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There have been two file locks used to protect lvm
"global state": "ORPHANS" and "GLOBAL".
Commands that used the ORPHAN flock in exclusive mode:
pvcreate, pvremove, vgcreate, vgextend, vgremove,
vgcfgrestore
Commands that used the ORPHAN flock in shared mode:
vgimportclone, pvs, pvscan, pvresize, pvmove,
pvdisplay, pvchange, fullreport
Commands that used the GLOBAL flock in exclusive mode:
pvchange, pvscan, vgimportclone, vgscan
Commands that used the GLOBAL flock in shared mode:
pvscan --cache, pvs
The ORPHAN lock covers the important cases of serializing
the use of orphan PVs. It also partially covers the
reporting of orphan PVs (although not correctly as
explained below.)
The GLOBAL lock doesn't seem to have a clear purpose
(it may have eroded over time.)
Neither lock correctly protects the VG namespace, or
orphan PV properties.
To simplify and correct these issues, the two separate
flocks are combined into the one GLOBAL flock, and this flock
is used from the locking sites that are in place for the
lvmlockd global lock.
The logic behind the lvmlockd (distributed) global lock is
that any command that changes "global state" needs to take
the global lock in ex mode. Global state in lvm is: the list
of VG names, the set of orphan PVs, and any properties of
orphan PVs. Reading this global state can use the global lock
in sh mode to ensure it doesn't change while being reported.
The locking of global state now looks like:
lockd_global()
previously named lockd_gl(), acquires the distributed
global lock through lvmlockd. This is unchanged.
It serializes distributed lvm commands that are changing
global state. This is a no-op when lvmlockd is not in use.
lockf_global()
acquires an flock on a local file. It serializes local lvm
commands that are changing global state.
lock_global()
first calls lockf_global() to acquire the local flock for
global state, and if this succeeds, it calls lockd_global()
to acquire the distributed lock for global state.
Replace instances of lockd_gl() with lock_global(), so that the
existing sites for lvmlockd global state locking are now also
used for local file locking of global state. Remove the previous
file locking calls lock_vol(GLOBAL) and lock_vol(ORPHAN).
The following commands which change global state are now
serialized with the exclusive global flock:
pvchange (of orphan), pvresize (of orphan), pvcreate, pvremove,
vgcreate, vgextend, vgremove, vgreduce, vgrename,
vgcfgrestore, vgimportclone, vgmerge, vgsplit
Commands that use a shared flock to read global state (and will
be serialized against the prior list) are those that use
process_each functions that are based on processing a list of
all VG names, or all PVs. The list of all VGs or all PVs is
global state and the shared lock prevents those lists from
changing while the command is processing them.
The ORPHAN lock previously attempted to produce an accurate
listing of orphan PVs, but it was only acquired at the end of
the command during the fake vg_read of the fake orphan vg.
This is not when orphan PVs were determined; they were
determined by elimination beforehand by processing all real
VGs, and subtracting the PVs in the real VGs from the list
of all PVs that had been identified during the initial scan.
This is fixed by holding the single global lock in shared mode
while processing all VGs to determine the list of orphan PVs.
which defines the amount of memory that lvm will allocate
for bcache. Increasing this setting is required if it is
smaller than a single copy of VG metadata.
Without this, the output from different commands in a single
log file could not be separated.
Change the default "indent" setting to 0 so that the default
debug output does not include variable spaces in the middle
of debug lines.
Ensure configure.h is always 1st. included header.
Maybe we could eventually introduce gcc -include option, but for now
this better uses dependency tracking.
Also move _REENTRANT and _GNU_SOURCE into configure.h so it
doesn't need to be present in various source files.
This ensures consistent compilation of headers like stdio.h since
it may produce different declaration.
io_setup() for aio may fail if a system has reached the
aio request limit. In this case, fall back to using
sync io. Also, lvm use of aio can be disabled entirely
with config setting global/use_aio=0.
The system limit for aio requests can be seen from
/proc/sys/fs/aio-max-nr
The current usage of aio requests can be seen from
/proc/sys/fs/aio-nr
The system limit for aio requests can be increased by
setting fs.aio-max-nr using sysctl.
Also add last-byte limit to the sync io code.
The last commit related to this was incomplete:
"Implement lock-override options without locking type"
This is further reworking and reduction of the locking.[ch]
layer which handled all clustering, but is now only used
for file locking. The "locking types" that this layer
implemented were removed previously, leaving only the
standard file locking. (Some cluster-related artifacts
remain to be cleared out later.)
Command options to override or modify locking behavior
are reimplemented here without using the locking types.
Also, deprecated locking_type values are recognized,
and implemented as if one of the equivalent override
options was set.
Options that override file locking are:
. --nolocking disables all file locking.
. --readonly grants read lock requests without actually
taking a file lock, and refuses write lock requests.
. --ignorelockingfailure tries to set up file locks and
uses them normally if possible. When not possible, it
behaves like --readonly, but allows activation.
. --sysinit is the same as ignorelockingfailure.
. global/metadata_read_only acquires actual read file
locks, and refuses write lock requests.
(Some of these options could probably be deprecated
because they were added as workarounds to various
locking_type behaviors that are now deprecated.)
The locking_type setting now has one valid value: 1 which
refers to standard file locking. Configs that contain
deprecated values are recognized and still work in
largely the same way:
. 0 disabled all locking, now implemented like --nolocking
is set. Allow the nolocking option in all commands.
. 1 is the normal file locking setting and is unchanged.
. 2 was for external locking which was not used, and
reverts to normal file locking.
. 3 was for cluster/clvm. This reverts to normal file
locking, and prints messages about lvmlockd.
. 4 was equivalent to readonly, now implemented like
--readonly is set.
. 5 disabled all locking, now implemented like
--nolocking is set.
The device-mapper directory now holds a copy of libdm source. At
the moment this code is identical to libdm. Over time code will
migrate out to appropriate places (see doc/refactoring.txt).
The libdm directory still exists, and contains the source for the
libdevmapper shared library, which we will continue to ship (though
not neccessarily update).
All code using libdm should now use the version in device-mapper.
As we start refactoring the code to break dependencies (see doc/refactoring.txt),
I want us to use full paths in the includes (eg, #include "base/data-struct/list.h").
This makes it more obvious when we're breaking abstraction boundaries, eg, including a file in
metadata/ from base/
I don't like having this in a common header because it means you end
up including too much and causing unneccessary dependencies. eg,
lib/misc/lib.h includes libdevmapper.h, internationalisation, and
logging stuff.
The copy of VG metadata stored in lvmcache was not being used
in general. It pretended to be a generic VG metadata cache,
but was not being used except for clvmd activation. There
it was used to avoid reading from disk while devices were
suspended, i.e. in resume.
This removes the code that attempted to make this look
like a generic metadata cache, and replaces with with
something narrowly targetted to what it's actually used for.
This is a way of passing the VG from suspend to resume in
clvmd. Since in the case of clvmd one caller can't simply
pass the same VG to both suspend and resume, suspend needs
to stash the VG somewhere that resume can grab it from.
(resume doesn't want to read it from disk since devices
are suspended.) The lvmcache vginfo struct is used as a
convenient place to stash the VG to pass it from suspend
to resume, even though it isn't related to the lvmcache
or vginfo. These suspended_vg* vginfo fields should
not be used or touched anywhere else, they are only to
be used for passing the VG data from suspend to resume
in clvmd. The VG data being passed between suspend and
resume is never modified, and will only exist in the
brief period between suspend and resume in clvmd.
suspend has both old (current) and new (precommitted)
copies of the VG metadata. It stashes both of these in
the vginfo prior to suspending devices. When vg_commit
is successful, it sets a flag in vginfo as before,
signaling the transition from old to new metadata.
resume grabs the VG stashed by suspend. If the vg_commit
happened, it grabs the new VG, and if the vg_commit didn't
happen it grabs the old VG. The VG is then used to resume
LVs.
This isolates clvmd-specific code and usage from the
normal lvm vg_read code, making the code simpler and
the behavior easier to verify.
Sequence of operations:
- lv_suspend() has both vg_old and vg_new
and stashes a copy of each onto the vginfo:
lvmcache_save_suspended_vg(vg_old);
lvmcache_save_suspended_vg(vg_new);
- vg_commit() happens, which causes all clvmd
instances to call lvmcache_commit_metadata(vg).
A flag is set in the vginfo indicating the
transition from the old to new VG:
vginfo->suspended_vg_committed = 1;
- lv_resume() needs either vg_old or vg_new
to use in resuming LVs. It doesn't want to
read the VG from disk since devices are
suspended, so it gets the VG stashed by
lv_suspend:
vg = lvmcache_get_suspended_vg(vgid);
If the vg_commit did not happen, suspended_vg_committed
will not be set, and in this case, lvmcache_get_suspended_vg()
will return the old VG instead of the new VG, and it will
resume LVs based on the old metadata.
When file-locking mode failed on locking, such description was leaked
(typically not an issue since command usually exists afterwards).
So shirt close() at the end of function and use it in all error paths.
Also make sure, when interrrupt is detected, it's really not holding
lock and returns 0.
SIGINT isn't blocked properly after a sigint_allow(),
sigint_restore() cycle leading to illicit interruptable
metadata updates. These can leave corrupted metadata behind.
Issues addressed in this commit:
sigint_allow() fails to set _oldmasked[] members properly due
to an offset by one bug on indexing the members of the array.
It bails out prematurely comparing to MAX_SIGINTS causing nesting
depths to be one less than MAX_SIGINTS. Fix the comparision.
Correct the related comparison flaw in sigint_restore().
Initialize all sig_atomic_t variables consequently.
Resolves: rhbz1440766
Add a macro for the clz (count leading zeros) operation.
Use the GCC __builtin_clz() for clz() if it is available and fall
back to a shift based implementation on systems that do not set
HAVE___BUILTIN_CLZ.
Currently, the output is separated in 3 parts and each part can go into
a separate and user-defined file descriptor:
- common output (stdout by default, customizable by LVM_OUT_FD environment variable)
- error output (stderr by default, customizable by LVM_ERR_FD environment variable)
- report output (stdout by default, customizable by LVM_REPORT_FD environment variable)
For example, each type of output goes to different output file:
[0] fedora/~ # export LVM_REPORT_FD=3
[0] fedora/~ # lvs fedora vg/abc 1>out 2>err 3>report
[0] fedora/~ # cat out
[0] fedora/~ # cat err
Volume group "vg" not found
Cannot process volume group vg
[0] fedora/~ # cat report
LV VG Attr LSize Layout Role CTime
root fedora -wi-ao---- 19.00g linear public Wed May 27 2015 08:09:21
swap fedora -wi-ao---- 500.00m linear public Wed May 27 2015 08:09:21
Another example in LVM shell where the report goes to "report" file:
[0] fedora/~ # export LVM_REPORT_FD=3
[0] fedora/~ # lvm 3>report
(in lvm shell)
lvm> vgs
(content of "report" file)
[1] fedora/~ # cat report
VG #PV #LV #SN Attr VSize VFree
fedora 1 2 0 wz--n- 19.49g 0
(in lvm shell)
lvm> lvs
(content of "report" file)
[1] fedora/~ # cat report
VG #PV #LV #SN Attr VSize VFree
fedora 1 2 0 wz--n- 19.49g 0
LV VG Attr LSize Layout Role CTime
root fedora -wi-ao---- 19.00g linear public Wed May 27 2015 08:09:21
swap fedora -wi-ao---- 500.00m linear public Wed May 27 2015 08:09:21
If compiling without udev_sync support, udev_get_library_context simply
returns NULL so we don't need to remember putting ifdef UDEV_SYNC_SUPPORT
in the code all the time we just need to check whether there's any udev
context initialized or not.
Make lvm2_disable_dmeventd_monitoring() more explicit.
As memlock_inc_daemon() is also used by clvmd, which
does changes dmeventd and suspend ignore state at
some stages - make updates of these 2 variable
tied to the call of lvm2_disable_dmeventd_monitoring().
Once this call is made dmeventd monitoring
and suspended devices are ignored.
TODO: all lvm-global settings should really be moved
to command context.
Relocate generated configure.h and lvm-version.h outside
of compilable .c source tree.
The reason is behind - when compiling in builddir != srcdir
the generated file in lib/misc/configure.h was used for all compiled
source file except ones located in lib/misc dir - those would have used
configure.h file located in this dir - if there have existed one (i.e.
from some other build)
This problem was only visible, when srcdir == buildir was used before
trying to use srcdri != builddir (as configure.h appeared then in
srcdir).
