diff options
author | Harshad Shirwadkar <harshads@google.com> | 2018-01-10 00:13:13 -0500 |
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committer | Theodore Ts'o <tytso@mit.edu> | 2018-01-10 00:13:13 -0500 |
commit | abbc3f9395c76d554a9ed27d4b1ebfb5d9b0e4ca (patch) | |
tree | 463181185ebf743f7dbee86b6215b20302b59b33 /fs/ext4/inode.c | |
parent | 9ee93ba3c430d5b5140ab72738dc70c4c54990e0 (diff) | |
download | linux-abbc3f9395c76d554a9ed27d4b1ebfb5d9b0e4ca.tar.bz2 |
ext4: fix a race in the ext4 shutdown path
This patch fixes a race between the shutdown path and bio completion
handling. In the ext4 direct io path with async io, after submitting a
bio to the block layer, if journal starting fails,
ext4_direct_IO_write() would bail out pretending that the IO
failed. The caller would have had no way of knowing whether or not the
IO was successfully submitted. So instead, we return -EIOCBQUEUED in
this case. Now, the caller knows that the IO was submitted. The bio
completion handler takes care of the error.
Tested: Ran the shutdown xfstest test 461 in loop for over 2 hours across
4 machines resulting in over 400 runs. Verified that the race didn't
occur. Usually the race was seen in about 20-30 iterations.
Signed-off-by: Harshad Shirwadkar <harshads@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
Diffstat (limited to 'fs/ext4/inode.c')
-rw-r--r-- | fs/ext4/inode.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 534a9130f625..4c2f8b57bdc7 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3767,10 +3767,18 @@ static ssize_t ext4_direct_IO_write(struct kiocb *iocb, struct iov_iter *iter) /* Credits for sb + inode write */ handle = ext4_journal_start(inode, EXT4_HT_INODE, 2); if (IS_ERR(handle)) { - /* This is really bad luck. We've written the data - * but cannot extend i_size. Bail out and pretend - * the write failed... */ - ret = PTR_ERR(handle); + /* + * We wrote the data but cannot extend + * i_size. Bail out. In async io case, we do + * not return error here because we have + * already submmitted the corresponding + * bio. Returning error here makes the caller + * think that this IO is done and failed + * resulting in race with bio's completion + * handler. + */ + if (!ret) + ret = PTR_ERR(handle); if (inode->i_nlink) ext4_orphan_del(NULL, inode); |