xfs: create predicate to determine if cursor is at inode root level

Create a predicate to decide if the given cursor and level point to the
root block in the inode immediate area instead of a disk block, and get
rid of the open-coded logic everywhere.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/libxfs/xfs_btree.c

@@ -749,8 +749,7 @@ xfs_btree_get_block(
 	int			level,	/* level in btree */
 	struct xfs_buf		**bpp)	/* buffer containing the block */
 {
-	if (cur->bc_ops->type == XFS_BTREE_TYPE_INODE &&
-	    level == cur->bc_nlevels - 1) {
+	if (xfs_btree_at_iroot(cur, level)) {
 		*bpp = NULL;
 		return xfs_btree_get_iroot(cur);
 	}
@@ -992,8 +991,7 @@ xfs_btree_readahead(
 	 * No readahead needed if we are at the root level and the
 	 * btree root is stored in the inode.
 	 */
-	if (cur->bc_ops->type == XFS_BTREE_TYPE_INODE &&
-	    lev == cur->bc_nlevels - 1)
+	if (xfs_btree_at_iroot(cur, lev))
 		return 0;
 
 	if ((cur->bc_levels[lev].ra | lr) == cur->bc_levels[lev].ra)
@@ -1814,8 +1812,7 @@ xfs_btree_lookup_get_block(
 	int			error = 0;
 
 	/* special case the root block if in an inode */
-	if (cur->bc_ops->type == XFS_BTREE_TYPE_INODE &&
-	    level == cur->bc_nlevels - 1) {
+	if (xfs_btree_at_iroot(cur, level)) {
 		*blkp = xfs_btree_get_iroot(cur);
 		return 0;
 	}
@@ -2350,8 +2347,7 @@ xfs_btree_lshift(
 	int			error;		/* error return value */
 	int			i;
 
-	if ((cur->bc_ops->type == XFS_BTREE_TYPE_INODE) &&
-	    level == cur->bc_nlevels - 1)
+	if (xfs_btree_at_iroot(cur, level))
 		goto out0;
 
 	/* Set up variables for this block as "right". */
@@ -2546,8 +2542,7 @@ xfs_btree_rshift(
 	int			error;		/* error return value */
 	int			i;		/* loop counter */
 
-	if (cur->bc_ops->type == XFS_BTREE_TYPE_INODE &&
-	    level == cur->bc_nlevels - 1)
+	if (xfs_btree_at_iroot(cur, level))
 		goto out0;
 
 	/* Set up variables for this block as "left". */
@@ -3246,8 +3241,7 @@ xfs_btree_make_block_unfull(
 {
 	int			error = 0;
 
-	if (cur->bc_ops->type == XFS_BTREE_TYPE_INODE &&
-	    level == cur->bc_nlevels - 1) {
+	if (xfs_btree_at_iroot(cur, level)) {
 		struct xfs_inode *ip = cur->bc_ino.ip;
 
 		if (numrecs < cur->bc_ops->get_dmaxrecs(cur, level)) {
@@ -3856,27 +3850,25 @@ xfs_btree_delrec(
 	 * Try to get rid of the next level down.  If we can't then there's
 	 * nothing left to do.
 	 */
-	if (level == cur->bc_nlevels - 1) {
-		if (cur->bc_ops->type == XFS_BTREE_TYPE_INODE) {
-			xfs_iroot_realloc(cur->bc_ino.ip, -1,
-					  cur->bc_ino.whichfork);
+	if (xfs_btree_at_iroot(cur, level)) {
+		xfs_iroot_realloc(cur->bc_ino.ip, -1, cur->bc_ino.whichfork);
 
-			error = xfs_btree_kill_iroot(cur);
-			if (error)
-				goto error0;
+		error = xfs_btree_kill_iroot(cur);
+		if (error)
+			goto error0;
 
-			error = xfs_btree_dec_cursor(cur, level, stat);
-			if (error)
-				goto error0;
-			*stat = 1;
-			return 0;
-		}
+		error = xfs_btree_dec_cursor(cur, level, stat);
+		if (error)
+			goto error0;
+		*stat = 1;
+		return 0;
+	}
 
-		/*
-		 * If this is the root level, and there's only one entry left,
-		 * and it's NOT the leaf level, then we can get rid of this
-		 * level.
-		 */
+	/*
+	 * If this is the root level, and there's only one entry left, and it's
+	 * NOT the leaf level, then we can get rid of this level.
+	 */
+	if (level == cur->bc_nlevels - 1) {
 		if (numrecs == 1 && level > 0) {
 			union xfs_btree_ptr	*pp;
 			/*

fs/xfs/libxfs/xfs_btree.h

@@ -747,4 +747,14 @@ void xfs_btree_destroy_cur_caches(void);
 
 int xfs_btree_goto_left_edge(struct xfs_btree_cur *cur);
 
+/* Does this level of the cursor point to the inode root (and not a block)? */
+static inline bool
+xfs_btree_at_iroot(
+	const struct xfs_btree_cur	*cur,
+	int				level)
+{
+	return cur->bc_ops->type == XFS_BTREE_TYPE_INODE &&
+	       level == cur->bc_nlevels - 1;
+}
+
 #endif	/* __XFS_BTREE_H__ */

fs/xfs/libxfs/xfs_btree_staging.c

@@ -398,8 +398,7 @@ xfs_btree_bload_prep_block(
 	struct xfs_btree_block		*new_block;
 	int				ret;
 
-	if (cur->bc_ops->type == XFS_BTREE_TYPE_INODE &&
-	    level == cur->bc_nlevels - 1) {
+	if (xfs_btree_at_iroot(cur, level)) {
 		struct xfs_ifork	*ifp = xfs_btree_ifork_ptr(cur);
 		size_t			new_size;