[25/54] libext2fs: Introduce dir_entry_tail to provide checksums for directory leaf nodes

Submitted by Darrick J. Wong on March 7, 2012, midnight

Details

Message ID 20120307000004.11945.38518.stgit@elm3b70.beaverton.ibm.com
State Superseded, archived
Delegated to: Theodore Ts'o
Headers show

Commit Message

Darrick J. Wong March 7, 2012, midnight
Introduce small structures for recording directory tree checksums, and some API
changes to support writing out directory blocks with checksums.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
---
 debugfs/htree.c           |    9 ++-
 e2fsck/pass1.c            |    2 -
 e2fsck/pass2.c            |   14 +++-
 e2fsck/pass3.c            |   10 ++-
 e2fsck/rehash.c           |   37 +++++++++--
 lib/ext2fs/csum.c         |  148 +++++++++++++++++++++++++++++++++++++++++++++
 lib/ext2fs/dir_iterate.c  |   14 +++-
 lib/ext2fs/dirblock.c     |   98 +++++++++++++-----------------
 lib/ext2fs/expanddir.c    |    5 +-
 lib/ext2fs/ext2_err.et.in |    3 +
 lib/ext2fs/ext2fs.h       |   18 +++++
 lib/ext2fs/link.c         |    6 ++
 lib/ext2fs/mkdir.c        |    2 -
 lib/ext2fs/newdir.c       |   15 ++++-
 lib/ext2fs/swapfs.c       |   62 +++++++++++++++++++
 15 files changed, 361 insertions(+), 82 deletions(-)



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diff --git a/debugfs/htree.c b/debugfs/htree.c
index 2fb804e..1932962 100644
--- a/debugfs/htree.c
+++ b/debugfs/htree.c
@@ -44,6 +44,11 @@  static void htree_dump_leaf_node(ext2_filsys fs, ext2_ino_t ino,
 	ext2_dirhash_t 	hash, minor_hash;
 	unsigned int	rec_len;
 	int		hash_alg;
+	int		csum_size = 0;
+
+	if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+				       EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+		csum_size = sizeof(struct ext2_dir_entry_tail);
 
 	errcode = ext2fs_bmap2(fs, ino, inode, buf, 0, blk, 0, &pblk);
 	if (errcode) {
@@ -53,7 +58,7 @@  static void htree_dump_leaf_node(ext2_filsys fs, ext2_ino_t ino,
 	}
 
 	printf("Reading directory block %llu, phys %llu\n", blk, pblk);
-	errcode = ext2fs_read_dir_block2(current_fs, pblk, buf, 0);
+	errcode = ext2fs_read_dir_block4(current_fs, pblk, buf, 0, ino);
 	if (errcode) {
 		com_err("htree_dump_leaf_node", errcode,
 			"while reading block %llu (%llu)\n",
@@ -65,7 +70,7 @@  static void htree_dump_leaf_node(ext2_filsys fs, ext2_ino_t ino,
 	    (fs->super->s_flags & EXT2_FLAGS_UNSIGNED_HASH))
 		hash_alg += 3;
 
-	while (offset < fs->blocksize) {
+	while (offset < (fs->blocksize - csum_size)) {
 		dirent = (struct ext2_dir_entry *) (buf + offset);
 		errcode = ext2fs_get_rec_len(fs, dirent, &rec_len);
 		if (errcode) {
diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
index 332cc22..42fca3e 100644
--- a/e2fsck/pass1.c
+++ b/e2fsck/pass1.c
@@ -473,7 +473,7 @@  static void check_is_really_dir(e2fsck_t ctx, struct problem_context *pctx,
 
 	/* read the first block */
 	ehandler_operation(_("reading directory block"));
-	retval = ext2fs_read_dir_block3(ctx->fs, blk, buf, 0);
+	retval = ext2fs_read_dir_block4(ctx->fs, blk, buf, 0, pctx->ino);
 	ehandler_operation(0);
 	if (retval)
 		return;
diff --git a/e2fsck/pass2.c b/e2fsck/pass2.c
index e4a06f3..5de301f 100644
--- a/e2fsck/pass2.c
+++ b/e2fsck/pass2.c
@@ -754,6 +754,7 @@  static int check_dir_block(ext2_filsys fs,
 	int	dups_found = 0;
 	int	ret;
 	int	dx_csum_size = 0;
+	int	failed_csum = 0;
 
 	cd = (struct check_dir_struct *) priv_data;
 	buf = cd->buf;
@@ -804,10 +805,14 @@  static int check_dir_block(ext2_filsys fs,
 #endif
 
 	ehandler_operation(_("reading directory block"));
-	cd->pctx.errcode = ext2fs_read_dir_block3(fs, block_nr, buf, 0);
+	cd->pctx.errcode = ext2fs_read_dir_block4(fs, block_nr, buf, 0, ino);
 	ehandler_operation(0);
 	if (cd->pctx.errcode == EXT2_ET_DIR_CORRUPTED)
 		cd->pctx.errcode = 0; /* We'll handle this ourselves */
+	else if (cd->pctx.errcode == EXT2_ET_DIR_CSUM_INVALID) {
+		cd->pctx.errcode = 0; /* We'll handle this ourselves */
+		failed_csum = 1;
+	}
 	if (cd->pctx.errcode) {
 		if (!fix_problem(ctx, PR_2_READ_DIRBLOCK, &cd->pctx)) {
 			ctx->flags |= E2F_FLAG_ABORT;
@@ -1145,7 +1150,7 @@  out_htree:
 		cd->pctx.dir = cd->pctx.ino;
 		if ((dx_db->type == DX_DIRBLOCK_ROOT) ||
 		    (dx_db->type == DX_DIRBLOCK_NODE))
-			parse_int_node(fs, db, cd, dx_dir, buf, 0);
+			parse_int_node(fs, db, cd, dx_dir, buf, failed_csum);
 	}
 #endif /* ENABLE_HTREE */
 	if (offset != fs->blocksize) {
@@ -1156,7 +1161,8 @@  out_htree:
 		}
 	}
 	if (dir_modified) {
-		cd->pctx.errcode = ext2fs_write_dir_block(fs, block_nr, buf);
+		cd->pctx.errcode = ext2fs_write_dir_block4(fs, block_nr, buf,
+							   0, ino);
 		if (cd->pctx.errcode) {
 			if (!fix_problem(ctx, PR_2_WRITE_DIRBLOCK,
 					 &cd->pctx))
@@ -1476,7 +1482,7 @@  static int allocate_dir_block(e2fsck_t ctx,
 		return 1;
 	}
 
-	pctx->errcode = ext2fs_write_dir_block(fs, blk, block);
+	pctx->errcode = ext2fs_write_dir_block4(fs, blk, block, 0, db->ino);
 	ext2fs_free_mem(&block);
 	if (pctx->errcode) {
 		pctx->str = "ext2fs_write_dir_block";
diff --git a/e2fsck/pass3.c b/e2fsck/pass3.c
index 565b8e3..4ae3a33 100644
--- a/e2fsck/pass3.c
+++ b/e2fsck/pass3.c
@@ -198,7 +198,8 @@  static void check_root(e2fsck_t ctx)
 		return;
 	}
 
-	pctx.errcode = ext2fs_write_dir_block(fs, blk, block);
+	pctx.errcode = ext2fs_write_dir_block4(fs, blk, block, 0,
+					       EXT2_ROOT_INO);
 	if (pctx.errcode) {
 		pctx.str = "ext2fs_write_dir_block";
 		fix_problem(ctx, PR_3_CREATE_ROOT_ERROR, &pctx);
@@ -444,7 +445,7 @@  ext2_ino_t e2fsck_get_lost_and_found(e2fsck_t ctx, int fix)
 		return 0;
 	}
 
-	retval = ext2fs_write_dir_block(fs, blk, block);
+	retval = ext2fs_write_dir_block4(fs, blk, block, 0, ino);
 	ext2fs_free_mem(&block);
 	if (retval) {
 		pctx.errcode = retval;
@@ -685,6 +686,7 @@  struct expand_dir_struct {
 	blk64_t			last_block;
 	errcode_t		err;
 	e2fsck_t		ctx;
+	ext2_ino_t		dir;
 };
 
 static int expand_dir_proc(ext2_filsys fs,
@@ -725,7 +727,8 @@  static int expand_dir_proc(ext2_filsys fs,
 			return BLOCK_ABORT;
 		}
 		es->num--;
-		retval = ext2fs_write_dir_block(fs, new_blk, block);
+		retval = ext2fs_write_dir_block4(fs, new_blk, block, 0,
+						 es->dir);
 	} else {
 		retval = ext2fs_get_mem(fs->blocksize, &block);
 		if (retval) {
@@ -778,6 +781,7 @@  errcode_t e2fsck_expand_directory(e2fsck_t ctx, ext2_ino_t dir,
 	es.err = 0;
 	es.newblocks = 0;
 	es.ctx = ctx;
+	es.dir = dir;
 
 	retval = ext2fs_block_iterate3(fs, dir, BLOCK_FLAG_APPEND,
 				       0, expand_dir_proc, &es);
diff --git a/e2fsck/rehash.c b/e2fsck/rehash.c
index 610b3bf..a77ef03 100644
--- a/e2fsck/rehash.c
+++ b/e2fsck/rehash.c
@@ -81,6 +81,7 @@  struct fill_dir_struct {
 	int dir_size;
 	int compress;
 	ino_t parent;
+	ext2_ino_t dir;
 };
 
 struct hash_entry {
@@ -125,7 +126,10 @@  static int fill_dir_block(ext2_filsys fs,
 		dirent = (struct ext2_dir_entry *) dir;
 		(void) ext2fs_set_rec_len(fs, fs->blocksize, dirent);
 	} else {
-		fd->err = ext2fs_read_dir_block3(fs, *block_nr, dir, 0);
+		fs->flags |= EXT2_FLAG_IGNORE_CSUM_ERRORS;
+		fd->err = ext2fs_read_dir_block4(fs, *block_nr, dir, 0,
+						 fd->dir);
+		fs->flags &= ~EXT2_FLAG_IGNORE_CSUM_ERRORS;
 		if (fd->err)
 			return BLOCK_ABORT;
 	}
@@ -416,7 +420,8 @@  static int duplicate_search_and_fix(e2fsck_t ctx, ext2_filsys fs,
 
 static errcode_t copy_dir_entries(e2fsck_t ctx,
 				  struct fill_dir_struct *fd,
-				  struct out_dir *outdir)
+				  struct out_dir *outdir,
+				  ext2_ino_t ino)
 {
 	ext2_filsys 		fs = ctx->fs;
 	errcode_t		retval;
@@ -427,6 +432,8 @@  static errcode_t copy_dir_entries(e2fsck_t ctx,
 	int			i, left;
 	ext2_dirhash_t		prev_hash;
 	int			offset, slack;
+	int			csum_size = 0;
+	struct			ext2_dir_entry_tail *t;
 
 	if (ctx->htree_slack_percentage == 255) {
 		profile_get_uint(ctx->profile, "options",
@@ -437,6 +444,10 @@  static errcode_t copy_dir_entries(e2fsck_t ctx,
 			ctx->htree_slack_percentage = 20;
 	}
 
+	if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+				       EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+		csum_size = sizeof(struct ext2_dir_entry_tail);
+
 	outdir->max = 0;
 	retval = alloc_size_dir(fs, outdir,
 				(fd->dir_size / fs->blocksize) + 2);
@@ -451,9 +462,9 @@  static errcode_t copy_dir_entries(e2fsck_t ctx,
 	dirent = (struct ext2_dir_entry *) block_start;
 	prev_rec_len = 0;
 	rec_len = 0;
-	left = fs->blocksize;
+	left = fs->blocksize - csum_size;
 	slack = fd->compress ? 12 :
-		(fs->blocksize * ctx->htree_slack_percentage)/100;
+		((fs->blocksize - csum_size) * ctx->htree_slack_percentage)/100;
 	if (slack < 12)
 		slack = 12;
 	for (i = 0; i < fd->num_array; i++) {
@@ -468,12 +479,17 @@  static errcode_t copy_dir_entries(e2fsck_t ctx,
 				if (retval)
 					return retval;
 			}
+			if (csum_size) {
+				t = EXT2_DIRENT_TAIL(block_start,
+						     fs->blocksize);
+				ext2fs_initialize_dirent_tail(fs, t);
+			}
 			if ((retval = get_next_block(fs, outdir,
 						      &block_start)))
 				return retval;
 			offset = 0;
 		}
-		left = fs->blocksize - offset;
+		left = (fs->blocksize - csum_size) - offset;
 		dirent = (struct ext2_dir_entry *) (block_start + offset);
 		if (offset == 0) {
 			if (ent->hash == prev_hash)
@@ -502,6 +518,10 @@  static errcode_t copy_dir_entries(e2fsck_t ctx,
 	}
 	if (left)
 		retval = ext2fs_set_rec_len(fs, rec_len + left, dirent);
+	if (csum_size) {
+		t = EXT2_DIRENT_TAIL(block_start, fs->blocksize);
+		ext2fs_initialize_dirent_tail(fs, t);
+	}
 
 	return retval;
 }
@@ -659,6 +679,7 @@  struct write_dir_struct {
 	errcode_t	err;
 	e2fsck_t	ctx;
 	int		cleared;
+	ext2_ino_t	dir;
 };
 
 /*
@@ -690,7 +711,7 @@  static int write_dir_block(ext2_filsys fs,
 		return 0;
 
 	dir = wd->outdir->buf + (blockcnt * fs->blocksize);
-	wd->err = ext2fs_write_dir_block3(fs, *block_nr, dir, 0);
+	wd->err = ext2fs_write_dir_block4(fs, *block_nr, dir, 0, wd->dir);
 	if (wd->err)
 		return BLOCK_ABORT;
 	return 0;
@@ -712,6 +733,7 @@  static errcode_t write_directory(e2fsck_t ctx, ext2_filsys fs,
 	wd.err = 0;
 	wd.ctx = ctx;
 	wd.cleared = 0;
+	wd.dir = ino;
 
 	retval = ext2fs_block_iterate3(fs, ino, 0, 0,
 				       write_dir_block, &wd);
@@ -764,6 +786,7 @@  errcode_t e2fsck_rehash_dir(e2fsck_t ctx, ext2_ino_t ino)
 	fd.err = 0;
 	fd.dir_size = 0;
 	fd.compress = 0;
+	fd.dir = ino;
 	if (!(fs->super->s_feature_compat & EXT2_FEATURE_COMPAT_DIR_INDEX) ||
 	    (inode.i_size / fs->blocksize) < 2)
 		fd.compress = 1;
@@ -823,7 +846,7 @@  resort:
 	 * Copy the directory entries.  In a htree directory these
 	 * will become the leaf nodes.
 	 */
-	retval = copy_dir_entries(ctx, &fd, &outdir);
+	retval = copy_dir_entries(ctx, &fd, &outdir, ino);
 	if (retval)
 		goto errout;
 
diff --git a/lib/ext2fs/csum.c b/lib/ext2fs/csum.c
index 8907459..1c06f5e 100644
--- a/lib/ext2fs/csum.c
+++ b/lib/ext2fs/csum.c
@@ -93,6 +93,122 @@  errcode_t ext2fs_get_dx_countlimit(ext2_filsys fs,
 	return __get_dx_countlimit(fs, dirent, cc, offset, 0);
 }
 
+void ext2fs_initialize_dirent_tail(ext2_filsys fs,
+				   struct ext2_dir_entry_tail *t)
+{
+	memset(t, 0, sizeof(struct ext2_dir_entry_tail));
+	ext2fs_set_rec_len(fs, sizeof(struct ext2_dir_entry_tail),
+			   (struct ext2_dir_entry *)t);
+	t->det_reserved_name_len = EXT2_DIR_NAME_LEN_CSUM;
+}
+
+static errcode_t __get_dirent_tail(ext2_filsys fs,
+				   struct ext2_dir_entry *dirent,
+				   struct ext2_dir_entry_tail **tt,
+				   int need_swab)
+{
+	struct ext2_dir_entry *d;
+	void *top;
+	struct ext2_dir_entry_tail *t;
+	unsigned int rec_len;
+	errcode_t retval = 0;
+	__u16 (*translate)(__u16) = (need_swab ? disk_to_host16 : do_nothing16);
+
+	d = dirent;
+	top = EXT2_DIRENT_TAIL(dirent, fs->blocksize);
+
+	rec_len = translate(d->rec_len);
+	while (rec_len && !(rec_len & 0x3)) {
+		d = (struct ext2_dir_entry *)(((void *)d) + rec_len);
+		if ((void *)d >= top)
+			break;
+		rec_len = translate(d->rec_len);
+	}
+
+	if (d != top)
+		return EXT2_ET_DIR_NO_SPACE_FOR_CSUM;
+
+	t = (struct ext2_dir_entry_tail *)d;
+	if (t->det_reserved_zero1 ||
+	    translate(t->det_rec_len) != sizeof(struct ext2_dir_entry_tail) ||
+	    translate(t->det_reserved_name_len) != EXT2_DIR_NAME_LEN_CSUM)
+		return EXT2_ET_DIR_NO_SPACE_FOR_CSUM;
+
+	if (tt)
+		*tt = t;
+	return retval;
+}
+
+int ext2fs_dirent_has_tail(ext2_filsys fs, struct ext2_dir_entry *dirent)
+{
+	return __get_dirent_tail(fs, dirent, NULL, 0) == 0;
+}
+
+static errcode_t ext2fs_dirent_csum(ext2_filsys fs, ext2_ino_t inum,
+				    struct ext2_dir_entry *dirent, __u32 *crc,
+				    int size)
+{
+	errcode_t retval;
+	char *buf = (char *)dirent;
+	__u32 gen;
+	struct ext2_inode inode;
+
+	retval = ext2fs_read_inode(fs, inum, &inode);
+	if (retval)
+		return retval;
+
+	inum = ext2fs_cpu_to_le32(inum);
+	gen = ext2fs_cpu_to_le32(inode.i_generation);
+	*crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)&inum,
+				sizeof(inum));
+	*crc = ext2fs_crc32c_le(*crc, (unsigned char *)&gen, sizeof(gen));
+	*crc = ext2fs_crc32c_le(*crc, (unsigned char *)buf, size);
+
+	return 0;
+}
+
+int ext2fs_dirent_csum_verify(ext2_filsys fs, ext2_ino_t inum,
+			      struct ext2_dir_entry *dirent)
+{
+	errcode_t retval;
+	__u32 calculated;
+	struct ext2_dir_entry_tail *t;
+
+	retval = __get_dirent_tail(fs, dirent, &t, 1);
+	if (retval)
+		return 1;
+
+	/*
+	 * The checksum field is overlaid with the dirent->name field
+	 * so the swapfs.c functions won't change the endianness.
+	 */
+	retval = ext2fs_dirent_csum(fs, inum, dirent, &calculated,
+				    (void *)t - (void *)dirent);
+	if (retval)
+		return 0;
+	return ext2fs_le32_to_cpu(t->det_checksum) == calculated;
+}
+
+static errcode_t ext2fs_dirent_csum_set(ext2_filsys fs, ext2_ino_t inum,
+					struct ext2_dir_entry *dirent)
+{
+	errcode_t retval;
+	__u32 crc;
+	struct ext2_dir_entry_tail *t;
+
+	retval = __get_dirent_tail(fs, dirent, &t, 1);
+	if (retval)
+		return retval;
+
+	/* swapfs.c functions don't change the checksum endianness */
+	retval = ext2fs_dirent_csum(fs, inum, dirent, &crc,
+				    (void *)t - (void *)dirent);
+	if (retval)
+		return retval;
+	t->det_checksum = ext2fs_cpu_to_le32(crc);
+	return 0;
+}
+
 static errcode_t ext2fs_dx_csum(ext2_filsys fs, ext2_ino_t inum,
 				struct ext2_dir_entry *dirent,
 				__u32 *crc, int count_offset, int count,
@@ -179,6 +295,38 @@  static errcode_t ext2fs_dx_csum_set(ext2_filsys fs, ext2_ino_t inum,
 	return retval;
 }
 
+int ext2fs_dir_block_csum_verify(ext2_filsys fs, ext2_ino_t inum,
+				 struct ext2_dir_entry *dirent)
+{
+	if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+					EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+		return 1;
+
+	if (__get_dirent_tail(fs, dirent, NULL, 1) == 0)
+		return ext2fs_dirent_csum_verify(fs, inum, dirent);
+	if (__get_dx_countlimit(fs, dirent, NULL, NULL, 1) == 0)
+		return ext2fs_dx_csum_verify(fs, inum, dirent);
+
+	return 0;
+}
+
+errcode_t ext2fs_dir_block_csum_set(ext2_filsys fs, ext2_ino_t inum,
+				    struct ext2_dir_entry *dirent)
+{
+	if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+					EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+		return 0;
+
+	if (__get_dirent_tail(fs, dirent, NULL, 1) == 0)
+		return ext2fs_dirent_csum_set(fs, inum, dirent);
+	if (__get_dx_countlimit(fs, dirent, NULL, NULL, 1) == 0)
+		return ext2fs_dx_csum_set(fs, inum, dirent);
+
+	if (fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS)
+		return 0;
+	return EXT2_ET_DIR_NO_SPACE_FOR_CSUM;
+}
+
 #define EXT3_EXTENT_TAIL_OFFSET(hdr)	(sizeof(struct ext3_extent_header) + \
 	(sizeof(struct ext3_extent) * ext2fs_le16_to_cpu((hdr)->eh_max)))
 
diff --git a/lib/ext2fs/dir_iterate.c b/lib/ext2fs/dir_iterate.c
index 5125d19..c24015c 100644
--- a/lib/ext2fs/dir_iterate.c
+++ b/lib/ext2fs/dir_iterate.c
@@ -192,17 +192,23 @@  int ext2fs_process_dir_block(ext2_filsys fs,
 	unsigned int	rec_len, size;
 	int		entry;
 	struct ext2_dir_entry *dirent;
+	int		csum_size = 0;
 
 	if (blockcnt < 0)
 		return 0;
 
 	entry = blockcnt ? DIRENT_OTHER_FILE : DIRENT_DOT_FILE;
 
-	ctx->errcode = ext2fs_read_dir_block3(fs, *blocknr, ctx->buf, 0);
+	ctx->errcode = ext2fs_read_dir_block4(fs, *blocknr, ctx->buf, 0,
+					      ctx->dir);
 	if (ctx->errcode)
 		return BLOCK_ABORT;
 
-	while (offset < fs->blocksize) {
+	if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+					EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+		csum_size = sizeof(struct ext2_dir_entry_tail);
+
+	while (offset < (fs->blocksize - csum_size)) {
 		dirent = (struct ext2_dir_entry *) (ctx->buf + offset);
 		if (ext2fs_get_rec_len(fs, dirent, &rec_len))
 			return BLOCK_ABORT;
@@ -259,8 +265,8 @@  next:
 	}
 
 	if (changed) {
-		ctx->errcode = ext2fs_write_dir_block3(fs, *blocknr, ctx->buf,
-						       0);
+		ctx->errcode = ext2fs_write_dir_block4(fs, *blocknr, ctx->buf,
+						       0, ctx->dir);
 		if (ctx->errcode)
 			return BLOCK_ABORT;
 	}
diff --git a/lib/ext2fs/dirblock.c b/lib/ext2fs/dirblock.c
index cb3a104..54b2777 100644
--- a/lib/ext2fs/dirblock.c
+++ b/lib/ext2fs/dirblock.c
@@ -20,45 +20,36 @@ 
 #include "ext2_fs.h"
 #include "ext2fs.h"
 
-errcode_t ext2fs_read_dir_block3(ext2_filsys fs, blk64_t block,
-				 void *buf, int flags EXT2FS_ATTR((unused)))
+errcode_t ext2fs_read_dir_block4(ext2_filsys fs, blk64_t block,
+				 void *buf, int flags EXT2FS_ATTR((unused)),
+				 ext2_ino_t ino)
 {
 	errcode_t	retval;
-	char		*p, *end;
-	struct ext2_dir_entry *dirent;
-	unsigned int	name_len, rec_len;
-
+	int		corrupt = 0;
 
 	retval = io_channel_read_blk64(fs->io, block, 1, buf);
 	if (retval)
 		return retval;
 
-	p = (char *) buf;
-	end = (char *) buf + fs->blocksize;
-	while (p < end-8) {
-		dirent = (struct ext2_dir_entry *) p;
-#ifdef WORDS_BIGENDIAN
-		dirent->inode = ext2fs_swab32(dirent->inode);
-		dirent->rec_len = ext2fs_swab16(dirent->rec_len);
-		dirent->name_len = ext2fs_swab16(dirent->name_len);
-#endif
-		name_len = dirent->name_len;
+	if (!(fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS) &&
+	    !ext2fs_dir_block_csum_verify(fs, ino,
+					  (struct ext2_dir_entry *)buf))
+		corrupt = 1;
+
 #ifdef WORDS_BIGENDIAN
-		if (flags & EXT2_DIRBLOCK_V2_STRUCT)
-			dirent->name_len = ext2fs_swab16(dirent->name_len);
+	retval = ext2fs_dirent_swab_in(fs, buf, flags);
 #endif
-		if ((retval = ext2fs_get_rec_len(fs, dirent, &rec_len)) != 0)
-			return retval;
-		if ((rec_len < 8) || (rec_len % 4)) {
-			rec_len = 8;
-			retval = EXT2_ET_DIR_CORRUPTED;
-		} else if (((name_len & 0xFF) + 8) > rec_len)
-			retval = EXT2_ET_DIR_CORRUPTED;
-		p += rec_len;
-	}
+	if (!retval && corrupt)
+		retval = EXT2_ET_DIR_CSUM_INVALID;
 	return retval;
 }
 
+errcode_t ext2fs_read_dir_block3(ext2_filsys fs, blk64_t block,
+				 void *buf, int flags EXT2FS_ATTR((unused)))
+{
+	return ext2fs_read_dir_block4(fs, block, buf, flags, 0);
+}
+
 errcode_t ext2fs_read_dir_block2(ext2_filsys fs, blk_t block,
 				 void *buf, int flags EXT2FS_ATTR((unused)))
 {
@@ -72,45 +63,40 @@  errcode_t ext2fs_read_dir_block(ext2_filsys fs, blk_t block,
 }
 
 
-errcode_t ext2fs_write_dir_block3(ext2_filsys fs, blk64_t block,
-				  void *inbuf, int flags EXT2FS_ATTR((unused)))
+errcode_t ext2fs_write_dir_block4(ext2_filsys fs, blk64_t block,
+				  void *inbuf, int flags EXT2FS_ATTR((unused)),
+				  ext2_ino_t ino)
 {
-#ifdef WORDS_BIGENDIAN
 	errcode_t	retval;
-	char		*p, *end;
-	char		*buf = 0;
-	unsigned int	rec_len;
-	struct ext2_dir_entry *dirent;
+	char		*buf = inbuf;
 
+#ifdef WORDS_BIGENDIAN
 	retval = ext2fs_get_mem(fs->blocksize, &buf);
 	if (retval)
 		return retval;
 	memcpy(buf, inbuf, fs->blocksize);
-	p = buf;
-	end = buf + fs->blocksize;
-	while (p < end) {
-		dirent = (struct ext2_dir_entry *) p;
-		if ((retval = ext2fs_get_rec_len(fs, dirent, &rec_len)) != 0)
-			return retval;
-		if ((rec_len < 8) ||
-		    (rec_len % 4)) {
-			ext2fs_free_mem(&buf);
-			return (EXT2_ET_DIR_CORRUPTED);
-		}
-		p += rec_len;
-		dirent->inode = ext2fs_swab32(dirent->inode);
-		dirent->rec_len = ext2fs_swab16(dirent->rec_len);
-		dirent->name_len = ext2fs_swab16(dirent->name_len);
-
-		if (flags & EXT2_DIRBLOCK_V2_STRUCT)
-			dirent->name_len = ext2fs_swab16(dirent->name_len);
-	}
+	retval = ext2fs_dirent_swab_out(fs, buf, flags);
+	if (retval)
+		return retval;
+#endif
+	retval = ext2fs_dir_block_csum_set(fs, ino,
+					   (struct ext2_dir_entry *)buf);
+	if (retval)
+		goto out;
+
 	retval = io_channel_write_blk64(fs->io, block, 1, buf);
+
+out:
+#ifdef WORDS_BIGENDIAN
 	ext2fs_free_mem(&buf);
-	return retval;
-#else
-	return io_channel_write_blk64(fs->io, block, 1, (char *) inbuf);
 #endif
+	return retval;
+}
+
+errcode_t ext2fs_write_dir_block3(ext2_filsys fs, blk64_t block,
+				  void *inbuf, int flags EXT2FS_ATTR((unused)))
+{
+	return ext2fs_write_dir_block4(fs, block, inbuf, flags, 0);
 }
 
 errcode_t ext2fs_write_dir_block2(ext2_filsys fs, blk_t block,
diff --git a/lib/ext2fs/expanddir.c b/lib/ext2fs/expanddir.c
index 41c4088..22558d6 100644
--- a/lib/ext2fs/expanddir.c
+++ b/lib/ext2fs/expanddir.c
@@ -24,6 +24,7 @@  struct expand_dir_struct {
 	int		newblocks;
 	blk64_t		goal;
 	errcode_t	err;
+	ext2_ino_t	dir;
 };
 
 static int expand_dir_proc(ext2_filsys	fs,
@@ -62,7 +63,8 @@  static int expand_dir_proc(ext2_filsys	fs,
 			return BLOCK_ABORT;
 		}
 		es->done = 1;
-		retval = ext2fs_write_dir_block(fs, new_blk, block);
+		retval = ext2fs_write_dir_block4(fs, new_blk, block, 0,
+						 es->dir);
 	} else {
 		retval = ext2fs_get_mem(fs->blocksize, &block);
 		if (retval) {
@@ -110,6 +112,7 @@  errcode_t ext2fs_expand_dir(ext2_filsys fs, ext2_ino_t dir)
 	es.err = 0;
 	es.goal = 0;
 	es.newblocks = 0;
+	es.dir = dir;
 
 	retval = ext2fs_block_iterate3(fs, dir, BLOCK_FLAG_APPEND,
 				       0, expand_dir_proc, &es);
diff --git a/lib/ext2fs/ext2_err.et.in b/lib/ext2fs/ext2_err.et.in
index 1e51384..ad0cb7a 100644
--- a/lib/ext2fs/ext2_err.et.in
+++ b/lib/ext2fs/ext2_err.et.in
@@ -455,4 +455,7 @@  ec	EXT2_ET_EXTENT_CSUM_INVALID,
 ec	EXT2_ET_DIR_NO_SPACE_FOR_CSUM,
 	"Directory block does not have space for checksum"
 
+ec	EXT2_ET_DIR_CSUM_INVALID,
+	"Directory block checksum does not match directory block"
+
 	end
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index e224e74..b75c712 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -952,6 +952,18 @@  extern __u32 ext2fs_crc32c_be(__u32 crc, unsigned char const *p, size_t len);
 extern __u32 ext2fs_crc32c_le(__u32 crc, unsigned char const *p, size_t len);
 
 /* csum.c */
+#define EXT2_DIRENT_TAIL(block, blocksize) \
+	((struct ext2_dir_entry_tail *)(((void *)(block)) + \
+	(blocksize) - sizeof(struct ext2_dir_entry_tail)))
+
+extern void ext2fs_initialize_dirent_tail(ext2_filsys fs,
+					  struct ext2_dir_entry_tail *t);
+extern int ext2fs_dirent_has_tail(ext2_filsys fs,
+				  struct ext2_dir_entry *dirent);
+extern int ext2fs_dir_block_csum_verify(ext2_filsys fs, ext2_ino_t inum,
+					struct ext2_dir_entry *dirent);
+extern errcode_t ext2fs_dir_block_csum_set(ext2_filsys fs, ext2_ino_t inum,
+					   struct ext2_dir_entry *dirent);
 extern errcode_t ext2fs_get_dx_countlimit(ext2_filsys fs,
 					  struct ext2_dir_entry *dirent,
 					  struct ext2_dx_countlimit **cc,
@@ -1035,12 +1047,16 @@  extern errcode_t ext2fs_read_dir_block2(ext2_filsys fs, blk_t block,
 					void *buf, int flags);
 extern errcode_t ext2fs_read_dir_block3(ext2_filsys fs, blk64_t block,
 					void *buf, int flags);
+extern errcode_t ext2fs_read_dir_block4(ext2_filsys fs, blk64_t block,
+					void *buf, int flags, ext2_ino_t ino);
 extern errcode_t ext2fs_write_dir_block(ext2_filsys fs, blk_t block,
 					void *buf);
 extern errcode_t ext2fs_write_dir_block2(ext2_filsys fs, blk_t block,
 					 void *buf, int flags);
 extern errcode_t ext2fs_write_dir_block3(ext2_filsys fs, blk64_t block,
 					 void *buf, int flags);
+extern errcode_t ext2fs_write_dir_block4(ext2_filsys fs, blk64_t block,
+					 void *buf, int flags, ext2_ino_t ino);
 
 /* dirhash.c */
 extern errcode_t ext2fs_dirhash(int version, const char *name, int len,
@@ -1434,6 +1450,8 @@  extern errcode_t ext2fs_read_bb_FILE(ext2_filsys fs, FILE *f,
 extern errcode_t ext2fs_create_resize_inode(ext2_filsys fs);
 
 /* swapfs.c */
+extern errcode_t ext2fs_dirent_swab_in(ext2_filsys fs, char *buf, int flags);
+extern errcode_t ext2fs_dirent_swab_out(ext2_filsys fs, char *buf, int flags);
 extern void ext2fs_swap_ext_attr(char *to, char *from, int bufsize,
 				 int has_header);
 extern void ext2fs_swap_ext_attr_header(struct ext2_ext_attr_header *to_header,
diff --git a/lib/ext2fs/link.c b/lib/ext2fs/link.c
index 2d03b57..2dec5dc 100644
--- a/lib/ext2fs/link.c
+++ b/lib/ext2fs/link.c
@@ -41,6 +41,7 @@  static int link_proc(struct ext2_dir_entry *dirent,
 	struct ext2_dir_entry *next;
 	unsigned int rec_len, min_rec_len, curr_rec_len;
 	int ret = 0;
+	int csum_size = 0;
 
 	rec_len = EXT2_DIR_REC_LEN(ls->namelen);
 
@@ -48,12 +49,15 @@  static int link_proc(struct ext2_dir_entry *dirent,
 	if (ls->err)
 		return DIRENT_ABORT;
 
+	if (EXT2_HAS_RO_COMPAT_FEATURE(ls->fs->super,
+				       EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+		csum_size = sizeof(struct ext2_dir_entry_tail);
 	/*
 	 * See if the following directory entry (if any) is unused;
 	 * if so, absorb it into this one.
 	 */
 	next = (struct ext2_dir_entry *) (buf + offset + curr_rec_len);
-	if ((offset + (int) curr_rec_len < blocksize - 8) &&
+	if ((offset + (int) curr_rec_len < blocksize - (8 + csum_size)) &&
 	    (next->inode == 0) &&
 	    (offset + (int) curr_rec_len + (int) next->rec_len <= blocksize)) {
 		curr_rec_len += next->rec_len;
diff --git a/lib/ext2fs/mkdir.c b/lib/ext2fs/mkdir.c
index 861ddab..4a85439 100644
--- a/lib/ext2fs/mkdir.c
+++ b/lib/ext2fs/mkdir.c
@@ -100,7 +100,7 @@  errcode_t ext2fs_mkdir(ext2_filsys fs, ext2_ino_t parent, ext2_ino_t inum,
 	retval = ext2fs_write_new_inode(fs, ino, &inode);
 	if (retval)
 		goto cleanup;
-	retval = ext2fs_write_dir_block(fs, blk, block);
+	retval = ext2fs_write_dir_block4(fs, blk, block, 0, ino);
 	if (retval)
 		goto cleanup;
 
diff --git a/lib/ext2fs/newdir.c b/lib/ext2fs/newdir.c
index b0a1e47..2cd541d 100644
--- a/lib/ext2fs/newdir.c
+++ b/lib/ext2fs/newdir.c
@@ -34,6 +34,8 @@  errcode_t ext2fs_new_dir_block(ext2_filsys fs, ext2_ino_t dir_ino,
 	char			*buf;
 	int			rec_len;
 	int			filetype = 0;
+	struct ext2_dir_entry_tail	*t;
+	int			csum_size = 0;
 
 	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 
@@ -43,7 +45,11 @@  errcode_t ext2fs_new_dir_block(ext2_filsys fs, ext2_ino_t dir_ino,
 	memset(buf, 0, fs->blocksize);
 	dir = (struct ext2_dir_entry *) buf;
 
-	retval = ext2fs_set_rec_len(fs, fs->blocksize, dir);
+	if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+				       EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+		csum_size = sizeof(struct ext2_dir_entry_tail);
+
+	retval = ext2fs_set_rec_len(fs, fs->blocksize - csum_size, dir);
 	if (retval)
 		return retval;
 
@@ -57,7 +63,7 @@  errcode_t ext2fs_new_dir_block(ext2_filsys fs, ext2_ino_t dir_ino,
 		dir->inode = dir_ino;
 		dir->name_len = 1 | filetype;
 		dir->name[0] = '.';
-		rec_len = fs->blocksize - EXT2_DIR_REC_LEN(1);
+		rec_len = (fs->blocksize - csum_size) - EXT2_DIR_REC_LEN(1);
 		dir->rec_len = EXT2_DIR_REC_LEN(1);
 
 		/*
@@ -73,6 +79,11 @@  errcode_t ext2fs_new_dir_block(ext2_filsys fs, ext2_ino_t dir_ino,
 		dir->name[1] = '.';
 
 	}
+
+	if (csum_size) {
+		t = EXT2_DIRENT_TAIL(buf, fs->blocksize);
+		ext2fs_initialize_dirent_tail(fs, t);
+	}
 	*block = buf;
 	return 0;
 }
diff --git a/lib/ext2fs/swapfs.c b/lib/ext2fs/swapfs.c
index 7c99373..69916e5 100644
--- a/lib/ext2fs/swapfs.c
+++ b/lib/ext2fs/swapfs.c
@@ -350,4 +350,66 @@  void ext2fs_swap_mmp(struct mmp_struct *mmp)
 	mmp->mmp_check_interval = ext2fs_swab16(mmp->mmp_check_interval);
 }
 
+errcode_t ext2fs_dirent_swab_in(ext2_filsys fs, char *buf, int flags)
+{
+	errcode_t	retval;
+	char		*p, *end;
+	struct ext2_dir_entry *dirent;
+	unsigned int	name_len, rec_len;
+
+	p = (char *) buf;
+	end = (char *) buf + fs->blocksize;
+	while (p < end-8) {
+		dirent = (struct ext2_dir_entry *) p;
+		dirent->inode = ext2fs_swab32(dirent->inode);
+		dirent->rec_len = ext2fs_swab16(dirent->rec_len);
+		dirent->name_len = ext2fs_swab16(dirent->name_len);
+		name_len = dirent->name_len;
+		if (flags & EXT2_DIRBLOCK_V2_STRUCT)
+			dirent->name_len = ext2fs_swab16(dirent->name_len);
+		retval = ext2fs_get_rec_len(fs, dirent, &rec_len);
+		if (retval)
+			return retval;
+		if ((rec_len < 8) || (rec_len % 4)) {
+			rec_len = 8;
+			retval = EXT2_ET_DIR_CORRUPTED;
+		} else if (((name_len & 0xFF) + 8) > rec_len)
+			retval = EXT2_ET_DIR_CORRUPTED;
+		p += rec_len;
+	}
+
+	return 0;
+}
+
+errcode_t ext2fs_dirent_swab_out(ext2_filsys fs, char *buf, int flags)
+{
+	errcode_t	retval;
+	char		*p, *end;
+	unsigned int	rec_len;
+	struct ext2_dir_entry *dirent;
+
+	p = buf;
+	end = buf + fs->blocksize;
+	while (p < end) {
+		dirent = (struct ext2_dir_entry *) p;
+		retval = ext2fs_get_rec_len(fs, dirent, &rec_len);
+		if (retval)
+			return retval;
+		if ((rec_len < 8) ||
+		    (rec_len % 4)) {
+			ext2fs_free_mem(&buf);
+			return EXT2_ET_DIR_CORRUPTED;
+		}
+		p += rec_len;
+		dirent->inode = ext2fs_swab32(dirent->inode);
+		dirent->rec_len = ext2fs_swab16(dirent->rec_len);
+		dirent->name_len = ext2fs_swab16(dirent->name_len);
+
+		if (flags & EXT2_DIRBLOCK_V2_STRUCT)
+			dirent->name_len = ext2fs_swab16(dirent->name_len);
+	}
+
+	return 0;
+}
+
 #endif