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    xfs: growfs: use uncached buffers for new headers · fd23683c
    Dave Chinner 提交于
    When writing the new AG headers to disk, we can't attach write
    verifiers because they have a dependency on the struct xfs-perag
    being attached to the buffer to be fully initialised and growfs
    can't fully initialise them until later in the process.
    
    The simplest way to avoid this problem is to use uncached buffers
    for writing the new headers. These buffers don't have the xfs-perag
    attached to them, so it's simple to detect in the write verifier and
    be able to skip the checks that need the xfs-perag.
    
    This enables us to attach the appropriate buffer ops to the buffer
    and hence calculate CRCs on the way to disk. IT also means that the
    buffer is torn down immediately, and so the first access to the AG
    headers will re-read the header from disk and perform full
    verification of the buffer. This way we also can catch corruptions
    due to problems that went undetected in growfs.
    Signed-off-by: NDave Chinner <dchinner@redhat.com>
    Reviewed-by Rich Johnston <rjohnston@sgi.com>
    Signed-off-by: NBen Myers <bpm@sgi.com>
    fd23683c
xfs_fsops.c 20.6 KB