xfs: convert buffer verifiers to an ops structure.

To separate the verifiers from iodone functions and associate read
and write verifiers at the same time, introduce a buffer verifier
operations structure to the xfs_buf.

This avoids the need for assigning the write verifier, clearing the
iodone function and re-running ioend processing in the read
verifier, and gets rid of the nasty "b_pre_io" name for the write
verifier function pointer. If we ever need to, it will also be
easier to add further content specific callbacks to a buffer with an
ops structure in place.

We also avoid needing to export verifier functions, instead we
can simply export the ops structures for those that are needed
outside the function they are defined in.

This patch also fixes a directory block readahead verifier issue
it exposed.

This patch also adds ops callbacks to the inode/alloc btree blocks
initialised by growfs. These will need more work before they will
work with CRCs.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Phil White <pwhite@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

1 files changed, 14 insertions, 10 deletions

diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 51bc16a1cd9c..23f5642480bb 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -111,6 +111,11 @@ struct xfs_buf_map {
 #define DEFINE_SINGLE_BUF_MAP(map, blkno, numblk) \
 	struct xfs_buf_map (map) = { .bm_bn = (blkno), .bm_len = (numblk) };
 
+struct xfs_buf_ops {
+	void (*verify_read)(struct xfs_buf *);
+	void (*verify_write)(struct xfs_buf *);
+};
+
 typedef struct xfs_buf {
 	/*
 	 * first cacheline holds all the fields needed for an uncontended cache
@@ -154,9 +159,7 @@ typedef struct xfs_buf {
 	unsigned int		b_page_count;	/* size of page array */
 	unsigned int		b_offset;	/* page offset in first page */
 	unsigned short		b_error;	/* error code on I/O */
-
-	void			(*b_pre_io)(struct xfs_buf *);
-						/* pre-io callback function */
+	const struct xfs_buf_ops	*b_ops;
 
 #ifdef XFS_BUF_LOCK_TRACKING
 	int			b_last_holder;
@@ -199,10 +202,11 @@ struct xfs_buf *xfs_buf_get_map(struct xfs_buftarg *target,
 			       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, xfs_buf_iodone_t verify);
+			       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,
-			       xfs_buf_iodone_t verify);
+			       const struct xfs_buf_ops *ops);
 
 static inline struct xfs_buf *
 xfs_buf_get(
@@ -221,10 +225,10 @@ xfs_buf_read(
 	xfs_daddr_t		blkno,
 	size_t			numblks,
 	xfs_buf_flags_t		flags,
-	xfs_buf_iodone_t	verify)
+	const struct xfs_buf_ops *ops)
 {
 	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
-	return xfs_buf_read_map(target, &map, 1, flags, verify);
+	return xfs_buf_read_map(target, &map, 1, flags, ops);
 }
 
 static inline void
@@ -232,10 +236,10 @@ xfs_buf_readahead(
 	struct xfs_buftarg	*target,
 	xfs_daddr_t		blkno,
 	size_t			numblks,
-	xfs_buf_iodone_t	verify)
+	const struct xfs_buf_ops *ops)
 {
 	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
-	return xfs_buf_readahead_map(target, &map, 1, verify);
+	return xfs_buf_readahead_map(target, &map, 1, ops);
 }
 
 struct xfs_buf *xfs_buf_get_empty(struct xfs_buftarg *target, size_t numblks);
@@ -246,7 +250,7 @@ struct xfs_buf *xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks,
 				int flags);
 struct xfs_buf *xfs_buf_read_uncached(struct xfs_buftarg *target,
 				xfs_daddr_t daddr, size_t numblks, int flags,
-				xfs_buf_iodone_t verify);
+				const struct xfs_buf_ops *ops);
 void xfs_buf_hold(struct xfs_buf *bp);
 
 /* Releasing Buffers */