buffer: add BH_Prio and BH_Meta flags

Add buffer_head flags so that buffer cache writebacks can be marked
with the the appropriate request flags, so that metadata blocks can be
marked appropriately in blktrace.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

2 files changed, 9 insertions, 0 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index b4dcb34c9635..a15575c0b9ee 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2988,6 +2988,11 @@ int submit_bh(int rw, struct buffer_head * bh)
         /* Take care of bh's that straddle the end of the device */
         guard_bh_eod(rw, bio, bh);
 
+        if (buffer_meta(bh))
+                rw |= REQ_META;
+        if (buffer_prio(bh))
+                rw |= REQ_PRIO;
+
         bio_get(bio);
         submit_bio(rw, bio);
 
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 5afc4f94d110..33c0f8103fe4 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -34,6 +34,8 @@ enum bh_state_bits {
         BH_Write_EIO,   /* I/O error on write */
         BH_Unwritten,   /* Buffer is allocated on disk but not written */
         BH_Quiet,       /* Buffer Error Prinks to be quiet */
+        BH_Meta,        /* Buffer contains metadata */
+        BH_Prio,        /* Buffer should be submitted with REQ_PRIO */
 
         BH_PrivateStart,/* not a state bit, but the first bit available
                          * for private allocation by other entities
@@ -124,6 +126,8 @@ BUFFER_FNS(Delay, delay)
 BUFFER_FNS(Boundary, boundary)
 BUFFER_FNS(Write_EIO, write_io_error)
 BUFFER_FNS(Unwritten, unwritten)
+BUFFER_FNS(Meta, meta)
+BUFFER_FNS(Prio, prio)
 
 #define bh_offset(bh)           ((unsigned long)(bh)->b_data & ~PAGE_MASK)