linux/fs/ocfs2
Changwei Ge 71a3694404 ocfs2: try to reuse extent block in dealloc without meta_alloc
A crash issue was reported by John Lightsey with a call trace as follows:

  ocfs2_split_extent+0x1ad3/0x1b40 [ocfs2]
  ocfs2_change_extent_flag+0x33a/0x470 [ocfs2]
  ocfs2_mark_extent_written+0x172/0x220 [ocfs2]
  ocfs2_dio_end_io+0x62d/0x910 [ocfs2]
  dio_complete+0x19a/0x1a0
  do_blockdev_direct_IO+0x19dd/0x1eb0
  __blockdev_direct_IO+0x43/0x50
  ocfs2_direct_IO+0x8f/0xa0 [ocfs2]
  generic_file_direct_write+0xb2/0x170
  __generic_file_write_iter+0xc3/0x1b0
  ocfs2_file_write_iter+0x4bb/0xca0 [ocfs2]
  __vfs_write+0xae/0xf0
  vfs_write+0xb8/0x1b0
  SyS_write+0x4f/0xb0
  system_call_fastpath+0x16/0x75

The BUG code told that extent tree wants to grow but no metadata was
reserved ahead of time.  From my investigation into this issue, the root
cause it that although enough metadata is not reserved, there should be
enough for following use.  Rightmost extent is merged into its left one
due to a certain times of marking extent written.  Because during
marking extent written, we got many physically continuous extents.  At
last, an empty extent showed up and the rightmost path is removed from
extent tree.

Add a new mechanism to reuse extent block cached in dealloc which were
just unlinked from extent tree to solve this crash issue.

Criteria is that during marking extents *written*, if extent rotation
and merging results in unlinking extent with growing extent tree later
without any metadata reserved ahead of time, try to reuse those extents
in dealloc in which deleted extents are cached.

Also, this patch addresses the issue John reported that ::dw_zero_count
is not calculated properly.

After applying this patch, the issue John reported was gone.  Thanks for
the reproducer provided by John.  And this patch has passed
ocfs2-test(29 cases) suite running by New H3C Group.

[ge.changwei@h3c.com: fix static checker warnning]
  Link: http://lkml.kernel.org/r/63ADC13FD55D6546B7DECE290D39E373F29196AE@H3CMLB12-EX.srv.huawei-3com.com
[akpm@linux-foundation.org: brelse(NULL) is legal]
Link: http://lkml.kernel.org/r/1515479070-32653-2-git-send-email-ge.changwei@h3c.com
Signed-off-by: Changwei Ge <ge.changwei@h3c.com>
Reported-by: John Lightsey <john@nixnuts.net>
Tested-by: John Lightsey <john@nixnuts.net>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Joseph Qi <jiangqi903@gmail.com>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Mark Fasheh <mfasheh@versity.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-01-31 17:18:35 -08:00
..
cluster ocfs2/cluster: close a race that fence can't be triggered 2018-01-31 17:18:35 -08:00
dlm fs/ocfs2/dlm/dlmmaster.c: clean up dead code 2018-01-31 17:18:34 -08:00
dlmfs fs: annotate ->poll() instances 2017-11-27 16:20:05 -05:00
acl.c ocfs2/acl: use 'ip_xattr_sem' to protect getting extended attribute 2018-01-31 17:18:35 -08:00
acl.h ocfs2: make ocfs2_set_acl() static 2017-09-06 17:27:24 -07:00
alloc.c ocfs2: try to reuse extent block in dealloc without meta_alloc 2018-01-31 17:18:35 -08:00
alloc.h ocfs2: try to reuse extent block in dealloc without meta_alloc 2018-01-31 17:18:35 -08:00
aops.c ocfs2: try to reuse extent block in dealloc without meta_alloc 2018-01-31 17:18:35 -08:00
aops.h
blockcheck.c
blockcheck.h
buffer_head_io.c
buffer_head_io.h ocfs2: clean up some unused function declarations 2017-11-15 18:21:01 -08:00
dcache.c
dcache.h
dir.c ocfs2: convert to new i_version API 2018-01-29 06:42:21 -05:00
dir.h
dlmglue.c ocfs2: try a blocking lock before return AOP_TRUNCATED_PAGE 2018-01-31 17:18:35 -08:00
dlmglue.h
export.c ocfs2: Use ERR_CAST() to avoid cross-structure cast 2017-05-28 10:11:49 -07:00
export.h
extent_map.c
extent_map.h
file.c Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
file.h
filecheck.c Pass mode to wait_on_atomic_t() action funcs and provide default actions 2017-11-13 15:38:16 +00:00
filecheck.h
heartbeat.c
heartbeat.h
inode.c ocfs2: convert to new i_version API 2018-01-29 06:42:21 -05:00
inode.h
ioctl.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ioctl.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
journal.c ocfs2: clean up some dead code 2017-09-06 17:27:24 -07:00
journal.h
Kconfig
localalloc.c
localalloc.h
locks.c
locks.h
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mmap.c
mmap.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
move_extents.c ocfs2: clean up some dead code 2017-09-06 17:27:24 -07:00
move_extents.h
namei.c ocfs2: convert to new i_version API 2018-01-29 06:42:21 -05:00
namei.h
ocfs1_fs_compat.h
ocfs2_fs.h ocfs2: use magic.h 2017-07-06 16:24:30 -07:00
ocfs2_ioctl.h
ocfs2_lockid.h
ocfs2_lockingver.h
ocfs2_trace.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ocfs2.h ocfs2: clean up some dead code 2017-09-06 17:27:24 -07:00
quota_global.c ocfs2: convert to new i_version API 2018-01-29 06:42:21 -05:00
quota_local.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
quota.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
refcounttree.c ocfs2: clean up some dead code 2017-09-06 17:27:24 -07:00
refcounttree.h
reservations.c
reservations.h
resize.c
resize.h
slot_map.c
slot_map.h
stack_o2cb.c
stack_user.c
stackglue.c ocfs2: constify attribute_group structures 2017-07-06 16:24:30 -07:00
stackglue.h
suballoc.c ocfs2: clean dead code in suballoc.c 2018-01-31 17:18:35 -08:00
suballoc.h
super.c ocfs2: return -EROFS to mount.ocfs2 if inode block is invalid 2018-01-31 17:18:35 -08:00
super.h ocfs2: remove unused declaration ocfs2_publish_get_mount_state() 2017-11-15 18:21:01 -08:00
symlink.c
symlink.h
sysfile.c
sysfile.h
uptodate.c
uptodate.h
xattr.c ocfs2/acl: use 'ip_xattr_sem' to protect getting extended attribute 2018-01-31 17:18:35 -08:00
xattr.h