block: separate priority boosting from REQ_META

Add a new REQ_PRIO to let requests preempt others in the cfq I/O schedule,
and lave REQ_META purely for marking requests as metadata in blktrace.

All existing callers of REQ_META except for XFS are updated to also
set REQ_PRIO for now.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/gfs2/meta_io.c b/fs/gfs2/meta_io.c
index 747238cd9f96..be29858900f6 100644
--- a/fs/gfs2/meta_io.c
+++ b/fs/gfs2/meta_io.c
@@ -37,7 +37,7 @@ static int gfs2_aspace_writepage(struct page *page, struct writeback_control *wb
 {
         struct buffer_head *bh, *head;
         int nr_underway = 0;
-        int write_op = REQ_META |
+        int write_op = REQ_META | REQ_PRIO |
                 (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE);
 
         BUG_ON(!PageLocked(page));
@@ -225,7 +225,7 @@ int gfs2_meta_read(struct gfs2_glock *gl, u64 blkno, int flags,
         }
         bh->b_end_io = end_buffer_read_sync;
         get_bh(bh);
-        submit_bh(READ_SYNC | REQ_META, bh);
+        submit_bh(READ_SYNC | REQ_META | REQ_PRIO, bh);
         if (!(flags & DIO_WAIT))
                 return 0;
 
@@ -435,7 +435,7 @@ struct buffer_head *gfs2_meta_ra(struct gfs2_glock *gl, u64 dblock, u32 extlen)
         if (buffer_uptodate(first_bh))
                 goto out;
         if (!buffer_locked(first_bh))
-                ll_rw_block(READ_SYNC | REQ_META, 1, &first_bh);
+                ll_rw_block(READ_SYNC | REQ_META | REQ_PRIO, 1, &first_bh);
 
         dblock++;
         extlen--;