[PATCH 5/9] xfs: make xfs_buf_read_map return an error code

["Darrick J. Wong" <darrick.wong@oracle.com>]

From: Darrick J. Wong <darrick.wong@oracle.com>

Convert xfs_buf_read_map() to return numeric error codes like most
everywhere else in xfs.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_alloc.c |    4 ++++
 fs/xfs/xfs_buf.c          |   24 +++++++++++++++---------
 fs/xfs/xfs_buf.h          |   12 +++++-------
 fs/xfs/xfs_trans_buf.c    |    9 +++------
 4 files changed, 27 insertions(+), 22 deletions(-)


diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index fc93fd88ec89..53410819691b 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -2960,6 +2960,10 @@ xfs_read_agf(
 			mp, tp, mp->m_ddev_targp,
 			XFS_AG_DADDR(mp, agno, XFS_AGF_DADDR(mp)),
 			XFS_FSS_TO_BB(mp, 1), flags, bpp, &xfs_agf_buf_ops);
+	if (error == -EAGAIN && (flags & XBF_TRYLOCK)) {
+		*bpp = NULL;
+		return 0;
+	}
 	if (error)
 		return error;
 	if (!*bpp)
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index a7d538b89bb5..1a3dfecb93e0 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -826,12 +826,13 @@ xfs_buf_reverify(
 	return bp->b_error;
 }
 
-xfs_buf_t *
+int
 xfs_buf_read_map(
 	struct xfs_buftarg	*target,
 	struct xfs_buf_map	*map,
 	int			nmaps,
 	xfs_buf_flags_t		flags,
+	struct xfs_buf		**bpp,
 	const struct xfs_buf_ops *ops)
 {
 	struct xfs_buf		*bp;
@@ -840,7 +841,7 @@ xfs_buf_read_map(
 
 	bp = xfs_buf_get_map(target, map, nmaps, flags);
 	if (!bp)
-		return NULL;
+		return -ENOMEM;
 
 	trace_xfs_buf_read(bp, flags, _RET_IP_);
 
@@ -848,7 +849,8 @@ xfs_buf_read_map(
 		XFS_STATS_INC(target->bt_mount, xb_get_read);
 		bp->b_ops = ops;
 		_xfs_buf_read(bp, flags);
-		return bp;
+		*bpp = bp;
+		return 0;
 	}
 
 	xfs_buf_reverify(bp, ops);
@@ -859,13 +861,15 @@ xfs_buf_read_map(
 		 * drop the buffer
 		 */
 		xfs_buf_relse(bp);
-		return NULL;
+		*bpp = NULL;
+		return 0;
 	}
 
 	/* We do not want read in the flags */
 	bp->b_flags &= ~XBF_READ;
 	ASSERT(bp->b_ops != NULL || ops == NULL);
-	return bp;
+	*bpp = bp;
+	return 0;
 }
 
 int
@@ -881,9 +885,9 @@ xfs_buf_read(
 	int			error;
 
 	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
-	bp = xfs_buf_read_map(target, &map, 1, flags, ops);
-	if (!bp)
-		return -ENOMEM;
+	error = xfs_buf_read_map(target, &map, 1, flags, &bp, ops);
+	if (error)
+		return error;
 	error = bp->b_error;
 	if (error) {
 		xfs_buf_ioerror_alert(bp, __func__);
@@ -911,11 +915,13 @@ xfs_buf_readahead_map(
 	int			nmaps,
 	const struct xfs_buf_ops *ops)
 {
+	struct xfs_buf		*bp;
+
 	if (bdi_read_congested(target->bt_bdev->bd_bdi))
 		return;
 
 	xfs_buf_read_map(target, map, nmaps,
-		     XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD, ops);
+		     XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD, &bp, ops);
 }
 
 /*
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index e0e8b0769758..7e01d168e437 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -195,13 +195,11 @@ struct xfs_buf *xfs_buf_incore(struct xfs_buftarg *target,
 struct xfs_buf *xfs_buf_get_map(struct xfs_buftarg *target,
 			       struct xfs_buf_map *map, int nmaps,
 			       xfs_buf_flags_t flags);
-struct xfs_buf *xfs_buf_read_map(struct xfs_buftarg *target,
-			       struct xfs_buf_map *map, int nmaps,
-			       xfs_buf_flags_t flags,
-			       const struct xfs_buf_ops *ops);
-void xfs_buf_readahead_map(struct xfs_buftarg *target,
-			       struct xfs_buf_map *map, int nmaps,
-			       const struct xfs_buf_ops *ops);
+int xfs_buf_read_map(struct xfs_buftarg *target, struct xfs_buf_map *map,
+		int nmaps, xfs_buf_flags_t flags, struct xfs_buf **bpp,
+		const struct xfs_buf_ops *ops);
+void xfs_buf_readahead_map(struct xfs_buftarg *target, struct xfs_buf_map *map,
+		int nmaps, const struct xfs_buf_ops *ops);
 
 int xfs_buf_get(struct xfs_buftarg *target, xfs_daddr_t blkno, size_t numblks,
 		struct xfs_buf **bpp);
diff --git a/fs/xfs/xfs_trans_buf.c b/fs/xfs/xfs_trans_buf.c
index b5b3a78ef31c..a2af6dec310d 100644
--- a/fs/xfs/xfs_trans_buf.c
+++ b/fs/xfs/xfs_trans_buf.c
@@ -298,12 +298,9 @@ xfs_trans_read_buf_map(
 		return 0;
 	}
 
-	bp = xfs_buf_read_map(target, map, nmaps, flags, ops);
-	if (!bp) {
-		if (!(flags & XBF_TRYLOCK))
-			return -ENOMEM;
-		return tp ? 0 : -EAGAIN;
-	}
+	error = xfs_buf_read_map(target, map, nmaps, flags, &bp, ops);
+	if (error)
+		return error;
 
 	/*
 	 * If we've had a read error, then the contents of the buffer are