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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: Roland Dreier <roland@purestorage.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Roland Dreier 2012-03-30 11:29:15 -07:00 committed by Nicholas Bellinger
parent 6f9e7f01b6
commit 957525a242
3 changed files with 0 additions and 79 deletions
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70
drivers/target/target_core_transport.c
View File

@ -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
*/

2
include/target/target_core_base.h
View File

@ -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;

7
include/target/target_core_fabric.h
View File

@ -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 *);