xfs: reuse _xfs_buf_read for re-reading the superblock

Instead of poking deeply into buffer cache internals when re-reading the
superblock during log recovery just generalize _xfs_buf_read and use it
there.  Note that we don't have to explicitly set up the ops as they
must be set from the initial read.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/xfs_buf.c

@@ -52,6 +52,15 @@ static kmem_zone_t *xfs_buf_zone;
  *	  b_lock (trylock due to inversion)
  */
 
+static int __xfs_buf_submit(struct xfs_buf *bp, bool wait);
+
+static inline int
+xfs_buf_submit(
+	struct xfs_buf		*bp)
+{
+	return __xfs_buf_submit(bp, !(bp->b_flags & XBF_ASYNC));
+}
+
 static inline int
 xfs_buf_is_vmapped(
 	struct xfs_buf	*bp)
@@ -751,7 +760,7 @@ xfs_buf_get_map(
 	return 0;
 }
 
-STATIC int
+int
 _xfs_buf_read(
 	xfs_buf_t		*bp,
 	xfs_buf_flags_t		flags)
@@ -759,7 +768,7 @@ _xfs_buf_read(
 	ASSERT(!(flags & XBF_WRITE));
 	ASSERT(bp->b_maps[0].bm_bn != XFS_BUF_DADDR_NULL);
 
-	bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD);
+	bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD | XBF_DONE);
 	bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);
 
 	return xfs_buf_submit(bp);
@@ -1639,7 +1648,7 @@ xfs_buf_iowait(
  * safe to reference the buffer after a call to this function unless the caller
  * holds an additional reference itself.
  */
-int
+static int
 __xfs_buf_submit(
 	struct xfs_buf	*bp,
 	bool		wait)

fs/xfs/xfs_buf.h

@@ -249,6 +249,7 @@ int xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks, int flags,
 int xfs_buf_read_uncached(struct xfs_buftarg *target, xfs_daddr_t daddr,
 			  size_t numblks, int flags, struct xfs_buf **bpp,
 			  const struct xfs_buf_ops *ops);
+int _xfs_buf_read(struct xfs_buf *bp, xfs_buf_flags_t flags);
 void xfs_buf_hold(struct xfs_buf *bp);
 
 /* Releasing Buffers */
@@ -275,14 +276,6 @@ extern void __xfs_buf_ioerror(struct xfs_buf *bp, int error,
 #define xfs_buf_ioerror(bp, err) __xfs_buf_ioerror((bp), (err), __this_address)
 extern void xfs_buf_ioerror_alert(struct xfs_buf *bp, xfs_failaddr_t fa);
 void xfs_buf_ioend_fail(struct xfs_buf *);
-
-extern int __xfs_buf_submit(struct xfs_buf *bp, bool);
-static inline int xfs_buf_submit(struct xfs_buf *bp)
-{
-	bool wait = bp->b_flags & XBF_ASYNC ? false : true;
-	return __xfs_buf_submit(bp, wait);
-}
-
 void xfs_buf_zero(struct xfs_buf *bp, size_t boff, size_t bsize);
 void __xfs_buf_mark_corrupt(struct xfs_buf *bp, xfs_failaddr_t fa);
 #define xfs_buf_mark_corrupt(bp) __xfs_buf_mark_corrupt((bp), __this_address)

fs/xfs/xfs_log_recover.c

@@ -3309,13 +3309,7 @@ xlog_do_recover(
 	 */
 	xfs_buf_lock(bp);
 	xfs_buf_hold(bp);
-	ASSERT(bp->b_flags & XBF_DONE);
-	bp->b_flags &= ~(XBF_DONE | XBF_ASYNC);
-	ASSERT(!(bp->b_flags & XBF_WRITE));
-	bp->b_flags |= XBF_READ;
-	bp->b_ops = &xfs_sb_buf_ops;
-
-	error = xfs_buf_submit(bp);
+	error = _xfs_buf_read(bp, XBF_READ);
 	if (error) {
 		if (!XFS_FORCED_SHUTDOWN(mp)) {
 			xfs_buf_ioerror_alert(bp, __this_address);