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| author | Abhi Das <adas@redhat.com> | 2019-05-01 00:53:47 +0300 |
|---|---|---|
| committer | Andreas Gruenbacher <agruenba@redhat.com> | 2019-05-08 00:39:14 +0300 |
| commit | 8f91821990fd6f170a5dca79697a441181a41b16 (patch) | |
| tree | 6efd729419e769c9a86681b5a8aca56e6c3e5995 /fs/gfs2/super.c | |
| parent | fbb27873f21d5fb9bf556edcaa67e9891636e5d4 (diff) | |
| download | linux-8f91821990fd6f170a5dca79697a441181a41b16.tar.xz | |
gfs2: fix race between gfs2_freeze_func and unmount
As part of the freeze operation, gfs2_freeze_func() is left blocking
on a request to hold the sd_freeze_gl in SH. This glock is held in EX
by the gfs2_freeze() code.
A subsequent call to gfs2_unfreeze() releases the EXclusively held
sd_freeze_gl, which allows gfs2_freeze_func() to acquire it in SH and
resume its operation.
gfs2_unfreeze(), however, doesn't wait for gfs2_freeze_func() to complete.
If a umount is issued right after unfreeze, it could result in an
inconsistent filesystem because some journal data (statfs update) isn't
written out.
Refer to commit 24972557b12c for a more detailed explanation of how
freeze/unfreeze work.
This patch causes gfs2_unfreeze() to wait for gfs2_freeze_func() to
complete before returning to the user.
Signed-off-by: Abhi Das <adas@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Diffstat (limited to 'fs/gfs2/super.c')
| -rw-r--r-- | fs/gfs2/super.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c index 6d89d0ecec2a..5b148cf03293 100644 --- a/fs/gfs2/super.c +++ b/fs/gfs2/super.c @@ -973,8 +973,7 @@ void gfs2_freeze_func(struct work_struct *work) if (error) { printk(KERN_INFO "GFS2: couldn't get freeze lock : %d\n", error); gfs2_assert_withdraw(sdp, 0); - } - else { + } else { atomic_set(&sdp->sd_freeze_state, SFS_UNFROZEN); error = thaw_super(sb); if (error) { @@ -987,6 +986,8 @@ void gfs2_freeze_func(struct work_struct *work) gfs2_glock_dq_uninit(&freeze_gh); } deactivate_super(sb); + clear_bit_unlock(SDF_FS_FROZEN, &sdp->sd_flags); + wake_up_bit(&sdp->sd_flags, SDF_FS_FROZEN); return; } @@ -1029,6 +1030,7 @@ static int gfs2_freeze(struct super_block *sb) msleep(1000); } error = 0; + set_bit(SDF_FS_FROZEN, &sdp->sd_flags); out: mutex_unlock(&sdp->sd_freeze_mutex); return error; @@ -1053,7 +1055,7 @@ static int gfs2_unfreeze(struct super_block *sb) gfs2_glock_dq_uninit(&sdp->sd_freeze_gh); mutex_unlock(&sdp->sd_freeze_mutex); - return 0; + return wait_on_bit(&sdp->sd_flags, SDF_FS_FROZEN, TASK_INTERRUPTIBLE); } /** |