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[SCSI] libiscsi: Check TMF state before sending PDU
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Patch and mail from both MikeC and HannesR:

Before we're trying to send a PDU we have to check whether a TMF
is active. If so and if the PDU will be affected by the TMF
we should allow only Data-out PDUs to be sent.

If fast_abort is set, no Data-out PDUs will be sent while
a LUN reset is being processed for a affected LUN.

fast_abort is now ingored during a ABORT TASK tmf. We will not
send any Data-outs for a task if the task is being aborted.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
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Mike Christie authored and James Bottomley committed Dec 4, 2009
1 parent 4f704dc commit 5d12c05
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Showing 2 changed files with 103 additions and 12 deletions.
113 changes: 101 additions & 12 deletions drivers/scsi/libiscsi.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -265,6 +265,88 @@ static int iscsi_prep_bidi_ahs(struct iscsi_task *task)
return 0;
}

/**
* iscsi_check_tmf_restrictions - check if a task is affected by TMF
* @task: iscsi task
* @opcode: opcode to check for
*
* During TMF a task has to be checked if it's affected.
* All unrelated I/O can be passed through, but I/O to the
* affected LUN should be restricted.
* If 'fast_abort' is set we won't be sending any I/O to the
* affected LUN.
* Otherwise the target is waiting for all TTTs to be completed,
* so we have to send all outstanding Data-Out PDUs to the target.
*/
static int iscsi_check_tmf_restrictions(struct iscsi_task *task, int opcode)
{
struct iscsi_conn *conn = task->conn;
struct iscsi_tm *tmf = &conn->tmhdr;
unsigned int hdr_lun;

if (conn->tmf_state == TMF_INITIAL)
return 0;

if ((tmf->opcode & ISCSI_OPCODE_MASK) != ISCSI_OP_SCSI_TMFUNC)
return 0;

switch (ISCSI_TM_FUNC_VALUE(tmf)) {
case ISCSI_TM_FUNC_LOGICAL_UNIT_RESET:
/*
* Allow PDUs for unrelated LUNs
*/
hdr_lun = scsilun_to_int((struct scsi_lun *)tmf->lun);
if (hdr_lun != task->sc->device->lun)
return 0;

/*
* Fail all SCSI cmd PDUs
*/
if (opcode != ISCSI_OP_SCSI_DATA_OUT) {
iscsi_conn_printk(KERN_INFO, conn,
"task [op %x/%x itt "
"0x%x/0x%x lun %u] "
"rejected.\n",
task->hdr->opcode, opcode,
task->itt, task->hdr_itt, hdr_lun);
return -EACCES;
}
/*
* And also all data-out PDUs in response to R2T
* if fast_abort is set.
*/
if (conn->session->fast_abort) {
iscsi_conn_printk(KERN_INFO, conn,
"task [op %x/%x itt "
"0x%x/0x%x lun %u] "
"fast abort.\n",
task->hdr->opcode, opcode,
task->itt, task->hdr_itt, hdr_lun);
return -EACCES;
}
break;
case ISCSI_TM_FUNC_ABORT_TASK:
/*
* the caller has already checked if the task
* they want to abort was in the pending queue so if
* we are here the cmd pdu has gone out already, and
* we will only hit this for data-outs
*/
if (opcode == ISCSI_OP_SCSI_DATA_OUT &&
task->hdr_itt == tmf->rtt) {
ISCSI_DBG_SESSION(conn->session,
"Preventing task %x/%x from sending "
"data-out due to abort task in "
"progress\n", task->itt,
task->hdr_itt);
return -EACCES;
}
break;
}

return 0;
}

/**
* iscsi_prep_scsi_cmd_pdu - prep iscsi scsi cmd pdu
* @task: iscsi task
Expand All @@ -282,6 +364,10 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_task *task)
itt_t itt;
int rc;

rc = iscsi_check_tmf_restrictions(task, ISCSI_OP_SCSI_CMD);
if (rc)
return rc;

if (conn->session->tt->alloc_pdu) {
rc = conn->session->tt->alloc_pdu(task, ISCSI_OP_SCSI_CMD);
if (rc)
Expand Down Expand Up @@ -1366,6 +1452,7 @@ EXPORT_SYMBOL_GPL(iscsi_requeue_task);
**/
static int iscsi_data_xmit(struct iscsi_conn *conn)
{
struct iscsi_task *task;
int rc = 0;

spin_lock_bh(&conn->session->lock);
Expand Down Expand Up @@ -1403,19 +1490,16 @@ static int iscsi_data_xmit(struct iscsi_conn *conn)

/* process pending command queue */
while (!list_empty(&conn->cmdqueue)) {
if (conn->tmf_state == TMF_QUEUED)
break;

conn->task = list_entry(conn->cmdqueue.next,
struct iscsi_task, running);
conn->task = list_entry(conn->cmdqueue.next, struct iscsi_task,
running);
list_del_init(&conn->task->running);
if (conn->session->state == ISCSI_STATE_LOGGING_OUT) {
fail_scsi_task(conn->task, DID_IMM_RETRY);
continue;
}
rc = iscsi_prep_scsi_cmd_pdu(conn->task);
if (rc) {
if (rc == -ENOMEM) {
if (rc == -ENOMEM || rc == -EACCES) {
list_add_tail(&conn->task->running,
&conn->cmdqueue);
conn->task = NULL;
Expand All @@ -1437,17 +1521,18 @@ static int iscsi_data_xmit(struct iscsi_conn *conn)
}

while (!list_empty(&conn->requeue)) {
if (conn->session->fast_abort && conn->tmf_state != TMF_INITIAL)
break;

/*
* we always do fastlogout - conn stop code will clean up.
*/
if (conn->session->state == ISCSI_STATE_LOGGING_OUT)
break;

conn->task = list_entry(conn->requeue.next,
struct iscsi_task, running);
task = list_entry(conn->requeue.next, struct iscsi_task,
running);
if (iscsi_check_tmf_restrictions(task, ISCSI_OP_SCSI_DATA_OUT))
break;

conn->task = task;
list_del_init(&conn->task->running);
conn->task->state = ISCSI_TASK_RUNNING;
rc = iscsi_xmit_task(conn);
Expand Down Expand Up @@ -1600,7 +1685,7 @@ int iscsi_queuecommand(struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
if (!ihost->workq) {
reason = iscsi_prep_scsi_cmd_pdu(task);
if (reason) {
if (reason == -ENOMEM) {
if (reason == -ENOMEM || reason == -EACCES) {
reason = FAILURE_OOM;
goto prepd_reject;
} else {
Expand Down Expand Up @@ -2120,6 +2205,7 @@ int iscsi_eh_abort(struct scsi_cmnd *sc)
spin_lock_bh(&session->lock);
fail_scsi_task(task, DID_ABORT);
conn->tmf_state = TMF_INITIAL;
memset(hdr, 0, sizeof(*hdr));
spin_unlock_bh(&session->lock);
iscsi_start_tx(conn);
goto success_unlocked;
Expand All @@ -2130,6 +2216,7 @@ int iscsi_eh_abort(struct scsi_cmnd *sc)
case TMF_NOT_FOUND:
if (!sc->SCp.ptr) {
conn->tmf_state = TMF_INITIAL;
memset(hdr, 0, sizeof(*hdr));
/* task completed before tmf abort response */
ISCSI_DBG_EH(session, "sc completed while abort in "
"progress\n");
Expand Down Expand Up @@ -2224,6 +2311,7 @@ int iscsi_eh_device_reset(struct scsi_cmnd *sc)
iscsi_suspend_tx(conn);

spin_lock_bh(&session->lock);
memset(hdr, 0, sizeof(*hdr));
fail_scsi_tasks(conn, sc->device->lun, DID_ERROR);
conn->tmf_state = TMF_INITIAL;
spin_unlock_bh(&session->lock);
Expand Down Expand Up @@ -2868,6 +2956,7 @@ static void iscsi_start_session_recovery(struct iscsi_session *session,
spin_lock_bh(&session->lock);
fail_scsi_tasks(conn, -1, DID_TRANSPORT_DISRUPTED);
fail_mgmt_tasks(session, conn);
memset(&conn->tmhdr, 0, sizeof(conn->tmhdr));
spin_unlock_bh(&session->lock);
mutex_unlock(&session->eh_mutex);
}
Expand Down
2 changes: 2 additions & 0 deletions include/scsi/iscsi_proto.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -279,6 +279,8 @@ struct iscsi_tm {
#define ISCSI_TM_FUNC_TARGET_COLD_RESET 7
#define ISCSI_TM_FUNC_TASK_REASSIGN 8

#define ISCSI_TM_FUNC_VALUE(hdr) ((hdr)->flags & ISCSI_FLAG_TM_FUNC_MASK)

/* SCSI Task Management Response Header */
struct iscsi_tm_rsp {
uint8_t opcode;
Expand Down

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