Updates to the VFS layer removed an extra ->sync_fs call into the
filesystem during the sync process (from the quota code).
Unfortunately the sync code was unknowingly relying on this call to
make sure metadata buffers were flushed via a xfs_buftarg_flush()
call to move the tail of the log forward in memory before the final
transactions of the sync process were issued.

As a result, the old code would write a very recent log tail value
to the log by the end of the sync process, and so a subsequent crash
would leave nothing for log recovery to do. Hence in qa test 182,
log recovery only replayed a small handle for inode fsync
transactions in this case.

However, with the removal of the extra ->sync_fs call, the log tail
was now not moved forward with the inode fsync transactions near the
end of the sync procese the first (and only) buftarg flush occurred
after these transactions went to disk. The result is that log
recovery now sees a large number of transactions for metadata that
is already on disk.

This usually isn't a problem, but when the transactions include
inode chunk allocation, the inode create transactions and all
subsequent changes are replayed as we cannt rely on what is on disk
is valid. As a result, if the inode was written and contains
unlogged changes, the unlogged changes are lost, thereby violating
sync semantics.

The fix is to always issue a transaction after the buftarg flush
occurs is the log iѕ not idle or covered. This results in a dummy
transaction being written that contains the up-to-date log tail
value, which will be very recent. Indeed, it will be at least as
recent as the old code would have left on disk, so log recovery
will behave exactly as it used to in this situation.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAlex Elder <aelder@sgi.com>

Currenly we pass opaque xfs_log_ticket_t handles instead of
struct xlog_ticket pointers, and void pointers instead of
struct xlog_in_core pointers to various log manager functions.
Instead pass properly typed pointers after adding forward
declarations for them to xfs_log.h, and adjust the touched
function prototypes to the standard XFS style while at it.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDave Chinner <david@fromorbit.com>
Signed-off-by: NAlex Elder <aelder@sgi.com>

Remove the XFS_LOG_FORCE argument which was always set, and the
XFS_LOG_URGE define, which was never used.

Split xfs_log_force into a two helpers - xfs_log_force which forces
the whole log, and xfs_log_force_lsn which forces up to the
specified LSN.  The underlying implementations already were entirely
separate, as were the users.

Also re-indent the new _xfs_log_force/_xfs_log_force which
previously had a weird coding style.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAlex Elder <aelder@sgi.com>

This macro only obsfucates the log item type assignments, so kill it.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDave Chinner <david@fromorbit.com>
Signed-off-by: NAlex Elder <aelder@sgi.com>

Don't bother using XFS_bwrite as it doesn't provide much code for
our use case.  Instead opencode it and fold xlog_bdstrat_cb into the
new xlog_bdstrat helper.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAlex Elder <aelder@sgi.com>

Change all async metadata buffers to use [READ|WRITE]_META I/O types
so that the I/O doesn't get issued immediately. This allows merging of
adjacent metadata requests but still prioritises them over bulk data.
This shows a 10-15% improvement in sequential create speed of small
files.

Don't include the log buffers in this classification - leave them as
sync types so they are issued immediately.
Signed-off-by: NDave Chinner <dgc@sgi.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAlex Elder <aelder@sgi.com>

Convert the old xfs tracing support that could only be used with the
out of tree kdb and xfsidbg patches to use the generic event tracer.

To use it make sure CONFIG_EVENT_TRACING is enabled and then enable
all xfs trace channels by:

   echo 1 > /sys/kernel/debug/tracing/events/xfs/enable

or alternatively enable single events by just doing the same in one
event subdirectory, e.g.

   echo 1 > /sys/kernel/debug/tracing/events/xfs/xfs_ihold/enable

or set more complex filters, etc. In Documentation/trace/events.txt
all this is desctribed in more detail.  To reads the events do a

   cat /sys/kernel/debug/tracing/trace

Compared to the last posting this patch converts the tracing mostly to
the one tracepoint per callsite model that other users of the new
tracing facility also employ.  This allows a very fine-grained control
of the tracing, a cleaner output of the traces and also enables the
perf tool to use each tracepoint as a virtual performance counter,
     allowing us to e.g. count how often certain workloads git various
     spots in XFS.  Take a look at

    http://lwn.net/Articles/346470/

for some examples.

Also the btree tracing isn't included at all yet, as it will require
additional core tracing features not in mainline yet, I plan to
deliver it later.

And the really nice thing about this patch is that it actually removes
many lines of code while adding this nice functionality:

 fs/xfs/Makefile                |    8
 fs/xfs/linux-2.6/xfs_acl.c     |    1
 fs/xfs/linux-2.6/xfs_aops.c    |   52 -
 fs/xfs/linux-2.6/xfs_aops.h    |    2
 fs/xfs/linux-2.6/xfs_buf.c     |  117 +--
 fs/xfs/linux-2.6/xfs_buf.h     |   33
 fs/xfs/linux-2.6/xfs_fs_subr.c |    3
 fs/xfs/linux-2.6/xfs_ioctl.c   |    1
 fs/xfs/linux-2.6/xfs_ioctl32.c |    1
 fs/xfs/linux-2.6/xfs_iops.c    |    1
 fs/xfs/linux-2.6/xfs_linux.h   |    1
 fs/xfs/linux-2.6/xfs_lrw.c     |   87 --
 fs/xfs/linux-2.6/xfs_lrw.h     |   45 -
 fs/xfs/linux-2.6/xfs_super.c   |  104 ---
 fs/xfs/linux-2.6/xfs_super.h   |    7
 fs/xfs/linux-2.6/xfs_sync.c    |    1
 fs/xfs/linux-2.6/xfs_trace.c   |   75 ++
 fs/xfs/linux-2.6/xfs_trace.h   | 1369 +++++++++++++++++++++++++++++++++++++++++
 fs/xfs/linux-2.6/xfs_vnode.h   |    4
 fs/xfs/quota/xfs_dquot.c       |  110 ---
 fs/xfs/quota/xfs_dquot.h       |   21
 fs/xfs/quota/xfs_qm.c          |   40 -
 fs/xfs/quota/xfs_qm_syscalls.c |    4
 fs/xfs/support/ktrace.c        |  323 ---------
 fs/xfs/support/ktrace.h        |   85 --
 fs/xfs/xfs.h                   |   16
 fs/xfs/xfs_ag.h                |   14
 fs/xfs/xfs_alloc.c             |  230 +-----
 fs/xfs/xfs_alloc.h             |   27
 fs/xfs/xfs_alloc_btree.c       |    1
 fs/xfs/xfs_attr.c              |  107 ---
 fs/xfs/xfs_attr.h              |   10
 fs/xfs/xfs_attr_leaf.c         |   14
 fs/xfs/xfs_attr_sf.h           |   40 -
 fs/xfs/xfs_bmap.c              |  507 +++------------
 fs/xfs/xfs_bmap.h              |   49 -
 fs/xfs/xfs_bmap_btree.c        |    6
 fs/xfs/xfs_btree.c             |    5
 fs/xfs/xfs_btree_trace.h       |   17
 fs/xfs/xfs_buf_item.c          |   87 --
 fs/xfs/xfs_buf_item.h          |   20
 fs/xfs/xfs_da_btree.c          |    3
 fs/xfs/xfs_da_btree.h          |    7
 fs/xfs/xfs_dfrag.c             |    2
 fs/xfs/xfs_dir2.c              |    8
 fs/xfs/xfs_dir2_block.c        |   20
 fs/xfs/xfs_dir2_leaf.c         |   21
 fs/xfs/xfs_dir2_node.c         |   27
 fs/xfs/xfs_dir2_sf.c           |   26
 fs/xfs/xfs_dir2_trace.c        |  216 ------
 fs/xfs/xfs_dir2_trace.h        |   72 --
 fs/xfs/xfs_filestream.c        |    8
 fs/xfs/xfs_fsops.c             |    2
 fs/xfs/xfs_iget.c              |  111 ---
 fs/xfs/xfs_inode.c             |   67 --
 fs/xfs/xfs_inode.h             |   76 --
 fs/xfs/xfs_inode_item.c        |    5
 fs/xfs/xfs_iomap.c             |   85 --
 fs/xfs/xfs_iomap.h             |    8
 fs/xfs/xfs_log.c               |  181 +----
 fs/xfs/xfs_log_priv.h          |   20
 fs/xfs/xfs_log_recover.c       |    1
 fs/xfs/xfs_mount.c             |    2
 fs/xfs/xfs_quota.h             |    8
 fs/xfs/xfs_rename.c            |    1
 fs/xfs/xfs_rtalloc.c           |    1
 fs/xfs/xfs_rw.c                |    3
 fs/xfs/xfs_trans.h             |   47 +
 fs/xfs/xfs_trans_buf.c         |   62 -
 fs/xfs/xfs_vnodeops.c          |    8
 70 files changed, 2151 insertions(+), 2592 deletions(-)
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAlex Elder <aelder@sgi.com>

Without SMP or preemption spin_is_locked always returns false,
so we can't do an assert with it.  Instead use assert_spin_locked,
which does the right thing on all builds.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NEric Sandeen <sandeen@sandeen.net>
Reported-by: NJohannes Engel <jcnengel@googlemail.com>
Tested-by: NJohannes Engel <jcnengel@googlemail.com>
Signed-off-by: NFelix Blyakher <felixb@sgi.com>

Without SMP or preemption spin_is_locked always returns false,
so we can't do an assert with it.  Instead use assert_spin_locked,
which does the right thing on all builds.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NEric Sandeen <sandeen@sandeen.net>
Reported-by: NJohannes Engel <jcnengel@googlemail.com>
Tested-by: NJohannes Engel <jcnengel@googlemail.com>
Signed-off-by: NFelix Blyakher <felixb@sgi.com>

When trying to reserve log space, we find the amount of space
we need, then go to sleep waiting for space. When we are
woken, we try to push the tail of the log forward to make
sure we have space available.

Unfortunately, this means that if there is not space available, and
everyone who needs space goes to sleep there is no-one left to push
the tail of the log to make space available. Once we have a thread
waiting for space to become available, the others queue up behind
it in a FIFO, and none of them push the tail of the log.

This can result in everyone going to sleep in xlog_grant_log_space()
if the first sleeper races with the last I/O that moves the tail
of the log forward. With no further I/O tomove the tail of the log,
there is nothing to wake the sleepers and hence all transactions
just stop.

Fix this by making sure the xfsaild will create enough space for the
transaction that is about to sleep by moving the push target far
enough forwards to ensure that that the curent proceeees will have
enough space available when it is woken. That is, we push the
AIL before we go to sleep.

Because we've inserted the log ticket into the queue before we've
pushed and gone to sleep, subsequent transactions will wait behind
this one. Hence we are guaranteed to have space available when we
are woken.
Signed-off-by: NDave Chinner <david@fromorbit.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

If the large log sector size feature bit is set in the
superblock by accident (say disk corruption), the then
fields that are now considered valid are not checked on
production kernels. The checks are present as ASSERT
statements so cause a panic on a debug kernel.

Change this so that the fields are validity checked if
the feature bit is set and abort the log mount if the
fields do not contain valid values.
Reported-by: NEric Sesterhenn <snakebyte@gmx.de>
Signed-off-by: NDave Chinner <david@fromorbit.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

Signed-off-by: NMalcolm Parsons <malcolm.parsons@gmail.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

Kill the current xfs_log_unmount wrapper and opencode the two function
calls in the only caller.  Rename the current xfs_log_unmount_dealloc to
xfs_log_unmount as it undoes xfs_log_mount and the new name makes that
more clear.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDave Chinner <david@fromorbit.com>

We can't just call xfs_log_unmount_dealloc on any failure because the
ail thread which is torn down by xfs_log_unmount_dealloc might not
be initialized yet.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NFelix Blyakher <felixb@sgi.com>
Reported-by: NLachlan McIlroy <lachlan@sgi.com>

Our default has been to always use 8 32KB log buffers for a while now, so
remove the special casing for larger block size filesystem to use the same
or even lower number of buffers.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDave Chinner <david@fromorbit.com>

All but one caller of xlog_state_want_sync drop and re-acquire
l_icloglock around the call to it, just so that xlog_state_want_sync can
acquire and drop it.

Move all lock operation out of l_icloglock and assert that the lock is
held when it is called.

Note that it would make sense to extende this scheme to
xlog_state_release_iclog, but the locking in there is more complicated
and we'd like to keep the atomic_dec_and_lock optmization for those
callers not having l_icloglock yet.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDave Chinner <david@fromorbit.com>
Signed-off-by: NNiv Sardi <xaiki@sgi.com>

Move all fields from xlog_iclog_fields_t into xlog_in_core_t instead of having
them in a substructure and the using #defines to make it look like they were
directly in xlog_in_core_t.  Also document that xlog_in_core_2_t is grossly
misnamed, and make all references to it typesafe.

(First sent on Semptember 15th)
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDave Chinner <david@fromorbit.com>
Signed-off-by: NNiv Sardi <xaiki@sgi.com>

xfs_log_force_umount may be called very early during log recovery where

If we fail a buffer read in xlog_recover_do_inode_trans we abort the mount.
But at that point log recovery has started delayed writeback of inode
buffers.   As part of the aborted mount we try to flush out all delwri
buffers, but at that point we have already freed the superblock, and set
mp->m_sb_bp to NULL, and xfs_log_force_umount which gets called after
the inode buffer writeback trips over it.

Make xfs_log_force_umount a little more careful when accessing mp->m_sb_bp
to avoid this.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NEric Sandeen <sandeen@sandeen.net>
Signed-off-by: NNiv Sardi <xaiki@sgi.com>

When an I/O error occurs during an intermediate commit on a rolling
transaction, xfs_trans_commit() will free the transaction structure
and the related ticket. However, the duplicate transaction that
gets used as the transaction continues still contains a pointer
to the ticket. Hence when the duplicate transaction is cancelled
and freed, we free the ticket a second time.

Add reference counting to the ticket so that we hold an extra
reference to the ticket over the transaction commit. We drop the
extra reference once we have checked that the transaction commit
did not return an error, thus avoiding a double free on commit
error.

Credit to Nick Piggin for tripping over the problem.

SGI-PV: 989741
Signed-off-by: NDave Chinner <david@fromorbit.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>

When there is no memory left in the system, xfs_buf_get_noaddr()
can fail. If this happens at mount time during xlog_alloc_log()
we fail to catch the error and oops.

Catch the error from xfs_buf_get_noaddr(), and allow other memory
allocations to fail and catch those errors too. Report the error
to the console and fail the mount with ENOMEM.

Tested by manually injecting errors into xfs_buf_get_noaddr() and
xlog_alloc_log().

Version 2:
o remove unnecessary casts of the returned pointer from kmem_zalloc()

SGI-PV: 987246
Signed-off-by: NDave Chinner <david@fromorbit.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>

When there is no memory left in the system, xfs_buf_get_noaddr()
can fail. If this happens at mount time during xlog_alloc_log()
we fail to catch the error and oops.

Catch the error from xfs_buf_get_noaddr(), and allow other memory
allocations to fail and catch those errors too. Report the error
to the console and fail the mount with ENOMEM.

Tested by manually injecting errors into xfs_buf_get_noaddr() and
xlog_alloc_log().

Version 2:
o remove unnecessary casts of the returned pointer from kmem_zalloc()

SGI-PV: 987246
Signed-off-by: NDave Chinner <david@fromorbit.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>

Change all the remaining AIL API functions that are passed struct
xfs_mount pointers to pass pointers directly to the struct xfs_ail being
used. With this conversion, all external access to the AIL is via the
struct xfs_ail. Hence the operation and referencing of the AIL is almost
entirely independent of the xfs_mount that is using it - it is now much
more tightly tied to the log and the items it is tracking in the log than
it is tied to the xfs_mount.

SGI-PV: 988143

SGI-Modid: xfs-linux-melb:xfs-kern:32353a
Signed-off-by: NDavid Chinner <david@fromorbit.com>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>
Signed-off-by: NChristoph Hellwig <hch@infradead.org>

When we need to go from the log to the AIL, we have to go via the
xfs_mount. Add a xfs_ail pointer to the log so we can go directly to the
AIL associated with the log.

SGI-PV: 988143

SGI-Modid: xfs-linux-melb:xfs-kern:32351a
Signed-off-by: NDavid Chinner <david@fromorbit.com>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>
Signed-off-by: NChristoph Hellwig <hch@infradead.org>

Bring the ail lock inside the struct xfs_ail. This means the AIL can be
entirely manipulated via the struct xfs_ail rather than needing both the
struct xfs_mount and the struct xfs_ail.

SGI-PV: 988143

SGI-Modid: xfs-linux-melb:xfs-kern:32350a
Signed-off-by: NDavid Chinner <david@fromorbit.com>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>
Signed-off-by: NChristoph Hellwig <hch@infradead.org>

With the new cursor interface, it makes sense to make all the traversing
code use the cursor interface and make the old one go away. This means
more of the AIL interfacing is done by passing struct xfs_ail pointers
around the place instead of struct xfs_mount pointers.

We can replace the use of xfs_trans_first_ail() in xfs_log_need_covered()
as it is only checking if the AIL is empty. We can do that with a call to
xfs_trans_ail_tail() instead, where a zero LSN returned indicates and
empty AIL...

SGI-PV: 988143

SGI-Modid: xfs-linux-melb:xfs-kern:32348a
Signed-off-by: NDavid Chinner <david@fromorbit.com>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>
Signed-off-by: NChristoph Hellwig <hch@infradead.org>

To replace the current generation number ensuring sanity of the AIL
traversal, replace it with an external cursor that is linked to the AIL.

Basically, we store the next item in the cursor whenever we want to drop
the AIL lock to do something to the current item. When we regain the lock.
the current item may already be free, so we can't reference it, but the
next item in the traversal is already held in the cursor.

When we move or delete an object, we search all the active cursors and if
there is an item match we clear the cursor(s) that point to the object.
This forces the traversal to restart transparently.

We don't invalidate the cursor on insert because the cursor still points
to a valid item. If the intem is inserted between the current item and the
cursor it does not matter; the traversal is considered to be past the
insertion point so it will be picked up in the next traversal.

Hence traversal restarts pretty much disappear altogether with this method
of traversal, which should substantially reduce the overhead of pushing on
a busy AIL.

Version 2 o add restart logic o comment cursor interface o minor cleanups

SGI-PV: 988143

SGI-Modid: xfs-linux-melb:xfs-kern:32347a
Signed-off-by: NDavid Chinner <david@fromorbit.com>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>
Signed-off-by: NChristoph Hellwig <hch@infradead.org>

Currently we disable barriers as soon as we get a buffer in xlog_iodone
that has the XBF_ORDERED flag cleared.  But this can be the case not only
for buffers where the barrier failed, but also the first buffer of a
split log write in case of a log wraparound.  Due to the disabled
barriers we can easily get directory corruption on unclean shutdowns.
So instead of using this check add a new buffer flag for failed barrier
writes.

This is a regression vs 2.6.26 caused by patch to use the right macro
to check for the ORDERED flag, as we previously got true returned for
every buffer.

Thanks to Toei Rei for reporting the bug.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NEric Sandeen <sandeen@sandeen.net>
Reviewed-by: NDavid Chinner <david@fromorbit.com>
Signed-off-by: NTim Shimmin <tes@sgi.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The current code in xlog_iodone() uses the wrong macro to check if the
barrier has been cleared due to an EOPNOTSUPP error form the lower layer.

SGI-PV: 986143

SGI-Modid: xfs-linux-melb:xfs-kern:31984a
Signed-off-by: NDavid Chinner <david@fromorbit.com>
Signed-off-by: NNathaniel W. Turner <nate@houseofnate.net>
Signed-off-by: NPeter Leckie <pleckie@sgi.com>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>

Memory allocations for log->l_grant_trace and iclog->ic_trace are done on
demand when the first event is logged. In xlog_state_get_iclog_space() we
call xlog_trace_iclog() under a spinlock and allocating memory here can
cause us to sleep with a spinlock held and deadlock the system.

For the log grant tracing we use KM_NOSLEEP but that means we can lose
trace entries. Since there is no locking to serialize the log grant
tracing we could race and have multiple allocations and leak memory.

So move the allocations to where we initialize the log/iclog structures.
Use KM_NOFS to avoid recursing into the filesystem and drop log->l_trace
since it's not even used.

SGI-PV: 983738

SGI-Modid: xfs-linux-melb:xfs-kern:31896a
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>
Signed-off-by: NChristoph Hellwig <hch@infradead.org>

The ticket allocation code got reworked in 2.6.26 and we now free tickets
whereas before we used to cache them so the use-after-free went
undetected.

SGI-PV: 985525

SGI-Modid: xfs-linux-melb:xfs-kern:31877a
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>
Signed-off-by: NDavid Chinner <david@fromorbit.com>

Use KM_NOFS to prevent recursion back into the filesystem which can cause
deadlocks.

In the case of xfs_iread() we hold the lock on the inode cluster buffer
while allocating memory for the trace buffers. If we recurse back into XFS
to flush data that may require a transaction to allocate extents which
needs log space. This can deadlock with the xfsaild thread which can't
push the tail of the log because it is trying to get the inode cluster
buffer lock.

SGI-PV: 981498

SGI-Modid: xfs-linux-melb:xfs-kern:31838a
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>
Signed-off-by: NDavid Chinner <david@fromorbit.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: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>

A lot of code has been converted away from semaphores, but there are still
comments that reference semaphore behaviour. The log code is the worst
offender. Update the comments to reflect what the code really does now.

SGI-PV: 981498

SGI-Modid: xfs-linux-melb:xfs-kern:31814a
Signed-off-by: NDavid Chinner <david@fromorbit.com>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>

The l_flushsema doesn't exactly have completion semantics, nor mutex
semantics. It's used as a list of tasks which are waiting to be notified
that a flush has completed. It was also being used in a way that was
potentially racy, depending on the semaphore implementation.

By using a sv_t instead of a semaphore we avoid the need for a separate
counter, since we know we just need to wake everything on the queue.

Original waitqueue implementation from Matthew Wilcox. Cleanup and
conversion to sv_t by Christoph Hellwig.

SGI-PV: 981507
SGI-Modid: xfs-linux-melb:xfs-kern:31059a
Signed-off-by: NMatthew Wilcox <willy@linux.intel.com>
Signed-off-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NDavid Chinner <dgc@sgi.com>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>

We found this while experimenting with 2GiB xfs logs. The previous code
never assumed that xfs logs would ever get so large.

SGI-PV: 981502
SGI-Modid: xfs-linux-melb:xfs-kern:31058a
Signed-off-by: NMichael Nishimoto <miken@agami.com>
Signed-off-by: NDavid Chinner <dgc@sgi.com>
Signed-off-by: NLachlan 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: NDenys Vlasenko <vda.linux@googlemail.com>
Signed-off-by: NDavid Chinner <dgc@sgi.com>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>

When we release the iclog, we do an atomic_dec_and_lock to determine if
we are the last reference and need to trigger update of log headers and
writeout.  However, in xlog_state_get_iclog_space() we also need to
check if we have the last reference count there.  If we do, we release
the log buffer, otherwise we decrement the reference count.

But the compare and decrement in xlog_state_get_iclog_space() is not
atomic, so both places can see a reference count of 2 and neither will
release the iclog.  That leads to a filesystem hang.

Close the race by replacing the atomic_read() and atomic_dec() pair with
atomic_add_unless() to ensure that they are executed atomically.
Signed-off-by: NDave Chinner <david@fromorbit.com>
Reviewed-by: NTim Shimmin <tes@sgi.com>
Tested-by: NEric Sandeen <sandeen@sandeen.net>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Unmounting the log can fail. unlikely, but it can. Catch all the error
conditions an make sure it's propagated upwards.

SGI-PV: 980084
SGI-Modid: xfs-linux-melb:xfs-kern:30833a
Signed-off-by: NDavid Chinner <dgc@sgi.com>
Signed-off-by: NNiv Sardi <xaiki@sgi.com>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>

xfs_log_force() is declared to return an error, but we almost never check
it. We don't need to check it in most cases; if there's a log I/O error
then we'll be shutting down the filesystem anyway and that means we'll
catch the error somewhere else.

However, on certain calls we should be returning an error - sync
transactions, fsync, sync writes, etc. so this isn't a pure black and
white distinction. Hence make xfs_log_force() a void function that issues
a warning to the syslog on error, and call _xfs_log_force() in all the
places where we actually care about the error status returned.

SGI-PV: 980084
SGI-Modid: xfs-linux-melb:xfs-kern:30832a
Signed-off-by: NDavid Chinner <dgc@sgi.com>
Signed-off-by: NNiv Sardi <xaiki@sgi.com>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>

__FUNCTION__ is gcc-specific, use __func__

SGI-PV: 976035
SGI-Modid: xfs-linux-melb:xfs-kern:30775a
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NDavid Chinner <dgc@sgi.com>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>