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  1. 08 12月, 2015 1 次提交
    • J
      ext4: fix races between page faults and hole punching · ea3d7209
      由 Jan Kara 提交于 
      Currently, page faults and hole punching are completely unsynchronized.
This can result in page fault faulting in a page into a range that we
are punching after truncate_pagecache_range() has been called and thus
we can end up with a page mapped to disk blocks that will be shortly
freed. Filesystem corruption will shortly follow. Note that the same
race is avoided for truncate by checking page fault offset against
i_size but there isn't similar mechanism available for punching holes.

Fix the problem by creating new rw semaphore i_mmap_sem in inode and
grab it for writing over truncate, hole punching, and other functions
removing blocks from extent tree and for read over page faults. We
cannot easily use i_data_sem for this since that ranks below transaction
start and we need something ranking above it so that it can be held over
the whole truncate / hole punching operation. Also remove various
workarounds we had in the code to reduce race window when page fault
could have created pages with stale mapping information.
Signed-off-by: NJan Kara <jack@suse.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
      ea3d7209
  3. 11 11月, 2015 1 次提交
    • R
      vfs: remove unused wrapper block_page_mkwrite() · 5c500029
      由 Ross Zwisler 提交于 
      The function currently called "__block_page_mkwrite()" used to be called
"block_page_mkwrite()" until a wrapper for this function was added by:

commit 24da4fab ("vfs: Create __block_page_mkwrite() helper passing
	error values back")

This wrapper, the current "block_page_mkwrite()", is currently unused.
__block_page_mkwrite() is used directly by ext4, nilfs2 and xfs.

Remove the unused wrapper, rename __block_page_mkwrite() back to
block_page_mkwrite() and update the comment above block_page_mkwrite().
Signed-off-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: NJan Kara <jack@suse.com>
Cc: Jan Kara <jack@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      5c500029
  5. 07 11月, 2015 1 次提交
  7. 18 10月, 2015 2 次提交
  9. 15 10月, 2015 1 次提交
    • T
      ext4: use private version of page_zero_new_buffers() for data=journal mode · b90197b6
      由 Theodore Ts'o 提交于 
      If there is a error while copying data from userspace into the page
cache during a write(2) system call, in data=journal mode, in
ext4_journalled_write_end() were using page_zero_new_buffers() from
fs/buffer.c.  Unfortunately, this sets the buffer dirty flag, which is
no good if journalling is enabled.  This is a long-standing bug that
goes back for years and years in ext3, but a combination of (a)
data=journal not being very common, (b) in many case it only results
in a warning message. and (c) only very rarely causes the kernel hang,
means that we only really noticed this as a problem when commit
998ef75d caused this failure to happen frequently enough to cause
generic/208 to fail when run in data=journal mode.

The fix is to have our own version of this function that doesn't call
mark_dirty_buffer(), since we will end up calling
ext4_handle_dirty_metadata() on the buffer head(s) in questions very
shortly afterwards in ext4_journalled_write_end().

Thanks to Dave Hansen and Linus Torvalds for helping to identify the
root cause of the problem.
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Reviewed-by: NJan Kara <jack@suse.com>
      b90197b6
  11. 03 10月, 2015 2 次提交
    • T
      ext4 crypto: ext4_page_crypto() doesn't need a encryption context · 3684de8c
      由 Theodore Ts'o 提交于 
      Since ext4_page_crypto() doesn't need an encryption context (at least
not any more), this allows us to simplify a number function signature
and also allows us to avoid needing to allocate a context in
ext4_block_write_begin().  It also means we no longer need a separate
ext4_decrypt_one() function.
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
      3684de8c
    • T
      ext4: optimize ext4_writepage() for attempted 4k delalloc writes · cccd147a
      由 Theodore Ts'o 提交于 
      In cases where the file system block size is the same as the page
size, and ext4_writepage() is asked to write out a page which is
either has the unwritten bit set in the extent tree, or which does not
yet have a block assigned due to delayed allocation, we can bail out
early and, unlocking the page earlier and avoiding a round trip
through ext4_bio_write_page() with the attendant calls to
set_page_writeback() and redirty_page_for_writeback().
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
      cccd147a
  13. 09 9月, 2015 2 次提交
  15. 29 7月, 2015 1 次提交
  17. 24 7月, 2015 1 次提交
  19. 04 7月, 2015 1 次提交
    • L
      ext4: fix reservation release on invalidatepage for delalloc fs · 9705acd6
      由 Lukas Czerner 提交于 
      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: NLukas Czerner <lczerner@redhat.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Reviewed-by: NJan Kara <jack@suse.cz>
Cc: stable@vger.kernel.org
      9705acd6
  21. 02 7月, 2015 1 次提交
    • T
      ext4: fix fencepost error in lazytime optimization · 0f0ff9a9
      由 Theodore Ts'o 提交于 
      Commit 8f4d8558: "ext4: fix lazytime optimization" was not a
complete fix.  In the case where the inode number is a multiple of 16,
and we could still end up updating an inode with dirty timestamps
written to the wrong inode on disk.  Oops.

This can be easily reproduced by using generic/005 with a file system
with metadata_csum and lazytime enabled.
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
      0f0ff9a9
  23. 22 6月, 2015 2 次提交
  25. 21 6月, 2015 1 次提交
    • T
      ext4: prevent ext4_quota_write() from failing due to ENOSPC · c5e298ae
      由 Theodore Ts'o 提交于 
      In order to prevent quota block tracking to be inaccurate when
ext4_quota_write() fails with ENOSPC, we make two changes.  The quota
file can now use the reserved block (since the quota file is arguably
file system metadata), and ext4_quota_write() now uses
ext4_should_retry_alloc() to retry the block allocation after a commit
has completed and released some blocks for allocation.

This fixes failures of xfstests generic/270:

Quota error (device vdc): write_blk: dquota write failed
Quota error (device vdc): qtree_write_dquot: Error -28 occurred while creating quota
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
      c5e298ae
  27. 13 6月, 2015 1 次提交
    • T
      ext4: fix race between truncate and __ext4_journalled_writepage() · bdf96838
      由 Theodore Ts'o 提交于 
      The commit cf108bca: "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: NTheodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
      bdf96838
  29. 04 6月, 2015 1 次提交
    • D
      dax: don't abuse get_block mapping for endio callbacks · e842f290
      由 Dave Chinner 提交于 
      dax_fault() currently relies on the get_block callback to attach an
io completion callback to the mapping buffer head so that it can
run unwritten extent conversion after zeroing allocated blocks.

Instead of this hack, pass the conversion callback directly into
dax_fault() similar to the get_block callback. When the filesystem
allocates unwritten extents, it will set the buffer_unwritten()
flag, and hence the dax_fault code can call the completion function
in the contexts where it is necessary without overloading the
mapping buffer head.

Note: The changes to ext4 to use this interface are suspect at best.
In fact, the way ext4 did this end_io assignment in the first place
looks suspect because it only set a completion callback when there
wasn't already some other write() call taking place on the same
inode. The ext4 end_io code looks rather intricate and fragile with
all it's reference counting and passing to different contexts for
modification via inode private pointers that aren't protected by
locks...
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Acked-by: NJan Kara <jack@suse.cz>
Signed-off-by: NDave Chinner <david@fromorbit.com>
      e842f290
  31. 15 5月, 2015 1 次提交
  33. 11 5月, 2015 2 次提交
  35. 03 5月, 2015 1 次提交
    • L
      ext4: fix data corruption caused by unwritten and delayed extents · d2dc317d
      由 Lukas Czerner 提交于 
      Currently it is possible to lose whole file system block worth of data
when we hit the specific interaction with unwritten and delayed extents
in status extent tree.

The problem is that when we insert delayed extent into extent status
tree the only way to get rid of it is when we write out delayed buffer.
However there is a limitation in the extent status tree implementation
so that when inserting unwritten extent should there be even a single
delayed block the whole unwritten extent would be marked as delayed.

At this point, there is no way to get rid of the delayed extents,
because there are no delayed buffers to write out. So when a we write
into said unwritten extent we will convert it to written, but it still
remains delayed.

When we try to write into that block later ext4_da_map_blocks() will set
the buffer new and delayed and map it to invalid block which causes
the rest of the block to be zeroed loosing already written data.

For now we can fix this by simply not allowing to set delayed status on
written extent in the extent status tree. Also add WARN_ON() to make
sure that we notice if this happens in the future.

This problem can be easily reproduced by running the following xfs_io.

xfs_io -f -c "pwrite -S 0xaa 4096 2048" \
          -c "falloc 0 131072" \
          -c "pwrite -S 0xbb 65536 2048" \
          -c "fsync" /mnt/test/fff

echo 3 > /proc/sys/vm/drop_caches
xfs_io -c "pwrite -S 0xdd 67584 2048" /mnt/test/fff

This can be theoretically also reproduced by at random by running fsx,
but it's not very reliable, though on machines with bigger page size
(like ppc) this can be seen more often (especially xfstest generic/127)
Signed-off-by: NLukas Czerner <lczerner@redhat.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
      d2dc317d
  37. 25 4月, 2015 1 次提交
    • J
      direct-io: only inc/dec inode->i_dio_count for file systems · fe0f07d0
      由 Jens Axboe 提交于 
      do_blockdev_direct_IO() increments and decrements the inode
->i_dio_count for each IO operation. It does this to protect against
truncate of a file. Block devices don't need this sort of protection.

For a capable multiqueue setup, this atomic int is the only shared
state between applications accessing the device for O_DIRECT, and it
presents a scaling wall for that. In my testing, as much as 30% of
system time is spent incrementing and decrementing this value. A mixed
read/write workload improved from ~2.5M IOPS to ~9.6M IOPS, with
better latencies too. Before:

clat percentiles (usec):
 |  1.00th=[   33],  5.00th=[   34], 10.00th=[   34], 20.00th=[   34],
 | 30.00th=[   34], 40.00th=[   34], 50.00th=[   35], 60.00th=[   35],
 | 70.00th=[   35], 80.00th=[   35], 90.00th=[   37], 95.00th=[   80],
 | 99.00th=[   98], 99.50th=[  151], 99.90th=[  155], 99.95th=[  155],
 | 99.99th=[  165]

After:

clat percentiles (usec):
 |  1.00th=[   95],  5.00th=[  108], 10.00th=[  129], 20.00th=[  149],
 | 30.00th=[  155], 40.00th=[  161], 50.00th=[  167], 60.00th=[  171],
 | 70.00th=[  177], 80.00th=[  185], 90.00th=[  201], 95.00th=[  270],
 | 99.00th=[  390], 99.50th=[  398], 99.90th=[  418], 99.95th=[  422],
 | 99.99th=[  438]

In other setups, Robert Elliott reported seeing good performance
improvements:

https://lkml.org/lkml/2015/4/3/557

The more applications accessing the device, the worse it gets.

Add a new direct-io flags, DIO_SKIP_DIO_COUNT, which tells
do_blockdev_direct_IO() that it need not worry about incrementing
or decrementing the inode i_dio_count for this caller.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Elliott, Robert (Server Storage) <elliott@hp.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJens Axboe <axboe@fb.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      fe0f07d0
  39. 16 4月, 2015 3 次提交
  41. 12 4月, 2015 6 次提交
  43. 08 4月, 2015 1 次提交
  45. 03 4月, 2015 1 次提交
  47. 26 3月, 2015 1 次提交
  49. 17 2月, 2015 1 次提交
  51. 13 2月, 2015 1 次提交
  53. 05 2月, 2015 2 次提交
    • T
      ext4: add optimization for the lazytime mount option · a26f4992
      由 Theodore Ts'o 提交于 
      Add an optimization for the MS_LAZYTIME mount option so that we will
opportunistically write out any inodes with the I_DIRTY_TIME flag set
in a particular inode table block when we need to update some inode in
that inode table block anyway.

Also add some temporary code so that we can set the lazytime mount
option without needing a modified /sbin/mount program which can set
MS_LAZYTIME.  We can eventually make this go away once util-linux has
added support.

Google-Bug-Id: 18297052
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      a26f4992
    • T
      vfs: add support for a lazytime mount option · 0ae45f63
      由 Theodore Ts'o 提交于 
      Add a new mount option which enables a new "lazytime" mode.  This mode
causes atime, mtime, and ctime updates to only be made to the
in-memory version of the inode.  The on-disk times will only get
updated when (a) if the inode needs to be updated for some non-time
related change, (b) if userspace calls fsync(), syncfs() or sync(), or
(c) just before an undeleted inode is evicted from memory.

This is OK according to POSIX because there are no guarantees after a
crash unless userspace explicitly requests via a fsync(2) call.

For workloads which feature a large number of random write to a
preallocated file, the lazytime mount option significantly reduces
writes to the inode table.  The repeated 4k writes to a single block
will result in undesirable stress on flash devices and SMR disk
drives.  Even on conventional HDD's, the repeated writes to the inode
table block will trigger Adjacent Track Interference (ATI) remediation
latencies, which very negatively impact long tail latencies --- which
is a very big deal for web serving tiers (for example).

Google-Bug-Id: 18297052
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      0ae45f63