linux-toradex.git/fs/ext4/inode.c, branch v3.12.11

ext4: fix deadlock when writing in ENOSPC conditions

2014-01-09T20:25:10+00:00

commit 34cf865d54813aab3497838132fb1bbd293f4054 upstream.

Akira-san has been reporting rare deadlocks of his machine when running
xfstests test 269 on ext4 filesystem. The problem turned out to be in
ext4_da_reserve_metadata() and ext4_da_reserve_space() which called
ext4_should_retry_alloc() while holding i_data_sem. Since
ext4_should_retry_alloc() can force a transaction commit, this is a
lock ordering violation and leads to deadlocks.

Fix the problem by just removing the retry loops. These functions should
just report ENOSPC to the caller (e.g. ext4_da_write_begin()) and that
function must take care of retrying after dropping all necessary locks.

Reported-and-tested-by: Akira Fujita 
Reviewed-by: Zheng Liu 
Signed-off-by: Jan Kara 
Signed-off-by: "Theodore Ts'o" 
Signed-off-by: Greg Kroah-Hartman

Merge tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

2013-10-12T19:55:15+00:00

Pull ext4 bugfixes from Ted Ts'o:
 "A bug fix and performance regression fix for ext4"

* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: fix memory leak in xattr
  ext4: fix performance regression in writeback of random writes

ext4: fix performance regression in writeback of random writes

2013-09-16T12:24:26+00:00

The Linux Kernel Performance project guys have reported that commit
4e7ea81db5 introduces a performance regression for the following fio
workload:

[global]
direct=0
ioengine=mmap
size=1500M
bs=4k
pre_read=1
numjobs=1
overwrite=1
loops=5
runtime=300
group_reporting
invalidate=0
directory=/mnt/
file_service_type=random:36
file_service_type=random:36

[job0]
startdelay=0
rw=randrw
filename=data0/f1:data0/f2

[job1]
startdelay=0
rw=randrw
filename=data0/f2:data0/f1
...

[job7]
startdelay=0
rw=randrw
filename=data0/f2:data0/f1

The culprit of the problem is that after the commit ext4_writepages()
are more aggressive in writing back pages. Thus we have less consecutive
dirty pages resulting in more seeking.

This increased aggressivity is caused by a bug in the condition
terminating ext4_writepages(). We start writing from the beginning of
the file even if we should have terminated ext4_writepages() because
wbc->nr_to_write <= 0.

After fixing the condition the throughput of the fio workload is about 20%
better than before writeback reorganization.

Reported-by: "Yan, Zheng" 
Signed-off-by: Jan Kara 
Signed-off-by: "Theodore Ts'o"

truncate: drop 'oldsize' truncate_pagecache() parameter

2013-09-12T22:38:02+00:00

truncate_pagecache() doesn't care about old size since commit
cedabed49b39 ("vfs: Fix vmtruncate() regression").  Let's drop it.

Signed-off-by: Kirill A. Shutemov 
Cc: OGAWA Hirofumi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2013-09-05T15:50:26+00:00

Pull vfs pile 1 from Al Viro:
 "Unfortunately, this merge window it'll have a be a lot of small piles -
  my fault, actually, for not keeping #for-next in anything that would
  resemble a sane shape ;-/

  This pile: assorted fixes (the first 3 are -stable fodder, IMO) and
  cleanups + %pd/%pD formats (dentry/file pathname, up to 4 last
  components) + several long-standing patches from various folks.

  There definitely will be a lot more (starting with Miklos'
  check_submount_and_drop() series)"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (26 commits)
  direct-io: Handle O_(D)SYNC AIO
  direct-io: Implement generic deferred AIO completions
  add formats for dentry/file pathnames
  kvm eventfd: switch to fdget
  powerpc kvm: use fdget
  switch fchmod() to fdget
  switch epoll_ctl() to fdget
  switch copy_module_from_fd() to fdget
  git simplify nilfs check for busy subtree
  ibmasmfs: don't bother passing superblock when not needed
  don't pass superblock to hypfs_{mkdir,create*}
  don't pass superblock to hypfs_diag_create_files
  don't pass superblock to hypfs_vm_create_files()
  oprofile: get rid of pointless forward declarations of struct super_block
  oprofilefs_create_...() do not need superblock argument
  oprofilefs_mkdir() doesn't need superblock argument
  don't bother with passing superblock to oprofile_create_stats_files()
  oprofile: don't bother with passing superblock to ->create_files()
  don't bother passing sb to oprofile_create_files()
  coh901318: don't open-code simple_read_from_buffer()
  ...

direct-io: Implement generic deferred AIO completions

2013-09-04T13:23:46+00:00

Add support to the core direct-io code to defer AIO completions to user
context using a workqueue.  This replaces opencoded and less efficient
code in XFS and ext4 (we save a memory allocation for each direct IO)
and will be needed to properly support O_(D)SYNC for AIO.

The communication between the filesystem and the direct I/O code requires
a new buffer head flag, which is a bit ugly but not avoidable until the
direct I/O code stops abusing the buffer_head structure for communicating
with the filesystems.

Currently this creates a per-superblock unbound workqueue for these
completions, which is taken from an earlier patch by Jan Kara.  I'm
not really convinced about this use and would prefer a "normal" global
workqueue with a high concurrency limit, but this needs further discussion.

JK: Fixed ext4 part, dynamic allocation of the workqueue.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Jan Kara 
Signed-off-by: Al Viro

ext4: Fix misspellings using 'codespell' tool

2013-08-28T18:40:12+00:00

Signed-off-by: Anatol Pomozov 
Signed-off-by: "Theodore Ts'o"

ext4: convert write_begin methods to stable_page_writes semantics

2013-08-28T18:30:47+00:00

Use wait_for_stable_page() instead of wait_on_page_writeback()

Signed-off-by: Dmitry Monakhov 
Signed-off-by: "Theodore Ts'o" 
Reviewed-by: Jan Kara

ext4: fix lost truncate due to race with writeback

2013-08-17T14:09:31+00:00

The following race can lead to a loss of i_disksize update from truncate
thus resulting in a wrong inode size if the inode size isn't updated
again before inode is reclaimed:

ext4_setattr()				mpage_map_and_submit_extent()
  EXT4_I(inode)->i_disksize = attr->ia_size;
  ...					  ...
					  disksize = ((loff_t)mpd->first_page) << PAGE_CACHE_SHIFT
					  /* False because i_size isn't
					   * updated yet */
					  if (disksize > i_size_read(inode))
					  /* True, because i_disksize is
					   * already truncated */
					  if (disksize > EXT4_I(inode)->i_disksize)
					    /* Overwrite i_disksize
					     * update from truncate */
					    ext4_update_i_disksize()
  i_size_write(inode, attr->ia_size);

For other places updating i_disksize such race cannot happen because
i_mutex prevents these races. Writeback is the only place where we do
not hold i_mutex and we cannot grab it there because of lock ordering.

We fix the race by doing both i_disksize and i_size update in truncate
atomically under i_data_sem and in mpage_map_and_submit_extent() we move
the check against i_size under i_data_sem as well.

Signed-off-by: Jan Kara 
Signed-off-by: "Theodore Ts'o" 
Cc: stable@vger.kernel.org

ext4: simplify truncation code in ext4_setattr()

2013-08-17T14:07:17+00:00

Merge conditions in ext4_setattr() handling inode size changes, also
move ext4_begin_ordered_truncate() call somewhat earlier because it
simplifies error recovery in case of failure. Also add error handling in
case i_disksize update fails.

Signed-off-by: Jan Kara 
Signed-off-by: "Theodore Ts'o" 
Cc: stable@vger.kernel.org