On Tue, Feb 18, 2014 at 05:52:21PM -0600, Eric Sandeen wrote: > When xfs_readsb() does the very first read of the superblock, > it makes a guess at the length of the buffer, based on the > sector size of the underlying storage. This may or may > not match the filesystem sector size in sb_sectsize, so > we can't i.e. do a CRC check on it; it might be too short. > > In fact, mounting a filesystem with sb_sectsize larger > than the device sector size will cause a mount failure > if CRCs are enabled, because we are checksumming a length > which exceeds the buffer passed to it. > > So always read twice; the first time we read with NULL > buffer ops to skip verification; then set the proper > read length, hook up the proper verifier, and give it > another go. > > Once we are sure that we've got the right buffer length, > we can also use bp->b_length in the xfs_sb_read_verify, > rather than the less-trusted on-disk sectorsize for > secondary superblocks. Before this we ran the risk of > passing junk to the crc32c routines, which didn't always > handle extreme values. > > Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx> Looks good. Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx> -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
