[openib-general][patch review] srp: fmr implementation,
Roland Dreier
rdreier at cisco.com
Mon Mar 20 15:55:14 PST 2006
So, I am working on merging the FMR stuff. However, looking at this
patch, I see too many nested conditionals -- we check if it's an SG
command or not, and then we check whether to use FMRs or not.
As a step towards cleaning things up, I made the following patch,
which makes up a fake scatterlist for non-SG commands. Since the SCSI
midlayer is moving towards having no non-SG commands (the only ones I
see now are mode sense -- ie none in the usual data path), eventually
we can delete even more code.
Anyway, I should be able to work on adding FMRs to this cleaner
framework now.
Thanks,
Roland
diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index a13dcdf..768ec8b 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -40,6 +40,7 @@
#include <linux/parser.h>
#include <linux/random.h>
#include <linux/jiffies.h>
+#include <linux/scatterlist.h>
#include <asm/atomic.h>
@@ -503,8 +504,10 @@ err:
static int srp_map_data(struct scsi_cmnd *scmnd, struct srp_target_port *target,
struct srp_request *req)
{
+ struct scatterlist *scat;
struct srp_cmd *cmd = req->cmd->buf;
- int len;
+ int len, nents, count;
+ int i;
u8 fmt;
if (!scmnd->request_buffer || scmnd->sc_data_direction == DMA_NONE)
@@ -517,82 +520,66 @@ static int srp_map_data(struct scsi_cmnd
return -EINVAL;
}
- if (scmnd->use_sg) {
- struct scatterlist *scat = scmnd->request_buffer;
- int n;
- int i;
+ /*
+ * This handling of non-SG commands can be killed when the
+ * SCSI midlayer no longer generates non-SG commands.
+ */
+ if (likely(scmnd->use_sg)) {
+ nents = scmnd->use_sg;
+ scat = scmnd->request_buffer;
+ } else {
+ nents = 1;
+ scat = &req->fake_sg;
+ sg_init_one(scat, scmnd->request_buffer, scmnd->request_bufflen);
+ }
- n = dma_map_sg(target->srp_host->dev->dma_device,
- scat, scmnd->use_sg, scmnd->sc_data_direction);
+ count = dma_map_sg(target->srp_host->dev->dma_device, scat, nents,
+ scmnd->sc_data_direction);
- if (n == 1) {
- struct srp_direct_buf *buf = (void *) cmd->add_data;
+ if (count == 1) {
+ struct srp_direct_buf *buf = (void *) cmd->add_data;
- fmt = SRP_DATA_DESC_DIRECT;
+ fmt = SRP_DATA_DESC_DIRECT;
- buf->va = cpu_to_be64(sg_dma_address(scat));
- buf->key = cpu_to_be32(target->srp_host->mr->rkey);
- buf->len = cpu_to_be32(sg_dma_len(scat));
+ buf->va = cpu_to_be64(sg_dma_address(scat));
+ buf->key = cpu_to_be32(target->srp_host->mr->rkey);
+ buf->len = cpu_to_be32(sg_dma_len(scat));
- len = sizeof (struct srp_cmd) +
- sizeof (struct srp_direct_buf);
- } else {
- struct srp_indirect_buf *buf = (void *) cmd->add_data;
- u32 datalen = 0;
+ len = sizeof (struct srp_cmd) +
+ sizeof (struct srp_direct_buf);
+ } else {
+ struct srp_indirect_buf *buf = (void *) cmd->add_data;
+ u32 datalen = 0;
- fmt = SRP_DATA_DESC_INDIRECT;
+ fmt = SRP_DATA_DESC_INDIRECT;
- if (scmnd->sc_data_direction == DMA_TO_DEVICE)
- cmd->data_out_desc_cnt = n;
- else
- cmd->data_in_desc_cnt = n;
+ if (scmnd->sc_data_direction == DMA_TO_DEVICE)
+ cmd->data_out_desc_cnt = count;
+ else
+ cmd->data_in_desc_cnt = count;
- buf->table_desc.va = cpu_to_be64(req->cmd->dma +
- sizeof *cmd +
- sizeof *buf);
- buf->table_desc.key =
+ buf->table_desc.va = cpu_to_be64(req->cmd->dma +
+ sizeof *cmd +
+ sizeof *buf);
+ buf->table_desc.key =
+ cpu_to_be32(target->srp_host->mr->rkey);
+ buf->table_desc.len =
+ cpu_to_be32(count * sizeof (struct srp_direct_buf));
+
+ for (i = 0; i < count; ++i) {
+ buf->desc_list[i].va = cpu_to_be64(sg_dma_address(&scat[i]));
+ buf->desc_list[i].key =
cpu_to_be32(target->srp_host->mr->rkey);
- buf->table_desc.len =
- cpu_to_be32(n * sizeof (struct srp_direct_buf));
-
- for (i = 0; i < n; ++i) {
- buf->desc_list[i].va = cpu_to_be64(sg_dma_address(&scat[i]));
- buf->desc_list[i].key =
- cpu_to_be32(target->srp_host->mr->rkey);
- buf->desc_list[i].len = cpu_to_be32(sg_dma_len(&scat[i]));
-
- datalen += sg_dma_len(&scat[i]);
- }
+ buf->desc_list[i].len = cpu_to_be32(sg_dma_len(&scat[i]));
- buf->len = cpu_to_be32(datalen);
-
- len = sizeof (struct srp_cmd) +
- sizeof (struct srp_indirect_buf) +
- n * sizeof (struct srp_direct_buf);
- }
- } else {
- struct srp_direct_buf *buf = (void *) cmd->add_data;
- dma_addr_t dma;
-
- dma = dma_map_single(target->srp_host->dev->dma_device,
- scmnd->request_buffer, scmnd->request_bufflen,
- scmnd->sc_data_direction);
- if (dma_mapping_error(dma)) {
- printk(KERN_WARNING PFX "unable to map %p/%d (dir %d)\n",
- scmnd->request_buffer, (int) scmnd->request_bufflen,
- scmnd->sc_data_direction);
- return -EINVAL;
+ datalen += sg_dma_len(&scat[i]);
}
- pci_unmap_addr_set(req, direct_mapping, dma);
-
- buf->va = cpu_to_be64(dma);
- buf->key = cpu_to_be32(target->srp_host->mr->rkey);
- buf->len = cpu_to_be32(scmnd->request_bufflen);
-
- fmt = SRP_DATA_DESC_DIRECT;
+ buf->len = cpu_to_be32(datalen);
- len = sizeof (struct srp_cmd) + sizeof (struct srp_direct_buf);
+ len = sizeof (struct srp_cmd) +
+ sizeof (struct srp_indirect_buf) +
+ count * sizeof (struct srp_direct_buf);
}
if (scmnd->sc_data_direction == DMA_TO_DEVICE)
@@ -600,7 +587,6 @@ static int srp_map_data(struct scsi_cmnd
else
cmd->buf_fmt = fmt;
-
return len;
}
@@ -608,20 +594,28 @@ static void srp_unmap_data(struct scsi_c
struct srp_target_port *target,
struct srp_request *req)
{
+ struct scatterlist *scat;
+ int nents;
+
if (!scmnd->request_buffer ||
(scmnd->sc_data_direction != DMA_TO_DEVICE &&
scmnd->sc_data_direction != DMA_FROM_DEVICE))
return;
- if (scmnd->use_sg)
- dma_unmap_sg(target->srp_host->dev->dma_device,
- (struct scatterlist *) scmnd->request_buffer,
- scmnd->use_sg, scmnd->sc_data_direction);
- else
- dma_unmap_single(target->srp_host->dev->dma_device,
- pci_unmap_addr(req, direct_mapping),
- scmnd->request_bufflen,
- scmnd->sc_data_direction);
+ /*
+ * This handling of non-SG commands can be killed when the
+ * SCSI midlayer no longer generates non-SG commands.
+ */
+ if (likely(scmnd->use_sg)) {
+ nents = scmnd->use_sg;
+ scat = (struct scatterlist *) scmnd->request_buffer;
+ } else {
+ nents = 1;
+ scat = (struct scatterlist *) scmnd->request_buffer;
+ }
+
+ dma_unmap_sg(target->srp_host->dev->dma_device, scat, nents,
+ scmnd->sc_data_direction);
}
static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h
index 4e7727d..a3290cc 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.h
+++ b/drivers/infiniband/ulp/srp/ib_srp.h
@@ -94,7 +94,11 @@ struct srp_request {
struct scsi_cmnd *scmnd;
struct srp_iu *cmd;
struct srp_iu *tsk_mgmt;
- DECLARE_PCI_UNMAP_ADDR(direct_mapping)
+ /*
+ * Fake scatterlist used when scmnd->use_sg==0. Can be killed
+ * when the SCSI midlayer no longer generates non-SG commands.
+ */
+ struct scatterlist fake_sg;
struct completion done;
short next;
u8 cmd_done;
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