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scsi: target: Fix LUN ref count handling 

Fix two bugs in the LUN refcounting:

 1. For the TCM_WRITE_PROTECTED case we were returning an error after
    taking a ref to the LUN, but never dropping it (caller just send status
    and drops cmd ref).

 2. We still need to do a percpu_ref_tryget_live for the virt LUN 0 like we
    do for other LUNs, because the TPG code does the refcount/wait process
    like it does with other LUNs.

Link: https://lore.kernel.org/r/1604257174-4524-2-git-send-email-michael.christie@oracle.com
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
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 2020-11-01 12:59:27 -06:00 committed by Martin K. Petersen
parent 00c00807a1
commit a2b5d6f975
1 changed files with 20 additions and 23 deletions
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43
drivers/target/target_core_device.c
View File

@ -65,6 +65,16 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd)
atomic_long_add(se_cmd->data_length,
&deve->read_bytes);
if ((se_cmd->data_direction == DMA_TO_DEVICE) &&
deve->lun_access_ro) {
pr_err("TARGET_CORE[%s]: Detected WRITE_PROTECTED LUN"
" Access for 0x%08llx\n",
se_cmd->se_tfo->fabric_name,
se_cmd->orig_fe_lun);
rcu_read_unlock();
return TCM_WRITE_PROTECTED;
}
se_lun = rcu_dereference(deve->se_lun);
if (!percpu_ref_tryget_live(&se_lun->lun_ref)) {
@ -76,17 +86,6 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd)
se_cmd->pr_res_key = deve->pr_res_key;
se_cmd->se_cmd_flags |= SCF_SE_LUN_CMD;
se_cmd->lun_ref_active = true;
if ((se_cmd->data_direction == DMA_TO_DEVICE) &&
deve->lun_access_ro) {
pr_err("TARGET_CORE[%s]: Detected WRITE_PROTECTED LUN"
" Access for 0x%08llx\n",
se_cmd->se_tfo->fabric_name,
se_cmd->orig_fe_lun);
rcu_read_unlock();
ret = TCM_WRITE_PROTECTED;
goto ref_dev;
}
}
out_unlock:
rcu_read_unlock();
@ -106,21 +105,20 @@ out_unlock:
return TCM_NON_EXISTENT_LUN;
}
se_lun = se_sess->se_tpg->tpg_virt_lun0;
se_cmd->se_lun = se_sess->se_tpg->tpg_virt_lun0;
se_cmd->se_cmd_flags |= SCF_SE_LUN_CMD;
percpu_ref_get(&se_lun->lun_ref);
se_cmd->lun_ref_active = true;
/*
* Force WRITE PROTECT for virtual LUN 0
*/
if ((se_cmd->data_direction != DMA_FROM_DEVICE) &&
(se_cmd->data_direction != DMA_NONE)) {
ret = TCM_WRITE_PROTECTED;
goto ref_dev;
}
(se_cmd->data_direction != DMA_NONE))
return TCM_WRITE_PROTECTED;
se_lun = se_sess->se_tpg->tpg_virt_lun0;
if (!percpu_ref_tryget_live(&se_lun->lun_ref))
return TCM_NON_EXISTENT_LUN;
se_cmd->se_lun = se_sess->se_tpg->tpg_virt_lun0;
se_cmd->se_cmd_flags |= SCF_SE_LUN_CMD;
se_cmd->lun_ref_active = true;
}
/*
* RCU reference protected by percpu se_lun->lun_ref taken above that
@ -128,7 +126,6 @@ out_unlock:
* pointer can be kfree_rcu() by the final se_lun->lun_group put via
* target_core_fabric_configfs.c:target_fabric_port_release
*/
ref_dev:
se_cmd->se_dev = rcu_dereference_raw(se_lun->lun_se_dev);
atomic_long_inc(&se_cmd->se_dev->num_cmds);