xfs: flag all buffers as metadata

Now that REQ_META bios aren't treated specially in the CFQ I/O schedule
anymore, we can tag all buffers as metadata to make blktrace traces more
meaningful.  Note that we use buffers also to zero out partial blocks
in the preallocation / hole punching code, and while they operate on
data blocks the zeros written certainly aren't data.  I think this case
is borderline metadata enough to not bother special casing it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index b2b411985591..d1fe74506c4c 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -1224,6 +1224,9 @@ _xfs_buf_ioapply(
                 rw = READ;
         }
 
+        /* we only use the buffer cache for meta-data */
+        rw |= REQ_META;
+
 next_chunk:
         atomic_inc(&bp->b_io_remaining);
         nr_pages = BIO_MAX_SECTORS >> (PAGE_SHIFT - BBSHIFT);