[PATCH 1/3] xfs: helper to set flags on uncached buffer reads

[Brian Foster <bfoster@redhat.com>]

xfs_buf_read_uncached() allocates an uncached buffer and performs a read
in one go. As part of the upcoming buftarg I/O accounting mechanism,
some sites may need to set flags on a buffer before I/O submission.

Create a new helper to support the ability to set flags on a buffer
before it is submitted for I/O. This use case is the exception, so
create a wrapper for the original xfs_buf_read_uncached().

Signed-off-by: Brian Foster <bfoster@redhat.com>
---
 fs/xfs/xfs_buf.c | 20 +++++++++++++++++---
 fs/xfs/xfs_buf.h |  4 ++++
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 4665ff6..f007713 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -693,13 +693,14 @@ xfs_buf_readahead_map(
  * buffer containing the disk contents or nothing.
  */
 int
-xfs_buf_read_uncached(
+xfs_buf_read_uncached_flags(
 	struct xfs_buftarg	*target,
 	xfs_daddr_t		daddr,
 	size_t			numblks,
 	int			flags,
 	struct xfs_buf		**bpp,
-	const struct xfs_buf_ops *ops)
+	const struct xfs_buf_ops *ops,
+	int			bflags)
 {
 	struct xfs_buf		*bp;
 
@@ -713,7 +714,7 @@ xfs_buf_read_uncached(
 	ASSERT(bp->b_map_count == 1);
 	bp->b_bn = XFS_BUF_DADDR_NULL;  /* always null for uncached buffers */
 	bp->b_maps[0].bm_bn = daddr;
-	bp->b_flags |= XBF_READ;
+	bp->b_flags |= XBF_READ | bflags;
 	bp->b_ops = ops;
 
 	xfs_buf_submit_wait(bp);
@@ -727,6 +728,19 @@ xfs_buf_read_uncached(
 	return 0;
 }
 
+int
+xfs_buf_read_uncached(
+	struct xfs_buftarg	*target,
+	xfs_daddr_t		daddr,
+	size_t			numblks,
+	int			flags,
+	struct xfs_buf		**bpp,
+	const struct xfs_buf_ops *ops)
+{
+	return xfs_buf_read_uncached_flags(target, daddr, numblks, flags, bpp,
+					   ops, 0);
+}
+
 /*
  * Return a buffer allocated as an empty buffer and associated to external
  * memory via xfs_buf_associate_memory() back to it's empty state.
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 8bfb974..a3c7ba4 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -295,6 +295,10 @@ struct xfs_buf *xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks,
 int xfs_buf_read_uncached(struct xfs_buftarg *target, xfs_daddr_t daddr,
 			  size_t numblks, int flags, struct xfs_buf **bpp,
 			  const struct xfs_buf_ops *ops);
+int xfs_buf_read_uncached_flags(struct xfs_buftarg *target, xfs_daddr_t daddr,
+				size_t numblks, int flags, struct xfs_buf **bpp,
+				const struct xfs_buf_ops *ops, int blags);
+
 void xfs_buf_hold(struct xfs_buf *bp);
 
 /* Releasing Buffers */
-- 
2.5.5

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