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| author | Theodore Ts'o <tytso@mit.edu> | 2013-04-04 04:02:52 +0200 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2013-04-04 04:02:52 +0200 |
| commit | d76a3a77113db020d9bb1e894822869410450bd9 (patch) | |
| tree | 3e73e273fd8c8e09b2bb87417615d391491eb38e /fs/ext4/fsync.c | |
| parent | ext4: add might_sleep() annotations (diff) | |
| download | linux-d76a3a77113db020d9bb1e894822869410450bd9.tar.xz linux-d76a3a77113db020d9bb1e894822869410450bd9.zip | |
ext4/jbd2: don't wait (forever) for stale tid caused by wraparound
In the case where an inode has a very stale transaction id (tid) in
i_datasync_tid or i_sync_tid, it's possible that after a very large
(2**31) number of transactions, that the tid number space might wrap,
causing tid_geq()'s calculations to fail.
Commit deeeaf13 "jbd2: fix fsync() tid wraparound bug", later modified
by commit e7b04ac0 "jbd2: don't wake kjournald unnecessarily",
attempted to fix this problem, but it only avoided kjournald spinning
forever by fixing the logic in jbd2_log_start_commit().
Unfortunately, in the codepaths in fs/ext4/fsync.c and fs/ext4/inode.c
that might call jbd2_log_start_commit() with a stale tid, those
functions will subsequently call jbd2_log_wait_commit() with the same
stale tid, and then wait for a very long time. To fix this, we
replace the calls to jbd2_log_start_commit() and
jbd2_log_wait_commit() with a call to a new function,
jbd2_complete_transaction(), which will correctly handle stale tid's.
As a bonus, jbd2_complete_transaction() will avoid locking
j_state_lock for writing unless a commit needs to be started. This
should have a small (but probably not measurable) improvement for
ext4's scalability.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reported-by: Ben Hutchings <ben@decadent.org.uk>
Reported-by: George Barnett <gbarnett@atlassian.com>
Cc: stable@vger.kernel.org
Diffstat (limited to 'fs/ext4/fsync.c')
| -rw-r--r-- | fs/ext4/fsync.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c index 3278e64e57b6..e0ba8a408def 100644 --- a/fs/ext4/fsync.c +++ b/fs/ext4/fsync.c @@ -166,8 +166,7 @@ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync) if (journal->j_flags & JBD2_BARRIER && !jbd2_trans_will_send_data_barrier(journal, commit_tid)) needs_barrier = true; - jbd2_log_start_commit(journal, commit_tid); - ret = jbd2_log_wait_commit(journal, commit_tid); + ret = jbd2_complete_transaction(journal, commit_tid); if (needs_barrier) { err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL); if (!ret) |