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| author | Ben Myers <bpm@sgi.com> | 2012-05-15 14:26:55 -0500 |
|---|---|---|
| committer | Ben Myers <bpm@sgi.com> | 2012-05-15 14:35:43 -0500 |
| commit | 1307bbd2af67283131728637e9489002adb26f10 (patch) | |
| tree | 76b3000b2cf8e7d101b8f4b4de20e6255d316b95 /fs | |
| parent | 3fe3e6b18216c1247497dfd51c35484338856e1b (diff) | |
| download | linux-1307bbd2af67283131728637e9489002adb26f10.tar.gz linux-1307bbd2af67283131728637e9489002adb26f10.tar.bz2 linux-1307bbd2af67283131728637e9489002adb26f10.zip | |
xfs: protect xfs_sync_worker with s_umount semaphore
xfs_sync_worker checks the MS_ACTIVE flag in s_flags to avoid doing
work during mount and unmount. This flag can be cleared by unmount
after the xfs_sync_worker checks it but before the work is completed.
The has caused crashes in the completion handler for the dummy
transaction commited by xfs_sync_worker:
PID: 27544 TASK: ffff88013544e040 CPU: 3 COMMAND: "kworker/3:0"
#0 [ffff88016fdff930] machine_kexec at ffffffff810244e9
#1 [ffff88016fdff9a0] crash_kexec at ffffffff8108d053
#2 [ffff88016fdffa70] oops_end at ffffffff813ad1b8
#3 [ffff88016fdffaa0] no_context at ffffffff8102bd48
#4 [ffff88016fdffaf0] __bad_area_nosemaphore at ffffffff8102c04d
#5 [ffff88016fdffb40] bad_area_nosemaphore at ffffffff8102c12e
#6 [ffff88016fdffb50] do_page_fault at ffffffff813afaee
#7 [ffff88016fdffc60] page_fault at ffffffff813ac635
[exception RIP: xlog_get_lowest_lsn+0x30]
RIP: ffffffffa04a9910 RSP: ffff88016fdffd10 RFLAGS: 00010246
RAX: ffffc90014e48000 RBX: ffff88014d879980 RCX: ffff88014d879980
RDX: ffff8802214ee4c0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff88016fdffd10 R8: ffff88014d879a80 R9: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffff8802214ee400
R13: ffff88014d879980 R14: 0000000000000000 R15: ffff88022fd96605
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
#8 [ffff88016fdffd18] xlog_state_do_callback at ffffffffa04aa186 [xfs]
#9 [ffff88016fdffd98] xlog_state_done_syncing at ffffffffa04aa568 [xfs]
Protect xfs_sync_worker by using the s_umount semaphore at the read
level to provide exclusion with unmount while work is progressing.
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/xfs/xfs_sync.c | 29 |
1 files changed, 16 insertions, 13 deletions
diff --git a/fs/xfs/xfs_sync.c b/fs/xfs/xfs_sync.c index d2422683ed76..c9d3409c5ca3 100644 --- a/fs/xfs/xfs_sync.c +++ b/fs/xfs/xfs_sync.c @@ -386,20 +386,23 @@ xfs_sync_worker( * We shouldn't write/force the log if we are in the mount/unmount * process or on a read only filesystem. The workqueue still needs to be * active in both cases, however, because it is used for inode reclaim - * during these times. hence use the MS_ACTIVE flag to avoid doing - * anything in these periods. + * during these times. Use the s_umount semaphore to provide exclusion + * with unmount. */ - if (!(mp->m_super->s_flags & MS_ACTIVE) && - !(mp->m_flags & XFS_MOUNT_RDONLY)) { - /* dgc: errors ignored here */ - if (mp->m_super->s_frozen == SB_UNFROZEN && - xfs_log_need_covered(mp)) - error = xfs_fs_log_dummy(mp); - else - xfs_log_force(mp, 0); - - /* start pushing all the metadata that is currently dirty */ - xfs_ail_push_all(mp->m_ail); + if (down_read_trylock(&mp->m_super->s_umount)) { + if (!(mp->m_flags & XFS_MOUNT_RDONLY)) { + /* dgc: errors ignored here */ + if (mp->m_super->s_frozen == SB_UNFROZEN && + xfs_log_need_covered(mp)) + error = xfs_fs_log_dummy(mp); + else + xfs_log_force(mp, 0); + + /* start pushing all the metadata that is currently + * dirty */ + xfs_ail_push_all(mp->m_ail); + } + up_read(&mp->m_super->s_umount); } /* queue us up again */ |