diff options
author | Darrick J. Wong <djwong@kernel.org> | 2022-07-14 11:06:17 -0700 |
---|---|---|
committer | Darrick J. Wong <djwong@kernel.org> | 2022-11-09 19:07:30 -0800 |
commit | a102b9915d8d841d24717a1a66e503554b9d5890 (patch) | |
tree | 184535c9e4e9e746ad39a9e4e947eb239cce099a /fs/xfs/scrub | |
parent | 17878f4d7d819724fcdf4b0a66e3d1a7d09064e8 (diff) |
xfs: repair cannot update the summary counters when logging quota flags
While running xfs/804 (quota repairs racing with fsstress), I observed a
filesystem shutdown in the primary sb write verifier:
run fstests xfs/804 at 2022-05-23 18:43:48
XFS (sda4): Mounting V5 Filesystem
XFS (sda4): Ending clean mount
XFS (sda4): Quotacheck needed: Please wait.
XFS (sda4): Quotacheck: Done.
XFS (sda4): EXPERIMENTAL online scrub feature in use. Use at your own risk!
XFS (sda4): SB ifree sanity check failed 0xb5 > 0x80
XFS (sda4): Metadata corruption detected at xfs_sb_write_verify+0x5e/0x100 [xfs], xfs_sb block 0x0
XFS (sda4): Unmount and run xfs_repair
The "SB ifree sanity check failed" message was a debugging printk that I
added to the kernel; observe that 0xb5 - 0x80 = 53, which is less than
one inode chunk.
I traced this to the xfs_log_sb calls from the online quota repair code,
which tries to clear the CHKD flags from the superblock to force a
mount-time quotacheck if the repair fails. On a V5 filesystem,
xfs_log_sb updates the ondisk sb summary counters with the current
contents of the percpu counters. This is done without quiescing other
writer threads, which means it could be racing with a thread that has
updated icount and is about to update ifree.
If the other write thread had incremented ifree before updating icount,
the repair thread will write icount > ifree into the logged update. If
the AIL writes the logged superblock back to disk before anyone else
fixes this siutation, this will lead to a write verifier failure, which
causes a filesystem shutdown.
Resolve this problem by updating the quota flags and calling
xfs_sb_to_disk directly, which does not touch the percpu counters.
While we're at it, we can elide the entire update if the selected qflags
aren't set.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Diffstat (limited to 'fs/xfs/scrub')
-rw-r--r-- | fs/xfs/scrub/repair.c | 41 |
1 files changed, 34 insertions, 7 deletions
diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c index ff901e3caa96..ac2bfaa92aed 100644 --- a/fs/xfs/scrub/repair.c +++ b/fs/xfs/scrub/repair.c @@ -678,6 +678,39 @@ xrep_find_ag_btree_roots( } #ifdef CONFIG_XFS_QUOTA +/* Update some quota flags in the superblock. */ +static void +xrep_update_qflags( + struct xfs_scrub *sc, + unsigned int clear_flags) +{ + struct xfs_mount *mp = sc->mp; + struct xfs_buf *bp; + + mutex_lock(&mp->m_quotainfo->qi_quotaofflock); + if ((mp->m_qflags & clear_flags) == 0) + goto no_update; + + mp->m_qflags &= ~clear_flags; + spin_lock(&mp->m_sb_lock); + mp->m_sb.sb_qflags &= ~clear_flags; + spin_unlock(&mp->m_sb_lock); + + /* + * Update the quota flags in the ondisk superblock without touching + * the summary counters. We have not quiesced inode chunk allocation, + * so we cannot coordinate with updates to the icount and ifree percpu + * counters. + */ + bp = xfs_trans_getsb(sc->tp); + xfs_sb_to_disk(bp->b_addr, &mp->m_sb); + xfs_trans_buf_set_type(sc->tp, bp, XFS_BLFT_SB_BUF); + xfs_trans_log_buf(sc->tp, bp, 0, sizeof(struct xfs_dsb) - 1); + +no_update: + mutex_unlock(&sc->mp->m_quotainfo->qi_quotaofflock); +} + /* Force a quotacheck the next time we mount. */ void xrep_force_quotacheck( @@ -690,13 +723,7 @@ xrep_force_quotacheck( if (!(flag & sc->mp->m_qflags)) return; - mutex_lock(&sc->mp->m_quotainfo->qi_quotaofflock); - sc->mp->m_qflags &= ~flag; - spin_lock(&sc->mp->m_sb_lock); - sc->mp->m_sb.sb_qflags &= ~flag; - spin_unlock(&sc->mp->m_sb_lock); - xfs_log_sb(sc->tp); - mutex_unlock(&sc->mp->m_quotainfo->qi_quotaofflock); + xrep_update_qflags(sc, flag); } /* |