[PATCH v2 04/13] libext2fs: add helper for dx_root_info lookup

From: Artem Blagodarenko <[email protected]>

Add dirdata support infrastructure in the new lfsck.h header, with
data structures (lu_fid, ext4_dirent_data_header, ext4_dirent_hash)
related to dirdata fields.

Also changes to ext2_fs.h and ext2fs.h to support INCOMPAT_DIRDATA.

Signed-off-by: Artem Blagodarenko <[email protected]>
Reviewed-by: Andreas Dilger <[email protected]>
---
 debugfs/htree.c     |  2 +-
 e2fsck/pass1.c      |  2 +-
 e2fsck/pass2.c      |  7 +++----
 lib/ext2fs/ext2fs.h | 19 +++++++++++++++++++
 4 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/debugfs/htree.c b/debugfs/htree.c
index 4ea8f30b3..efb858271 100644
--- a/debugfs/htree.c
+++ b/debugfs/htree.c
@@ -298,7 +298,7 @@ void do_htree_dump(int argc, ss_argv_t argv, int sci_idx EXT2FS_ATTR((unused)),
 		goto errout;
 	}
 
-	rootnode = (struct ext2_dx_root_info *) (buf + 24);
+	rootnode = ext2fs_get_dx_root_info(current_fs, buf);
 
 	fprintf(pager, "Root node dump:\n");
 	fprintf(pager, "\t Reserved zero: %u\n", rootnode->reserved_zero);
diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
index 39d1255f9..12925ce2f 100644
--- a/e2fsck/pass1.c
+++ b/e2fsck/pass1.c
@@ -2801,7 +2801,7 @@ static int handle_htree(e2fsck_t ctx, struct problem_context *pctx,
 		return 1;
 
 	/* XXX should check that beginning matches a directory */
-	root = (struct ext2_dx_root_info *) (block_buf + 24);
+	root = ext2fs_get_dx_root_info(fs, block_buf);
 
 	if ((root->reserved_zero || root->info_length < 8) &&
 	    fix_problem(ctx, PR_1_HTREE_BADROOT, pctx))
diff --git a/e2fsck/pass2.c b/e2fsck/pass2.c
index 319e7e0e3..cf1678c85 100644
--- a/e2fsck/pass2.c
+++ b/e2fsck/pass2.c
@@ -650,7 +650,7 @@ static void parse_int_node(ext2_filsys fs,
 	int		csum_size = 0;
 
 	if (db->blockcnt == 0) {
-		root = (struct ext2_dx_root_info *) (block_buf + 24);
+		root = ext2fs_get_dx_root_info(fs, block_buf);
 
 #ifdef DX_DEBUG
 		printf("Root node dump:\n");
@@ -677,8 +677,7 @@ static void parse_int_node(ext2_filsys fs,
 				&cd->pctx)))
 			goto clear_and_exit;
 	}
-
-	limit = (struct ext2_dx_countlimit *) ent;
+	limit = (struct ext2_dx_countlimit *)ent;
 
 #ifdef DX_DEBUG
 	printf("Number of entries (count): %d\n",
@@ -1236,7 +1235,7 @@ inline_read_fail:
 		(void) ext2fs_get_rec_len(fs, dirent, &rec_len);
 		limit = (struct ext2_dx_countlimit *) (buf+8);
 		if (db->blockcnt == 0) {
-			root = (struct ext2_dx_root_info *) (buf + 24);
+			root = ext2fs_get_dx_root_info(fs, buf);
 			dx_db->type = DX_DIRBLOCK_ROOT;
 			dx_db->flags |= DX_FLAG_FIRST | DX_FLAG_LAST;
 
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 91d269865..cf12716e3 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -2262,6 +2262,25 @@ _INLINE_ int ext2fs_htree_intnode_maxrecs(ext2_filsys fs, int blocks)
 						sizeof(struct ext2_dx_entry));
 }
 
+_INLINE_ struct ext2_dx_root_info *ext2fs_get_dx_root_info(ext2_filsys fs,
+							 char *buf)
+{
+	struct ext2_dir_entry *de = (struct ext2_dir_entry *)buf;
+
+	if (!(fs->super->s_feature_incompat & EXT4_FEATURE_INCOMPAT_DIRDATA))
+		return (struct ext2_dx_root_info *)(buf +
+						    EXT2_DIR_NAME_LEN(1) +
+						    EXT2_DIR_NAME_LEN(2));
+
+	/* get dotdot first */
+	de = (struct ext2_dir_entry *)((char *)de + de->rec_len);
+
+	/* dx root info is after dotdot entry */
+	de = EXT2_NEXT_DIRENT(de);
+
+	return (struct ext2_dx_root_info *)de;
+}
+
 /*
  * log base 2, rounded down
  */
-- 
2.43.7