Commit a6360785 authored by Nicholas Bellinger's avatar Nicholas Bellinger

target: Add target_submit_cmd() for process context fabric submission

This patch adds a target_submit_cmd() caller that can be used by fabrics
to submit an uninitialized se_cmd descriptor to an struct se_session +
unpacked_lun from workqueue process context.  This call will invoke the
following steps:

- transport_init_se_cmd() to setup se_cmd specific pointers
- Obtain se_cmd->cmd_kref references with target_get_sess_cmd()
- set se_cmd->t_tasks_bidi
- transport_lookup_cmd_lun() to setup struct se_cmd->se_lun from
  the passed unpacked_lun
- transport_generic_allocate_tasks() to setup the passed *cdb, and
- transport_handle_cdb_direct() handle READ dispatch or WRITE
  ready-to-transfer callback to fabric

v2 changes from hch feedback:

*) Add target_sc_flags_table for target_submit_cmd flags
*) Rename bidi parameter to flags, add TARGET_SCF_BIDI_OP
*) Convert checks to BUG_ON
*) Add out_check_cond for transport_send_check_condition_and_sense
   usage

v3 changes:

*) Add TARGET_SCF_ACK_KREF for target_submit_cmd into
   target_get_sess_cmd to determine when the fabric caller is expecting
   a second kref_put() from fabric packet acknowledgement.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Roland Dreier <roland@purestorage.com>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 7481deb4
......@@ -1642,6 +1642,80 @@ int transport_handle_cdb_direct(
}
EXPORT_SYMBOL(transport_handle_cdb_direct);
/**
* target_submit_cmd - lookup unpacked lun and submit uninitialized se_cmd
*
* @se_cmd: command descriptor to submit
* @se_sess: associated se_sess for endpoint
* @cdb: pointer to SCSI CDB
* @sense: pointer to SCSI sense buffer
* @unpacked_lun: unpacked LUN to reference for struct se_lun
* @data_length: fabric expected data transfer length
* @task_addr: SAM task attribute
* @data_dir: DMA data direction
* @flags: flags for command submission from target_sc_flags_tables
*
* This may only be called from process context, and also currently
* assumes internal allocation of fabric payload buffer by target-core.
**/
int target_submit_cmd(struct se_cmd *se_cmd, struct se_session *se_sess,
unsigned char *cdb, unsigned char *sense, u32 unpacked_lun,
u32 data_length, int task_attr, int data_dir, int flags)
{
struct se_portal_group *se_tpg;
int rc;
se_tpg = se_sess->se_tpg;
BUG_ON(!se_tpg);
BUG_ON(se_cmd->se_tfo || se_cmd->se_sess);
BUG_ON(in_interrupt());
/*
* Initialize se_cmd for target operation. From this point
* exceptions are handled by sending exception status via
* target_core_fabric_ops->queue_status() callback
*/
transport_init_se_cmd(se_cmd, se_tpg->se_tpg_tfo, se_sess,
data_length, data_dir, task_attr, sense);
/*
* Obtain struct se_cmd->cmd_kref reference and add new cmd to
* se_sess->sess_cmd_list. A second kref_get here is necessary
* for fabrics using TARGET_SCF_ACK_KREF that expect a second
* kref_put() to happen during fabric packet acknowledgement.
*/
target_get_sess_cmd(se_sess, se_cmd, (flags & TARGET_SCF_ACK_KREF));
/*
* Signal bidirectional data payloads to target-core
*/
if (flags & TARGET_SCF_BIDI_OP)
se_cmd->se_cmd_flags |= SCF_BIDI;
/*
* Locate se_lun pointer and attach it to struct se_cmd
*/
if (transport_lookup_cmd_lun(se_cmd, unpacked_lun) < 0)
goto out_check_cond;
/*
* Sanitize CDBs via transport_generic_cmd_sequencer() and
* allocate the necessary tasks to complete the received CDB+data
*/
rc = transport_generic_allocate_tasks(se_cmd, cdb);
if (rc != 0)
goto out_check_cond;
/*
* Dispatch se_cmd descriptor to se_lun->lun_se_dev backend
* for immediate execution of READs, otherwise wait for
* transport_generic_handle_data() to be called for WRITEs
* when fabric has filled the incoming buffer.
*/
transport_handle_cdb_direct(se_cmd);
return 0;
out_check_cond:
transport_send_check_condition_and_sense(se_cmd,
se_cmd->scsi_sense_reason, 0);
return 0;
}
EXPORT_SYMBOL(target_submit_cmd);
/*
* Used by fabric module frontends defining a TFO->new_cmd_map() caller
* to queue up a newly setup se_cmd w/ TRANSPORT_NEW_CMD_MAP in order to
......@@ -3910,13 +3984,21 @@ EXPORT_SYMBOL(transport_generic_free_cmd);
/* target_get_sess_cmd - Add command to active ->sess_cmd_list
* @se_sess: session to reference
* @se_cmd: command descriptor to add
* @ack_kref: Signal that fabric will perform an ack target_put_sess_cmd()
*/
void target_get_sess_cmd(struct se_session *se_sess, struct se_cmd *se_cmd)
void target_get_sess_cmd(struct se_session *se_sess, struct se_cmd *se_cmd,
bool ack_kref)
{
unsigned long flags;
kref_init(&se_cmd->cmd_kref);
kref_get(&se_cmd->cmd_kref);
/*
* Add a second kref if the fabric caller is expecting to handle
* fabric acknowledgement that requires two target_put_sess_cmd()
* invocations before se_cmd descriptor release.
*/
if (ack_kref == true)
kref_get(&se_cmd->cmd_kref);
spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
list_add_tail(&se_cmd->se_cmd_list, &se_sess->sess_cmd_list);
......
......@@ -226,6 +226,11 @@ enum tcm_sense_reason_table {
TCM_RESERVATION_CONFLICT = 0x10,
};
enum target_sc_flags_table {
TARGET_SCF_BIDI_OP = 0x01,
TARGET_SCF_ACK_KREF = 0x02,
};
/* fabric independent task management function values */
enum tcm_tmreq_table {
TMR_ABORT_TASK = 1,
......
......@@ -118,6 +118,8 @@ void transport_init_se_cmd(struct se_cmd *, struct target_core_fabric_ops *,
struct se_session *, u32, int, int, unsigned char *);
int transport_lookup_cmd_lun(struct se_cmd *, u32);
int transport_generic_allocate_tasks(struct se_cmd *, unsigned char *);
int target_submit_cmd(struct se_cmd *, struct se_session *, unsigned char *,
unsigned char *, u32, u32, int, int, int);
int transport_handle_cdb_direct(struct se_cmd *);
int transport_generic_handle_cdb_map(struct se_cmd *);
int transport_generic_handle_data(struct se_cmd *);
......@@ -134,7 +136,7 @@ bool transport_wait_for_tasks(struct se_cmd *);
int transport_check_aborted_status(struct se_cmd *, int);
int transport_send_check_condition_and_sense(struct se_cmd *, u8, int);
void target_get_sess_cmd(struct se_session *, struct se_cmd *);
void target_get_sess_cmd(struct se_session *, struct se_cmd *, bool);
int target_put_sess_cmd(struct se_session *, struct se_cmd *);
void target_splice_sess_cmd_list(struct se_session *);
void target_wait_for_sess_cmds(struct se_session *, int);
......
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