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    Subject[032/102] IB/srp: Avoid duplicate devices from LUN scan
    3.0-stable review patch.  If anyone has any objections, please let us know.

    ------------------

    From: Bart Van Assche <bvanassche@acm.org>

    commit fd1b6c4a693c9cac59375ffb36ffe5d7c079037c upstream.

    SCSI scanning of a channel:id:lun triplet in Linux works as follows
    (function scsi_scan_target() in drivers/scsi/scsi_scan.c):

    - If lun == SCAN_WILD_CARD, send a REPORT LUNS command to the target
    and process the result.

    - If lun != SCAN_WILD_CARD, send an INQUIRY command to the LUN
    corresponding to the specified channel:id:lun triplet to verify
    whether the LUN exists.

    So a SCSI driver must either take the channel and target id values in
    account in its quecommand() function or it should declare that it only
    supports one channel and one target id.

    Currently the ib_srp driver does neither. As a result scanning the
    SCSI bus via e.g. rescan-scsi-bus.sh causes many duplicate SCSI
    devices to be created. For each 0:0:L device, several duplicates are
    created with the same LUN number and with (C:I) != (0:0). Fix this by
    declaring that the ib_srp driver only supports one channel and one
    target id.

    Signed-off-by: Bart Van Assche <bvanassche@acm.org>
    Acked-by: David Dillow <dillowda@ornl.gov>
    Signed-off-by: Roland Dreier <roland@purestorage.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    drivers/infiniband/ulp/srp/ib_srp.c | 2 ++
    1 file changed, 2 insertions(+)

    --- a/drivers/infiniband/ulp/srp/ib_srp.c
    +++ b/drivers/infiniband/ulp/srp/ib_srp.c
    @@ -2127,6 +2127,8 @@ static ssize_t srp_create_target(struct
    return -ENOMEM;

    target_host->transportt = ib_srp_transport_template;
    + target_host->max_channel = 0;
    + target_host->max_id = 1;
    target_host->max_lun = SRP_MAX_LUN;
    target_host->max_cmd_len = sizeof ((struct srp_cmd *) (void *) 0L)->cdb;




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