[lkml]   [2003]   [Aug]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: data corruption using raid0+lvm2+jfs with 2.6.0-test3
    On Tuesday August 12, wrote:
    > Tupshin Harper <> wrote:
    > >
    > > raid0_make_request bug: can't convert block across chunks or bigger than
    > > 8k 12436792 8
    > There is a fix for this at
    > Results of testing are always appreciated...

    I don't think this will help. It is a different problem.

    As far as I can tell, the problem is that dm doesn't honour the
    merge_bvec_fn of the underlying device (neither does md for that
    I think it does honour the max_sectors restriction, so it will only
    allow a request as big as one chunk, but it will allow such a requests
    to span a chunk boundary.

    Probably the simplest solution to this is to put in calls to
    bio_split, which will need to be strengthed to handle multi-page bios.

    The policy would be:
    "a client of a block device *should* honour the various bio size
    restrictions, and may suffer performance loss if it doesn't;
    a block device driver *must* handle any bio it is passed, and may
    call bio_split to help out".

    A better solution, which is too much for 2.6.0, is to have a cleaner
    interface wherein the client of the block device uses a two-stage
    process to submit requests.
    Firstly it says:
    I want to do IO at this location, what is the max number of sectors
    Then it adds pages to the bio upto that limit.
    Finally it say
    OK, here is the request.

    The first and final stages have to be properly paired so that a
    device knows if there are any pending requests and can hold-off any
    device reconfiguration until all pending requests have completed.

    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2005-03-22 13:47    [W:0.032 / U:8.620 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site