On Sun, 11 Sep 2022 12:52:04 +0800, Zhihao Cheng wrote:
> 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
>
> [...]
Applied, thanks!
[1/1] ext4: Fix dir corruption when ext4_dx_add_entry() fails
commit: 7a3584fd605e6a72036c5759a6e9ed2c46d14899
Best regards,
--
Theodore Ts'o <tytso@xxxxxxx>
