linux-stable.git/fs/ext4, branch v3.12.52 Linux kernel stable tree ext4, jbd2: ensure entering into panic after recording an error in superblock 2016-01-05T16:48:50+00:00 Daeho Jeong daeho.jeong@samsung.com 2015-10-18T21:02:56+00:00 d8cd31d22be717be1db3bbb21c85acf8c90be2e8 commit 4327ba52afd03fc4b5afa0ee1d774c9c5b0e85c5 upstream. If a EXT4 filesystem utilizes JBD2 journaling and an error occurs, the journaling will be aborted first and the error number will be recorded into JBD2 superblock and, finally, the system will enter into the panic state in "errors=panic" option. But, in the rare case, this sequence is little twisted like the below figure and it will happen that the system enters into panic state, which means the system reset in mobile environment, before completion of recording an error in the journal superblock. In this case, e2fsck cannot recognize that the filesystem failure occurred in the previous run and the corruption wouldn't be fixed. Task A Task B ext4_handle_error() -> jbd2_journal_abort() -> __journal_abort_soft() -> __jbd2_journal_abort_hard() | -> journal->j_flags |= JBD2_ABORT; | | __ext4_abort() | -> jbd2_journal_abort() | | -> __journal_abort_soft() | | -> if (journal->j_flags & JBD2_ABORT) | | return; | -> panic() | -> jbd2_journal_update_sb_errno() Tested-by: Hobin Woo <hobin.woo@samsung.com> Signed-off-by: Daeho Jeong <daeho.jeong@samsung.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jiri Slaby <jslaby@suse.cz> 
commit 4327ba52afd03fc4b5afa0ee1d774c9c5b0e85c5 upstream.

If a EXT4 filesystem utilizes JBD2 journaling and an error occurs, the
journaling will be aborted first and the error number will be recorded
into JBD2 superblock and, finally, the system will enter into the
panic state in "errors=panic" option.  But, in the rare case, this
sequence is little twisted like the below figure and it will happen
that the system enters into panic state, which means the system reset
in mobile environment, before completion of recording an error in the
journal superblock. In this case, e2fsck cannot recognize that the
filesystem failure occurred in the previous run and the corruption
wouldn't be fixed.

Task A                        Task B
ext4_handle_error()
-> jbd2_journal_abort()
  -> __journal_abort_soft()
    -> __jbd2_journal_abort_hard()
    | -> journal->j_flags |= JBD2_ABORT;
    |
    |                         __ext4_abort()
    |                         -> jbd2_journal_abort()
    |                         | -> __journal_abort_soft()
    |                         |   -> if (journal->j_flags & JBD2_ABORT)
    |                         |           return;
    |                         -> panic()
    |
    -> jbd2_journal_update_sb_errno()

Tested-by: Hobin Woo <hobin.woo@samsung.com>
Signed-off-by: Daeho Jeong <daeho.jeong@samsung.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
ext4: fix potential use after free in __ext4_journal_stop 2016-01-05T16:48:49+00:00 Lukas Czerner lczerner@redhat.com 2015-10-18T02:57:06+00:00 34fe4014b5e4b6f95195369c66c23b48c99da1e2 commit 6934da9238da947628be83635e365df41064b09b upstream. There is a use-after-free possibility in __ext4_journal_stop() in the case that we free the handle in the first jbd2_journal_stop() because we're referencing handle->h_err afterwards. This was introduced in 9705acd63b125dee8b15c705216d7186daea4625 and it is wrong. Fix it by storing the handle->h_err value beforehand and avoid referencing potentially freed handle. Fixes: 9705acd63b125dee8b15c705216d7186daea4625 Signed-off-by: Lukas Czerner <lczerner@redhat.com> Reviewed-by: Andreas Dilger <adilger@dilger.ca> Signed-off-by: Jiri Slaby <jslaby@suse.cz> 
commit 6934da9238da947628be83635e365df41064b09b upstream.

There is a use-after-free possibility in __ext4_journal_stop() in the
case that we free the handle in the first jbd2_journal_stop() because
we're referencing handle->h_err afterwards. This was introduced in
9705acd63b125dee8b15c705216d7186daea4625 and it is wrong. Fix it by
storing the handle->h_err value beforehand and avoid referencing
potentially freed handle.

Fixes: 9705acd63b125dee8b15c705216d7186daea4625
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
ext4: move check under lock scope to close a race. 2015-09-18T07:26:31+00:00 Davide Italiano dccitaliano@gmail.com 2015-09-16T14:36:23+00:00 7e7ec82ecd66ed0cfd77346d8cb4676e06b881ec commit 280227a75b56ab5d35854f3a77ef74a7ad56a203 upstream fallocate() checks that the file is extent-based and returns EOPNOTSUPP in case is not. Other tasks can convert from and to indirect and extent so it's safe to check only after grabbing the inode mutex. [Nikolay Borisov: Bakported to 3.12.47 - Adjusted context - Add the 'out' label] Signed-off-by: Davide Italiano <dccitaliano@gmail.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Nikolay Borisov <kernel@kyup.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jiri Slaby <jslaby@suse.cz> 
commit 280227a75b56ab5d35854f3a77ef74a7ad56a203 upstream

fallocate() checks that the file is extent-based and returns
EOPNOTSUPP in case is not. Other tasks can convert from and to
indirect and extent so it's safe to check only after grabbing
the inode mutex.

[Nikolay Borisov: Bakported to 3.12.47
 - Adjusted context
 - Add the 'out' label]

Signed-off-by: Davide Italiano <dccitaliano@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
ext4: replace open coded nofail allocation in ext4_free_blocks() 2015-08-04T14:52:04+00:00 Michal Hocko mhocko@suse.cz 2015-07-05T16:33:44+00:00 5ee7802aa8090e6a2a5073af6d49e443a4711acf commit 7444a072c387a93ebee7066e8aee776954ab0e41 upstream. ext4_free_blocks is looping around the allocation request and mimics __GFP_NOFAIL behavior without any allocation fallback strategy. Let's remove the open coded loop and replace it with __GFP_NOFAIL. Without the flag the allocator has no way to find out never-fail requirement and cannot help in any way. Signed-off-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jiri Slaby <jslaby@suse.cz> 
commit 7444a072c387a93ebee7066e8aee776954ab0e41 upstream.

ext4_free_blocks is looping around the allocation request and mimics
__GFP_NOFAIL behavior without any allocation fallback strategy. Let's
remove the open coded loop and replace it with __GFP_NOFAIL. Without the
flag the allocator has no way to find out never-fail requirement and
cannot help in any way.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
ext4: correctly migrate a file with a hole at the beginning 2015-08-04T14:52:03+00:00 Eryu Guan guaneryu@gmail.com 2015-07-04T04:03:44+00:00 e275aeb62ca0102a415b94a1a9af49c06282ec8c commit 8974fec7d72e3e02752fe0f27b4c3719c78d9a15 upstream. Currently ext4_ind_migrate() doesn't correctly handle a file which contains a hole at the beginning of the file. This caused the migration to be done incorrectly, and then if there is a subsequent following delayed allocation write to the "hole", this would reclaim the same data blocks again and results in fs corruption. # assmuing 4k block size ext4, with delalloc enabled # skip the first block and write to the second block xfs_io -fc "pwrite 4k 4k" -c "fsync" /mnt/ext4/testfile # converting to indirect-mapped file, which would move the data blocks # to the beginning of the file, but extent status cache still marks # that region as a hole chattr -e /mnt/ext4/testfile # delayed allocation writes to the "hole", reclaim the same data block # again, results in i_blocks corruption xfs_io -c "pwrite 0 4k" /mnt/ext4/testfile umount /mnt/ext4 e2fsck -nf /dev/sda6 ... Inode 53, i_blocks is 16, should be 8. Fix? no ... Signed-off-by: Eryu Guan <guaneryu@gmail.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jiri Slaby <jslaby@suse.cz> 
commit 8974fec7d72e3e02752fe0f27b4c3719c78d9a15 upstream.

Currently ext4_ind_migrate() doesn't correctly handle a file which
contains a hole at the beginning of the file.  This caused the migration
to be done incorrectly, and then if there is a subsequent following
delayed allocation write to the "hole", this would reclaim the same data
blocks again and results in fs corruption.

  # assmuing 4k block size ext4, with delalloc enabled
  # skip the first block and write to the second block
  xfs_io -fc "pwrite 4k 4k" -c "fsync" /mnt/ext4/testfile

  # converting to indirect-mapped file, which would move the data blocks
  # to the beginning of the file, but extent status cache still marks
  # that region as a hole
  chattr -e /mnt/ext4/testfile

  # delayed allocation writes to the "hole", reclaim the same data block
  # again, results in i_blocks corruption
  xfs_io -c "pwrite 0 4k" /mnt/ext4/testfile
  umount /mnt/ext4
  e2fsck -nf /dev/sda6
  ...
  Inode 53, i_blocks is 16, should be 8.  Fix? no
  ...

Signed-off-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
ext4: be more strict when migrating to non-extent based file 2015-08-04T14:52:03+00:00 Eryu Guan guaneryu@gmail.com 2015-07-04T03:56:50+00:00 fea167d1eff08178ba2af0b22eb0f8c6993411ed commit d6f123a9297496ad0b6335fe881504c4b5b2a5e5 upstream. Currently the check in ext4_ind_migrate() is not enough before doing the real conversion: a) delayed allocated extents could bypass the check on eh->eh_entries and eh->eh_depth This can be demonstrated by this script xfs_io -fc "pwrite 0 4k" -c "pwrite 8k 4k" /mnt/ext4/testfile chattr -e /mnt/ext4/testfile where testfile has two extents but still be converted to non-extent based file format. b) only extent length is checked but not the offset, which would result in data lose (delalloc) or fs corruption (nodelalloc), because non-extent based file only supports at most (12 + 2^10 + 2^20 + 2^30) blocks This can be demostrated by xfs_io -fc "pwrite 5T 4k" /mnt/ext4/testfile chattr -e /mnt/ext4/testfile sync If delalloc is enabled, dmesg prints EXT4-fs warning (device dm-4): ext4_block_to_path:105: block 1342177280 > max in inode 53 EXT4-fs (dm-4): Delayed block allocation failed for inode 53 at logical offset 1342177280 with max blocks 1 with error 5 EXT4-fs (dm-4): This should not happen!! Data will be lost If delalloc is disabled, e2fsck -nf shows corruption Inode 53, i_size is 5497558142976, should be 4096. Fix? no Fix the two issues by a) forcing all delayed allocation blocks to be allocated before checking eh->eh_depth and eh->eh_entries b) limiting the last logical block of the extent is within direct map Signed-off-by: Eryu Guan <guaneryu@gmail.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jiri Slaby <jslaby@suse.cz> 
commit d6f123a9297496ad0b6335fe881504c4b5b2a5e5 upstream.

Currently the check in ext4_ind_migrate() is not enough before doing the
real conversion:

a) delayed allocated extents could bypass the check on eh->eh_entries
   and eh->eh_depth

This can be demonstrated by this script

  xfs_io -fc "pwrite 0 4k" -c "pwrite 8k 4k" /mnt/ext4/testfile
  chattr -e /mnt/ext4/testfile

where testfile has two extents but still be converted to non-extent
based file format.

b) only extent length is checked but not the offset, which would result
   in data lose (delalloc) or fs corruption (nodelalloc), because
   non-extent based file only supports at most (12 + 2^10 + 2^20 + 2^30)
   blocks

This can be demostrated by

  xfs_io -fc "pwrite 5T 4k" /mnt/ext4/testfile
  chattr -e /mnt/ext4/testfile
  sync

If delalloc is enabled, dmesg prints
  EXT4-fs warning (device dm-4): ext4_block_to_path:105: block 1342177280 > max in inode 53
  EXT4-fs (dm-4): Delayed block allocation failed for inode 53 at logical offset 1342177280 with max blocks 1 with error 5
  EXT4-fs (dm-4): This should not happen!! Data will be lost

If delalloc is disabled, e2fsck -nf shows corruption
  Inode 53, i_size is 5497558142976, should be 4096.  Fix? no

Fix the two issues by

a) forcing all delayed allocation blocks to be allocated before checking
   eh->eh_depth and eh->eh_entries
b) limiting the last logical block of the extent is within direct map

Signed-off-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
ext4: fix reservation release on invalidatepage for delalloc fs 2015-08-04T14:52:02+00:00 Lukas Czerner lczerner@redhat.com 2015-07-04T01:13:55+00:00 db8d470933df21693ff7e7af48d85c15154bf876 commit 9705acd63b125dee8b15c705216d7186daea4625 upstream. On delalloc enabled file system on invalidatepage operation in ext4_da_page_release_reservation() we want to clear the delayed buffer and remove the extent covering the delayed buffer from the extent status tree. However currently there is a bug where on the systems with page size > block size we will always remove extents from the start of the page regardless where the actual delayed buffers are positioned in the page. This leads to the errors like this: EXT4-fs warning (device loop0): ext4_da_release_space:1225: ext4_da_release_space: ino 13, to_free 1 with only 0 reserved data blocks This however can cause data loss on writeback time if the file system is in ENOSPC condition because we're releasing reservation for someones else delayed buffer. Fix this by only removing extents that corresponds to the part of the page we want to invalidate. This problem is reproducible by the following fio receipt (however I was only able to reproduce it with fio-2.1 or older. [global] bs=8k iodepth=1024 iodepth_batch=60 randrepeat=1 size=1m directory=/mnt/test numjobs=20 [job1] ioengine=sync bs=1k direct=1 rw=randread filename=file1:file2 [job2] ioengine=libaio rw=randwrite direct=1 filename=file1:file2 [job3] bs=1k ioengine=posixaio rw=randwrite direct=1 filename=file1:file2 [job5] bs=1k ioengine=sync rw=randread filename=file1:file2 [job7] ioengine=libaio rw=randwrite filename=file1:file2 [job8] ioengine=posixaio rw=randwrite filename=file1:file2 [job10] ioengine=mmap rw=randwrite bs=1k filename=file1:file2 [job11] ioengine=mmap rw=randwrite direct=1 filename=file1:file2 Signed-off-by: Lukas Czerner <lczerner@redhat.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jiri Slaby <jslaby@suse.cz> 
commit 9705acd63b125dee8b15c705216d7186daea4625 upstream.

On delalloc enabled file system on invalidatepage operation
in ext4_da_page_release_reservation() we want to clear the delayed
buffer and remove the extent covering the delayed buffer from the extent
status tree.

However currently there is a bug where on the systems with page size >
block size we will always remove extents from the start of the page
regardless where the actual delayed buffers are positioned in the page.
This leads to the errors like this:

EXT4-fs warning (device loop0): ext4_da_release_space:1225:
ext4_da_release_space: ino 13, to_free 1 with only 0 reserved data
blocks

This however can cause data loss on writeback time if the file system is
in ENOSPC condition because we're releasing reservation for someones
else delayed buffer.

Fix this by only removing extents that corresponds to the part of the
page we want to invalidate.

This problem is reproducible by the following fio receipt (however I was
only able to reproduce it with fio-2.1 or older.

[global]
bs=8k
iodepth=1024
iodepth_batch=60
randrepeat=1
size=1m
directory=/mnt/test
numjobs=20
[job1]
ioengine=sync
bs=1k
direct=1
rw=randread
filename=file1:file2
[job2]
ioengine=libaio
rw=randwrite
direct=1
filename=file1:file2
[job3]
bs=1k
ioengine=posixaio
rw=randwrite
direct=1
filename=file1:file2
[job5]
bs=1k
ioengine=sync
rw=randread
filename=file1:file2
[job7]
ioengine=libaio
rw=randwrite
filename=file1:file2
[job8]
ioengine=posixaio
rw=randwrite
filename=file1:file2
[job10]
ioengine=mmap
rw=randwrite
bs=1k
filename=file1:file2
[job11]
ioengine=mmap
rw=randwrite
direct=1
filename=file1:file2

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
ext4: don't retry file block mapping on bigalloc fs with non-extent file 2015-08-04T14:52:02+00:00 Darrick J. Wong darrick.wong@oracle.com 2015-06-22T01:10:51+00:00 592eb13673e8b083fbf72b54f410c711f950fb71 commit 292db1bc6c105d86111e858859456bcb11f90f91 upstream. ext4 isn't willing to map clusters to a non-extent file. Don't signal this with an out of space error, since the FS will retry the allocation (which didn't fail) forever. Instead, return EUCLEAN so that the operation will fail immediately all the way back to userspace. (The fix is either to run e2fsck -E bmap2extent, or to chattr +e the file.) Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jiri Slaby <jslaby@suse.cz> 
commit 292db1bc6c105d86111e858859456bcb11f90f91 upstream.

ext4 isn't willing to map clusters to a non-extent file.  Don't signal
this with an out of space error, since the FS will retry the
allocation (which didn't fail) forever.  Instead, return EUCLEAN so
that the operation will fail immediately all the way back to userspace.

(The fix is either to run e2fsck -E bmap2extent, or to chattr +e the file.)

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
ext4: call sync_blockdev() before invalidate_bdev() in put_super() 2015-08-04T14:52:02+00:00 Theodore Ts'o tytso@mit.edu 2015-06-21T02:50:33+00:00 18cb11c2ca2e4e786aa1b1f58c978aa33885944a commit 89d96a6f8e6491f24fc8f99fd6ae66820e85c6c1 upstream. Normally all of the buffers will have been forced out to disk before we call invalidate_bdev(), but there will be some cases, where a file system operation was aborted due to an ext4_error(), where there may still be some dirty buffers in the buffer cache for the device. So try to force them out to memory before calling invalidate_bdev(). This fixes a warning triggered by generic/081: WARNING: CPU: 1 PID: 3473 at /usr/projects/linux/ext4/fs/block_dev.c:56 __blkdev_put+0xb5/0x16f() Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jiri Slaby <jslaby@suse.cz> 
commit 89d96a6f8e6491f24fc8f99fd6ae66820e85c6c1 upstream.

Normally all of the buffers will have been forced out to disk before
we call invalidate_bdev(), but there will be some cases, where a file
system operation was aborted due to an ext4_error(), where there may
still be some dirty buffers in the buffer cache for the device.  So
try to force them out to memory before calling invalidate_bdev().

This fixes a warning triggered by generic/081:

WARNING: CPU: 1 PID: 3473 at /usr/projects/linux/ext4/fs/block_dev.c:56 __blkdev_put+0xb5/0x16f()

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
ext4: fix race between truncate and __ext4_journalled_writepage() 2015-08-04T14:52:01+00:00 Theodore Ts'o tytso@mit.edu 2015-06-13T03:45:33+00:00 ea7fac0e77d18783fd70cc40abc390d88aac8422 commit bdf96838aea6a265f2ae6cbcfb12a778c84a0b8e upstream. The commit cf108bca465d: "ext4: Invert the locking order of page_lock and transaction start" caused __ext4_journalled_writepage() to drop the page lock before the page was written back, as part of changing the locking order to jbd2_journal_start -> page_lock. However, this introduced a potential race if there was a truncate racing with the data=journalled writeback mode. Fix this by grabbing the page lock after starting the journal handle, and then checking to see if page had gotten truncated out from under us. This fixes a number of different warnings or BUG_ON's when running xfstests generic/086 in data=journalled mode, including: jbd2_journal_dirty_metadata: vdc-8: bad jh for block 115643: transaction (ee3fe7 c0, 164), jh->b_transaction ( (null), 0), jh->b_next_transaction ( (null), 0), jlist 0 - and - kernel BUG at /usr/projects/linux/ext4/fs/jbd2/transaction.c:2200! ... Call Trace: [<c02b2ded>] ? __ext4_journalled_invalidatepage+0x117/0x117 [<c02b2de5>] __ext4_journalled_invalidatepage+0x10f/0x117 [<c02b2ded>] ? __ext4_journalled_invalidatepage+0x117/0x117 [<c027d883>] ? lock_buffer+0x36/0x36 [<c02b2dfa>] ext4_journalled_invalidatepage+0xd/0x22 [<c0229139>] do_invalidatepage+0x22/0x26 [<c0229198>] truncate_inode_page+0x5b/0x85 [<c022934b>] truncate_inode_pages_range+0x156/0x38c [<c0229592>] truncate_inode_pages+0x11/0x15 [<c022962d>] truncate_pagecache+0x55/0x71 [<c02b913b>] ext4_setattr+0x4a9/0x560 [<c01ca542>] ? current_kernel_time+0x10/0x44 [<c026c4d8>] notify_change+0x1c7/0x2be [<c0256a00>] do_truncate+0x65/0x85 [<c0226f31>] ? file_ra_state_init+0x12/0x29 - and - WARNING: CPU: 1 PID: 1331 at /usr/projects/linux/ext4/fs/jbd2/transaction.c:1396 irty_metadata+0x14a/0x1ae() ... Call Trace: [<c01b879f>] ? console_unlock+0x3a1/0x3ce [<c082cbb4>] dump_stack+0x48/0x60 [<c0178b65>] warn_slowpath_common+0x89/0xa0 [<c02ef2cf>] ? jbd2_journal_dirty_metadata+0x14a/0x1ae [<c0178bef>] warn_slowpath_null+0x14/0x18 [<c02ef2cf>] jbd2_journal_dirty_metadata+0x14a/0x1ae [<c02d8615>] __ext4_handle_dirty_metadata+0xd4/0x19d [<c02b2f44>] write_end_fn+0x40/0x53 [<c02b4a16>] ext4_walk_page_buffers+0x4e/0x6a [<c02b59e7>] ext4_writepage+0x354/0x3b8 [<c02b2f04>] ? mpage_release_unused_pages+0xd4/0xd4 [<c02b1b21>] ? wait_on_buffer+0x2c/0x2c [<c02b5a4b>] ? ext4_writepage+0x3b8/0x3b8 [<c02b5a5b>] __writepage+0x10/0x2e [<c0225956>] write_cache_pages+0x22d/0x32c [<c02b5a4b>] ? ext4_writepage+0x3b8/0x3b8 [<c02b6ee8>] ext4_writepages+0x102/0x607 [<c019adfe>] ? sched_clock_local+0x10/0x10e [<c01a8a7c>] ? __lock_is_held+0x2e/0x44 [<c01a8ad5>] ? lock_is_held+0x43/0x51 [<c0226dff>] do_writepages+0x1c/0x29 [<c0276bed>] __writeback_single_inode+0xc3/0x545 [<c0277c07>] writeback_sb_inodes+0x21f/0x36d ... Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jiri Slaby <jslaby@suse.cz> 
commit bdf96838aea6a265f2ae6cbcfb12a778c84a0b8e upstream.

The commit cf108bca465d: "ext4: Invert the locking order of page_lock
and transaction start" caused __ext4_journalled_writepage() to drop
the page lock before the page was written back, as part of changing
the locking order to jbd2_journal_start -> page_lock.  However, this
introduced a potential race if there was a truncate racing with the
data=journalled writeback mode.

Fix this by grabbing the page lock after starting the journal handle,
and then checking to see if page had gotten truncated out from under
us.

This fixes a number of different warnings or BUG_ON's when running
xfstests generic/086 in data=journalled mode, including:

jbd2_journal_dirty_metadata: vdc-8: bad jh for block 115643: transaction (ee3fe7
c0, 164), jh->b_transaction (  (null), 0), jh->b_next_transaction (  (null), 0), jlist 0

	      	      	  - and -

kernel BUG at /usr/projects/linux/ext4/fs/jbd2/transaction.c:2200!
    ...
Call Trace:
 [<c02b2ded>] ? __ext4_journalled_invalidatepage+0x117/0x117
 [<c02b2de5>] __ext4_journalled_invalidatepage+0x10f/0x117
 [<c02b2ded>] ? __ext4_journalled_invalidatepage+0x117/0x117
 [<c027d883>] ? lock_buffer+0x36/0x36
 [<c02b2dfa>] ext4_journalled_invalidatepage+0xd/0x22
 [<c0229139>] do_invalidatepage+0x22/0x26
 [<c0229198>] truncate_inode_page+0x5b/0x85
 [<c022934b>] truncate_inode_pages_range+0x156/0x38c
 [<c0229592>] truncate_inode_pages+0x11/0x15
 [<c022962d>] truncate_pagecache+0x55/0x71
 [<c02b913b>] ext4_setattr+0x4a9/0x560
 [<c01ca542>] ? current_kernel_time+0x10/0x44
 [<c026c4d8>] notify_change+0x1c7/0x2be
 [<c0256a00>] do_truncate+0x65/0x85
 [<c0226f31>] ? file_ra_state_init+0x12/0x29

	      	      	  - and -

WARNING: CPU: 1 PID: 1331 at /usr/projects/linux/ext4/fs/jbd2/transaction.c:1396
irty_metadata+0x14a/0x1ae()
    ...
Call Trace:
 [<c01b879f>] ? console_unlock+0x3a1/0x3ce
 [<c082cbb4>] dump_stack+0x48/0x60
 [<c0178b65>] warn_slowpath_common+0x89/0xa0
 [<c02ef2cf>] ? jbd2_journal_dirty_metadata+0x14a/0x1ae
 [<c0178bef>] warn_slowpath_null+0x14/0x18
 [<c02ef2cf>] jbd2_journal_dirty_metadata+0x14a/0x1ae
 [<c02d8615>] __ext4_handle_dirty_metadata+0xd4/0x19d
 [<c02b2f44>] write_end_fn+0x40/0x53
 [<c02b4a16>] ext4_walk_page_buffers+0x4e/0x6a
 [<c02b59e7>] ext4_writepage+0x354/0x3b8
 [<c02b2f04>] ? mpage_release_unused_pages+0xd4/0xd4
 [<c02b1b21>] ? wait_on_buffer+0x2c/0x2c
 [<c02b5a4b>] ? ext4_writepage+0x3b8/0x3b8
 [<c02b5a5b>] __writepage+0x10/0x2e
 [<c0225956>] write_cache_pages+0x22d/0x32c
 [<c02b5a4b>] ? ext4_writepage+0x3b8/0x3b8
 [<c02b6ee8>] ext4_writepages+0x102/0x607
 [<c019adfe>] ? sched_clock_local+0x10/0x10e
 [<c01a8a7c>] ? __lock_is_held+0x2e/0x44
 [<c01a8ad5>] ? lock_is_held+0x43/0x51
 [<c0226dff>] do_writepages+0x1c/0x29
 [<c0276bed>] __writeback_single_inode+0xc3/0x545
 [<c0277c07>] writeback_sb_inodes+0x21f/0x36d
    ...

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>