[PATCH 03/12] xfs: split out a lower-level xfs_buf_get_map helper from xfs_find_get_buf

[Christoph Hellwig <hch@lst.de>]

xfs_buf_get_map is currently reused to implement xfs_buf_read_map and
xfs_buf_readahead_map.  This causes double accounting of buf_get stat
and leads to some ugly overload of the flags.

Split out a slightly lower-level xfs_find_get_buf helper and use that to
implement xfs_buf_get_map, xfs_buf_read_map and xfs_buf_readahead_map.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_buf.c | 41 +++++++++++++++++++++++++++++------------
 1 file changed, 29 insertions(+), 12 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index e56d4b8b0771..2cf359b4c446 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -514,8 +514,8 @@ xfs_buf_find_insert(
  * cache hits, as metadata intensive workloads will see 3 orders of magnitude
  * more hits than misses.
  */
-int
-xfs_buf_get_map(
+static int
+xfs_find_get_buf(
 	struct xfs_buftarg	*btp,
 	struct xfs_buf_map	*map,
 	int			nmaps,
@@ -552,16 +552,33 @@ xfs_buf_get_map(
 		return error;
 	}
 
+	*bpp = bp;
+	return 0;
+}
+
+int
+xfs_buf_get_map(
+	struct xfs_buftarg	*btp,
+	struct xfs_buf_map	*map,
+	int			nmaps,
+	xfs_buf_flags_t		flags,
+	struct xfs_buf		**bpp)
+{
+	int			error;
+
+	ASSERT(!(flags & ~(XBF_TRYLOCK | XBF_INCORE | XBF_LIVESCAN)));
+	ASSERT(!(flags & XBF_LIVESCAN) || (flags & XBF_INCORE));
+
 	/*
-	 * Clear b_error if this is a lookup from a caller that doesn't expect
-	 * valid data to be found in the buffer.
+	 * Zero the buffer and clear b_error as xfs_buf_get_map callers don't
+	 * expect valid data to be found in the buffer.
 	 */
-	if (!(flags & XBF_READ))
-		xfs_buf_ioerror(bp, 0);
-
+	error = xfs_find_get_buf(btp, map, nmaps, flags, bpp);
+	if (error)
+		return error;
 	XFS_STATS_INC(btp->bt_mount, xb_get);
-	trace_xfs_buf_get(bp, flags, _RET_IP_);
-	*bpp = bp;
+	trace_xfs_buf_get(*bpp, flags, _RET_IP_);
+	xfs_buf_ioerror(*bpp, 0);
 	return 0;
 }
 
@@ -625,12 +642,12 @@ xfs_buf_read_map(
 	struct xfs_buf		*bp;
 	int			error;
 
-	ASSERT(!(flags & (XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD)));
+	ASSERT(!(flags & ~XBF_TRYLOCK));
 
 	flags |= XBF_READ;
 	*bpp = NULL;
 
-	error = xfs_buf_get_map(target, map, nmaps, flags, &bp);
+	error = xfs_find_get_buf(target, map, nmaps, flags, &bp);
 	if (error)
 		return error;
 
@@ -706,7 +723,7 @@ xfs_buf_readahead_map(
 	if (xfs_buftarg_is_mem(target))
 		return;
 
-	if (xfs_buf_get_map(target, map, nmaps, flags | XBF_TRYLOCK, &bp))
+	if (xfs_find_get_buf(target, map, nmaps, flags | XBF_TRYLOCK, &bp))
 		return;
 	trace_xfs_buf_readahead(bp, 0, _RET_IP_);
 
-- 
2.53.0