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    Subject[34-longterm 131/247] md: correctly handle probe of an 'mdp' device.
    Date
    From: NeilBrown <neilb@suse.de>

    -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.
    -------------------

    commit 8f5f02c460b7ca74ce55ce126ce0c1e58a3f923d upstream.

    'mdp' devices are md devices with preallocated device numbers
    for partitions. As such it is possible to mknod and open a partition
    before opening the whole device.

    this causes md_probe() to be called with a device number of a
    partition, which in-turn calls mddev_find with such a number.

    However mddev_find expects the number of a 'whole device' and
    does the wrong thing with partition numbers.

    So add code to mddev_find to remove the 'partition' part of
    a device number and just work with the 'whole device'.

    This patch addresses https://bugzilla.kernel.org/show_bug.cgi?id=28652

    Reported-by: hkmaly@bigfoot.com
    Signed-off-by: NeilBrown <neilb@suse.de>
    Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
    ---
    drivers/md/md.c | 3 +++
    1 files changed, 3 insertions(+), 0 deletions(-)

    diff --git a/drivers/md/md.c b/drivers/md/md.c
    index 7db9ceb..f468ec6 100644
    --- a/drivers/md/md.c
    +++ b/drivers/md/md.c
    @@ -410,6 +410,9 @@ static mddev_t * mddev_find(dev_t unit)
    {
    mddev_t *mddev, *new = NULL;

    + if (unit && MAJOR(unit) != MD_MAJOR)
    + unit &= ~((1<<MdpMinorShift)-1);
    +
    retry:
    spin_lock(&all_mddevs_lock);

    --
    1.7.4.4


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