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Commit 3e609135 authored by Xiubo Li's avatar Xiubo Li Committed by Nicholas Bellinger
Browse files

tcmu: clean up the scatter helper 



Add some comments to make the scatter code to be more readable,
and drop unused arg to new_iov.

Signed-off-by: default avatarXiubo Li <lixiubo@cmss.chinamobile.com>
Signed-off-by: default avatarMike Christie <mchristi@redhat.com>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 3c0f26ff

drivers/target/target_core_user.c

+25 −5
Original line number Diff line number Diff line
@@ -492,8 +492,7 @@ 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)

static inline void new_iov(struct iovec **iov, int *iov_cnt)

{

	struct iovec *iovec;
@@ -546,19 +545,38 @@ static void scatter_data_area(struct tcmu_dev *udev, 
				to = kmap_atomic(page);

			}



			copy_bytes = min_t(size_t, sg_remaining,

					block_remaining);

			/*

			 * Covert to virtual offset of the ring data area.

			 */

			to_offset = get_block_offset_user(udev, dbi,

					block_remaining);



			/*

			 * The following code will gather and map the blocks

			 * to the same iovec when the blocks are all next to

			 * each other.

			 */

			copy_bytes = min_t(size_t, sg_remaining,

					block_remaining);

			if (*iov_cnt != 0 &&

			    to_offset == iov_tail(*iov)) {

				/*

				 * Will append to the current iovec, because

				 * the current block page is next to the

				 * previous one.

				 */

				(*iov)->iov_len += copy_bytes;

			} else {

				new_iov(iov, iov_cnt, udev);

				/*

				 * Will allocate a new iovec because we are

				 * first time here or the current block page

				 * is not next to the previous one.

				 */

				new_iov(iov, iov_cnt);

				(*iov)->iov_base = (void __user *)to_offset;

				(*iov)->iov_len = copy_bytes;

			}



			if (copy_data) {

				offset = DATA_BLOCK_SIZE - block_remaining;

				memcpy(to + offset,
@@ -566,11 +584,13 @@ static void scatter_data_area(struct tcmu_dev *udev, 
				       copy_bytes);

				tcmu_flush_dcache_range(to, copy_bytes);

			}



			sg_remaining -= copy_bytes;

			block_remaining -= copy_bytes;

		}

		kunmap_atomic(from - sg->offset);

	}



	if (to)

		kunmap_atomic(to);

}