• Jan Kara's avatar
    ext4: check journal inode extents more carefully · ce9f24cc
    Jan Kara authored
    Currently, system zones just track ranges of block, that are "important"
    fs metadata (bitmaps, group descriptors, journal blocks, etc.). This
    however complicates how extent tree (or indirect blocks) can be checked
    for inodes that actually track such metadata - currently the journal
    inode but arguably we should be treating quota files or resize inode
    similarly. We cannot run __ext4_ext_check() on such metadata inodes when
    loading their extents as that would immediately trigger the validity
    checks and so we just hack around that and special-case the journal
    inode. This however leads to a situation that a journal inode which has
    extent tree of depth at least one can have invalid extent tree that gets
    unnoticed until ext4_cache_extents() crashes.
    
    To overcome this limitation, track inode number each system zone belongs
    to (0 is used for zones not belonging to any inode). We can then verify
    inode number matches the expected one when verifying extent tree and
    thus avoid the false errors. With this there's no need to to
    special-case journal inode during extent tree checking anymore so remove
    it.
    
    Fixes: 0a944e8a ("ext4: don't perform block validity checks on the journal inode")
    Reported-by: default avatarWolfgang Frisch <wolfgang.frisch@suse.com>
    Reviewed-by: default avatarLukas Czerner <lczerner@redhat.com>
    Signed-off-by: default avatarJan Kara <jack@suse.cz>
    Link: https://lore.kernel.org/r/20200728130437.7804-4-jack@suse.czSigned-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
    ce9f24cc
extents.c 157 KB