• Dmitry Mishin's avatar
    [PATCH] ext3: errors behaviour fix · 2245d7c2
    Dmitry Mishin authored
    Current error behaviour for ext2 and ext3 filesystems does not fully
    correspond to the documentation and should be fixed.
    
    According to man 8 mount, ext2 and ext3 file systems allow to set one of 3
    different on-errors behaviours:
    
      ---- start of quote man 8 mount ----
    
      errors=continue / errors=remount-ro / errors=panic
    
        Define the behaviour when an error is encountered.  (Either ignore
        errors and just mark the file system erroneous and continue, or remount
        the file system read-only, or panic and halt the system.) The default is
        set in the filesystem superblock, and can be changed using tune2fs(8).
    
      ---- end of quote ----
    
    However EXT3_ERRORS_CONTINUE is not read from the superblock, and thus
    ERRORS_CONT is not saved on the sbi->s_mount_opt.  It leads to the incorrect
    handle of errors on ext3.
    
    Then we've checked corresponding code in ext2 and discovered that it is buggy
    as well:
    
    - EXT2_ERRORS_CONTINUE is not read from the superblock (the same);
    
    - parse_option() does not clean the alternative values and thus something
      like (ERRORS_CONT|ERRORS_RO) can be set;
    
    - if options are omitted, parse_option() does not set any of these options.
    
    Therefore it is possible to set any combination of these options on the ext2:
    
    - none of them may be set: EXT2_ERRORS_CONTINUE on superblock / empty mount
      options;
    
    - any of them may be set using mount options;
    
    - 2 any options may be set: by using EXT2_ERRORS_RO/EXT2_ERRORS_PANIC on the
      superblock and other value in mount options;
    
    - and finally all three options may be set by adding third option in remount.
    
    Currently ext2 uses these values only in ext2_error() and it is not leading to
    any noticeable troubles.  However somebody may be discouraged when he will try
    to workaround EXT2_ERRORS_PANIC on the superblock by using errors=continue in
    mount options.
    
    This patch:
    
    EXT3_ERRORS_CONTINUE should be taken from the superblock as default value for
    error behaviour.
    Signed-off-by: default avatarDmitry Mishin <dim@openvz.org>
    Acked-by: default avatarVasily Averin <vvs@sw.ru>
    Acked-by: default avatarKirill Korotaev <dev@openvz.org>
    Cc: <linux-ext4@vger.kernel.org>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    2245d7c2
super.c 75.8 KB