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, 43 insertions, 9 deletions

diff --git a/fs/xfs/xfs_dir2_data.c b/fs/xfs/xfs_dir2_data.c
index dcb8a87..ffcf177 100644
--- a/fs/xfs/xfs_dir2_data.c
+++ b/fs/xfs/xfs_dir2_data.c
@@ -202,23 +202,57 @@ xfs_dir2_data_verify(
 	}
 }
 
-void
-xfs_dir2_data_write_verify(
+/*
+ * Readahead of the first block of the directory when it is opened is completely
+ * oblivious to the format of the directory. Hence we can either get a block
+ * format buffer or a data format buffer on readahead.
+ */
+static void
+xfs_dir2_data_reada_verify(
+	struct xfs_buf		*bp)
+{
+	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_dir2_data_hdr *hdr = bp->b_addr;
+
+	switch (hdr->magic) {
+	case cpu_to_be32(XFS_DIR2_BLOCK_MAGIC):
+		bp->b_ops = &xfs_dir2_block_buf_ops;
+		bp->b_ops->verify_read(bp);
+		return;
+	case cpu_to_be32(XFS_DIR2_DATA_MAGIC):
+		xfs_dir2_data_verify(bp);
+		return;
+	default:
+		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, hdr);
+		xfs_buf_ioerror(bp, EFSCORRUPTED);
+		break;
+	}
+}
+
+static void
+xfs_dir2_data_read_verify(
 	struct xfs_buf	*bp)
 {
 	xfs_dir2_data_verify(bp);
 }
 
 static void
-xfs_dir2_data_read_verify(
+xfs_dir2_data_write_verify(
 	struct xfs_buf	*bp)
 {
 	xfs_dir2_data_verify(bp);
-	bp->b_pre_io = xfs_dir2_data_write_verify;
-	bp->b_iodone = NULL;
-	xfs_buf_ioend(bp, 0);
 }
 
+const struct xfs_buf_ops xfs_dir2_data_buf_ops = {
+	.verify_read = xfs_dir2_data_read_verify,
+	.verify_write = xfs_dir2_data_write_verify,
+};
+
+static const struct xfs_buf_ops xfs_dir2_data_reada_buf_ops = {
+	.verify_read = xfs_dir2_data_reada_verify,
+	.verify_write = xfs_dir2_data_write_verify,
+};
+
 
 int
 xfs_dir2_data_read(
@@ -229,7 +263,7 @@ xfs_dir2_data_read(
 	struct xfs_buf		**bpp)
 {
 	return xfs_da_read_buf(tp, dp, bno, mapped_bno, bpp,
-				XFS_DATA_FORK, xfs_dir2_data_read_verify);
+				XFS_DATA_FORK, &xfs_dir2_data_buf_ops);
 }
 
 int
@@ -240,7 +274,7 @@ xfs_dir2_data_readahead(
 	xfs_daddr_t		mapped_bno)
 {
 	return xfs_da_reada_buf(tp, dp, bno, mapped_bno,
-				XFS_DATA_FORK, xfs_dir2_data_read_verify);
+				XFS_DATA_FORK, &xfs_dir2_data_reada_buf_ops);
 }
 
 /*
@@ -484,7 +518,7 @@ xfs_dir2_data_init(
 		XFS_DATA_FORK);
 	if (error)
 		return error;
-	bp->b_pre_io = xfs_dir2_data_write_verify;
+	bp->b_ops = &xfs_dir2_data_buf_ops;
 
 	/*
 	 * Initialize the header.