xfs: mark dquot buffers in cache

dquot buffers always have write IO callbacks, so by marking them
directly we can avoid needing to attach ->b_iodone functions to
them. This avoids an indirect call, and makes future modifications
much simpler.

This is largely a rearrangement of the code at this point - no IO
completion functionality changes at this point, just how the
code is run is modified.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/xfs_buf.c

@@ -1212,6 +1212,11 @@ xfs_buf_ioend(
 		return;
 	}
 
+	if (bp->b_flags & _XBF_DQUOTS) {
+		xfs_buf_dquot_iodone(bp);
+		return;
+	}
+
 	if (bp->b_iodone) {
 		(*(bp->b_iodone))(bp);
 		return;

fs/xfs/xfs_buf.h

@@ -32,6 +32,7 @@
 
 /* buffer type flags for write callbacks */
 #define _XBF_INODES	 (1 << 16)/* inode buffer */
+#define _XBF_DQUOTS	 (1 << 17)/* dquot buffer */
 
 /* flags used only internally */
 #define _XBF_PAGES	 (1 << 20)/* backed by refcounted pages */
@@ -54,6 +55,7 @@ typedef unsigned int xfs_buf_flags_t;
 	{ XBF_STALE,		"STALE" }, \
 	{ XBF_WRITE_FAIL,	"WRITE_FAIL" }, \
 	{ _XBF_INODES,		"INODES" }, \
+	{ _XBF_DQUOTS,		"DQUOTS" }, \
 	{ _XBF_PAGES,		"PAGES" }, \
 	{ _XBF_KMEM,		"KMEM" }, \
 	{ _XBF_DELWRI_Q,	"DELWRI_Q" }, \

fs/xfs/xfs_buf_item.c

@@ -1210,6 +1210,16 @@ xfs_buf_inode_iodone(
 	xfs_buf_ioend_finish(bp);
 }
 
+/*
+ * Dquot buffer iodone callback function.
+ */
+void
+xfs_buf_dquot_iodone(
+	struct xfs_buf		*bp)
+{
+	xfs_buf_run_callbacks(bp);
+	xfs_buf_ioend_finish(bp);
+}
 
 /*
  * This is the iodone() function for buffers which have been

fs/xfs/xfs_buf_item.h

@@ -60,6 +60,7 @@ void	xfs_buf_attach_iodone(struct xfs_buf *,
 void	xfs_buf_iodone_callbacks(struct xfs_buf *);
 void	xfs_buf_iodone(struct xfs_buf *, struct xfs_log_item *);
 void	xfs_buf_inode_iodone(struct xfs_buf *);
+void	xfs_buf_dquot_iodone(struct xfs_buf *);
 bool	xfs_buf_log_check_iovec(struct xfs_log_iovec *iovec);
 
 extern kmem_zone_t	*xfs_buf_item_zone;

fs/xfs/xfs_dquot.c

@@ -1179,6 +1179,7 @@ xfs_qm_dqflush(
 	 * Attach an iodone routine so that we can remove this dquot from the
 	 * AIL and release the flush lock once the dquot is synced to disk.
 	 */
+	bp->b_flags |= _XBF_DQUOTS;
 	xfs_buf_attach_iodone(bp, xfs_qm_dqflush_done,
 				  &dqp->q_logitem.qli_item);
 

fs/xfs/xfs_trans_buf.c

@@ -788,5 +788,6 @@ xfs_trans_dquot_buf(
 		break;
 	}
 
+	bp->b_flags |= _XBF_DQUOTS;
 	xfs_trans_buf_set_type(tp, bp, type);
 }