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    ext4: don't update sb journal_devnum when RO dev · c41303ce
    Maciej Żenczykowski 提交于
    An ext4 filesystem on a read-only device, with an external journal
    which is at a different device number then recorded in the superblock
    will fail to honor the read-only setting of the device and trigger
    a superblock update (write).
    
    For example:
      - ext4 on a software raid which is in read-only mode
      - external journal on a read-write device which has changed device num
      - attempt to mount with -o journal_dev=<new_number>
      - hits BUG_ON(mddev->ro = 1) in md.c
    
    Cc: Theodore Ts'o <tytso@mit.edu>
    Signed-off-by: NMaciej Żenczykowski <zenczykowski@gmail.com>
    Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
    c41303ce
super.c 132.8 KB