libext2fs: add space for checksum when unconverting a hashed directory block

The ext2fs_link function has the unfortunate habit of converting
hashed directories into unhashed directories.  It doesn't notice that
it's slicing and dicing directory entries from a former dx_{root,node}
block, and therefore doesn't write a protective dirent into the end of
the block to store the checksum.  Teach it to do this.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/lib/ext2fs/link.c b/lib/ext2fs/link.c
index e3ff450..2a44575 100644 (file)
--- a/lib/ext2fs/link.c
+++ b/lib/ext2fs/link.c
@@ -42,6 +42,7 @@ static int link_proc(struct ext2_dir_entry *dirent,
        unsigned int rec_len, min_rec_len, curr_rec_len;
        int ret = 0;
        int csum_size = 0;
+       struct ext2_dir_entry_tail *t;
 
        if (ls->done)
                return 0;
@@ -71,6 +72,40 @@ static int link_proc(struct ext2_dir_entry *dirent,
        }
 
        /*
+        * Since ext2fs_link blows away htree data, we need to be
+        * careful -- if metadata_csum is enabled and we're passed in
+        * a dirent that contains htree data, we need to create the
+        * fake entry at the end of the block that hides the checksum.
+        */
+
+       /* De-convert a dx_node block */
+       if (csum_size &&
+           curr_rec_len == ls->fs->blocksize &&
+           !dirent->inode) {
+               curr_rec_len -= csum_size;
+               ls->err = ext2fs_set_rec_len(ls->fs, curr_rec_len, dirent);
+               if (ls->err)
+                       return DIRENT_ABORT;
+               t = EXT2_DIRENT_TAIL(buf, ls->fs->blocksize);
+               ext2fs_initialize_dirent_tail(ls->fs, t);
+               ret = DIRENT_CHANGED;
+       }
+
+       /* De-convert a dx_root block */
+       if (csum_size &&
+           curr_rec_len == ls->fs->blocksize - EXT2_DIR_REC_LEN(1) &&
+           offset == EXT2_DIR_REC_LEN(1) &&
+           dirent->name[0] == '.' && dirent->name[1] == '.') {
+               curr_rec_len -= csum_size;
+               ls->err = ext2fs_set_rec_len(ls->fs, curr_rec_len, dirent);
+               if (ls->err)
+                       return DIRENT_ABORT;
+               t = EXT2_DIRENT_TAIL(buf, ls->fs->blocksize);
+               ext2fs_initialize_dirent_tail(ls->fs, t);
+               ret = DIRENT_CHANGED;
+       }
+
+       /*
         * If the directory entry is used, see if we can split the
         * directory entry to make room for the new name.  If so,
         * truncate it and return.
@@ -152,6 +187,11 @@ errcode_t ext2fs_link(ext2_filsys fs, ext2_ino_t dir, const char *name,
        if ((retval = ext2fs_read_inode(fs, dir, &inode)) != 0)
                return retval;
 
+       /*
+        * If this function changes to preserve the htree, remove the
+        * two hunks in link_proc that shove checksum tails into the
+        * former dx_root/dx_node blocks.
+        */
        if (inode.i_flags & EXT2_INDEX_FL) {
                inode.i_flags &= ~EXT2_INDEX_FL;
                if ((retval = ext2fs_write_inode(fs, dir, &inode)) != 0)