ext4: mark all metadata I/O with REQ_META
As Dave Chinner pointed out at the 2013 LSF/MM workshop, it's
important that metadata I/O requests are marked as such to avoid
priority inversions caused by I/O bandwidth throttling.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
index b3b1f7d..214461e 100644
--- a/fs/ext4/mmp.c
+++ b/fs/ext4/mmp.c
@@ -54,7 +54,7 @@
lock_buffer(bh);
bh->b_end_io = end_buffer_write_sync;
get_bh(bh);
- submit_bh(WRITE_SYNC, bh);
+ submit_bh(WRITE_SYNC | REQ_META | REQ_PRIO, bh);
wait_on_buffer(bh);
sb_end_write(sb);
if (unlikely(!buffer_uptodate(bh)))
@@ -86,7 +86,7 @@
get_bh(*bh);
lock_buffer(*bh);
(*bh)->b_end_io = end_buffer_read_sync;
- submit_bh(READ_SYNC, *bh);
+ submit_bh(READ_SYNC | REQ_META | REQ_PRIO, *bh);
wait_on_buffer(*bh);
if (!buffer_uptodate(*bh)) {
brelse(*bh);