To support zero-copy for user backend, allow backend allocating sgl pages.
Unfortunately we need extra copy in tcm_loop for user backend, but since it's
just for test, not a big deal.
Signed-off-by: Shaohua Li <shli@xxxxxxxxxx>
---
drivers/target/loopback/tcm_loop.c | 49 ++++++++++++++++++++++++++++++++-
drivers/target/target_core_transport.c | 24 +++++++++++-----
drivers/target/target_core_xcopy.c | 4 +-
include/target/target_core_backend.h | 5 ++-
4 files changed, 71 insertions(+), 11 deletions(-)
Index: linux/drivers/target/loopback/tcm_loop.c
===================================================================
--- linux.orig/drivers/target/loopback/tcm_loop.c 2013-11-16 09:13:55.606790041 +0800
+++ linux/drivers/target/loopback/tcm_loop.c 2013-11-16 09:13:55.594790204 +0800
@@ -33,6 +33,7 @@
#include <scsi/scsi_cmnd.h>
#include <target/target_core_base.h>
+#include <target/target_core_backend.h>
#include <target/target_core_fabric.h>
#include <target/target_core_fabric_configfs.h>
#include <target/target_core_configfs.h>
@@ -166,6 +167,9 @@ static void tcm_loop_submission_work(str
struct scatterlist *sgl_bidi = NULL;
u32 sgl_bidi_count = 0;
int rc;
+ struct se_lun *se_lun;
+ struct se_device *dev;
+ bool alloc_sgl = false;
tl_hba = *(struct tcm_loop_hba **)shost_priv(sc->device->host);
tl_tpg = &tl_hba->tl_hba_tpgs[sc->device->id];
@@ -194,7 +198,21 @@ static void tcm_loop_submission_work(str
se_cmd->se_cmd_flags |= SCF_BIDI;
}
- rc = target_submit_cmd_map_sgls(se_cmd, tl_nexus->se_sess, sc->cmnd,
+
+ spin_lock(&tl_tpg->tl_se_tpg.tpg_lun_lock);
+ se_lun = tl_tpg->tl_se_tpg.tpg_lun_list[tl_cmd->sc->device->lun];
+ dev = se_lun->lun_se_dev;
+ if (dev->transport->alloc_sgl)
+ alloc_sgl = true;
+ spin_unlock(&tl_tpg->tl_se_tpg.tpg_lun_lock);
+
+ if (alloc_sgl)
+ rc = target_submit_cmd(se_cmd, tl_nexus->se_sess, sc->cmnd,
+ &tl_cmd->tl_sense_buf[0], tl_cmd->sc->device->lun,
+ scsi_bufflen(sc), tcm_loop_sam_attr(sc),
+ sc->sc_data_direction, 0);
+ else
+ rc = target_submit_cmd_map_sgls(se_cmd, tl_nexus->se_sess, sc->cmnd,
&tl_cmd->tl_sense_buf[0], tl_cmd->sc->device->lun,
scsi_bufflen(sc), tcm_loop_sam_attr(sc),
sc->sc_data_direction, 0,
@@ -720,8 +738,36 @@ static void tcm_loop_close_session(struc
return;
};
+static void tcm_loop_copy_sgl(struct se_cmd *se_cmd, bool to_scsi)
+{
+ struct tcm_loop_cmd *tl_cmd = container_of(se_cmd,
+ struct tcm_loop_cmd, tl_se_cmd);
+ struct scsi_cmnd *sc = tl_cmd->sc;
+ void *buf;
+
+ if (!se_cmd->se_dev->transport->alloc_sgl)
+ return;
+
+ buf = vmalloc(scsi_bufflen(sc));
+
+ if (to_scsi) {
+ sg_copy_to_buffer(se_cmd->t_data_sg, se_cmd->t_data_nents,
+ buf, scsi_bufflen(sc));
+ sg_copy_from_buffer(scsi_sglist(sc), scsi_sg_count(sc),
+ buf, scsi_bufflen(sc));
+ } else {
+ sg_copy_to_buffer(scsi_sglist(sc), scsi_sg_count(sc),
+ buf, scsi_bufflen(sc));
+ sg_copy_from_buffer(se_cmd->t_data_sg, se_cmd->t_data_nents,
+ buf, scsi_bufflen(sc));
+ }
+ vfree(buf);
+}
+
static int tcm_loop_write_pending(struct se_cmd *se_cmd)
{
+ tcm_loop_copy_sgl(se_cmd, false);
+
/*
* Since Linux/SCSI has already sent down a struct scsi_cmnd
* sc->sc_data_direction of DMA_TO_DEVICE with struct scatterlist array
@@ -754,6 +800,7 @@ static int tcm_loop_queue_data_in(struct
if ((se_cmd->se_cmd_flags & SCF_OVERFLOW_BIT) ||
(se_cmd->se_cmd_flags & SCF_UNDERFLOW_BIT))
scsi_set_resid(sc, se_cmd->residual_count);
+ tcm_loop_copy_sgl(se_cmd, true);
sc->scsi_done(sc);
return 0;
}
Index: linux/drivers/target/target_core_transport.c
===================================================================
--- linux.orig/drivers/target/target_core_transport.c 2013-11-16 09:13:55.606790041 +0800
+++ linux/drivers/target/target_core_transport.c 2013-11-16 09:13:55.598790131 +0800
@@ -1998,11 +1998,17 @@ queue_full:
transport_handle_queue_full(cmd, cmd->se_dev);
}
-static inline void transport_free_sgl(struct scatterlist *sgl, int nents)
+static inline void transport_free_sgl(struct se_device *se_dev,
+ struct scatterlist *sgl, int nents)
{
struct scatterlist *sg;
int count;
+ if (se_dev->transport->free_sgl) {
+ se_dev->transport->free_sgl(se_dev, sgl, nents);
+ return;
+ }
+
for_each_sg(sgl, sg, nents, count)
__free_page(sg_page(sg));
@@ -2033,11 +2039,11 @@ static inline void transport_free_pages(
}
transport_reset_sgl_orig(cmd);
- transport_free_sgl(cmd->t_data_sg, cmd->t_data_nents);
+ transport_free_sgl(cmd->se_dev, 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);
+ transport_free_sgl(cmd->se_dev, cmd->t_bidi_data_sg, cmd->t_bidi_data_nents);
cmd->t_bidi_data_sg = NULL;
cmd->t_bidi_data_nents = 0;
}
@@ -2128,8 +2134,8 @@ void transport_kunmap_data_sg(struct se_
EXPORT_SYMBOL(transport_kunmap_data_sg);
int
-target_alloc_sgl(struct scatterlist **sgl, unsigned int *nents, u32 length,
- bool zero_page)
+target_alloc_sgl(struct se_device *se_dev, struct scatterlist **sgl,
+ unsigned int *nents, u32 length, bool zero_page)
{
struct scatterlist *sg;
struct page *page;
@@ -2137,6 +2143,10 @@ target_alloc_sgl(struct scatterlist **sg
unsigned int nent;
int i = 0;
+ if (se_dev->transport->alloc_sgl)
+ return se_dev->transport->alloc_sgl(se_dev, sgl,
+ nents, length, zero_page);
+
nent = DIV_ROUND_UP(length, PAGE_SIZE);
sg = kmalloc(sizeof(struct scatterlist) * nent, GFP_KERNEL);
if (!sg)
@@ -2196,14 +2206,14 @@ transport_generic_new_cmd(struct se_cmd
else
bidi_length = cmd->data_length;
- ret = target_alloc_sgl(&cmd->t_bidi_data_sg,
+ ret = target_alloc_sgl(cmd->se_dev, &cmd->t_bidi_data_sg,
&cmd->t_bidi_data_nents,
bidi_length, zero_flag);
if (ret < 0)
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
}
- ret = target_alloc_sgl(&cmd->t_data_sg, &cmd->t_data_nents,
+ ret = target_alloc_sgl(cmd->se_dev, &cmd->t_data_sg, &cmd->t_data_nents,
cmd->data_length, zero_flag);
if (ret < 0)
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
Index: linux/drivers/target/target_core_xcopy.c
===================================================================
--- linux.orig/drivers/target/target_core_xcopy.c 2013-11-16 09:13:55.606790041 +0800
+++ linux/drivers/target/target_core_xcopy.c 2013-11-16 09:13:55.598790131 +0800
@@ -626,8 +626,8 @@ 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);
+ rc = target_alloc_sgl(cmd->se_dev, &cmd->t_data_sg,
+ &cmd->t_data_nents, cmd->data_length, false);
if (rc < 0) {
ret = rc;
goto out;
Index: linux/include/target/target_core_backend.h
===================================================================
--- linux.orig/include/target/target_core_backend.h 2013-11-16 09:13:55.606790041 +0800
+++ linux/include/target/target_core_backend.h 2013-11-16 09:13:55.602790072 +0800
@@ -36,6 +36,9 @@ struct se_subsystem_api {
sector_t (*get_blocks)(struct se_device *);
unsigned char *(*get_sense_buffer)(struct se_cmd *);
bool (*get_write_cache)(struct se_device *);
+ int (*alloc_sgl)(struct se_device *, struct scatterlist **,
+ unsigned int *, uint32_t, bool);
+ void (*free_sgl)(struct se_device *, struct scatterlist *, int);
};
struct sbc_ops {
@@ -75,7 +78,7 @@ int transport_set_vpd_ident(struct t10_v
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);
+int target_alloc_sgl(struct se_device*, struct scatterlist **, unsigned int *, u32, bool);
sense_reason_t transport_generic_map_mem_to_cmd(struct se_cmd *,
struct scatterlist *, u32, struct scatterlist *, u32);
--
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