[PATCH] jbd: wait for already submitted t_sync_datalist buffer to complete

In the current jbd code, if a buffer on BJ_SyncData list is dirty and not
locked, the buffer is refiled to BJ_Locked list, submitted to the IO and
waited for IO completion.

But the fsstress test showed the case that when a buffer was already
submitted to the IO just before the buffer_dirty(bh) check, the buffer was
not waited for IO completion.

Following patch solves this problem.  If it is assumed that a buffer is
submitted to the IO before the buffer_dirty(bh) check and still being
written to disk, this buffer is refiled to BJ_Locked list.

Signed-off-by: Hisashi Hifumi <hifumi.hisashi@oss.ntt.co.jp>
Cc: Jan Kara <jack@ucw.cz>
Cc: "Stephen C. Tweedie" <sct@redhat.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/fs/jbd/commit.c b/fs/jbd/commit.c
index 10be512..be4648b 100644 (file)
--- a/fs/jbd/commit.c
+++ b/fs/jbd/commit.c
@@ -248,8 +248,12 @@ write_out_data:
                                bufs = 0;
                                goto write_out_data;
                        }
-               }
-               else {
+               } else if (!locked && buffer_locked(bh)) {
+                       __journal_file_buffer(jh, commit_transaction,
+                                               BJ_Locked);
+                       jbd_unlock_bh_state(bh);
+                       put_bh(bh);
+               } else {
                        BUFFER_TRACE(bh, "writeout complete: unfile");
                        __journal_unfile_buffer(jh);
                        jbd_unlock_bh_state(bh);