At several places we modify EXT4_I(inode)->i_flags without holding
i_mutex (ext4_do_update_inode, ...). These modifications are racy and
we can lose updates to i_flags. So convert handling of i_flags to use
bitops which are atomic.

https://bugzilla.kernel.org/show_bug.cgi?id=15792Signed-off-by: NDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

EXT4_ERROR_INODE() tends to provide better error information and in a
more consistent format.  Some errors were not even identifying the inode
or directory which was corrupted, which made them not very useful.

Addresses-Google-Bug: #2507977
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

This saves a huge amount of stack space by avoiding unnecesary struct
buffer_head's from being allocated on the stack.

In addition, to make the code easier to understand, collapse and
refactor ext4_get_block(), ext4_get_block_write(),
noalloc_get_block_write(), into a single function.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Jack up ext4_get_blocks() and add a new function, ext4_map_blocks()
which uses a much smaller structure, struct ext4_map_blocks which is
20 bytes, as opposed to a struct buffer_head, which nearly 5 times
bigger on an x86_64 machine.  By switching things to use
ext4_map_blocks(), we can save stack space by using ext4_map_blocks()
since we can avoid allocating a struct buffer_head on the stack.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Make a copy of write_cache_pages() for the benefit of
ext4_da_writepages().  This allows us to simplify the code some, and
will allow us to further customize the code in future patches.

There are some nasty hacks in write_cache_pages(), which Linus has
(correctly) characterized as vile.  I've just copied it into
write_cache_pages_da(), without trying to clean those bits up lest I
break something in the ext4's delalloc implementation, which is a bit
fragile right now.  This will allow Dave Chinner to clean up
write_cache_pages() in mm/page-writeback.c, without worrying about
breaking ext4.  Eventually write_cache_pages_da() will go away when I
rewrite ext4's delayed allocation and create a general
ext4_writepages() which is used for all of ext4's writeback.  Until
now this is the lowest risk way to clean up the core
write_cache_pages() function.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Cc: Dave Chinner <david@fromorbit.com>

Addresses-Google-Bug: #2562325
Signed-off-by: NCurt Wohlgemuth <curtw@google.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Because we can badly over-reserve metadata when we
calculate worst-case, it complicates things for quota, since
we must reserve and then claim later, retry on EDQUOT, etc.
Quota is also a generally smaller pool than fs free blocks,
so this over-reservation hurts more, and more often.

I'm of the opinion that it's not the worst thing to allow
metadata to push a user slightly over quota.  This simplifies
the code and avoids the false quota rejections that result
from worst-case speculation.

This patch stops the speculative quota-charging for
worst-case metadata requirements, and just charges quota
when the blocks are allocated at writeout.  It also is
able to remove the try-again loop on EDQUOT.

This patch has been tested indirectly by running the xfstests
suite with a hack to mount & enable quota prior to the test.

I also did a more specific test of fragmenting freespace
and then doing a large delalloc write under quota; quota
stopped me at the right amount of file IO, and then the
writeout generated enough metadata (due to the fragmentation)
that it put me slightly over quota, as expected.
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

There was a bug reported on RHEL5 that a 10G dd on a 12G box
had a very, very slow sync after that.

At issue was the loop in write_cache_pages scanning all the way
to the end of the 10G file, even though the subsequent call
to mpage_da_submit_io would only actually write a smallish amt; then
we went back to the write_cache_pages loop ... wasting tons of time
in calling __mpage_da_writepage for thousands of pages we would
just revisit (many times) later.

Upstream it's not such a big issue for sys_sync because we get
to the loop with a much smaller nr_to_write, which limits the loop.

However, talking with Aneesh he realized that fsync upstream still
gets here with a very large nr_to_write and we face the same problem.

This patch makes mpage_add_bh_to_extent stop the loop after we've
accumulated 2048 pages, by setting mpd->io_done = 1; which ultimately
causes the write_cache_pages loop to break.

Repeating the test with a dirty_ratio of 80 (to leave something for
fsync to do), I don't see huge IO performance gains, but the reduction
in cpu usage is striking: 80% usage with stock, and 2% with the
below patch.  Instrumenting the loop in write_cache_pages clearly
shows that we are wasting time here.

Eventually we need to change mpage_da_map_pages() also submit its I/O
to the block layer, subsuming mpage_da_submit_io(), and then change it
call ext4_get_blocks() multiple times.
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

allocated_meta_data is already included in 'used' variable.
Signed-off-by: NDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Calls to ext4_get_inode_loc() returns with a reference to a buffer
head in iloc->bh.  The callers of this function in ext4_write_inode()
when in no journal mode and in ext4_xattr_fiemap() don't release the
buffer head after using it.

Addresses-Google-Bug: #2548165
Signed-off-by: NCurt Wohlgemuth <curtw@google.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

In the no-journal case, ext4_write_inode() will fetch the bh and call
sync_dirty_buffer() on it.  However, if the bh has already been
written and the bh reclaimed for some other purpose, AND if the inode
is the only one in the inode table block in use, then
ext4_get_inode_loc() will not read the inode table block from disk,
but as an optimization, fill the block with zero's assuming that its
caller will copy in the on-disk version of the inode.  This is not
done by ext4_write_inode(), so the contents of the inode can simply
get lost.  The fix is to use __ext4_get_inode_loc() with in_mem set to
0, instead of ext4_get_inode_loc().  Long term the API needs to be
fixed so it's obvious why latter is not safe.

Addresses-Google-Bug: #2526446
Signed-off-by: NCurt Wohlgemuth <curtw@google.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: NTejun Heo <tj@kernel.org>
Guess-its-ok-by: NChristoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>

http://bugzilla.kernel.org/show_bug.cgi?id=15420Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

This gives the filesystem more information about the writeback that
is happening.  Trond requested this for the NFS unstable write handling,
and other filesystems might benefit from this too by beeing able to
distinguish between the different callers in more detail.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Get rid of the initialize dquot operation - it is now always called from
the filesystem and if a filesystem really needs it's own (which none
currently does) it can just call into it's own routine directly.

Rename the now static low-level dquot_initialize helper to __dquot_initialize
and vfs_dq_init to dquot_initialize to have a consistent namespace.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJan Kara <jack@suse.cz>

Currently various places in the VFS call vfs_dq_init directly.  This means
we tie the quota code into the VFS.  Get rid of that and make the
filesystem responsible for the initialization.   For most metadata operations
this is a straight forward move into the methods, but for truncate and
open it's a bit more complicated.

For truncate we currently only call vfs_dq_init for the sys_truncate case
because open already takes care of it for ftruncate and open(O_TRUNC) - the
new code causes an additional vfs_dq_init for those which is harmless.

For open the initialization is moved from do_filp_open into the open method,
which means it happens slightly earlier now, and only for regular files.
The latter is fine because we don't need to initialize it for operations
on special files, and we already do it as part of the namespace operations
for directories.

Add a dquot_file_open helper that filesystems that support generic quotas
can use to fill in ->open.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJan Kara <jack@suse.cz>

Get rid of the transfer dquot operation - it is now always called from
the filesystem and if a filesystem really needs it's own (which none
currently does) it can just call into it's own routine directly.

Rename the now static low-level dquot_transfer helper to __dquot_transfer
and vfs_dq_transfer to dquot_transfer to have a consistent namespace,
and make the new dquot_transfer return a normal negative errno value
which all callers expect.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJan Kara <jack@suse.cz>

Get rid of the alloc_space, free_space, reserve_space, claim_space and
release_rsv dquot operations - they are always called from the filesystem
and if a filesystem really needs their own (which none currently does)
it can just call into it's own routine directly.

Move shared logic into the common __dquot_alloc_space,
dquot_claim_space_nodirty and __dquot_free_space low-level methods,
and rationalize the wrappers around it to move as much as possible
code into the common block for CONFIG_QUOTA vs not.  Also rename
all these helpers to be named dquot_* instead of vfs_dq_*.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJan Kara <jack@suse.cz>

We forget to release page references we acquire in
ext4_da_block_invalidatepages.  Luckily, this function gets called only if we
are not able to allocate blocks for delay-allocated data so that function
should better never be called.

Also cleanup handling of index variable.
Reported-by: NWu Fengguang <fengguang.wu@intel.com>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Convert a bunch of BUG_ONs to emit a ext4_error() message and return
EIO.  This is a first pass and most notably does _not_ cover
mballoc.c, which is a morass of void functions.
Signed-off-by: NFrank Mayhar <fmayhar@google.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Signed-off-by: NJiaying Zhang <jiayingz@google.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Allocate uninitialized extent before ext4 buffer write and
convert the extent to initialized after io completes.
The purpose is to make sure an extent can only be marked
initialized after it has been written with new data so
we can safely drop the i_mutex lock in ext4 DIO read without
exposing stale data. This helps to improve multi-thread DIO
read performance on high-speed disks.

Skip the nobh and data=journal mount cases to make things simple for now.
Signed-off-by: NJiaying Zhang <jiayingz@google.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

This commit renames some of the direct I/O's block allocation flags,
variables, and functions introduced in Mingming's "Direct IO for holes
and fallocate" patches so that they can be used by ext4's buffered
write path as well.  Also changed the related function comments
accordingly to cover both direct write and buffered write cases.
Signed-off-by: NJiaying Zhang <jiayingz@google.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Otherwise non-empty orphan list will be triggered on umount.
Signed-off-by: NDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fallocate() may potentially instantiate blocks past EOF, depending
on the flags used when it is called.

e2fsck currently has a test for blocks past i_size, and it
sometimes trips up - noticeably on xfstests 013 which runs fsstress.

This patch from Jiayang does fix it up - it (along with
e2fsprogs updates and other patches recently from Aneesh) has
survived many fsstress runs in a row.
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Signed-off-by: NJiaying Zhang <jiayingz@google.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Calls to ext4_handle_dirty_metadata should only pass in an inode
pointer for inode-specific metadata, and not for shared metadata
blocks such as inode table blocks, block group descriptors, the
superblock, etc.

The BUG_ON can get tripped when updating a special device (such as a
block device) that is opened (so that i_mapping is set in
fs/block_dev.c) and the file system is mounted in no journal mode.

Addresses-Google-Bug: #2404870
Signed-off-by: NCurt Wohlgemuth <curtw@google.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Just a pet peeve of mine; we had a mishash of calls with either __func__
or "function_name" and the latter tends to get out of sync.

I think it's easier to just hide the __func__ in a macro, and it'll
be consistent from then on.
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

At several places we modify EXT4_I(inode)->i_state without holding
i_mutex (ext4_release_file, ext4_bmap, ext4_journalled_writepage,
ext4_do_update_inode, ...). These modifications are racy and we can
lose updates to i_state. So convert handling of i_state to use bitops
which are atomic.

Cc: Jan Kara <jack@suse.cz>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

We should update reserve space if it is delalloc buffer
and that is indicated by EXT4_GET_BLOCKS_DELALLOC_RESERVE flag.
So use EXT4_GET_BLOCKS_DELALLOC_RESERVE in place of
EXT4_GET_BLOCKS_UPDATE_RESERVE_SPACE
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

When we fallocate a region of the file which we had recently written,
and which is still in the page cache marked as delayed allocated blocks
we need to make sure we don't do the quota update on writepage path.
This is because the needed quota updated would have already be done
by fallocate.
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

We need to release the journal before we do a write_inode.  Otherwise
we could deadlock.
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

In the past, ext4_calc_metadata_amount(), and its sub-functions
ext4_ext_calc_metadata_amount() and ext4_indirect_calc_metadata_amount()
badly over-estimated the number of metadata blocks that might be
required for delayed allocation blocks.  This didn't matter as much
when functions which managed the reserved metadata blocks were more
aggressive about dropping reserved metadata blocks as delayed
allocation blocks were written, but unfortunately they were too
aggressive.  This was fixed in commit 0637c6f4, but as a result the
over-estimation by ext4_calc_metadata_amount() would lead to reserving
2-3 times the number of pending delayed allocation blocks as
potentially required metadata blocks.  So if there are 1 megabytes of
blocks which have been not yet been allocation, up to 3 megabytes of
space would get reserved out of the user's quota and from the file
system free space pool until all of the inode's data blocks have been
allocated.

This commit addresses this problem by much more accurately estimating
the number of metadata blocks that will be required.  It will still
somewhat over-estimate the number of blocks needed, since it must make
a worst case estimate not knowing which physical blocks will be
needed, but it is much more accurate than before.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Commit 0637c6f4 had a typo which caused the reserved metadata blocks to
not be released correctly.   Fix this.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

As reported in Kernel Bugzilla #14936, commit d21cd8f1 triggered a BUG
in the function ext4_da_update_reserve_space() found in
fs/ext4/inode.c.  The root cause of this BUG() was caused by the fact
that ext4_calc_metadata_amount() can severely over-estimate how many
metadata blocks will be needed, especially when using direct
block-mapped files.

In addition, it can also badly *under* estimate how much space is
needed, since ext4_calc_metadata_amount() assumes that the blocks are
contiguous, and this is not always true.  If the application is
writing blocks to a sparse file, the number of metadata blocks
necessary can be severly underestimated by the functions
ext4_da_reserve_space(), ext4_da_update_reserve_space() and
ext4_da_release_space().  This was the cause of the dq_claim_space
reports found on kerneloops.org.

Unfortunately, doing this right means that we need to massively
over-estimate the amount of free space needed.  So in some cases we
may need to force the inode to be written to disk asynchronously in
to avoid spurious quota failures.

http://bugzilla.kernel.org/show_bug.cgi?id=14936Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

When ext4_da_writepages increases the nr_to_write in writeback_control
then it must always re-base the return value.  Originally there was a
(misguided) attempt prevent wbc.nr_to_write from going negative.  In
fact, it's necessary to allow nr_to_write to be negative so that
wb_writeback() can correctly calculate how many pages were actually
written.  
Signed-off-by: NRichard Kennedy <richard@rsk.demon.co.uk>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Creating many small files in rapid succession on a small
filesystem can lead to spurious ENOSPC; on a 104MB filesystem:

for i in `seq 1 22500`; do
    echo -n > $SCRATCH_MNT/$i
    echo XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX > $SCRATCH_MNT/$i
done

leads to ENOSPC even though after a sync, 40% of the fs is free
again.

This is because we reserve worst-case metadata for delalloc writes,
and when data is allocated that worst-case reservation is not
usually needed.

When freespace is low, kicking off an async writeback will start
converting that worst-case space usage into something more realistic,
almost always freeing up space to continue.

This resolves the testcase for me, and survives all 4 generic
ENOSPC tests in xfstests.

We'll still need a hard synchronous sync to squeeze out the last bit,
but this fixes things up to a large degree.
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Unlock i_block_reservation_lock before vfs_dq_reserve_block().
This patch fixes http://bugzilla.kernel.org/show_bug.cgi?id=14739

CC: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: NDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: NJan Kara <jack@suse.cz>

We have to delay vfs_dq_claim_space() until allocation context destruction.
Currently we have following call-trace:
ext4_mb_new_blocks()
  /* task is already holding ac->alloc_semp */
 ->ext4_mb_mark_diskspace_used
    ->vfs_dq_claim_space()  /*  acquire dqptr_sem here. Possible deadlock */
 ->ext4_mb_release_context() /* drop ac->alloc_semp here */

Let's move quota claiming to ext4_da_update_reserve_space()

 =======================================================
 [ INFO: possible circular locking dependency detected ]
 2.6.32-rc7 #18
 -------------------------------------------------------
 write-truncate-/3465 is trying to acquire lock:
  (&s->s_dquot.dqptr_sem){++++..}, at: [<c025e73b>] dquot_claim_space+0x3b/0x1b0

 but task is already holding lock:
  (&meta_group_info[i]->alloc_sem){++++..}, at: [<c02ce962>] ext4_mb_load_buddy+0xb2/0x370

 which lock already depends on the new lock.

 the existing dependency chain (in reverse order) is:

 -> #3 (&meta_group_info[i]->alloc_sem){++++..}:
        [<c017d04b>] __lock_acquire+0xd7b/0x1260
        [<c017d5ea>] lock_acquire+0xba/0xd0
        [<c0527191>] down_read+0x51/0x90
        [<c02ce962>] ext4_mb_load_buddy+0xb2/0x370
        [<c02d0c1c>] ext4_mb_free_blocks+0x46c/0x870
        [<c029c9d3>] ext4_free_blocks+0x73/0x130
        [<c02c8cfc>] ext4_ext_truncate+0x76c/0x8d0
        [<c02a8087>] ext4_truncate+0x187/0x5e0
        [<c01e0f7b>] vmtruncate+0x6b/0x70
        [<c022ec02>] inode_setattr+0x62/0x190
        [<c02a2d7a>] ext4_setattr+0x25a/0x370
        [<c022ee81>] notify_change+0x151/0x340
        [<c021349d>] do_truncate+0x6d/0xa0
        [<c0221034>] may_open+0x1d4/0x200
        [<c022412b>] do_filp_open+0x1eb/0x910
        [<c021244d>] do_sys_open+0x6d/0x140
        [<c021258e>] sys_open+0x2e/0x40
        [<c0103100>] sysenter_do_call+0x12/0x32

 -> #2 (&ei->i_data_sem){++++..}:
        [<c017d04b>] __lock_acquire+0xd7b/0x1260
        [<c017d5ea>] lock_acquire+0xba/0xd0
        [<c0527191>] down_read+0x51/0x90
        [<c02a5787>] ext4_get_blocks+0x47/0x450
        [<c02a74c1>] ext4_getblk+0x61/0x1d0
        [<c02a7a7f>] ext4_bread+0x1f/0xa0
        [<c02bcddc>] ext4_quota_write+0x12c/0x310
        [<c0262d23>] qtree_write_dquot+0x93/0x120
        [<c0261708>] v2_write_dquot+0x28/0x30
        [<c025d3fb>] dquot_commit+0xab/0xf0
        [<c02be977>] ext4_write_dquot+0x77/0x90
        [<c02be9bf>] ext4_mark_dquot_dirty+0x2f/0x50
        [<c025e321>] dquot_alloc_inode+0x101/0x180
        [<c029fec2>] ext4_new_inode+0x602/0xf00
        [<c02ad789>] ext4_create+0x89/0x150
        [<c0221ff2>] vfs_create+0xa2/0xc0
        [<c02246e7>] do_filp_open+0x7a7/0x910
        [<c021244d>] do_sys_open+0x6d/0x140
        [<c021258e>] sys_open+0x2e/0x40
        [<c0103100>] sysenter_do_call+0x12/0x32

 -> #1 (&sb->s_type->i_mutex_key#7/4){+.+...}:
        [<c017d04b>] __lock_acquire+0xd7b/0x1260
        [<c017d5ea>] lock_acquire+0xba/0xd0
        [<c0526505>] mutex_lock_nested+0x65/0x2d0
        [<c0260c9d>] vfs_load_quota_inode+0x4bd/0x5a0
        [<c02610af>] vfs_quota_on_path+0x5f/0x70
        [<c02bc812>] ext4_quota_on+0x112/0x190
        [<c026345a>] sys_quotactl+0x44a/0x8a0
        [<c0103100>] sysenter_do_call+0x12/0x32

 -> #0 (&s->s_dquot.dqptr_sem){++++..}:
        [<c017d361>] __lock_acquire+0x1091/0x1260
        [<c017d5ea>] lock_acquire+0xba/0xd0
        [<c0527191>] down_read+0x51/0x90
        [<c025e73b>] dquot_claim_space+0x3b/0x1b0
        [<c02cb95f>] ext4_mb_mark_diskspace_used+0x36f/0x380
        [<c02d210a>] ext4_mb_new_blocks+0x34a/0x530
        [<c02c83fb>] ext4_ext_get_blocks+0x122b/0x13c0
        [<c02a5966>] ext4_get_blocks+0x226/0x450
        [<c02a5ff3>] mpage_da_map_blocks+0xc3/0xaa0
        [<c02a6ed6>] ext4_da_writepages+0x506/0x790
        [<c01de272>] do_writepages+0x22/0x50
        [<c01d766d>] __filemap_fdatawrite_range+0x6d/0x80
        [<c01d7b9b>] filemap_flush+0x2b/0x30
        [<c02a40ac>] ext4_alloc_da_blocks+0x5c/0x60
        [<c029e595>] ext4_release_file+0x75/0xb0
        [<c0216b59>] __fput+0xf9/0x210
        [<c0216c97>] fput+0x27/0x30
        [<c02122dc>] filp_close+0x4c/0x80
        [<c014510e>] put_files_struct+0x6e/0xd0
        [<c01451b7>] exit_files+0x47/0x60
        [<c0146a24>] do_exit+0x144/0x710
        [<c0147028>] do_group_exit+0x38/0xa0
        [<c0159abc>] get_signal_to_deliver+0x2ac/0x410
        [<c0102849>] do_notify_resume+0xb9/0x890
        [<c01032d2>] work_notifysig+0x13/0x21

 other info that might help us debug this:

 3 locks held by write-truncate-/3465:
  #0:  (jbd2_handle){+.+...}, at: [<c02e1f8f>] start_this_handle+0x38f/0x5c0
  #1:  (&ei->i_data_sem){++++..}, at: [<c02a57f6>] ext4_get_blocks+0xb6/0x450
  #2:  (&meta_group_info[i]->alloc_sem){++++..}, at: [<c02ce962>] ext4_mb_load_buddy+0xb2/0x370

 stack backtrace:
 Pid: 3465, comm: write-truncate- Not tainted 2.6.32-rc7 #18
 Call Trace:
  [<c0524cb3>] ? printk+0x1d/0x22
  [<c017ac9a>] print_circular_bug+0xca/0xd0
  [<c017d361>] __lock_acquire+0x1091/0x1260
  [<c016bca2>] ? sched_clock_local+0xd2/0x170
  [<c0178fd0>] ? trace_hardirqs_off_caller+0x20/0xd0
  [<c017d5ea>] lock_acquire+0xba/0xd0
  [<c025e73b>] ? dquot_claim_space+0x3b/0x1b0
  [<c0527191>] down_read+0x51/0x90
  [<c025e73b>] ? dquot_claim_space+0x3b/0x1b0
  [<c025e73b>] dquot_claim_space+0x3b/0x1b0
  [<c02cb95f>] ext4_mb_mark_diskspace_used+0x36f/0x380
  [<c02d210a>] ext4_mb_new_blocks+0x34a/0x530
  [<c02c601d>] ? ext4_ext_find_extent+0x25d/0x280
  [<c02c83fb>] ext4_ext_get_blocks+0x122b/0x13c0
  [<c016bca2>] ? sched_clock_local+0xd2/0x170
  [<c016be60>] ? sched_clock_cpu+0x120/0x160
  [<c016beef>] ? cpu_clock+0x4f/0x60
  [<c0178fd0>] ? trace_hardirqs_off_caller+0x20/0xd0
  [<c052712c>] ? down_write+0x8c/0xa0
  [<c02a5966>] ext4_get_blocks+0x226/0x450
  [<c016be60>] ? sched_clock_cpu+0x120/0x160
  [<c016beef>] ? cpu_clock+0x4f/0x60
  [<c017908b>] ? trace_hardirqs_off+0xb/0x10
  [<c02a5ff3>] mpage_da_map_blocks+0xc3/0xaa0
  [<c01d69cc>] ? find_get_pages_tag+0x16c/0x180
  [<c01d6860>] ? find_get_pages_tag+0x0/0x180
  [<c02a73bd>] ? __mpage_da_writepage+0x16d/0x1a0
  [<c01dfc4e>] ? pagevec_lookup_tag+0x2e/0x40
  [<c01ddf1b>] ? write_cache_pages+0xdb/0x3d0
  [<c02a7250>] ? __mpage_da_writepage+0x0/0x1a0
  [<c02a6ed6>] ext4_da_writepages+0x506/0x790
  [<c016beef>] ? cpu_clock+0x4f/0x60
  [<c016bca2>] ? sched_clock_local+0xd2/0x170
  [<c016be60>] ? sched_clock_cpu+0x120/0x160
  [<c016be60>] ? sched_clock_cpu+0x120/0x160
  [<c02a69d0>] ? ext4_da_writepages+0x0/0x790
  [<c01de272>] do_writepages+0x22/0x50
  [<c01d766d>] __filemap_fdatawrite_range+0x6d/0x80
  [<c01d7b9b>] filemap_flush+0x2b/0x30
  [<c02a40ac>] ext4_alloc_da_blocks+0x5c/0x60
  [<c029e595>] ext4_release_file+0x75/0xb0
  [<c0216b59>] __fput+0xf9/0x210
  [<c0216c97>] fput+0x27/0x30
  [<c02122dc>] filp_close+0x4c/0x80
  [<c014510e>] put_files_struct+0x6e/0xd0
  [<c01451b7>] exit_files+0x47/0x60
  [<c0146a24>] do_exit+0x144/0x710
  [<c017b163>] ? lock_release_holdtime+0x33/0x210
  [<c0528137>] ? _spin_unlock_irq+0x27/0x30
  [<c0147028>] do_group_exit+0x38/0xa0
  [<c017babb>] ? trace_hardirqs_on+0xb/0x10
  [<c0159abc>] get_signal_to_deliver+0x2ac/0x410
  [<c0102849>] do_notify_resume+0xb9/0x890
  [<c0178fd0>] ? trace_hardirqs_off_caller+0x20/0xd0
  [<c017b163>] ? lock_release_holdtime+0x33/0x210
  [<c0165b50>] ? autoremove_wake_function+0x0/0x50
  [<c017ba54>] ? trace_hardirqs_on_caller+0x134/0x190
  [<c017babb>] ? trace_hardirqs_on+0xb/0x10
  [<c0300ba4>] ? security_file_permission+0x14/0x20
  [<c0215761>] ? vfs_write+0x131/0x190
  [<c0214f50>] ? do_sync_write+0x0/0x120
  [<c0103115>] ? sysenter_do_call+0x27/0x32
  [<c01032d2>] work_notifysig+0x13/0x21

CC: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: NDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: NJan Kara <jack@suse.cz>

This patch also fixes write vs chown race condition.
Acked-by: N"Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: NDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: NJan Kara <jack@suse.cz>

Add tracepoints for ext4_da_reserve_space(),
ext4_da_update_reserve_space(), and ext4_da_release_space().
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>