xfs: avoid usage of struct xfs_dir2_data

In most places we can simply pass around and use the struct xfs_dir2_data_hdr,
which is the first and most important member of struct xfs_dir2_data instead
of the full structure.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/xfs_da_btree.c

@@ -2079,16 +2079,13 @@ xfs_da_do_buf(
 	 * For read_buf, check the magic number.
 	 */
 	if (caller == 1) {
-		xfs_dir2_data_t		*data;
-		xfs_dir2_free_t		*free;
-		xfs_da_blkinfo_t	*info;
+		xfs_dir2_data_hdr_t	*hdr = rbp->data;
+		xfs_dir2_free_t		*free = rbp->data;
+		xfs_da_blkinfo_t	*info = rbp->data;
 		uint			magic, magic1;
 
-		info = rbp->data;
-		data = rbp->data;
-		free = rbp->data;
 		magic = be16_to_cpu(info->magic);
-		magic1 = be32_to_cpu(data->hdr.magic);
+		magic1 = be32_to_cpu(hdr->magic);
 		if (unlikely(
 		    XFS_TEST_ERROR((magic != XFS_DA_NODE_MAGIC) &&
 				   (magic != XFS_ATTR_LEAF_MAGIC) &&

fs/xfs/xfs_dir2_block.c

@@ -282,7 +282,7 @@ xfs_dir2_block_addname(
 		 * This needs to happen before the next call to use_free.
 		 */
 		if (needscan) {
-			xfs_dir2_data_freescan(mp, (xfs_dir2_data_t *)hdr, &needlog);
+			xfs_dir2_data_freescan(mp, hdr, &needlog);
 			needscan = 0;
 		}
 	}
@@ -331,8 +331,7 @@ xfs_dir2_block_addname(
 		 * This needs to happen before the next call to use_free.
 		 */
 		if (needscan) {
-			xfs_dir2_data_freescan(mp, (xfs_dir2_data_t *)hdr,
-				&needlog);
+			xfs_dir2_data_freescan(mp, hdr, &needlog);
 			needscan = 0;
 		}
 		/*
@@ -417,7 +416,7 @@ xfs_dir2_block_addname(
 	 * Clean up the bestfree array and log the header, tail, and entry.
 	 */
 	if (needscan)
-		xfs_dir2_data_freescan(mp, (xfs_dir2_data_t *)hdr, &needlog);
+		xfs_dir2_data_freescan(mp, hdr, &needlog);
 	if (needlog)
 		xfs_dir2_data_log_header(tp, bp);
 	xfs_dir2_block_log_tail(tp, bp);
@@ -783,7 +782,7 @@ xfs_dir2_block_removename(
 	 * Fix up bestfree, log the header if necessary.
 	 */
 	if (needscan)
-		xfs_dir2_data_freescan(mp, (xfs_dir2_data_t *)hdr, &needlog);
+		xfs_dir2_data_freescan(mp, hdr, &needlog);
 	if (needlog)
 		xfs_dir2_data_log_header(tp, bp);
 	xfs_dir2_data_check(dp, bp);
@@ -982,7 +981,7 @@ xfs_dir2_leaf_to_block(
 	 * Scan the bestfree if we need it and log the data block header.
 	 */
 	if (needscan)
-		xfs_dir2_data_freescan(mp, (xfs_dir2_data_t *)hdr, &needlog);
+		xfs_dir2_data_freescan(mp, hdr, &needlog);
 	if (needlog)
 		xfs_dir2_data_log_header(tp, dbp);
 	/*
@@ -1177,8 +1176,7 @@ xfs_dir2_sf_to_block(
 			*xfs_dir2_data_unused_tag_p(dup) = cpu_to_be16(
 				((char *)dup - (char *)hdr));
 			xfs_dir2_data_log_unused(tp, bp, dup);
-			(void)xfs_dir2_data_freeinsert((xfs_dir2_data_t *)hdr,
-				dup, &dummy);
+			xfs_dir2_data_freeinsert(hdr, dup, &dummy);
 			offset += be16_to_cpu(dup->length);
 			continue;
 		}