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target: enhance and export target_alloc_sgl/target_free_sgl
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The SRP target driver will need to allocate and chain it's own SGLs soon.
For this export target_alloc_sgl, and add a new argument to it so that it
can allocate an additional chain entry that doesn't point to a page.  Also
export transport_free_sgl after renaming it to target_free_sgl to free
these SGLs again.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
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Christoph Hellwig authored and dledford committed May 13, 2016
1 parent a060b56 commit e64aa65
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Showing 4 changed files with 23 additions and 16 deletions.
32 changes: 18 additions & 14 deletions drivers/target/target_core_transport.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2195,7 +2195,7 @@ static void target_complete_ok_work(struct work_struct *work)
transport_handle_queue_full(cmd, cmd->se_dev);
}

static inline void transport_free_sgl(struct scatterlist *sgl, int nents)
void target_free_sgl(struct scatterlist *sgl, int nents)
{
struct scatterlist *sg;
int count;
Expand All @@ -2205,6 +2205,7 @@ static inline void transport_free_sgl(struct scatterlist *sgl, int nents)

kfree(sgl);
}
EXPORT_SYMBOL(target_free_sgl);

static inline void transport_reset_sgl_orig(struct se_cmd *cmd)
{
Expand All @@ -2225,7 +2226,7 @@ static inline void transport_reset_sgl_orig(struct se_cmd *cmd)
static inline void transport_free_pages(struct se_cmd *cmd)
{
if (!(cmd->se_cmd_flags & SCF_PASSTHROUGH_PROT_SG_TO_MEM_NOALLOC)) {
transport_free_sgl(cmd->t_prot_sg, cmd->t_prot_nents);
target_free_sgl(cmd->t_prot_sg, cmd->t_prot_nents);
cmd->t_prot_sg = NULL;
cmd->t_prot_nents = 0;
}
Expand All @@ -2236,7 +2237,7 @@ static inline void transport_free_pages(struct se_cmd *cmd)
* SG_TO_MEM_NOALLOC to function with COMPARE_AND_WRITE
*/
if (cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE) {
transport_free_sgl(cmd->t_bidi_data_sg,
target_free_sgl(cmd->t_bidi_data_sg,
cmd->t_bidi_data_nents);
cmd->t_bidi_data_sg = NULL;
cmd->t_bidi_data_nents = 0;
Expand All @@ -2246,11 +2247,11 @@ static inline void transport_free_pages(struct se_cmd *cmd)
}
transport_reset_sgl_orig(cmd);

transport_free_sgl(cmd->t_data_sg, cmd->t_data_nents);
target_free_sgl(cmd->t_data_sg, cmd->t_data_nents);
cmd->t_data_sg = NULL;
cmd->t_data_nents = 0;

transport_free_sgl(cmd->t_bidi_data_sg, cmd->t_bidi_data_nents);
target_free_sgl(cmd->t_bidi_data_sg, cmd->t_bidi_data_nents);
cmd->t_bidi_data_sg = NULL;
cmd->t_bidi_data_nents = 0;
}
Expand Down Expand Up @@ -2324,20 +2325,22 @@ EXPORT_SYMBOL(transport_kunmap_data_sg);

int
target_alloc_sgl(struct scatterlist **sgl, unsigned int *nents, u32 length,
bool zero_page)
bool zero_page, bool chainable)
{
struct scatterlist *sg;
struct page *page;
gfp_t zero_flag = (zero_page) ? __GFP_ZERO : 0;
unsigned int nent;
unsigned int nalloc, nent;
int i = 0;

nent = DIV_ROUND_UP(length, PAGE_SIZE);
sg = kmalloc(sizeof(struct scatterlist) * nent, GFP_KERNEL);
nalloc = nent = DIV_ROUND_UP(length, PAGE_SIZE);
if (chainable)
nalloc++;
sg = kmalloc_array(nalloc, sizeof(struct scatterlist), GFP_KERNEL);
if (!sg)
return -ENOMEM;

sg_init_table(sg, nent);
sg_init_table(sg, nalloc);

while (length) {
u32 page_len = min_t(u32, length, PAGE_SIZE);
Expand All @@ -2361,6 +2364,7 @@ target_alloc_sgl(struct scatterlist **sgl, unsigned int *nents, u32 length,
kfree(sg);
return -ENOMEM;
}
EXPORT_SYMBOL(target_alloc_sgl);

/*
* Allocate any required resources to execute the command. For writes we
Expand All @@ -2376,7 +2380,7 @@ transport_generic_new_cmd(struct se_cmd *cmd)
if (cmd->prot_op != TARGET_PROT_NORMAL &&
!(cmd->se_cmd_flags & SCF_PASSTHROUGH_PROT_SG_TO_MEM_NOALLOC)) {
ret = target_alloc_sgl(&cmd->t_prot_sg, &cmd->t_prot_nents,
cmd->prot_length, true);
cmd->prot_length, true, false);
if (ret < 0)
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
}
Expand All @@ -2401,13 +2405,13 @@ transport_generic_new_cmd(struct se_cmd *cmd)

ret = target_alloc_sgl(&cmd->t_bidi_data_sg,
&cmd->t_bidi_data_nents,
bidi_length, zero_flag);
bidi_length, zero_flag, false);
if (ret < 0)
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
}

ret = target_alloc_sgl(&cmd->t_data_sg, &cmd->t_data_nents,
cmd->data_length, zero_flag);
cmd->data_length, zero_flag, false);
if (ret < 0)
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
} else if ((cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE) &&
Expand All @@ -2421,7 +2425,7 @@ transport_generic_new_cmd(struct se_cmd *cmd)

ret = target_alloc_sgl(&cmd->t_bidi_data_sg,
&cmd->t_bidi_data_nents,
caw_length, zero_flag);
caw_length, zero_flag, false);
if (ret < 0)
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
}
Expand Down
2 changes: 1 addition & 1 deletion drivers/target/target_core_xcopy.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -563,7 +563,7 @@ static int target_xcopy_setup_pt_cmd(

if (alloc_mem) {
rc = target_alloc_sgl(&cmd->t_data_sg, &cmd->t_data_nents,
cmd->data_length, false);
cmd->data_length, false, false);
if (rc < 0) {
ret = rc;
goto out;
Expand Down
1 change: 0 additions & 1 deletion include/target/target_core_backend.h
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Original file line number Diff line number Diff line change
Expand Up @@ -85,7 +85,6 @@ extern struct configfs_attribute *passthrough_attrib_attrs[];
void *transport_kmap_data_sg(struct se_cmd *);
void transport_kunmap_data_sg(struct se_cmd *);
/* core helpers also used by xcopy during internal command setup */
int target_alloc_sgl(struct scatterlist **, unsigned int *, u32, bool);
sense_reason_t transport_generic_map_mem_to_cmd(struct se_cmd *,
struct scatterlist *, u32, struct scatterlist *, u32);

Expand Down
4 changes: 4 additions & 0 deletions include/target/target_core_fabric.h
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Original file line number Diff line number Diff line change
Expand Up @@ -185,6 +185,10 @@ int core_tpg_set_initiator_node_tag(struct se_portal_group *,
int core_tpg_register(struct se_wwn *, struct se_portal_group *, int);
int core_tpg_deregister(struct se_portal_group *);

int target_alloc_sgl(struct scatterlist **sgl, unsigned int *nents,
u32 length, bool zero_page, bool chainable);
void target_free_sgl(struct scatterlist *sgl, int nents);

/*
* The LIO target core uses DMA_TO_DEVICE to mean that data is going
* to the target (eg handling a WRITE) and DMA_FROM_DEVICE to mean
Expand Down

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