• Konstantin Khlebnikov's avatar
    md/raid5: limit request size according to implementation limits · 1c8841c9
    Konstantin Khlebnikov authored
    commit e8d7c332 upstream.
    
    Current implementation employ 16bit counter of active stripes in lower
    bits of bio->bi_phys_segments. If request is big enough to overflow
    this counter bio will be completed and freed too early.
    
    Fortunately this not happens in default configuration because several
    other limits prevent that: stripe_cache_size * nr_disks effectively
    limits count of active stripes. And small max_sectors_kb at lower
    disks prevent that during normal read/write operations.
    
    Overflow easily happens in discard if it's enabled by module parameter
    "devices_handle_discard_safely" and stripe_cache_size is set big enough.
    
    This patch limits requests size with 256Mb - 8Kb to prevent overflows.
    Signed-off-by: default avatarKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
    Cc: Shaohua Li <shli@kernel.org>
    Cc: Neil Brown <neilb@suse.com>
    Signed-off-by: default avatarShaohua Li <shli@fb.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    1c8841c9
raid5.c 223 KB