xfs: mark inode buffers in cache

Inode 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.

While this is largely a refactor of existing functionality, we
broaden the scope of the flag to beyond where inodes are explicitly
attached because future changes need to know what type of log items
are attached to the buffer. Adding this buffer flag may invoke the
inode iodone callback in cases where it wouldn't have been
previously, but this is not a functional change because the callback
is identical to the normal buffer write iodone callback when inodes
are not attached.
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

@@ -14,6 +14,8 @@
 #include "xfs_mount.h"
 #include "xfs_trace.h"
 #include "xfs_log.h"
+#include "xfs_trans.h"
+#include "xfs_buf_item.h"
 #include "xfs_errortag.h"
 #include "xfs_error.h"
 
@@ -1202,12 +1204,21 @@ xfs_buf_ioend(
 		bp->b_flags |= XBF_DONE;
 	}
 
-	if (bp->b_iodone)
+	if (read)
+		goto out_finish;
+
+	if (bp->b_flags & _XBF_INODES) {
+		xfs_buf_inode_iodone(bp);
+		return;
+	}
+
+	if (bp->b_iodone) {
 		(*(bp->b_iodone))(bp);
-	else if (bp->b_flags & XBF_ASYNC)
-		xfs_buf_relse(bp);
-	else
-		complete(&bp->b_iowait);
+		return;
+	}
+
+out_finish:
+	xfs_buf_ioend_finish(bp);
 }
 
 static void

fs/xfs/xfs_buf.h

@@ -30,15 +30,18 @@
 #define XBF_STALE	 (1 << 6) /* buffer has been staled, do not find it */
 #define XBF_WRITE_FAIL	 (1 << 7) /* async writes have failed on this buffer */
 
-/* flags used only as arguments to access routines */
-#define XBF_TRYLOCK	 (1 << 16)/* lock requested, but do not wait */
-#define XBF_UNMAPPED	 (1 << 17)/* do not map the buffer */
+/* buffer type flags for write callbacks */
+#define _XBF_INODES	 (1 << 16)/* inode buffer */
 
 /* flags used only internally */
 #define _XBF_PAGES	 (1 << 20)/* backed by refcounted pages */
 #define _XBF_KMEM	 (1 << 21)/* backed by heap memory */
 #define _XBF_DELWRI_Q	 (1 << 22)/* buffer on a delwri queue */
 
+/* flags used only as arguments to access routines */
+#define XBF_TRYLOCK	 (1 << 30)/* lock requested, but do not wait */
+#define XBF_UNMAPPED	 (1 << 31)/* do not map the buffer */
+
 typedef unsigned int xfs_buf_flags_t;
 
 #define XFS_BUF_FLAGS \
@@ -50,12 +53,13 @@ typedef unsigned int xfs_buf_flags_t;
 	{ XBF_DONE,		"DONE" }, \
 	{ XBF_STALE,		"STALE" }, \
 	{ XBF_WRITE_FAIL,	"WRITE_FAIL" }, \
-	{ XBF_TRYLOCK,		"TRYLOCK" },	/* should never be set */\
-	{ XBF_UNMAPPED,		"UNMAPPED" },	/* ditto */\
+	{ _XBF_INODES,		"INODES" }, \
 	{ _XBF_PAGES,		"PAGES" }, \
 	{ _XBF_KMEM,		"KMEM" }, \
-	{ _XBF_DELWRI_Q,	"DELWRI_Q" }
-
+	{ _XBF_DELWRI_Q,	"DELWRI_Q" }, \
+	/* The following interface flags should never be set */ \
+	{ XBF_TRYLOCK,		"TRYLOCK" }, \
+	{ XBF_UNMAPPED,		"UNMAPPED" }
 
 /*
  * Internal state flags.
@@ -257,9 +261,23 @@ extern void xfs_buf_unlock(xfs_buf_t *);
 #define xfs_buf_islocked(bp) \
 	((bp)->b_sema.count <= 0)
 
+static inline void xfs_buf_relse(xfs_buf_t *bp)
+{
+	xfs_buf_unlock(bp);
+	xfs_buf_rele(bp);
+}
+
 /* Buffer Read and Write Routines */
 extern int xfs_bwrite(struct xfs_buf *bp);
 extern void xfs_buf_ioend(struct xfs_buf *bp);
+static inline void xfs_buf_ioend_finish(struct xfs_buf *bp)
+{
+	if (bp->b_flags & XBF_ASYNC)
+		xfs_buf_relse(bp);
+	else
+		complete(&bp->b_iowait);
+}
+
 extern void __xfs_buf_ioerror(struct xfs_buf *bp, int error,
 		xfs_failaddr_t failaddr);
 #define xfs_buf_ioerror(bp, err) __xfs_buf_ioerror((bp), (err), __this_address)
@@ -324,12 +342,6 @@ static inline int xfs_buf_ispinned(struct xfs_buf *bp)
 	return atomic_read(&bp->b_pin_count);
 }
 
-static inline void xfs_buf_relse(xfs_buf_t *bp)
-{
-	xfs_buf_unlock(bp);
-	xfs_buf_rele(bp);
-}
-
 static inline int
 xfs_buf_verify_cksum(struct xfs_buf *bp, unsigned long cksum_offset)
 {

fs/xfs/xfs_buf_item.c

@@ -1158,20 +1158,15 @@ xfs_buf_iodone_callback_error(
 	return false;
 }
 
-/*
- * This is the iodone() function for buffers which have had callbacks attached
- * to them by xfs_buf_attach_iodone(). We need to iterate the items on the
- * callback list, mark the buffer as having no more callbacks and then push the
- * buffer through IO completion processing.
- */
-void
-xfs_buf_iodone_callbacks(
+static void
+xfs_buf_run_callbacks(
 	struct xfs_buf		*bp)
 {
+
 	/*
-	 * If there is an error, process it. Some errors require us
-	 * to run callbacks after failure processing is done so we
-	 * detect that and take appropriate action.
+	 * If there is an error, process it. Some errors require us to run
+	 * callbacks after failure processing is done so we detect that and take
+	 * appropriate action.
 	 */
 	if (bp->b_error && xfs_buf_iodone_callback_error(bp))
 		return;
@@ -1188,9 +1183,34 @@ xfs_buf_iodone_callbacks(
 	bp->b_log_item = NULL;
 	list_del_init(&bp->b_li_list);
 	bp->b_iodone = NULL;
+}
+
+/*
+ * This is the iodone() function for buffers which have had callbacks attached
+ * to them by xfs_buf_attach_iodone(). We need to iterate the items on the
+ * callback list, mark the buffer as having no more callbacks and then push the
+ * buffer through IO completion processing.
+ */
+void
+xfs_buf_iodone_callbacks(
+	struct xfs_buf		*bp)
+{
+	xfs_buf_run_callbacks(bp);
 	xfs_buf_ioend(bp);
 }
 
+/*
+ * Inode buffer iodone callback function.
+ */
+void
+xfs_buf_inode_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
  * logged.  It is called when they are eventually flushed out.

fs/xfs/xfs_buf_item.h

@@ -59,6 +59,7 @@ void	xfs_buf_attach_iodone(struct xfs_buf *,
 			      struct xfs_log_item *);
 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 *);
 bool	xfs_buf_log_check_iovec(struct xfs_log_iovec *iovec);
 
 extern kmem_zone_t	*xfs_buf_item_zone;

fs/xfs/xfs_inode.c

@@ -3862,13 +3862,13 @@ xfs_iflush_int(
 	 * completion on the buffer to remove the inode from the AIL and release
 	 * the flush lock.
 	 */
+	bp->b_flags |= _XBF_INODES;
 	xfs_buf_attach_iodone(bp, xfs_iflush_done, &iip->ili_item);
 
 	/* generate the checksum. */
 	xfs_dinode_calc_crc(mp, dip);
 
 	ASSERT(!list_empty(&bp->b_li_list));
-	ASSERT(bp->b_iodone != NULL);
 	return error;
 }
 

fs/xfs/xfs_trans_buf.c

@@ -626,6 +626,7 @@ xfs_trans_inode_buf(
 	ASSERT(atomic_read(&bip->bli_refcount) > 0);
 
 	bip->bli_flags |= XFS_BLI_INODE_BUF;
+	bp->b_flags |= _XBF_INODES;
 	xfs_trans_buf_set_type(tp, bp, XFS_BLFT_DINO_BUF);
 }
 
@@ -651,6 +652,7 @@ xfs_trans_stale_inode_buf(
 
 	bip->bli_flags |= XFS_BLI_STALE_INODE;
 	bip->bli_item.li_cb = xfs_buf_iodone;
+	bp->b_flags |= _XBF_INODES;
 	xfs_trans_buf_set_type(tp, bp, XFS_BLFT_DINO_BUF);
 }
 
@@ -675,6 +677,7 @@ xfs_trans_inode_alloc_buf(
 	ASSERT(atomic_read(&bip->bli_refcount) > 0);
 
 	bip->bli_flags |= XFS_BLI_INODE_ALLOC_BUF;
+	bp->b_flags |= _XBF_INODES;
 	xfs_trans_buf_set_type(tp, bp, XFS_BLFT_DINO_BUF);
 }