e2fsck: insert a missing dirent tail for checksums if possible

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>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/e2fsck/pass2.c b/e2fsck/pass2.c
index ac93c56..d0e334f 100644 (file)
--- 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 +1310,12 @@ skip_checksum:
                if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
                                EXT4_FEATURE_RO_COMPAT_METADATA_CSUM) &&
                    is_leaf &&
-                   !ext2fs_dirent_has_tail(fs, (struct ext2_dir_entry *)buf))
+                   !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))