Use KM_MAYFAIL for the m_perag allocation, we can deal with the error
easily and blocking forever during mount is not a good idea either.
SGI-PV: 981498
SGI-Modid: xfs-linux-melb:xfs-kern:31837a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
xfs_mount_free mostly frees the perag data, which is something that is
duplicated in the mount error path.
Move the XFS_QM_DONE call to the caller and remove the useless
mutex_destroy/spinlock_destroy calls so that we can re-use it for the
mount error path. Also rename it to xfs_free_perag to reflect what it
does.
SGI-PV: 981498
SGI-Modid: xfs-linux-melb:xfs-kern:31836a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
xfs_readsb is called before xfs_mount so xfs_freesb should be called after
xfs_unmountfs, too. This means it now happens after a few things during
the of xfs_unmount which all have nothing to do with the superblock.
SGI-PV: 981498
SGI-Modid: xfs-linux-melb:xfs-kern:31835a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
xfs_unmounts can't and shouldn't return errors so declare it as returning
void.
SGI-PV: 981498
SGI-Modid: xfs-linux-melb:xfs-kern:31833a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Remove all the useless flags and code keyed off it in xfs_mountfs.
SGI-PV: 981498
SGI-Modid: xfs-linux-melb:xfs-kern:31831a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
The root inode is allocated in xfs_mountfs so it should be release in
xfs_unmountfs. For the unmount case that means we do it after the the
xfs_sync(mp, SYNC_WAIT | SYNC_CLOSE) in the forced shutdown case and the
dmapi unmount event. Note that both reference the rip variable which might
be freed by that time in case inode flushing has kicked in, so strictly
speaking this might count as a bug fix
SGI-PV: 981498
SGI-Modid: xfs-linux-melb:xfs-kern:31830a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
All the error injection is already enabled through ifdef DEBUG, so kill
the never set second cpp symbol to activate it without the rest of the
debugging infrastructure.
SGI-PV: 981498
SGI-Modid: xfs-linux-melb:xfs-kern:31771a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Niv Sardi <xaiki@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Add a helper to free the m_fsname/m_rtname/m_logname allocations and use
it properly for all mount failure cases. Also switch the allocations for
these to kstrdup while we're at it.
SGI-PV: 981498
SGI-Modid: xfs-linux-melb:xfs-kern:31728a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Niv Sardi <xaiki@sgi.com>
Signed-off-by: David Chinner <david@fromorbit.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
If we don't do the blocksize/PAGESIZE check before calling
xfs_sb_validate_fsb_count() we can assert if we try to mount with a
blocksize > pagesize. The assert is valid so leave it and just move the
blocksize/pagesize check earlier.
SGI-PV: 983734
SGI-Modid: xfs-linux-melb:xfs-kern:31365a
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: David Chinner <dgc@sgi.com>
xfs_mount_init is inlined into xfs_fs_fill_super and allocation switched
to kzalloc. Plug a leak of the mount structure for most early mount
failures. Move xfs_icsb_init_counters to as late as possible in the mount
path and make sure to undo it so that no stale hotplug cpu notifiers are
left around on mount failures.
SGI-PV: 981951
SGI-Modid: xfs-linux-melb:xfs-kern:31196a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Currently closing the rt/log block device is done in the wrong spot, and
far too early. So revampt it:
- xfs_blkdev_put moved out of xfs_free_buftarg into the caller so that
it is done after tearing down the buftarg completely.
- call to xfs_unmountfs_close moved from xfs_mountfs into caller so
that it's done after tearing down the filesystem completely.
- xfs_unmountfs_close is renamed to xfs_close_devices and made static
in xfs_super.c
- opening of the block devices is split into a helper xfs_open_devices
that is symetric in use to xfs_close_devices
- xfs_unmountfs can now lose struct cred
- error handling around device opening sanitized in xfs_fs_fill_super
SGI-PV: 981951
SGI-Modid: xfs-linux-melb:xfs-kern:31193a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Freeing of the superblock is already handled in the caller, and that is
more symmetric with the mount path, too.
SGI-PV: 981951
SGI-Modid: xfs-linux-melb:xfs-kern:31192a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Quite useless wrapper that doesn't help making the code more readable.
SGI-PV: 981498
SGI-Modid: xfs-linux-melb:xfs-kern:31184a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Recent changes to update the version number during mount (attr2 stuff)
failed to change the assert that checked for calid flags being changed on
mount. Clearly this path hasn't been exercised by the test code....
SGI-PV: 981950
SGI-Modid: xfs-linux-melb:xfs-kern:31183a
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
kmem_free() function takes (ptr, size) arguments but doesn't actually use
second one.
This patch removes size argument from all callsites.
SGI-PV: 981498
SGI-Modid: xfs-linux-melb:xfs-kern:31050a
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
features2 fields.
Previously, mounting with noattr2 failed to achieve anything because
although it cleared the attr2 mount flag, it would set it again as soon as
it processed the superblock fields. The fix now has an explicit noattr2
flag and uses it later to fix up the versionnum and features2 fields.
SGI-PV: 980021
SGI-Modid: xfs-linux-melb:xfs-kern:31003a
Signed-off-by: Tim Shimmin <tes@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
With the last two patches XFS_ICSB_SB_LOCKED is never checked and only
superflously passed to xfs_icsb_count, so kill it.
SGI-PV: 976035
SGI-Modid: xfs-linux-melb:xfs-kern:30920a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Add an xfs_icsb_balance_counter_locked for the case where mp->m_sb_lock is
already locked.
SGI-PV: 976035
SGI-Modid: xfs-linux-melb:xfs-kern:30918a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Add a new xfs_icsb_sync_counters_locked for the case where m_sb_lock
is already taken and add a flags argument to xfs_icsb_sync_counters so
that xfs_icsb_sync_counters_flags is not needed.
SGI-PV: 976035
SGI-Modid: xfs-linux-melb:xfs-kern:30917a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
xfsbdstrat() is declared to return an error. That is never checked because
the error is propagated by the xfs_buf_t that is passed through the
function.
Mark xfsbdstrat() as returning void and comment the prototype on the
methods needed for error checking.
SGI-PV: 980084
SGI-Modid: xfs-linux-melb:xfs-kern:30823a
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Niv Sardi <xaiki@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
xfs_trans_commit() can return errors when there are problems in the
transaction subsystem. They are indicative that the entire transaction may
be incomplete, and hence the error should be propagated as there is a good
possibility that there is something fatally wrong in the filesystem. Catch
and propagate or warn about commit errors in the places where they are
currently ignored.
SGI-PV: 980084
SGI-Modid: xfs-linux-melb:xfs-kern:30795a
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Niv Sardi <xaiki@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
xfs_reserve_blocks() can fail in interesting ways. In neither case is it a
fatal error, but the result can lead to sub-optimal behaviour. Warn to the
syslog if the call fails but otherwise continue.
SGI-PV: 980084
SGI-Modid: xfs-linux-melb:xfs-kern:30784a
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Niv Sardi <xaiki@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Most VN_RELE calls either directly contain a XFS_ITOV or have the
corresponding xfs_inode already in scope. Use the IRELE helper instead of
VN_RELE to clarify the code. With a little more work we can kill VN_RELE
altogether and define IRELE in terms of iput directly.
SGI-PV: 976035
SGI-Modid: xfs-linux-melb:xfs-kern:30710a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
When xfs_mountfs is called by xfs_mount xfs_readsb was called 35 lines
above unconditionally, so there is no need to try to read the superblock
if it's not present. If any other port doesn't have the superblock read at
this point it should just call it directly from it's xfs_mount equivalent.
SGI-PV: 976035
SGI-Modid: xfs-linux-melb:xfs-kern:30603a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Donald Douwsma <donaldd@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Since older kernels may look in the sb_bad_features2 slot for flags,
rather than zeroing it out on fixup, we should make it equal to the
sb_features2 value.
Also, if the ATTR2 flag was not found prior to features2 fixup, it was not
set in the mount flags, so re-check after the fixup so that the current
session will use the feature.
Also fix up the comments to reflect these changes.
SGI-PV: 980085
SGI-Modid: xfs-linux-melb:xfs-kern:30778a
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Due to the xfs_dsb_t structure not being 64 bit aligned, the last field of
the on-disk superblock can vary in location This causes problems when the
filesystem gets moved to a different platform, or there is a 32 bit
userspace and 64 bit kernel.
This patch detects the defect at mount time, logs a warning such as:
XFS: correcting sb_features alignment problem
in dmesg and corrects the problem so that everything is OK. it also
blacklists the bad field in the superblock so it does not get used for
something else later on.
SGI-PV: 977636
SGI-Modid: xfs-linux-melb:xfs-kern:30539a
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Remove macro-to-small-function indirection from xfs_sb.h, and remove some
which are completely unused.
SGI-PV: 976035
SGI-Modid: xfs-linux-melb:xfs-kern:30528a
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Donald Douwsma <donaldd@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
When many hundreds to thousands of threads all try to do simultaneous
transactions and the log is in a tail-pushing situation (i.e. full), we
can get multiple threads walking the AIL list and contending on the AIL
lock.
The AIL push is, in effect, a simple I/O dispatch algorithm complicated by
the ordering constraints placed on it by the transaction subsystem. It
really does not need multiple threads to push on it - even when only a
single CPU is pushing the AIL, it can push the I/O out far faster that
pretty much any disk subsystem can handle.
So, to avoid contention problems stemming from multiple list walkers, move
the list walk off into another thread and simply provide a "target" to
push to. When a thread requires a push, it sets the target and wakes the
push thread, then goes to sleep waiting for the required amount of space
to become available in the log.
This mechanism should also be a lot fairer under heavy load as the waiters
will queue in arrival order, rather than queuing in "who completed a push
first" order.
Also, by moving the pushing to a separate thread we can do more
effectively overload detection and prevention as we can keep context from
loop iteration to loop iteration. That is, we can push only part of the
list each loop and not have to loop back to the start of the list every
time we run. This should also help by reducing the number of items we try
to lock and/or push items that we cannot move.
Note that this patch is not intended to solve the inefficiencies in the
AIL structure and the associated issues with extremely large list
contents. That needs to be addresses separately; parallel access would
cause problems to any new structure as well, so I'm only aiming to isolate
the structure from unbounded parallelism here.
SGI-PV: 972759
SGI-Modid: xfs-linux-melb:xfs-kern:30371a
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
These are mostly locking annotations, marking things static, casts where
needed and declaring stuff in header files.
SGI-PV: 971186
SGI-Modid: xfs-linux-melb:xfs-kern:30002a
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Refactoring xfs_mountfs() to call sub-functions for logical chunks can
help save a bit of stack, and can make it easier to read this long
function.
The mount path is one of the longest common callchains, easily getting to
within a few bytes of the end of a 4k stack when over lvm, quotas are
enabled, and quotacheck must be done.
With this change on top of the other stack-related changes I've sent, I
can get xfs to survive a normal xfsqa run on 4k stacks over lvm.
SGI-PV: 971186
SGI-Modid: xfs-linux-melb:xfs-kern:29834a
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Donald Douwsma <donaldd@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
remove spinlock init abstraction macro in spin.h, remove the callers, and
remove the file. Move no-op spinlock_destroy to xfs_linux.h Cleanup
spinlock locals in xfs_mount.c
SGI-PV: 970382
SGI-Modid: xfs-linux-melb:xfs-kern:29751a
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Donald Douwsma <donaldd@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
Un-obfuscate XFS_SB_LOCK, remove XFS_SB_LOCK->mutex_lock->spin_lock
macros, call spin_lock directly, remove extraneous cookie holdover from
old xfs code, and change lock type to spinlock_t.
SGI-PV: 970382
SGI-Modid: xfs-linux-melb:xfs-kern:29746a
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Donald Douwsma <donaldd@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
Currently there is an indirection called ioops in the XFS data I/O path.
Various functions are called by functions pointers, but there is no
coherence in what this is for, and of course for XFS itself it's entirely
unused. This patch removes it instead and significantly reduces source and
binary size of XFS while making maintaince easier.
SGI-PV: 970841
SGI-Modid: xfs-linux-melb:xfs-kern:29737a
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tim Shimmin <tes@sgi.com>
m_growlock only needs plain binary mutex semantics, so use a struct mutex
instead of a semaphore for it.
SGI-PV: 968563
SGI-Modid: xfs-linux-melb:xfs-kern:29512a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
Now that struct bhv_vfs doesn't have any members left we can kill it and
go directly from the super_block to the xfs_mount everywhere.
SGI-PV: 969608
SGI-Modid: xfs-linux-melb:xfs-kern:29509a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
All flags are added to xfs_mount's m_flag instead. Note that the 32bit
inode flag was duplicated in both of them, but only cleared in the mount
when it was not nessecary due to the filesystem beeing small enough. Two
flags are still required here - one to indicate the mount option setting,
and one to indicate if it applies or not.
SGI-PV: 969608
SGI-Modid: xfs-linux-melb:xfs-kern:29507a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
vfs_altfsid was just a pointer to mp->m_fixedfsid so we can trivially
replace it with the latter. vfs_fsid also was identical to m_fixedfsid
through rather obfuscated ways so we can kill it as well and simply its
only user.
SGI-PV: 969608
SGI-Modid: xfs-linux-melb:xfs-kern:29506a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
Also remove the now dead behavior code.
SGI-PV: 969608
SGI-Modid: xfs-linux-melb:xfs-kern:29505a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
In the next patch we need to look at the mount structure until just before
it's freed, so we need to be able to free it as the very last thing in
xfs_unmount.
SGI-PV: 969608
SGI-Modid: xfs-linux-melb:xfs-kern:29501a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
One of the perpetual scaling problems XFS has is indexing it's incore
inodes. We currently uses hashes and the default hash sizes chosen can
only ever be a tradeoff between memory consumption and the maximum
realistic size of the cache.
As a result, anyone who has millions of inodes cached on a filesystem
needs to tunes the size of the cache via the ihashsize mount option to
allow decent scalability with inode cache operations.
A further problem is the separate inode cluster hash, whose size is based
on the ihashsize but is smaller, and so under certain conditions (sparse
cluster cache population) this can become a limitation long before the
inode hash is causing issues.
The following patchset removes the inode hash and cluster hash and
replaces them with radix trees to avoid the scalability limitations of the
hashes. It also reduces the size of the inodes by 3 pointers....
SGI-PV: 969561
SGI-Modid: xfs-linux-melb:xfs-kern:29481a
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tim Shimmin <tes@sgi.com>
Creates a new xfs_dsb_t that is __be annotated and keeps xfs_sb_t for the
incore one. xfs_xlatesb is renamed to xfs_sb_to_disk and only handles the
incore -> disk conversion. A new helper xfs_sb_from_disk handles the other
direction and doesn't need the slightly hacky table-driven approach
because we only ever read the full sb from disk.
The handling of shared r/o filesystems has been buggy on little endian
system and fixing this required shuffling around of some code in that
area.
SGI-PV: 968563
SGI-Modid: xfs-linux-melb:xfs-kern:29477a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
If we fail to open the the log device buftarg, we can fall through to
error handling code that fails to check for a NULL log device buftarg
before calling xfs_free_buftarg().
This patch fixes the issue by checking mp->m_logdev_targp against NULL in
xfs_unmountfs_close() and doing the proper xfs_blkdev_put(logdev); and
xfs_blkdev_put(rtdev); on (!mp->m_rtdev_targp) in xfs_mount().
Discovered by the Coverity checker.
SGI-PV: 968563
SGI-Modid: xfs-linux-melb:xfs-kern:29328a
Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
Remove scaling of inode "clusters" based on machine memory; small cluster
cut-point was an unrealistic 32MB and was probably never tested.
Removes another user of xfs_physmem.
SGI-PV: 968563
SGI-Modid: xfs-linux-melb:xfs-kern:29324a
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
m_nreadaheads in the mount struct is never used; remove it and the various
macros assigned to it. Also remove a couple other unused macros in the
same areas.
Removes one user of xfs_physmem.
SGI-PV: 968563
SGI-Modid: xfs-linux-melb:xfs-kern:29322a
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
During delayed allocation extent conversion or unwritten extent
conversion, we need to reserve some blocks for transactions reservations.
We need to reserve these blocks in case a btree split occurs and we need
to allocate some blocks.
Unfortunately, we've only ever reserved the number of data blocks we are
allocating, so in both the unwritten and delalloc case we can get ENOSPC
to the transaction reservation. This is bad because in both cases we
cannot report the failure to the writing application.
The fix is two-fold:
1 - leverage the reserved block infrastructure XFS already
has to reserve a small pool of blocks by default to allow
specially marked transactions to dip into when we are at
ENOSPC.
Default setting is min(5%, 1024 blocks).
2 - convert critical transaction reservations to be allowed
to dip into this pool. Spots changed are delalloc
conversion, unwritten extent conversion and growing a
filesystem at ENOSPC.
This also allows growing the filesytsem to succeed at ENOSPC.
SGI-PV: 964468
SGI-Modid: xfs-linux-melb:xfs-kern:28865a
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
When we are unmounting the filesystem, we flush all the inodes to disk.
Unfortunately, if we have an inode cluster that has just been freed and
marked stale sitting in an incore log buffer (i.e. hasn't been flushed to
disk), it will be holding all the flush locks on the inodes in that
cluster.
xfs_iflush_all() which is called during unmount walks all the inodes
trying to reclaim them, and it doing so calls xfs_finish_reclaim() on each
inode. If the inode is dirty, if grabs the flush lock and flushes it.
Unfortunately, find dirty inodes that already have their flush lock held
and so we sleep.
At this point in the unmount process, we are running single-threaded.
There is nothing more that can push on the log to force the transaction
holding the inode flush locks to disk and hence we deadlock.
The fix is to issue a log force before flushing the inodes on unmount so
that all the flush locks will be released before we start flushing the
inodes.
SGI-PV: 964538
SGI-Modid: xfs-linux-melb:xfs-kern:28862a
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
When we have a couple of hundred transactions on the fly at once, they all
typically modify the on disk superblock in some way.
create/unclink/mkdir/rmdir modify inode counts, allocation/freeing modify
free block counts.
When these counts are modified in a transaction, they must eventually lock
the superblock buffer and apply the mods. The buffer then remains locked
until the transaction is committed into the incore log buffer. The result
of this is that with enough transactions on the fly the incore superblock
buffer becomes a bottleneck.
The result of contention on the incore superblock buffer is that
transaction rates fall - the more pressure that is put on the superblock
buffer, the slower things go.
The key to removing the contention is to not require the superblock fields
in question to be locked. We do that by not marking the superblock dirty
in the transaction. IOWs, we modify the incore superblock but do not
modify the cached superblock buffer. In short, we do not log superblock
modifications to critical fields in the superblock on every transaction.
In fact we only do it just before we write the superblock to disk every
sync period or just before unmount.
This creates an interesting problem - if we don't log or write out the
fields in every transaction, then how do the values get recovered after a
crash? the answer is simple - we keep enough duplicate, logged information
in other structures that we can reconstruct the correct count after log
recovery has been performed.
It is the AGF and AGI structures that contain the duplicate information;
after recovery, we walk every AGI and AGF and sum their individual
counters to get the correct value, and we do a transaction into the log to
correct them. An optimisation of this is that if we have a clean unmount
record, we know the value in the superblock is correct, so we can avoid
the summation walk under normal conditions and so mount/recovery times do
not change under normal operation.
One wrinkle that was discovered during development was that the blocks
used in the freespace btrees are never accounted for in the AGF counters.
This was once a valid optimisation to make; when the filesystem is full,
the free space btrees are empty and consume no space. Hence when it
matters, the "accounting" is correct. But that means the when we do the
AGF summations, we would not have a correct count and xfs_check would
complain. Hence a new counter was added to track the number of blocks used
by the free space btrees. This is an *on-disk format change*.
As a result of this, lazy superblock counters are a mkfs option and at the
moment on linux there is no way to convert an old filesystem. This is
possible - xfs_db can be used to twiddle the right bits and then
xfs_repair will do the format conversion for you. Similarly, you can
convert backwards as well. At some point we'll add functionality to
xfs_admin to do the bit twiddling easily....
SGI-PV: 964999
SGI-Modid: xfs-linux-melb:xfs-kern:28652a
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tim Shimmin <tes@sgi.com>
Christoph Hellwig