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scsi: target: xen-scsiback: Convert to new submission API 

target_submit_cmd_map_sgls() is being removed, so convert xen to the new
submission API. This has it use target_init_cmd(), target_submit_prep(), or
target_submit() because we need to have LIO core map sgls which is now done
in target_submit_prep(). target_init_cmd() will never fail for xen because
it does its own sync during session shutdown, so we can remove that code.

Note: xen never calls target_stop_session() so target_submit_cmd_map_sgls()
never failed (in the new API target_init_cmd() handles
target_stop_session() being called when cmds are being submitted). If it
were to have used target_stop_session() and got an error, we would have hit
a refcount bug like xen and usb, because it does:

    if (rc < 0) {
            transport_send_check_condition_and_sense(se_cmd,
                            TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0);
            transport_generic_free_cmd(se_cmd, 0);
    }

transport_send_check_condition_and_sense() calls queue_status which calls
scsiback_cmd_done->target_put_sess_cmd. We do an extra
transport_generic_free_cmd() call above which would have dropped the
refcount to -1 and the refcount code would spit out errors.

Link: https://lore.kernel.org/r/20210227170006.5077-13-michael.christie@oracle.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Mike Christie 2021-02-27 10:59:53 -06:00 committed by Martin K. Petersen
parent eb929804db
commit 1f48b065da
1 changed files with 9 additions and 12 deletions
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21
drivers/xen/xen-scsiback.c
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@ -360,21 +360,18 @@ static void scsiback_cmd_exec(struct vscsibk_pend *pending_req)
{
struct se_cmd *se_cmd = &pending_req->se_cmd;
struct se_session *sess = pending_req->v2p->tpg->tpg_nexus->tvn_se_sess;
int rc;
scsiback_get(pending_req->info);
se_cmd->tag = pending_req->rqid;
rc = target_submit_cmd_map_sgls(se_cmd, sess, pending_req->cmnd,
pending_req->sense_buffer, pending_req->v2p->lun,
pending_req->data_len, 0,
pending_req->sc_data_direction, TARGET_SCF_ACK_KREF,
pending_req->sgl, pending_req->n_sg,
NULL, 0, NULL, 0);
if (rc < 0) {
transport_send_check_condition_and_sense(se_cmd,
TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0);
transport_generic_free_cmd(se_cmd, 0);
}
target_init_cmd(se_cmd, sess, pending_req->sense_buffer,
pending_req->v2p->lun, pending_req->data_len, 0,
pending_req->sc_data_direction, TARGET_SCF_ACK_KREF);
if (target_submit_prep(se_cmd, pending_req->cmnd, pending_req->sgl,
pending_req->n_sg, NULL, 0, NULL, 0))
return;
target_submit(se_cmd);
}
static int scsiback_gnttab_data_map_batch(struct gnttab_map_grant_ref *map,