xfs: make xfs_trans_get_buf_map return an error code

Convert xfs_trans_get_buf_map() to return numeric error codes like most
everywhere else in xfs.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/libxfs/xfs_da_btree.c

@@ -2591,13 +2591,9 @@ xfs_da_get_buf(
 	if (error || nmap == 0)
 		goto out_free;
 
-	bp = xfs_trans_get_buf_map(tp, mp->m_ddev_targp, mapp, nmap, 0);
-	error = bp ? bp->b_error : -EIO;
-	if (error) {
-		if (bp)
-			xfs_trans_brelse(tp, bp);
+	error = xfs_trans_get_buf_map(tp, mp->m_ddev_targp, mapp, nmap, 0, &bp);
+	if (error)
 		goto out_free;
-	}
 
 	*bpp = bp;
 

fs/xfs/xfs_trans.h

@@ -169,10 +169,9 @@ int		xfs_trans_alloc_empty(struct xfs_mount *mp,
 			struct xfs_trans **tpp);
 void		xfs_trans_mod_sb(xfs_trans_t *, uint, int64_t);
 
-struct xfs_buf	*xfs_trans_get_buf_map(struct xfs_trans *tp,
-				       struct xfs_buftarg *target,
-				       struct xfs_buf_map *map, int nmaps,
-				       uint flags);
+int xfs_trans_get_buf_map(struct xfs_trans *tp, struct xfs_buftarg *target,
+		struct xfs_buf_map *map, int nmaps, xfs_buf_flags_t flags,
+		struct xfs_buf **bpp);
 
 static inline struct xfs_buf *
 xfs_trans_get_buf(
@@ -182,8 +181,14 @@ xfs_trans_get_buf(
 	int			numblks,
 	uint			flags)
 {
+	struct xfs_buf		*bp;
+	int			error;
+
 	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
-	return xfs_trans_get_buf_map(tp, target, &map, 1, flags);
+	error = xfs_trans_get_buf_map(tp, target, &map, 1, flags, &bp);
+	if (error)
+		return NULL;
+	return bp;
 }
 
 int		xfs_trans_read_buf_map(struct xfs_mount *mp,

fs/xfs/xfs_trans_buf.c

@@ -112,24 +112,22 @@ xfs_trans_bjoin(
  * If the transaction pointer is NULL, make this just a normal
  * get_buf() call.
  */
-struct xfs_buf *
+int
 xfs_trans_get_buf_map(
 	struct xfs_trans	*tp,
 	struct xfs_buftarg	*target,
 	struct xfs_buf_map	*map,
 	int			nmaps,
-	xfs_buf_flags_t		flags)
+	xfs_buf_flags_t		flags,
+	struct xfs_buf		**bpp)
 {
 	xfs_buf_t		*bp;
 	struct xfs_buf_log_item	*bip;
 	int			error;
 
-	if (!tp) {
-		error = xfs_buf_get_map(target, map, nmaps, flags, &bp);
-		if (error)
-			return NULL;
-		return bp;
-	}
+	*bpp = NULL;
+	if (!tp)
+		return xfs_buf_get_map(target, map, nmaps, flags, bpp);
 
 	/*
 	 * If we find the buffer in the cache with this transaction
@@ -151,18 +149,20 @@ xfs_trans_get_buf_map(
 		ASSERT(atomic_read(&bip->bli_refcount) > 0);
 		bip->bli_recur++;
 		trace_xfs_trans_get_buf_recur(bip);
-		return bp;
+		*bpp = bp;
+		return 0;
 	}
 
 	error = xfs_buf_get_map(target, map, nmaps, flags, &bp);
 	if (error)
-		return NULL;
+		return error;
 
 	ASSERT(!bp->b_error);
 
 	_xfs_trans_bjoin(tp, bp, 1);
 	trace_xfs_trans_get_buf(bp->b_log_item);
-	return bp;
+	*bpp = bp;
+	return 0;
 }
 
 /*