We don't need use one iovec per scatter-gather list entry, since data
area are continuous.
Signed-off-by: Sheng Yang <sheng@xxxxxxxxxx>
---
drivers/target/target_core_user.c | 41 +++++++++++++++++++++++++--------------
1 file changed, 26 insertions(+), 15 deletions(-)
diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index 94f5154..93de51f 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -231,6 +231,23 @@ static inline size_t head_to_end(size_t head, size_t size)
return size - head;
}
+static inline void new_iov(struct iovec **iov, int *iov_cnt,
+ struct tcmu_dev *udev)
+{
+ struct iovec *iovec;
+
+ if (*iov_cnt != 0)
+ (*iov)++;
+ (*iov_cnt)++;
+
+ iovec = *iov;
+ memset(iovec, 0, sizeof(struct iovec));
+
+ /* Even iov_base is relative to mb_addr */
+ iovec->iov_base = (void __user *) udev->data_off +
+ udev->data_head;
+}
+
#define UPDATE_HEAD(head, used, size) smp_store_release(&head, ((head % size) + used) % size)
static void alloc_and_scatter_data_area(struct tcmu_dev *udev,
@@ -242,6 +259,10 @@ static void alloc_and_scatter_data_area(struct tcmu_dev *udev,
size_t copy_bytes;
struct scatterlist *sg;
+ if (data_nents == 0)
+ return;
+
+ new_iov(iov, iov_cnt, udev);
for_each_sg(data_sg, sg, data_nents, i) {
copy_bytes = min_t(size_t, sg->length,
head_to_end(udev->data_head, udev->data_size));
@@ -253,12 +274,7 @@ static void alloc_and_scatter_data_area(struct tcmu_dev *udev,
tcmu_flush_dcache_range(to, copy_bytes);
}
- /* Even iov_base is relative to mb_addr */
- (*iov)->iov_len = copy_bytes;
- (*iov)->iov_base = (void __user *) udev->data_off +
- udev->data_head;
- (*iov_cnt)++;
- (*iov)++;
+ (*iov)->iov_len += copy_bytes;
UPDATE_HEAD(udev->data_head, copy_bytes, udev->data_size);
@@ -268,9 +284,8 @@ static void alloc_and_scatter_data_area(struct tcmu_dev *udev,
copy_bytes = sg->length - copy_bytes;
+ new_iov(iov, iov_cnt, udev);
(*iov)->iov_len = copy_bytes;
- (*iov)->iov_base = (void __user *) udev->data_off +
- udev->data_head;
if (copy_data) {
to = (void *) udev->mb_addr +
@@ -279,8 +294,6 @@ static void alloc_and_scatter_data_area(struct tcmu_dev *udev,
tcmu_flush_dcache_range(to, copy_bytes);
}
- (*iov_cnt)++;
- (*iov)++;
UPDATE_HEAD(udev->data_head,
copy_bytes, udev->data_size);
@@ -393,12 +406,10 @@ static int tcmu_queue_cmd_ring(struct tcmu_cmd *tcmu_cmd)
* Must be a certain minimum size for response sense info, but
* also may be larger if the iov array is large.
*
- * iovs = sgl_nents+1, for end-of-ring case, plus another 1
- * b/c size == offsetof one-past-element.
+ * 3 iovs since we can describe the whole continuous are using one
+ * for data, one for bidi and one more in the case of wrap.
*/
- base_command_size = max(offsetof(struct tcmu_cmd_entry,
- req.iov[se_cmd->t_bidi_data_nents +
- se_cmd->t_data_nents + 2]),
+ base_command_size = max(offsetof(struct tcmu_cmd_entry, req.iov[3]),
sizeof(struct tcmu_cmd_entry));
command_size = base_command_size
+ round_up(scsi_command_size(se_cmd->t_task_cdb), TCMU_OP_ALIGN_SIZE);
--
2.1.4
--
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