 88.00MiB path /dev/loop2

Co-developed-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12 16:44:17 +02:00