[PATCH 6/9] xfs: make xfs_buf_get_map return an error code

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

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

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

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/xfs_buf.c       |   45 ++++++++++++++++++++++-----------------------
 fs/xfs/xfs_buf.h       |    5 ++---
 fs/xfs/xfs_trans_buf.c |   14 +++++++++-----
 3 files changed, 33 insertions(+), 31 deletions(-)


diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 1a3dfecb93e0..d974954b4fc9 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -684,53 +684,49 @@ xfs_buf_incore(
  * cache hits, as metadata intensive workloads will see 3 orders of magnitude
  * more hits than misses.
  */
-struct xfs_buf *
+int
 xfs_buf_get_map(
 	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)
 {
 	struct xfs_buf		*bp;
 	struct xfs_buf		*new_bp;
 	int			error = 0;
 
 	error = xfs_buf_find(target, map, nmaps, flags, NULL, &bp);
-
 	switch (error) {
 	case 0:
 		/* cache hit */
 		goto found;
-	case -EAGAIN:
-		/* cache hit, trylock failure, caller handles failure */
-		ASSERT(flags & XBF_TRYLOCK);
-		return NULL;
 	case -ENOENT:
 		/* cache miss, go for insert */
 		break;
+	case -EAGAIN:
+		/* cache hit, trylock failure, caller handles failure */
+		ASSERT(flags & XBF_TRYLOCK);
+		/* fall through */
 	case -EFSCORRUPTED:
 	default:
-		/*
-		 * None of the higher layers understand failure types
-		 * yet, so return NULL to signal a fatal lookup error.
-		 */
-		return NULL;
+		return error;
 	}
 
 	error = _xfs_buf_alloc(target, map, nmaps, flags, &new_bp);
 	if (unlikely(error))
-		return NULL;
+		return error;
 
 	error = xfs_buf_allocate_memory(new_bp, flags);
 	if (error) {
 		xfs_buf_free(new_bp);
-		return NULL;
+		return error;
 	}
 
 	error = xfs_buf_find(target, map, nmaps, flags, new_bp, &bp);
 	if (error) {
 		xfs_buf_free(new_bp);
-		return NULL;
+		return error;
 	}
 
 	if (bp != new_bp)
@@ -743,7 +739,7 @@ xfs_buf_get_map(
 			xfs_warn(target->bt_mount,
 				"%s: failed to map pagesn", __func__);
 			xfs_buf_relse(bp);
-			return NULL;
+			return error;
 		}
 	}
 
@@ -756,7 +752,8 @@ xfs_buf_get_map(
 
 	XFS_STATS_INC(target->bt_mount, xb_get);
 	trace_xfs_buf_get(bp, flags, _RET_IP_);
-	return bp;
+	*bpp = bp;
+	return 0;
 }
 
 int
@@ -767,11 +764,12 @@ xfs_buf_get(
 	struct xfs_buf		**bpp)
 {
 	struct xfs_buf		*bp;
+	int			error;
 
 	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
-	bp = xfs_buf_get_map(target, &map, 1, 0);
-	if (!bp)
-		return -ENOMEM;
+	error = xfs_buf_get_map(target, &map, 1, 0, &bp);
+	if (error)
+		return error;
 
 	*bpp = bp;
 	return 0;
@@ -836,12 +834,13 @@ xfs_buf_read_map(
 	const struct xfs_buf_ops *ops)
 {
 	struct xfs_buf		*bp;
+	int			error;
 
 	flags |= XBF_READ;
 
-	bp = xfs_buf_get_map(target, map, nmaps, flags);
-	if (!bp)
-		return -ENOMEM;
+	error = xfs_buf_get_map(target, map, nmaps, flags, &bp);
+	if (error)
+		return error;
 
 	trace_xfs_buf_read(bp, flags, _RET_IP_);
 
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 7e01d168e437..8702e9099468 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -192,9 +192,8 @@ struct xfs_buf *xfs_buf_incore(struct xfs_buftarg *target,
 			   xfs_daddr_t blkno, size_t numblks,
 			   xfs_buf_flags_t flags);
 
-struct xfs_buf *xfs_buf_get_map(struct xfs_buftarg *target,
-			       struct xfs_buf_map *map, int nmaps,
-			       xfs_buf_flags_t flags);
+int xfs_buf_get_map(struct xfs_buftarg *target, struct xfs_buf_map *map,
+		int nmaps, xfs_buf_flags_t flags, struct xfs_buf **bpp);
 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);
diff --git a/fs/xfs/xfs_trans_buf.c b/fs/xfs/xfs_trans_buf.c
index a2af6dec310d..bf61e61b38c7 100644
--- a/fs/xfs/xfs_trans_buf.c
+++ b/fs/xfs/xfs_trans_buf.c
@@ -122,9 +122,14 @@ xfs_trans_get_buf_map(
 {
 	xfs_buf_t		*bp;
 	struct xfs_buf_log_item	*bip;
+	int			error;
 
-	if (!tp)
-		return xfs_buf_get_map(target, map, nmaps, flags);
+	if (!tp) {
+		error = xfs_buf_get_map(target, map, nmaps, flags, &bp);
+		if (error)
+			return NULL;
+		return bp;
+	}
 
 	/*
 	 * If we find the buffer in the cache with this transaction
@@ -149,10 +154,9 @@ xfs_trans_get_buf_map(
 		return bp;
 	}
 
-	bp = xfs_buf_get_map(target, map, nmaps, flags);
-	if (bp == NULL) {
+	error = xfs_buf_get_map(target, map, nmaps, flags, &bp);
+	if (error)
 		return NULL;
-	}
 
 	ASSERT(!bp->b_error);