diff options
author | Harshad Shirwadkar <harshads@google.com> | 2018-01-10 00:13:13 -0500 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-02-22 15:40:05 +0100 |
commit | 385daa60a706cac0ff19f66bb65625a431229cbf (patch) | |
tree | 525bc3e0641c95ef920aa4d4393f20fc2b41a4c2 /fs | |
parent | 08d8ce8cc0de8db49da7eff09b6ee006baf7015f (diff) |
ext4: fix a race in the ext4 shutdown path
commit abbc3f9395c76d554a9ed27d4b1ebfb5d9b0e4ca upstream.
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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs')
-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); |