Commit f97ec7db authored by Ilias Tsitsimpis's avatar Ilias Tsitsimpis Committed by Nicholas Bellinger
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target/user: Refactor data area allocation code 



Introduce alloc_and_scatter_data_area()/gather_and_free_data_area()
functions that allocate/deallocate space from the data area and copy
data to/from a given scatter-gather list. These functions are needed so
the next patch, introducing support for bidirectional commands in TCMU,
can use the same code path both for t_data_sg and for t_bidi_data_sg.

Signed-off-by: default avatarIlias Tsitsimpis <iliastsi@arrikto.com>
Signed-off-by: default avatarVangelis Koukis <vkoukis@arrikto.com>
Reviewed-by: default avatarAndy Grover <agrover@redhat.com>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent b32bd0a8

drivers/target/target_core_user.c

+106 −83
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2013 Shaohua Li <shli@kernel.org>

 * Copyright (C) 2014 Red Hat, Inc.

 * Copyright (C) 2015 Arrikto, Inc.

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms and conditions of the GNU General Public License,
@@ -224,9 +225,104 @@ static inline size_t head_to_end(size_t head, size_t size) 


#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,

	struct scatterlist *data_sg, unsigned int data_nents,

	struct iovec **iov, int *iov_cnt, bool copy_data)

{

	int i;

	void *from, *to;

	size_t copy_bytes;

	struct scatterlist *sg;



	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));

		from = kmap_atomic(sg_page(sg)) + sg->offset;

		to = (void *) udev->mb_addr + udev->data_off + udev->data_head;



		if (copy_data) {

			memcpy(to, from, copy_bytes);

			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)++;



		UPDATE_HEAD(udev->data_head, copy_bytes, udev->data_size);



		/* Uh oh, we wrapped the buffer. Must split sg across 2 iovs. */

		if (sg->length != copy_bytes) {

			from += copy_bytes;

			copy_bytes = sg->length - copy_bytes;



			(*iov)->iov_len = copy_bytes;

			(*iov)->iov_base = (void __user *) udev->data_off +

							udev->data_head;



			if (copy_data) {

				to = (void *) udev->mb_addr +

					udev->data_off + udev->data_head;

				memcpy(to, from, copy_bytes);

				tcmu_flush_dcache_range(to, copy_bytes);

			}



			(*iov_cnt)++;

			(*iov)++;



			UPDATE_HEAD(udev->data_head,

				copy_bytes, udev->data_size);

		}



		kunmap_atomic(from);

	}

}



static void gather_and_free_data_area(struct tcmu_dev *udev,

	struct scatterlist *data_sg, unsigned int data_nents)

{

	int i;

	void *from, *to;

	size_t copy_bytes;

	struct scatterlist *sg;



	/* It'd be easier to look at entry's iovec again, but UAM */

	for_each_sg(data_sg, sg, data_nents, i) {

		copy_bytes = min_t(size_t, sg->length,

				 head_to_end(udev->data_tail, udev->data_size));



		to = kmap_atomic(sg_page(sg)) + sg->offset;

		WARN_ON(sg->length + sg->offset > PAGE_SIZE);

		from = (void *) udev->mb_addr +

			udev->data_off + udev->data_tail;

		tcmu_flush_dcache_range(from, copy_bytes);

		memcpy(to, from, copy_bytes);



		UPDATE_HEAD(udev->data_tail, copy_bytes, udev->data_size);



		/* Uh oh, wrapped the data buffer for this sg's data */

		if (sg->length != copy_bytes) {

			from = (void *) udev->mb_addr +

				udev->data_off + udev->data_tail;

			WARN_ON(udev->data_tail);

			to += copy_bytes;

			copy_bytes = sg->length - copy_bytes;

			tcmu_flush_dcache_range(from, copy_bytes);

			memcpy(to, from, copy_bytes);



			UPDATE_HEAD(udev->data_tail,

				copy_bytes, udev->data_size);

		}

		kunmap_atomic(to);

	}

}



/*

 * We can't queue a command until we have space available on the cmd ring *and* space

 * space avail on the data ring.

 * We can't queue a command until we have space available on the cmd ring *and*

 * space available on the data ring.

 *

 * Called with ring lock held.

 */
@@ -274,12 +370,11 @@ static int tcmu_queue_cmd_ring(struct tcmu_cmd *tcmu_cmd) 
	size_t base_command_size, command_size;

	struct tcmu_mailbox *mb;

	struct tcmu_cmd_entry *entry;

	int i;

	struct scatterlist *sg;

	struct iovec *iov;

	int iov_cnt = 0;

	int iov_cnt;

	uint32_t cmd_head;

	uint64_t cdb_off;

	bool copy_to_data_area;



	if (test_bit(TCMU_DEV_BIT_BROKEN, &udev->flags))

		return -EINVAL;
@@ -360,49 +455,10 @@ static int tcmu_queue_cmd_ring(struct tcmu_cmd *tcmu_cmd) 
	 * Fix up iovecs, and handle if allocation in data ring wrapped.

	 */

	iov = &entry->req.iov[0];

	for_each_sg(se_cmd->t_data_sg, sg, se_cmd->t_data_nents, i) {

		size_t copy_bytes = min((size_t)sg->length,

				     head_to_end(udev->data_head, udev->data_size));

		void *from = kmap_atomic(sg_page(sg)) + sg->offset;

		void *to = (void *) mb + udev->data_off + udev->data_head;



		if (tcmu_cmd->se_cmd->data_direction == DMA_TO_DEVICE) {

			memcpy(to, from, copy_bytes);

			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++;



		UPDATE_HEAD(udev->data_head, copy_bytes, udev->data_size);



		/* Uh oh, we wrapped the buffer. Must split sg across 2 iovs. */

		if (sg->length != copy_bytes) {

			from += copy_bytes;

			copy_bytes = sg->length - copy_bytes;



			iov->iov_len = copy_bytes;

			iov->iov_base = (void __user *) udev->data_off +

							udev->data_head;



			if (se_cmd->data_direction == DMA_TO_DEVICE) {

				to = (void *) mb + udev->data_off + udev->data_head;

				memcpy(to, from, copy_bytes);

				tcmu_flush_dcache_range(to, copy_bytes);

			}



			iov_cnt++;

			iov++;



			UPDATE_HEAD(udev->data_head, copy_bytes, udev->data_size);

		}



		kunmap_atomic(from);

	}

	iov_cnt = 0;

	copy_to_data_area = (se_cmd->data_direction == DMA_TO_DEVICE);

	alloc_and_scatter_data_area(udev, se_cmd->t_data_sg,

		se_cmd->t_data_nents, &iov, &iov_cnt, copy_to_data_area);

	entry->req.iov_cnt = iov_cnt;

	entry->req.iov_bidi_cnt = 0;

	entry->req.iov_dif_cnt = 0;
@@ -481,41 +537,8 @@ static void tcmu_handle_completion(struct tcmu_cmd *cmd, struct tcmu_cmd_entry * 
		UPDATE_HEAD(udev->data_tail, cmd->data_length, udev->data_size);

	}

	else if (se_cmd->data_direction == DMA_FROM_DEVICE) {

		struct scatterlist *sg;

		int i;



		/* It'd be easier to look at entry's iovec again, but UAM */

		for_each_sg(se_cmd->t_data_sg, sg, se_cmd->t_data_nents, i) {

			size_t copy_bytes;

			void *to;

			void *from;



			copy_bytes = min((size_t)sg->length,

					 head_to_end(udev->data_tail, udev->data_size));



			to = kmap_atomic(sg_page(sg)) + sg->offset;

			WARN_ON(sg->length + sg->offset > PAGE_SIZE);

			from = (void *) udev->mb_addr + udev->data_off + udev->data_tail;

			tcmu_flush_dcache_range(from, copy_bytes);

			memcpy(to, from, copy_bytes);



			UPDATE_HEAD(udev->data_tail, copy_bytes, udev->data_size);



			/* Uh oh, wrapped the data buffer for this sg's data */

			if (sg->length != copy_bytes) {

				from = (void *) udev->mb_addr + udev->data_off + udev->data_tail;

				WARN_ON(udev->data_tail);

				to += copy_bytes;

				copy_bytes = sg->length - copy_bytes;

				tcmu_flush_dcache_range(from, copy_bytes);

				memcpy(to, from, copy_bytes);



				UPDATE_HEAD(udev->data_tail, copy_bytes, udev->data_size);

			}



			kunmap_atomic(to);

		}



		gather_and_free_data_area(udev,

			se_cmd->t_data_sg, se_cmd->t_data_nents);

	} else if (se_cmd->data_direction == DMA_TO_DEVICE) {

		UPDATE_HEAD(udev->data_tail, cmd->data_length, udev->data_size);

	} else if (se_cmd->data_direction != DMA_NONE) {

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