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| author | Dave Chinner <dchinner@redhat.com> | 2012-03-22 05:15:11 +0000 |
|---|---|---|
| committer | Ben Myers <bpm@sgi.com> | 2012-03-26 17:47:24 -0500 |
| commit | 3948659e30808fbaa7673bbe89de2ae9769e20a7 (patch) | |
| tree | 06ff528be9bd33a4f2579fb05514460b7fa1ec8a /fs/xfs/xfs_log.c | |
| parent | 5132ba8f2b7705fb6b06fa6ad3d009233c816b67 (diff) | |
| download | lwn-3948659e30808fbaa7673bbe89de2ae9769e20a7.tar.gz lwn-3948659e30808fbaa7673bbe89de2ae9769e20a7.zip | |
xfs: Account log unmount transaction correctly
There have been a few reports of this warning appearing recently:
XFS (dm-4): xlog_space_left: head behind tail
tail_cycle = 129, tail_bytes = 20163072
GH cycle = 129, GH bytes = 20162880
The common cause appears to be lots of freeze and unfreeze cycles,
and the output from the warnings indicates that we are leaking
around 8 bytes of log space per freeze/unfreeze cycle.
When we freeze the filesystem, we write an unmount record and that
uses xlog_write directly - a special type of transaction,
effectively. What it doesn't do, however, is correctly account for
the log space it uses. The unmount record writes an 8 byte structure
with a special magic number into the log, and the space this
consumes is not accounted for in the log ticket tracking the
operation. Hence we leak 8 bytes every unmount record that is
written.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>
Diffstat (limited to 'fs/xfs/xfs_log.c')
| -rw-r--r-- | fs/xfs/xfs_log.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c index 98a9cb5ffd17..6db1fef38bff 100644 --- a/fs/xfs/xfs_log.c +++ b/fs/xfs/xfs_log.c @@ -726,8 +726,9 @@ xfs_log_unmount_write(xfs_mount_t *mp) .lv_iovecp = ®, }; - /* remove inited flag */ + /* remove inited flag, and account for space used */ tic->t_flags = 0; + tic->t_curr_res -= sizeof(magic); error = xlog_write(log, &vec, tic, &lsn, NULL, XLOG_UNMOUNT_TRANS); /* |