[PATCH 12/37] e2fsck: insert a missing dirent tail for checksums if possible

Darrick J. Wong
2014-05-01T23:13:45Z

If e2fsck is writing a block of directory entries to disk, it should
adjust the dirents to add the dirent tail if one is missing. It's not
a big deal if there's no space to do this since rehash (pass 3A) will
reconstruct directories for us. However, we may as well avoid
unnecessary work.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
e2fsck/pass2.c | 40 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 40 insertions(+)

diff --git a/e2fsck/pass2.c b/e2fsck/pass2.c
index 5488c73..95f51b7 100644
--- a/e2fsck/pass2.c
+++ b/e2fsck/pass2.c
@@ -739,6 +739,41 @@ static int is_last_entry(ext2_filsys fs, int inline_data_size,
return (offset < fs->blocksize - csum_size);
}

+static errcode_t insert_dirent_tail(ext2_filsys fs, void *dirbuf)
+{
+ struct ext2_dir_entry *d;
+ void *top;
+ struct ext2_dir_entry_tail *t;
+ unsigned int rec_len;
+
+ d = dirbuf;
+ top = EXT2_DIRENT_TAIL(dirbuf, fs->blocksize);
+
+ rec_len = d->rec_len;
+ while (rec_len && !(rec_len & 0x3)) {
+ d = (struct ext2_dir_entry *)(((char *)d) + rec_len);
+ if (((void *)d) + d->rec_len >= top)
+ break;
+ rec_len = d->rec_len;
+ }
+
+ if (d != top) {
+ size_t min_size = EXT2_DIR_REC_LEN(
+ ext2fs_dirent_name_len(dirbuf));
+ if (min_size > d->rec_len - sizeof(struct ext2_dir_entry_tail))
+ return EXT2_ET_DIR_NO_SPACE_FOR_CSUM;
+ d->rec_len -= sizeof(struct ext2_dir_entry_tail);
+ }
+
+ t = (struct ext2_dir_entry_tail *)top;
+ if (t->det_reserved_zero1 ||
+ t->det_rec_len != sizeof(struct ext2_dir_entry_tail) ||
+ t->det_reserved_name_len != EXT2_DIR_NAME_LEN_CSUM)
+ ext2fs_initialize_dirent_tail(fs, t);
+
+ return 0;
+}
+
static int check_dir_block(ext2_filsys fs,
struct ext2_db_entry2 *db,
void *priv_data)
@@ -1275,8 +1310,13 @@ skip_checksum:
if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
EXT4_FEATURE_RO_COMPAT_METADATA_CSUM) &&
is_leaf &&
+ !inline_data_size &&
!ext2fs_dirent_has_tail(fs, (struct ext2_dir_entry *)buf))
+ {
+ if (insert_dirent_tail(fs, buf) == 0)
+ goto write_and_fix;
e2fsck_rehash_dir_later(ctx, ino);
+ }

write_and_fix:
if (e2fsck_dir_will_be_rehashed(ctx, ino))