xfs: kill struct xfs_dir2_block

Remove the confusing xfs_dir2_block structure.  It is supposed to describe
an XFS dir2 block format btree block, but due to the variable sized nature
of almost all elements in it it can't actuall do anything close to that
job.  In addition to accessing the fixed offset header structure it was
only used to get a pointer to the first dir or unused entry after it,
which can be trivially replaced by pointer arithmetics on the header
pointer.  For most users that is actually more natural anyway, as they
don't use a typed pointer but rather a character pointer for further
arithmetics.

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_dir2_block.c

@@ -437,7 +437,6 @@ xfs_dir2_block_getdents(
 	xfs_off_t		*offset,
 	filldir_t		filldir)
 {
-	xfs_dir2_block_t	*block;		/* directory block structure */
 	xfs_dir2_data_hdr_t	*hdr;		/* block header */
 	xfs_dabuf_t		*bp;		/* buffer for block */
 	xfs_dir2_block_tail_t	*btp;		/* block tail */
@@ -471,14 +470,13 @@ xfs_dir2_block_getdents(
 	 * We'll skip entries before this.
 	 */
 	wantoff = xfs_dir2_dataptr_to_off(mp, *offset);
-	block = bp->data;
-	hdr = &block->hdr;
+	hdr = bp->data;
 	xfs_dir2_data_check(dp, bp);
 	/*
 	 * Set up values for the loop.
 	 */
 	btp = xfs_dir2_block_tail_p(mp, hdr);
-	ptr = (char *)block->u;
+	ptr = (char *)(hdr + 1);
 	endptr = (char *)xfs_dir2_block_leaf_p(btp);
 
 	/*
@@ -1020,7 +1018,6 @@ xfs_dir2_sf_to_block(
 	xfs_da_args_t		*args)		/* operation arguments */
 {
 	xfs_dir2_db_t		blkno;		/* dir-relative block # (0) */
-	xfs_dir2_block_t	*block;		/* block structure */
 	xfs_dir2_data_hdr_t	*hdr;		/* block header */
 	xfs_dir2_leaf_entry_t	*blp;		/* block leaf entries */
 	xfs_dabuf_t		*bp;		/* block buffer */
@@ -1091,8 +1088,7 @@ xfs_dir2_sf_to_block(
 		kmem_free(sfp);
 		return error;
 	}
-	block = bp->data;
-	hdr = &block->hdr;
+	hdr = bp->data;
 	hdr->magic = cpu_to_be32(XFS_DIR2_BLOCK_MAGIC);
 	/*
 	 * Compute size of block "tail" area.
@@ -1103,7 +1099,7 @@ xfs_dir2_sf_to_block(
 	 * The whole thing is initialized to free by the init routine.
 	 * Say we're using the leaf and tail area.
 	 */
-	dup = (xfs_dir2_data_unused_t *)block->u;
+	dup = (xfs_dir2_data_unused_t *)(hdr + 1);
 	needlog = needscan = 0;
 	xfs_dir2_data_use_free(tp, bp, dup, mp->m_dirblksize - i, i, &needlog,
 		&needscan);

fs/xfs/xfs_dir2_block.h

@@ -19,10 +19,30 @@
 #define	__XFS_DIR2_BLOCK_H__
 
 /*
- * xfs_dir2_block.h
- * Directory version 2, single block format structures
+ * Directory version 2, single block format structures.
+ *
+ * The single block format looks like the following drawing on disk:
+ *
+ *    +-------------------------------------------------+
+ *    | xfs_dir2_data_hdr_t                             |
+ *    +-------------------------------------------------+
+ *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t |
+ *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t |
+ *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t |
+ *    | ...                                             |
+ *    +-------------------------------------------------+
+ *    | unused space                                    |
+ *    +-------------------------------------------------+
+ *    | ...                                             |
+ *    | xfs_dir2_leaf_entry_t                           |
+ *    | xfs_dir2_leaf_entry_t                           |
+ *    +-------------------------------------------------+
+ *    | xfs_dir2_block_tail_t                           |
+ *    +-------------------------------------------------+
+ *
+ * As all the entries are variable size structures the accessors in this
+ * file and xfs_dir2_data.h should be used to iterate over them.
  */
-
 struct uio;
 struct xfs_dabuf;
 struct xfs_da_args;
@@ -32,31 +52,13 @@ struct xfs_inode;
 struct xfs_mount;
 struct xfs_trans;
 
-/*
- * The single block format is as follows:
- * xfs_dir2_data_hdr_t structure
- * xfs_dir2_data_entry_t and xfs_dir2_data_unused_t structures
- * xfs_dir2_leaf_entry_t structures
- * xfs_dir2_block_tail_t structure
- */
-
 #define	XFS_DIR2_BLOCK_MAGIC	0x58443242	/* XD2B: for one block dirs */
 
 typedef struct xfs_dir2_block_tail {
 	__be32		count;			/* count of leaf entries */
 	__be32		stale;			/* count of stale lf entries */
 } xfs_dir2_block_tail_t;
 
-/*
- * Generic single-block structure, for xfs_db.
- */
-typedef struct xfs_dir2_block {
-	xfs_dir2_data_hdr_t	hdr;		/* magic XFS_DIR2_BLOCK_MAGIC */
-	xfs_dir2_data_union_t	u[1];
-	xfs_dir2_leaf_entry_t	leaf[1];
-	xfs_dir2_block_tail_t	tail;
-} xfs_dir2_block_t;
-
 /*
  * Pointer to the leaf header embedded in a data block (1-block format)
  */

fs/xfs/xfs_dir2_sf.c

@@ -226,7 +226,7 @@ xfs_dir2_block_to_sf(
 	int			size,		/* shortform directory size */
 	xfs_dir2_sf_hdr_t	*sfhp)		/* shortform directory hdr */
 {
-	xfs_dir2_block_t	*block;		/* block structure */
+	xfs_dir2_data_hdr_t	*hdr;		/* block header */
 	xfs_dir2_block_tail_t	*btp;		/* block tail pointer */
 	xfs_dir2_data_entry_t	*dep;		/* data entry pointer */
 	xfs_inode_t		*dp;		/* incore directory inode */
@@ -248,8 +248,8 @@ xfs_dir2_block_to_sf(
 	 * Make a copy of the block data, so we can shrink the inode
 	 * and add local data.
 	 */
-	block = kmem_alloc(mp->m_dirblksize, KM_SLEEP);
-	memcpy(block, bp->data, mp->m_dirblksize);
+	hdr = kmem_alloc(mp->m_dirblksize, KM_SLEEP);
+	memcpy(hdr, bp->data, mp->m_dirblksize);
 	logflags = XFS_ILOG_CORE;
 	if ((error = xfs_dir2_shrink_inode(args, mp->m_dirdatablk, bp))) {
 		ASSERT(error != ENOSPC);
@@ -277,8 +277,8 @@ xfs_dir2_block_to_sf(
 	/*
 	 * Set up to loop over the block's entries.
 	 */
-	btp = xfs_dir2_block_tail_p(mp, &block->hdr);
-	ptr = (char *)block->u;
+	btp = xfs_dir2_block_tail_p(mp, hdr);
+	ptr = (char *)(hdr + 1);
 	endptr = (char *)xfs_dir2_block_leaf_p(btp);
 	sfep = xfs_dir2_sf_firstentry(sfp);
 	/*
@@ -314,7 +314,7 @@ xfs_dir2_block_to_sf(
 			sfep->namelen = dep->namelen;
 			xfs_dir2_sf_put_offset(sfep,
 				(xfs_dir2_data_aoff_t)
-				((char *)dep - (char *)block));
+				((char *)dep - (char *)hdr));
 			memcpy(sfep->name, dep->name, dep->namelen);
 			xfs_dir2_sfe_put_ino(sfp, sfep,
 					     be64_to_cpu(dep->inumber));
@@ -327,7 +327,7 @@ xfs_dir2_block_to_sf(
 	xfs_dir2_sf_check(args);
 out:
 	xfs_trans_log_inode(args->trans, dp, logflags);
-	kmem_free(block);
+	kmem_free(hdr);
 	return error;
 }