The next patches has libiscsi use the blk/scsi mq scsi cmd preallocation
callouts to allocate the iscsi_task and the LLD's per task data so
libiscsi does not have to add extra locking to manage it's cmd pool
for scsi cmds. This means we need to separate the itt allocation and
lookup from the task allocation. In this patch we just use a sbitmap.
Signed-off-by: Mike Christie <michael.christie@xxxxxxxxxx>
---
drivers/scsi/be2iscsi/be_main.c | 2 +-
drivers/scsi/libiscsi.c | 112 ++++++++++++++++++++++++++++++++++------
include/scsi/libiscsi.h | 2 +
3 files changed, 99 insertions(+), 17 deletions(-)
diff --git a/drivers/scsi/be2iscsi/be_main.c b/drivers/scsi/be2iscsi/be_main.c
index 202ba92..cd3189b 100644
--- a/drivers/scsi/be2iscsi/be_main.c
+++ b/drivers/scsi/be2iscsi/be_main.c
@@ -306,7 +306,7 @@ static int beiscsi_eh_device_reset(struct scsi_cmnd *sc)
spin_lock(&session->back_lock);
for (i = 0; i < conn->session->cmds_max; i++) {
task = conn->session->cmds[i];
- if (!task->sc)
+ if (!task || !task->sc)
continue;
if (sc->device->lun != task->sc->device->lun)
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 6621a69..39d7d81 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -331,6 +331,43 @@ static int iscsi_check_tmf_restrictions(struct iscsi_task *task, int opcode)
return 0;
}
+static int iscsi_alloc_itt(struct iscsi_session *session,
+ struct iscsi_task *task)
+{
+ int itt;
+
+ itt = sbitmap_get(&session->itts, 0, false);
+ if (itt < 0) {
+ iscsi_session_printk(KERN_ERR, session,
+ "Could not allocate ITT\n");
+ return -ENOMEM;
+ }
+
+ task->itt = itt;
+ session->cmds[itt] = task;
+ /*
+ * If the code path is not holding the frwd and back locks and doing
+ * a lookup make sure it sees the update.
+ */
+ smp_wmb();
+ return 0;
+}
+
+static void iscsi_free_itt(struct iscsi_session *session,
+ struct iscsi_task *task)
+{
+ /*
+ * We don't need a barrier in this path because it's run from the
+ * itt alloc path or from lookup which has the barrier already.
+ */
+ if (task->itt == ISCSI_RESERVED_TAG)
+ return;
+
+ session->cmds[task->itt] = NULL;
+ sbitmap_clear_bit(&session->itts, task->itt);
+ task->itt = ISCSI_RESERVED_TAG;
+}
+
/**
* iscsi_prep_scsi_cmd_pdu - prep iscsi scsi cmd pdu
* @task: iscsi task
@@ -352,10 +389,14 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_task *task)
if (rc)
return rc;
+ rc = iscsi_alloc_itt(session, task);
+ if (rc)
+ return rc;
+
if (conn->session->tt->alloc_pdu) {
rc = conn->session->tt->alloc_pdu(task, ISCSI_OP_SCSI_CMD);
if (rc)
- return rc;
+ goto free_itt;
}
hdr = (struct iscsi_scsi_req *)task->hdr;
itt = hdr->itt;
@@ -369,7 +410,7 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_task *task)
task->hdr_len = 0;
rc = iscsi_add_hdr(task, sizeof(*hdr));
if (rc)
- return rc;
+ goto free_itt;
hdr->opcode = ISCSI_OP_SCSI_CMD;
hdr->flags = ISCSI_ATTR_SIMPLE;
int_to_scsilun(sc->device->lun, &hdr->lun);
@@ -381,7 +422,7 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_task *task)
else if (cmd_len > ISCSI_CDB_SIZE) {
rc = iscsi_prep_ecdb_ahs(task);
if (rc)
- return rc;
+ goto free_itt;
cmd_len = ISCSI_CDB_SIZE;
}
memcpy(hdr->cdb, sc->cmnd, cmd_len);
@@ -453,8 +494,10 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_task *task)
hdr->hlength = hdrlength & 0xFF;
hdr->cmdsn = task->cmdsn = cpu_to_be32(session->cmdsn);
- if (session->tt->init_task && session->tt->init_task(task))
- return -EIO;
+ if (session->tt->init_task && session->tt->init_task(task)) {
+ rc = -EIO;
+ goto free_itt;
+ }
task->state = ISCSI_TASK_RUNNING;
session->cmdsn++;
@@ -469,6 +512,14 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_task *task)
task->itt, transfer_length, session->cmdsn,
session->max_cmdsn - session->exp_cmdsn + 1);
return 0;
+
+free_itt:
+ iscsi_free_itt(session, task);
+ /*
+ * The resources allocated in the LLD callouts will be freed by
+ * the caller's cleanup_task call.
+ */
+ return rc;
}
/**
@@ -498,6 +549,7 @@ static void iscsi_free_task(struct iscsi_task *task)
if (conn->login_task == task)
return;
+ iscsi_free_itt(session, task);
kfifo_in(&session->cmdpool.queue, (void*)&task, sizeof(void*));
/*
@@ -762,6 +814,14 @@ static int iscsi_prep_mgmt_task(struct iscsi_conn *conn,
if (!kfifo_out(&session->cmdpool.queue,
(void*)&task, sizeof(void*)))
return NULL;
+
+ if (iscsi_alloc_itt(session, task)) {
+ spin_lock(&session->back_lock);
+ kfifo_in(&session->cmdpool.queue, (void *)&task,
+ sizeof(void *));
+ spin_unlock(&session->back_lock);
+ return NULL;
+ }
}
/*
* released in complete pdu for task we expect a response for, and
@@ -1172,7 +1232,8 @@ struct iscsi_task *iscsi_itt_to_task(struct iscsi_conn *conn, itt_t itt)
i = get_itt(itt);
if (i >= session->cmds_max)
return NULL;
-
+ /* make sure we see the map addition */
+ smp_rmb();
return session->cmds[i];
}
EXPORT_SYMBOL_GPL(iscsi_itt_to_task);
@@ -1672,6 +1733,7 @@ static inline struct iscsi_task *iscsi_alloc_task(struct iscsi_conn *conn,
sc->SCp.ptr = (char *) task;
refcount_set(&task->refcount, 1);
+ task->itt = ISCSI_RESERVED_TAG;
task->state = ISCSI_TASK_PENDING;
task->conn = conn;
task->sc = sc;
@@ -1923,7 +1985,7 @@ static void fail_scsi_tasks(struct iscsi_conn *conn, u64 lun, int error)
for (i = 0; i < conn->session->cmds_max; i++) {
task = conn->session->cmds[i];
- if (!task->sc || task->state == ISCSI_TASK_FREE)
+ if (!task || !task->sc || task->state == ISCSI_TASK_FREE)
continue;
if (lun != -1 && lun != task->sc->device->lun)
@@ -2080,7 +2142,7 @@ enum blk_eh_timer_return iscsi_eh_cmd_timed_out(struct scsi_cmnd *sc)
for (i = 0; i < conn->session->cmds_max; i++) {
running_task = conn->session->cmds[i];
- if (!running_task->sc || running_task == task ||
+ if (!running_task || !running_task->sc || running_task == task ||
running_task->state != ISCSI_TASK_RUNNING)
continue;
@@ -2870,19 +2932,25 @@ struct iscsi_cls_session *
spin_lock_init(&session->frwd_lock);
spin_lock_init(&session->back_lock);
+ if (sbitmap_init_node(&session->itts, session->cmds_max, -1,
+ GFP_KERNEL, NUMA_NO_NODE))
+ goto itts_fail;
+
+ session->cmds = kcalloc(session->cmds_max, sizeof(struct iscsi_task *),
+ GFP_KERNEL);
+ if (!session->cmds)
+ goto cmds_alloc_fail;
+
/* initialize SCSI PDU commands pool */
- if (iscsi_pool_init(&session->cmdpool, session->cmds_max,
- (void***)&session->cmds,
+ if (iscsi_pool_init(&session->cmdpool, session->cmds_max, NULL,
cmd_task_size + sizeof(struct iscsi_task)))
goto cmdpool_alloc_fail;
- /* pre-format cmds pool with ITT */
for (cmd_i = 0; cmd_i < session->cmds_max; cmd_i++) {
struct iscsi_task *task = session->cmds[cmd_i];
if (cmd_task_size)
task->dd_data = &task[1];
- task->itt = cmd_i;
task->state = ISCSI_TASK_FREE;
INIT_LIST_HEAD(&task->running);
@@ -2910,6 +2978,10 @@ struct iscsi_cls_session *
iscsi_pool_free(&session->cmdpool);
cmdpool_alloc_fail:
+ kfree(session->cmds);
+cmds_alloc_fail:
+ sbitmap_free(&session->itts);
+itts_fail:
iscsi_free_session(cls_session);
dec_session_count:
iscsi_host_dec_session_cnt(shost);
@@ -2952,6 +3024,9 @@ void iscsi_session_teardown(struct iscsi_cls_session *cls_session)
kfree(session->portal_type);
kfree(session->discovery_parent_type);
+ kfree(session->cmds);
+ sbitmap_free(&session->itts);
+
iscsi_free_session(cls_session);
iscsi_host_dec_session_cnt(shost);
@@ -3006,6 +3081,9 @@ struct iscsi_cls_conn *
}
spin_unlock_bh(&session->frwd_lock);
+ if (iscsi_alloc_itt(session, conn->login_task))
+ goto login_itt_fail;
+
data = (char *) __get_free_pages(GFP_KERNEL,
get_order(ISCSI_DEF_MAX_RECV_SEG_LEN));
if (!data)
@@ -3018,8 +3096,12 @@ struct iscsi_cls_conn *
return cls_conn;
login_task_data_alloc_fail:
+ iscsi_free_itt(session, conn->login_task);
+login_itt_fail:
+ spin_lock_bh(&session->frwd_lock);
kfifo_in(&session->cmdpool.queue, (void*)&conn->login_task,
sizeof(void*));
+ spin_unlock_bh(&session->frwd_lock);
login_task_alloc_fail:
iscsi_destroy_conn(cls_conn);
return NULL;
@@ -3065,6 +3147,7 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn)
kfifo_in(&session->cmdpool.queue, (void*)&conn->login_task,
sizeof(void*));
spin_unlock_bh(&session->back_lock);
+ iscsi_free_itt(session, conn->login_task);
if (session->leadconn == conn)
session->leadconn = NULL;
spin_unlock_bh(&session->frwd_lock);
@@ -3149,10 +3232,7 @@ int iscsi_conn_start(struct iscsi_cls_conn *cls_conn)
for (i = 0; i < conn->session->cmds_max; i++) {
task = conn->session->cmds[i];
- if (task->sc)
- continue;
-
- if (task->state == ISCSI_TASK_FREE)
+ if (!task || task->sc || task->state == ISCSI_TASK_FREE)
continue;
ISCSI_DBG_SESSION(conn->session,
diff --git a/include/scsi/libiscsi.h b/include/scsi/libiscsi.h
index 2f99ad6..e4dd975 100644
--- a/include/scsi/libiscsi.h
+++ b/include/scsi/libiscsi.h
@@ -17,6 +17,7 @@
#include <linux/workqueue.h>
#include <linux/kfifo.h>
#include <linux/refcount.h>
+#include <linux/sbitmap.h>
#include <scsi/iscsi_proto.h>
#include <scsi/iscsi_if.h>
#include <scsi/scsi_transport_iscsi.h>
@@ -342,6 +343,7 @@ struct iscsi_session {
int cmds_max; /* size of cmds array */
struct iscsi_task **cmds; /* Original Cmds arr */
struct iscsi_pool cmdpool; /* PDU's pool */
+ struct sbitmap itts;
void *dd_data; /* LLD private data */
};
--
1.8.3.1
