• NeilBrown's avatar
    md/raid1: avoid reading from known bad blocks. · d2eb35ac
    NeilBrown authored
    Now that we have a bad block list, we should not read from those
    blocks.
    There are several main parts to this:
      1/ read_balance needs to check for bad blocks, and return not only
         the chosen device, but also how many good blocks are available
         there.
      2/ fix_read_error needs to avoid trying to read from bad blocks.
      3/ read submission must be ready to issue multiple reads to
         different devices as different bad blocks on different devices
         could mean that a single large read cannot be served by any one
         device, but can still be served by the array.
         This requires keeping count of the number of outstanding requests
         per bio.  This count is stored in 'bi_phys_segments'
      4/ retrying a read needs to also be ready to submit a smaller read
         and queue another request for the rest.
    
    This does not yet handle bad blocks when reading to perform resync,
    recovery, or check.
    
    'md_trim_bio' will also be used for RAID10, so put it in md.c and
    export it.
    Signed-off-by: default avatarNeilBrown <neilb@suse.de>
    d2eb35ac
raid1.c 62.6 KB