[PATCH 06/12] xfs: make xfs_buf_get_map return an error code

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

From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>

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

Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
---
 fs/xfs/xfs_buf.c       |   45 ++++++++++++++++-----------------------------
 fs/xfs/xfs_buf.h       |   14 +++-----------
 fs/xfs/xfs_trans_buf.c |   14 +++++++++-----
 3 files changed, 28 insertions(+), 45 deletions(-)


diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 8a1c5c705b29..b420e865b32e 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -685,53 +685,39 @@ 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;
 
+	*bpp = NULL;
 	error = xfs_buf_find(target, map, nmaps, flags, NULL, &bp);
-
-	switch (error) {
-	case 0:
-		/* cache hit */
+	if (!error)
 		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 -EFSCORRUPTED:
-	default:
-		/*
-		 * None of the higher layers understand failure types
-		 * yet, so return NULL to signal a fatal lookup error.
-		 */
-		return NULL;
-	}
+	if (error != -ENOENT)
+		return error;
 
 	error = _xfs_buf_alloc(target, map, nmaps, flags, &new_bp);
 	if (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)
@@ -744,7 +730,7 @@ xfs_buf_get_map(
 			xfs_warn(target->bt_mount,
 				"%s: failed to map pagesn", __func__);
 			xfs_buf_relse(bp);
-			return NULL;
+			return error;
 		}
 	}
 
@@ -757,7 +743,8 @@ 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;
 }
 
 STATIC int
@@ -824,9 +811,9 @@ xfs_buf_read_map(
 	flags |= XBF_READ;
 	*bpp = NULL;
 
-	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 14209db07684..d1908a5038a2 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);
@@ -208,16 +207,9 @@ xfs_buf_get(
 	size_t			numblks,
 	struct xfs_buf		**bpp)
 {
-	struct xfs_buf		*bp;
 	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 
-	*bpp = NULL;
-	bp = xfs_buf_get_map(target, &map, 1, 0);
-	if (!bp)
-		return -ENOMEM;
-
-	*bpp = bp;
-	return 0;
+	return xfs_buf_get_map(target, &map, 1, 0, bpp);
 }
 
 static inline int
diff --git a/fs/xfs/xfs_trans_buf.c b/fs/xfs/xfs_trans_buf.c
index 56e7f8126cd7..6b7ef9dc167d 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);