Commit 750a1d93 authored by Mike Christie's avatar Mike Christie Committed by Martin K. Petersen
Browse files

scsi: target: core: Break up target_submit_cmd_map_sgls() 

This breaks up target_submit_cmd_map_sgls() into 3 helpers:

 - target_init_cmd(): Do the basic general setup and get a refcount to the
   session to make sure the caller can execute the cmd.

 - target_submit_prep(): Do the mapping, cdb processing and get a ref to
   the LUN.

 - target_submit(): Pass the cmd to LIO core for execution.

The above functions must be used by drivers that either:

 1. Rely on LIO for session shutdown synchronization by calling
    target_stop_session().

 2. Need to map sgls.

When the next patches are applied then simple drivers that do not need the
extra functionality above can use target_submit_cmd() and not worry about
failures being returned and how to handle them, since many drivers were
getting this wrong and would have hit refcount bugs.

Also, by breaking target_submit_cmd_map_sgls() up into these 3 helper
functions, we can allow the later patches to do the init/prep from
interrupt context and then do the submission from a workqueue.

Link: https://lore.kernel.org/r/20210227170006.5077-5-michael.christie@oracle.com


Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Nilesh Javali <njavali@marvell.com>
Cc: Michael Cyr <mikecyr@linux.ibm.com>
Cc: Chris Boot <bootc@bootc.net>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Tested-by: default avatarLaurence Oberman <loberman@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarHimanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: default avatarMike Christie <michael.christie@oracle.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent a78b7136

drivers/target/target_core_transport.c

+140 −61
Original line number Diff line number Diff line
@@ -1573,46 +1573,31 @@ transport_generic_map_mem_to_cmd(struct se_cmd *cmd, struct scatterlist *sgl, 
}



/**

 * target_submit_cmd_map_sgls - lookup unpacked lun and submit uninitialized

 * 			 se_cmd + use pre-allocated SGL memory.

 *

 * @se_cmd: command descriptor to submit

 * target_init_cmd - initialize se_cmd

 * @se_cmd: command descriptor to init

 * @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_attr: SAM task attribute

 * @data_dir: DMA data direction

 * @flags: flags for command submission from target_sc_flags_tables

 * @sgl: struct scatterlist memory for unidirectional mapping

 * @sgl_count: scatterlist count for unidirectional mapping

 * @sgl_bidi: struct scatterlist memory for bidirectional READ mapping

 * @sgl_bidi_count: scatterlist count for bidirectional READ mapping

 * @sgl_prot: struct scatterlist memory protection information

 * @sgl_prot_count: scatterlist count for protection information

 *

 * Task tags are supported if the caller has set @se_cmd->tag.

 *

 * Returns non zero to signal active I/O shutdown failure.  All other

 * setup exceptions will be returned as a SCSI CHECK_CONDITION response,

 * but still return zero here.

 * Returns:

 *	- less than zero to signal active I/O shutdown failure.

 *	- zero on success.

 *

 * This may only be called from process context, and also currently

 * assumes internal allocation of fabric payload buffer by target-core.

 * If the fabric driver calls target_stop_session, then it must check the

 * return code and handle failures. This will never fail for other drivers,

 * and the return code can be ignored.

 */

int target_submit_cmd_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess,

		unsigned char *cdb, unsigned char *sense, u64 unpacked_lun,

		u32 data_length, int task_attr, int data_dir, int flags,

		struct scatterlist *sgl, u32 sgl_count,

		struct scatterlist *sgl_bidi, u32 sgl_bidi_count,

		struct scatterlist *sgl_prot, u32 sgl_prot_count)

int target_init_cmd(struct se_cmd *se_cmd, struct se_session *se_sess,

		    unsigned char *sense, u64 unpacked_lun,

		    u32 data_length, int task_attr, int data_dir, int flags)

{

	struct se_portal_group *se_tpg;

	sense_reason_t rc;

	int ret;



	might_sleep();



	se_tpg = se_sess->se_tpg;

	BUG_ON(!se_tpg);
@@ -1620,53 +1605,69 @@ int target_submit_cmd_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess 


	if (flags & TARGET_SCF_USE_CPUID)

		se_cmd->se_cmd_flags |= SCF_USE_CPUID;

	/*

	 * Signal bidirectional data payloads to target-core

	 */

	if (flags & TARGET_SCF_BIDI_OP)

		se_cmd->se_cmd_flags |= SCF_BIDI;



	if (flags & TARGET_SCF_UNKNOWN_SIZE)

		se_cmd->unknown_data_length = 1;

	/*

	 * Initialize se_cmd for target operation.  From this point

	 * exceptions are handled by sending exception status via

	 * target_core_fabric_ops->queue_status() callback

	 */

	__target_init_cmd(se_cmd, se_tpg->se_tpg_tfo, se_sess,

			  data_length, data_dir, task_attr, sense,

			  unpacked_lun);

	__target_init_cmd(se_cmd, se_tpg->se_tpg_tfo, se_sess, data_length,

			  data_dir, task_attr, sense, unpacked_lun);



	if (flags & TARGET_SCF_UNKNOWN_SIZE)

		se_cmd->unknown_data_length = 1;

	/*

	 * Obtain struct se_cmd->cmd_kref reference. 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.

	 */

	ret = target_get_sess_cmd(se_cmd, flags & TARGET_SCF_ACK_KREF);

	if (ret)

		return ret;

	/*

	 * Signal bidirectional data payloads to target-core

	return target_get_sess_cmd(se_cmd, flags & TARGET_SCF_ACK_KREF);

}

EXPORT_SYMBOL_GPL(target_init_cmd);



/**

 * target_submit_prep - prepare cmd for submission

 * @se_cmd: command descriptor to prep

 * @cdb: pointer to SCSI CDB

 * @sgl: struct scatterlist memory for unidirectional mapping

 * @sgl_count: scatterlist count for unidirectional mapping

 * @sgl_bidi: struct scatterlist memory for bidirectional READ mapping

 * @sgl_bidi_count: scatterlist count for bidirectional READ mapping

 * @sgl_prot: struct scatterlist memory protection information

 * @sgl_prot_count: scatterlist count for protection information

 *

 * Returns:

 *	- less than zero to signal failure.

 *	- zero on success.

 * If failure is returned, lio will the callers queue_status to complete

 * the cmd.

 */

	if (flags & TARGET_SCF_BIDI_OP)

		se_cmd->se_cmd_flags |= SCF_BIDI;

int target_submit_prep(struct se_cmd *se_cmd, unsigned char *cdb,

		       struct scatterlist *sgl, u32 sgl_count,

		       struct scatterlist *sgl_bidi, u32 sgl_bidi_count,

		       struct scatterlist *sgl_prot, u32 sgl_prot_count)

{

	sense_reason_t rc;



	rc = target_cmd_init_cdb(se_cmd, cdb);

	if (rc) {

		transport_send_check_condition_and_sense(se_cmd, rc, 0);

		target_put_sess_cmd(se_cmd);

		return 0;

	}

	if (rc)

		goto send_cc_direct;



	/*

	 * Locate se_lun pointer and attach it to struct se_cmd

	 */

	rc = transport_lookup_cmd_lun(se_cmd);

	if (rc) {

		transport_send_check_condition_and_sense(se_cmd, rc, 0);

		target_put_sess_cmd(se_cmd);

		return 0;

	}

	if (rc)

		goto send_cc_direct;



	rc = target_cmd_parse_cdb(se_cmd);

	if (rc != 0) {

		transport_generic_request_failure(se_cmd, rc);

		return 0;

	}

	if (rc != 0)

		goto generic_fail;



	/*

	 * Save pointers for SGLs containing protection information,
@@ -1686,6 +1687,41 @@ int target_submit_cmd_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess 
	if (sgl_count != 0) {

		BUG_ON(!sgl);



		rc = transport_generic_map_mem_to_cmd(se_cmd, sgl, sgl_count,

				sgl_bidi, sgl_bidi_count);

		if (rc != 0)

			goto generic_fail;

	}



	return 0;



send_cc_direct:

	transport_send_check_condition_and_sense(se_cmd, rc, 0);

	target_put_sess_cmd(se_cmd);

	return -EIO;



generic_fail:

	transport_generic_request_failure(se_cmd, rc);

	return -EIO;

}

EXPORT_SYMBOL_GPL(target_submit_prep);



/**

 * target_submit - perform final initialization and submit cmd to LIO core

 * @se_cmd: command descriptor to submit

 *

 * target_submit_prep must have been called on the cmd, and this must be

 * called from process context.

 */

void target_submit(struct se_cmd *se_cmd)

{

	struct scatterlist *sgl = se_cmd->t_data_sg;

	unsigned char *buf = NULL;



	might_sleep();



	if (se_cmd->t_data_nents != 0) {

		BUG_ON(!sgl);

		/*

		 * A work-around for tcm_loop as some userspace code via

		 * scsi-generic do not memset their associated read buffers,
@@ -1696,8 +1732,6 @@ int target_submit_cmd_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess 
		 */

		if (!(se_cmd->se_cmd_flags & SCF_SCSI_DATA_CDB) &&

		     se_cmd->data_direction == DMA_FROM_DEVICE) {

			unsigned char *buf = NULL;



			if (sgl)

				buf = kmap(sg_page(sgl)) + sgl->offset;
@@ -1707,12 +1741,6 @@ int target_submit_cmd_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess 
			}

		}



		rc = transport_generic_map_mem_to_cmd(se_cmd, sgl, sgl_count,

				sgl_bidi, sgl_bidi_count);

		if (rc != 0) {

			transport_generic_request_failure(se_cmd, rc);

			return 0;

		}

	}



	/*
@@ -1722,6 +1750,57 @@ int target_submit_cmd_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess 
	core_alua_check_nonop_delay(se_cmd);



	transport_handle_cdb_direct(se_cmd);

}

EXPORT_SYMBOL_GPL(target_submit);



/**

 * target_submit_cmd_map_sgls - lookup unpacked lun and submit uninitialized

 *					se_cmd + use pre-allocated SGL memory.

 *

 * @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_attr: SAM task attribute

 * @data_dir: DMA data direction

 * @flags: flags for command submission from target_sc_flags_tables

 * @sgl: struct scatterlist memory for unidirectional mapping

 * @sgl_count: scatterlist count for unidirectional mapping

 * @sgl_bidi: struct scatterlist memory for bidirectional READ mapping

 * @sgl_bidi_count: scatterlist count for bidirectional READ mapping

 * @sgl_prot: struct scatterlist memory protection information

 * @sgl_prot_count: scatterlist count for protection information

 *

 * Task tags are supported if the caller has set @se_cmd->tag.

 *

 * Returns non zero to signal active I/O shutdown failure.  All other

 * setup exceptions will be returned as a SCSI CHECK_CONDITION response,

 * but still return zero here.

 *

 * 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_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess,

		unsigned char *cdb, unsigned char *sense, u64 unpacked_lun,

		u32 data_length, int task_attr, int data_dir, int flags,

		struct scatterlist *sgl, u32 sgl_count,

		struct scatterlist *sgl_bidi, u32 sgl_bidi_count,

		struct scatterlist *sgl_prot, u32 sgl_prot_count)

{

	int rc;



	rc = target_init_cmd(se_cmd, se_sess, sense, unpacked_lun,

			     data_length, task_attr, data_dir, flags);

	if (rc < 0)

		return rc;



	if (target_submit_prep(se_cmd, cdb, sgl, sgl_count, sgl_bidi,

			       sgl_bidi_count, sgl_prot, sgl_prot_count))

		return 0;



	target_submit(se_cmd);

	return 0;

}

EXPORT_SYMBOL(target_submit_cmd_map_sgls);

include/target/target_core_fabric.h

+8 −0
Original line number Diff line number Diff line
@@ -151,6 +151,14 @@ void transport_deregister_session(struct se_session *); 
void	__target_init_cmd(struct se_cmd *,

		const struct target_core_fabric_ops *,

		struct se_session *, u32, int, int, unsigned char *, u64);

int	target_init_cmd(struct se_cmd *se_cmd, struct se_session *se_sess,

		unsigned char *sense, u64 unpacked_lun, u32 data_length,

		int task_attr, int data_dir, int flags);

int	target_submit_prep(struct se_cmd *se_cmd, unsigned char *cdb,

		struct scatterlist *sgl, u32 sgl_count,

		struct scatterlist *sgl_bidi, u32 sgl_bidi_count,

		struct scatterlist *sgl_prot, u32 sgl_prot_count);

void	target_submit(struct se_cmd *se_cmd);

sense_reason_t transport_lookup_cmd_lun(struct se_cmd *);

sense_reason_t target_cmd_init_cdb(struct se_cmd *, unsigned char *);

sense_reason_t target_cmd_parse_cdb(struct se_cmd *);