xfs: make xfs_buf_read return an error code

Convert xfs_buf_read() 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_attr_remote.c

@@ -418,10 +418,10 @@ xfs_attr_rmtval_get(
 			       (map[i].br_startblock != HOLESTARTBLOCK));
 			dblkno = XFS_FSB_TO_DADDR(mp, map[i].br_startblock);
 			dblkcnt = XFS_FSB_TO_BB(mp, map[i].br_blockcount);
-			bp = xfs_buf_read(mp->m_ddev_targp, dblkno, dblkcnt, 0,
-					&xfs_attr3_rmt_buf_ops);
-			if (!bp)
-				return -ENOMEM;
+			error = xfs_buf_read(mp->m_ddev_targp, dblkno, dblkcnt,
+					0, &bp, &xfs_attr3_rmt_buf_ops);
+			if (error)
+				return error;
 
 			error = xfs_attr_rmtval_copyout(mp, bp, args->dp->i_ino,
 							&offset, &valuelen,

fs/xfs/xfs_buf.h

@@ -213,22 +213,18 @@ xfs_buf_get(
 	return xfs_buf_get_map(target, &map, 1, 0, bpp);
 }
 
-static inline struct xfs_buf *
+static inline int
 xfs_buf_read(
 	struct xfs_buftarg	*target,
 	xfs_daddr_t		blkno,
 	size_t			numblks,
 	xfs_buf_flags_t		flags,
+	struct xfs_buf		**bpp,
 	const struct xfs_buf_ops *ops)
 {
-	struct xfs_buf		*bp;
-	int			error;
 	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 
-	error = xfs_buf_read_map(target, &map, 1, flags, &bp, ops);
-	if (error)
-		return NULL;
-	return bp;
+	return xfs_buf_read_map(target, &map, 1, flags, bpp, ops);
 }
 
 static inline void

fs/xfs/xfs_log_recover.c

@@ -2745,10 +2745,10 @@ xlog_recover_buffer_pass2(
 	if (buf_f->blf_flags & XFS_BLF_INODE_BUF)
 		buf_flags |= XBF_UNMAPPED;
 
-	bp = xfs_buf_read(mp->m_ddev_targp, buf_f->blf_blkno, buf_f->blf_len,
-			  buf_flags, NULL);
-	if (!bp)
-		return -ENOMEM;
+	error = xfs_buf_read(mp->m_ddev_targp, buf_f->blf_blkno, buf_f->blf_len,
+			  buf_flags, &bp, NULL);
+	if (error)
+		return error;
 
 	/*
 	 * Recover the buffer only if we get an LSN from it and it's less than
@@ -2945,12 +2945,10 @@ xlog_recover_inode_pass2(
 	}
 	trace_xfs_log_recover_inode_recover(log, in_f);
 
-	bp = xfs_buf_read(mp->m_ddev_targp, in_f->ilf_blkno, in_f->ilf_len, 0,
-			  &xfs_inode_buf_ops);
-	if (!bp) {
-		error = -ENOMEM;
+	error = xfs_buf_read(mp->m_ddev_targp, in_f->ilf_blkno, in_f->ilf_len,
+			0, &bp, &xfs_inode_buf_ops);
+	if (error)
 		goto error;
-	}
 	ASSERT(in_f->ilf_fields & XFS_ILOG_CORE);
 	dip = xfs_buf_offset(bp, in_f->ilf_boffset);
 

fs/xfs/xfs_symlink.c

@@ -53,10 +53,10 @@ xfs_readlink_bmap_ilocked(
 		d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
 		byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
 
-		bp = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0,
-				  &xfs_symlink_buf_ops);
-		if (!bp)
-			return -ENOMEM;
+		error = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0,
+				&bp, &xfs_symlink_buf_ops);
+		if (error)
+			return error;
 		byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
 		if (pathlen < byte_cnt)
 			byte_cnt = pathlen;