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Commit 957525a2 authored by Roland Dreier's avatar Roland Dreier Committed by Nicholas Bellinger
Browse files

target: Remove transport_do_task_sg_chain() and associated detritus 



Now that all fabrics are converted over to using se_cmd->t_data_sg
directly, we can drop the task sg chaining support.  With the modern
memory allocation in target core, task sg chaining is needless
overhead -- we would split up the main cmd sglist into pieces, and
then splice those pieces back together instead of just using the
original list directly.

Signed-off-by: default avatarRoland Dreier <roland@purestorage.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 6f9e7f01

drivers/target/target_core_transport.c

+0 −70
Original line number Diff line number Diff line
@@ -3699,76 +3699,6 @@ static inline sector_t transport_limit_task_sectors( 
	return sectors;

}





/*

 * This function can be used by HW target mode drivers to create a linked

 * scatterlist from all contiguously allocated struct se_task->task_sg[].

 * This is intended to be called during the completion path by TCM Core

 * when struct target_core_fabric_ops->check_task_sg_chaining is enabled.

 */

void transport_do_task_sg_chain(struct se_cmd *cmd)

{

	struct scatterlist *sg_first = NULL;

	struct scatterlist *sg_prev = NULL;

	int sg_prev_nents = 0;

	struct scatterlist *sg;

	struct se_task *task;

	u32 chained_nents = 0;

	int i;



	BUG_ON(!cmd->se_tfo->task_sg_chaining);



	/*

	 * Walk the struct se_task list and setup scatterlist chains

	 * for each contiguously allocated struct se_task->task_sg[].

	 */

	list_for_each_entry(task, &cmd->t_task_list, t_list) {

		if (!task->task_sg)

			continue;



		if (!sg_first) {

			sg_first = task->task_sg;

			chained_nents = task->task_sg_nents;

		} else {

			sg_chain(sg_prev, sg_prev_nents, task->task_sg);

			chained_nents += task->task_sg_nents;

		}

		/*

		 * For the padded tasks, use the extra SGL vector allocated

		 * in transport_allocate_data_tasks() for the sg_prev_nents

		 * offset into sg_chain() above.

		 *

		 * We do not need the padding for the last task (or a single

		 * task), but in that case we will never use the sg_prev_nents

		 * value below which would be incorrect.

		 */

		sg_prev_nents = (task->task_sg_nents + 1);

		sg_prev = task->task_sg;

	}

	/*

	 * Setup the starting pointer and total t_tasks_sg_linked_no including

	 * padding SGs for linking and to mark the end.

	 */

	cmd->t_tasks_sg_chained = sg_first;

	cmd->t_tasks_sg_chained_no = chained_nents;



	pr_debug("Setup cmd: %p cmd->t_tasks_sg_chained: %p and"

		" t_tasks_sg_chained_no: %u\n", cmd, cmd->t_tasks_sg_chained,

		cmd->t_tasks_sg_chained_no);



	for_each_sg(cmd->t_tasks_sg_chained, sg,

			cmd->t_tasks_sg_chained_no, i) {



		pr_debug("SG[%d]: %p page: %p length: %d offset: %d\n",

			i, sg, sg_page(sg), sg->length, sg->offset);

		if (sg_is_chain(sg))

			pr_debug("SG: %p sg_is_chain=1\n", sg);

		if (sg_is_last(sg))

			pr_debug("SG: %p sg_is_last=1\n", sg);

	}

}

EXPORT_SYMBOL(transport_do_task_sg_chain);



/*

 * Break up cmd into chunks transport can handle

 */

include/target/target_core_base.h

+0 −2
Original line number Diff line number Diff line
@@ -572,7 +572,6 @@ struct se_cmd { 
	unsigned char		*t_task_cdb;

	unsigned char		__t_task_cdb[TCM_MAX_COMMAND_SIZE];

	unsigned long long	t_task_lba;

	u32			t_tasks_sg_chained_no;

	atomic_t		t_fe_count;

	atomic_t		t_se_count;

	atomic_t		t_task_cdbs_left;
@@ -593,7 +592,6 @@ struct se_cmd { 
	struct completion	t_transport_stop_comp;

	struct completion	transport_lun_fe_stop_comp;

	struct completion	transport_lun_stop_comp;

	struct scatterlist	*t_tasks_sg_chained;



	struct work_struct	work;

include/target/target_core_fabric.h

+0 −7
Original line number Diff line number Diff line
@@ -3,12 +3,6 @@ 


struct target_core_fabric_ops {

	struct configfs_subsystem *tf_subsys;

	/*

	 * Optional to signal struct se_task->task_sg[] padding entries

	 * for scatterlist chaining using transport_do_task_sg_link(),

	 * disabled by default

	 */

	bool task_sg_chaining;

	char *(*get_fabric_name)(void);

	u8 (*get_fabric_proto_ident)(struct se_portal_group *);

	char *(*tpg_get_wwn)(struct se_portal_group *);
@@ -124,7 +118,6 @@ int transport_generic_handle_cdb_map(struct se_cmd *); 
int	transport_generic_handle_data(struct se_cmd *);

int	transport_generic_map_mem_to_cmd(struct se_cmd *cmd,

		struct scatterlist *, u32, struct scatterlist *, u32);

void	transport_do_task_sg_chain(struct se_cmd *);

int	transport_generic_new_cmd(struct se_cmd *);



void	transport_generic_process_write(struct se_cmd *);