Following process may lead to fs corruption:
1. ext4_create(dir/foo)
ext4_add_nondir
ext4_add_entry
ext4_dx_add_entry
a. add_dirent_to_buf
ext4_mark_inode_dirty
ext4_handle_dirty_metadata // dir inode bh is recorded into journal
b. ext4_append // dx_get_count(entries) == dx_get_limit(entries)
ext4_bread(EXT4_GET_BLOCKS_CREATE)
ext4_getblk
ext4_map_blocks
ext4_ext_map_blocks
ext4_mb_new_blocks
dquot_alloc_block
dquot_alloc_space_nodirty
inode_add_bytes // update dir's i_blocks
ext4_ext_insert_extent
ext4_ext_dirty // record extent bh into journal
ext4_handle_dirty_metadata(bh)
// record new block into journal
inode->i_size += inode->i_sb->s_blocksize // new size(in mem)
c. ext4_handle_dirty_dx_node(bh2)
// record dir's new block(dx_node) into journal
d. ext4_handle_dirty_dx_node((frame - 1)->bh)
e. ext4_handle_dirty_dx_node(frame->bh)
f. do_split // ret err!
g. add_dirent_to_buf
ext4_mark_inode_dirty(dir) // update raw_inode on disk(skipped)
2. fsck -a /dev/sdb
drop last block(dx_node) which beyonds dir's i_size.
/dev/sdb: recovering journal
/dev/sdb contains a file system with errors, check forced.
/dev/sdb: Inode 12, end of extent exceeds allowed value
(logical block 128, physical block 3938, len 1)
3. fsck -fn /dev/sdb
dx_node->entry[i].blk > dir->i_size
Pass 2: Checking directory structure
Problem in HTREE directory inode 12 (/dir): bad block number 128.
Clear HTree index? no
Problem in HTREE directory inode 12: block #3 has invalid depth (2)
Problem in HTREE directory inode 12: block #3 has bad max hash
Problem in HTREE directory inode 12: block #3 not referenced
Just like make_indexed_dir() does, update dir inode if error occurs.
Fetch a reproducer in [Link].
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216466
CC: stable@xxxxxxxxxxxxxxx
Signed-off-by: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>
---
fs/ext4/namei.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 3a31b662f661..f04871fa4ead 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2617,6 +2617,13 @@ static int ext4_dx_add_entry(handle_t *handle, struct ext4_filename *fname,
*/
if (restart && err == 0)
goto again;
+ /*
+ * Even if the dx_add_entry failed, we have to properly write
+ * out all the changes we did so far. Otherwise we can end up
+ * with corrupted filesystem.
+ */
+ if (err)
+ ext4_mark_inode_dirty(handle, dir);
return err;
}
--
2.31.1
