From: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
Subject: Re: [PATCH v2] add bidi support for block pc requests
Date: Thu, 10 May 2007 15:53:22 +0900
> From: Boaz Harrosh <bharrosh@xxxxxxxxxxx>
> Subject: Re: [PATCH v2] add bidi support for block pc requests
> Date: Wed, 09 May 2007 19:54:32 +0300
>
> > James Bottomley wrote:
> > > Actually, the first order of business is to use accessors on the command
> > > pointers in the drivers to free them from the internal layout of the
> > > structure (and where it is allocated).
> > >
> > Thanks! I totally second that. Let me look into my old patches and come
> > up with all the needed accessors. I hope 3-5 will be enough.
> > I will send some suggestions tomorrow.
> > >
> > > No, that's why you do the accessors. Convert all of the common drivers
> > > to accessors on the current structure, then throw the switch to convert
> > > to the new structure (whatever form is finally settled on). Then any
> > > unconverted drivers break and people fix the ones they care about.
> >
> > Last time I was able to compile 97% of drivers and convert by search-and-replace
> > the rest. Not a huge deal.
>
> We need to remove the non-use-sg code in the drivers and convert
> them. So it's a bit more complicated than search-and-replace.
Here's a patch to convert ibmvscsi to use helper functions (though it
needs more testings).
---
diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
index fbc1d5c..fb764ff 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -353,20 +353,18 @@ static void unmap_cmd_data(struct srp_cm
}
}
-static int map_sg_list(int num_entries,
- struct scatterlist *sg,
- struct srp_direct_buf *md)
+static int map_sg_list(struct scsi_cmnd *cmd, int nseg, struct srp_direct_buf *md)
{
int i;
+ struct scatterlist *sg;
u64 total_length = 0;
- for (i = 0; i < num_entries; ++i) {
+ scsi_for_each_sg(cmd, nseg, i) {
struct srp_direct_buf *descr = md + i;
- struct scatterlist *sg_entry = &sg[i];
- descr->va = sg_dma_address(sg_entry);
- descr->len = sg_dma_len(sg_entry);
+ descr->va = sg_dma_address(sg);
+ descr->len = sg_dma_len(sg);
descr->key = 0;
- total_length += sg_dma_len(sg_entry);
+ total_length += sg_dma_len(sg);
}
return total_length;
}
@@ -384,43 +382,39 @@ static int map_sg_data(struct scsi_cmnd
struct srp_event_struct *evt_struct,
struct srp_cmd *srp_cmd, struct device *dev)
{
-
int sg_mapped;
u64 total_length = 0;
- struct scatterlist *sg = cmd->request_buffer;
struct srp_direct_buf *data =
(struct srp_direct_buf *) srp_cmd->add_data;
struct srp_indirect_buf *indirect =
(struct srp_indirect_buf *) data;
- sg_mapped = dma_map_sg(dev, sg, cmd->use_sg, DMA_BIDIRECTIONAL);
-
- if (sg_mapped == 0)
+ sg_mapped = scsi_dma_map(dev, cmd);
+ if (!sg_mapped)
+ return 1;
+ else if (sg_mapped < 0)
return 0;
+ else if (sg_mapped > SG_ALL) {
+ printk(KERN_ERR
+ "ibmvscsi: More than %d mapped sg entries, got %d\n",
+ SG_ALL, sg_mapped);
+ return 0;
+ }
set_srp_direction(cmd, srp_cmd, sg_mapped);
/* special case; we can use a single direct descriptor */
if (sg_mapped == 1) {
- data->va = sg_dma_address(&sg[0]);
- data->len = sg_dma_len(&sg[0]);
- data->key = 0;
+ map_sg_list(cmd, sg_mapped, data);
return 1;
}
- if (sg_mapped > SG_ALL) {
- printk(KERN_ERR
- "ibmvscsi: More than %d mapped sg entries, got %d\n",
- SG_ALL, sg_mapped);
- return 0;
- }
-
indirect->table_desc.va = 0;
indirect->table_desc.len = sg_mapped * sizeof(struct srp_direct_buf);
indirect->table_desc.key = 0;
if (sg_mapped <= MAX_INDIRECT_BUFS) {
- total_length = map_sg_list(sg_mapped, sg,
+ total_length = map_sg_list(cmd, sg_mapped,
&indirect->desc_list[0]);
indirect->len = total_length;
return 1;
@@ -429,61 +423,27 @@ static int map_sg_data(struct scsi_cmnd
/* get indirect table */
if (!evt_struct->ext_list) {
evt_struct->ext_list = (struct srp_direct_buf *)
- dma_alloc_coherent(dev,
+ dma_alloc_coherent(dev,
SG_ALL * sizeof(struct srp_direct_buf),
&evt_struct->ext_list_token, 0);
if (!evt_struct->ext_list) {
printk(KERN_ERR
"ibmvscsi: Can't allocate memory for indirect table\n");
return 0;
-
}
}
- total_length = map_sg_list(sg_mapped, sg, evt_struct->ext_list);
+ total_length = map_sg_list(cmd, sg_mapped, evt_struct->ext_list);
indirect->len = total_length;
indirect->table_desc.va = evt_struct->ext_list_token;
indirect->table_desc.len = sg_mapped * sizeof(indirect->desc_list[0]);
memcpy(indirect->desc_list, evt_struct->ext_list,
MAX_INDIRECT_BUFS * sizeof(struct srp_direct_buf));
-
return 1;
}
/**
- * map_single_data: - Maps memory and initializes memory decriptor fields
- * @cmd: struct scsi_cmnd with the memory to be mapped
- * @srp_cmd: srp_cmd that contains the memory descriptor
- * @dev: device for which to map dma memory
- *
- * Called by map_data_for_srp_cmd() when building srp cmd from scsi cmd.
- * Returns 1 on success.
-*/
-static int map_single_data(struct scsi_cmnd *cmd,
- struct srp_cmd *srp_cmd, struct device *dev)
-{
- struct srp_direct_buf *data =
- (struct srp_direct_buf *) srp_cmd->add_data;
-
- data->va =
- dma_map_single(dev, cmd->request_buffer,
- cmd->request_bufflen,
- DMA_BIDIRECTIONAL);
- if (dma_mapping_error(data->va)) {
- printk(KERN_ERR
- "ibmvscsi: Unable to map request_buffer for command!\n");
- return 0;
- }
- data->len = cmd->request_bufflen;
- data->key = 0;
-
- set_srp_direction(cmd, srp_cmd, 1);
-
- return 1;
-}
-
-/**
* map_data_for_srp_cmd: - Calls functions to map data for srp cmds
* @cmd: struct scsi_cmnd with the memory to be mapped
* @srp_cmd: srp_cmd that contains the memory descriptor
@@ -513,11 +473,7 @@ static int map_data_for_srp_cmd(struct s
return 0;
}
- if (!cmd->request_buffer)
- return 1;
- if (cmd->use_sg)
- return map_sg_data(cmd, evt_struct, srp_cmd, dev);
- return map_single_data(cmd, srp_cmd, dev);
+ return map_sg_data(cmd, evt_struct, srp_cmd, dev);
}
/* ------------------------------------------------------------
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 9f7482d..dd6fdf6 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -2292,3 +2292,29 @@ void scsi_kunmap_atomic_sg(void *virt)
kunmap_atomic(virt, KM_BIO_SRC_IRQ);
}
EXPORT_SYMBOL(scsi_kunmap_atomic_sg);
+
+int scsi_dma_map(struct device *dev, struct scsi_cmnd *cmd)
+{
+ int nseg = 0;
+
+ if (cmd->use_sg) {
+ struct scatterlist *sg =
+ (struct scatterlist *) cmd->request_buffer;
+
+ nseg = dma_map_sg(dev, sg, cmd->use_sg, cmd->sc_data_direction);
+ if (unlikely(!nseg))
+ return -ENOMEM;
+ }
+ return nseg;
+}
+EXPORT_SYMBOL(scsi_dma_map);
+
+void scsi_dma_unmap(struct device *dev, struct scsi_cmnd *cmd)
+{
+ if (cmd->use_sg) {
+ struct scatterlist *sg =
+ (struct scatterlist *) cmd->request_buffer;
+ dma_unmap_sg(dev, sg, cmd->use_sg, cmd->sc_data_direction);
+ }
+}
+EXPORT_SYMBOL(scsi_dma_unmap);
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index d6948d0..799f204 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -138,4 +138,17 @@ extern void scsi_kunmap_atomic_sg(void *
extern struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *, gfp_t);
extern void scsi_free_sgtable(struct scatterlist *, int);
+extern int scsi_dma_map(struct device *dev, struct scsi_cmnd *cmd);
+extern void scsi_dma_unmap(struct device *dev, struct scsi_cmnd *cmd);
+
+/* moved to scatterlist.h after chaining sg */
+#define sg_next(sg) ((sg) + 1)
+
+#define scsi_for_each_sg(cmd, nseg, i) \
+ for (i = 0, sg = (cmd)->request_buffer; i < nseg; \
+ sg = sg_next(sg), i++) \
+
+#define scsi_sg_count(cmd) ((cmd)->use_sg)
+#define scsi_bufferlen(cmd) ((cmd)->request_bufflen)
+
#endif /* _SCSI_SCSI_CMND_H */
-
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
