2 files changed, 173 insertions, 88 deletions

diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
index b455d9ab6f3d..020d4fbb947c 100644
--- a/drivers/vhost/Kconfig
+++ b/drivers/vhost/Kconfig
@@ -47,6 +47,7 @@ config VHOST_SCSI
 	tristate "VHOST_SCSI TCM fabric driver"
 	depends on TARGET_CORE && EVENTFD
 	select VHOST
+	select SG_POOL
 	default n
 	help
 	Say M here to enable the vhost_scsi TCM fabric module
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index c087fbc6f8d3..c7bb8485e447 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -46,6 +46,50 @@
 #define VHOST_SCSI_PREALLOC_UPAGES 2048
 #define VHOST_SCSI_PREALLOC_PROT_SGLS 2048
 
+static unsigned int vhost_scsi_inline_sg_cnt = VHOST_SCSI_PREALLOC_SGLS;
+
+#ifdef CONFIG_ARCH_NO_SG_CHAIN
+static int vhost_scsi_set_inline_sg_cnt(const char *buf,
+					const struct kernel_param *kp)
+{
+	pr_err("Setting inline_sg_cnt is not supported.\n");
+	return -EOPNOTSUPP;
+}
+#else
+static int vhost_scsi_set_inline_sg_cnt(const char *buf,
+					const struct kernel_param *kp)
+{
+	unsigned int cnt;
+	int ret;
+
+	ret = kstrtouint(buf, 10, &cnt);
+	if (ret)
+		return ret;
+
+	if (ret > VHOST_SCSI_PREALLOC_SGLS) {
+		pr_err("Max inline_sg_cnt is %u\n", VHOST_SCSI_PREALLOC_SGLS);
+		return -EINVAL;
+	}
+
+	vhost_scsi_inline_sg_cnt = cnt;
+	return 0;
+}
+#endif
+
+static int vhost_scsi_get_inline_sg_cnt(char *buf,
+					const struct kernel_param *kp)
+{
+	return sprintf(buf, "%u\n", vhost_scsi_inline_sg_cnt);
+}
+
+static const struct kernel_param_ops vhost_scsi_inline_sg_cnt_op = {
+	.get = vhost_scsi_get_inline_sg_cnt,
+	.set = vhost_scsi_set_inline_sg_cnt,
+};
+
+module_param_cb(inline_sg_cnt, &vhost_scsi_inline_sg_cnt_op, NULL, 0644);
+MODULE_PARM_DESC(inline_sg_cnt, "Set the number of scatterlist entries to pre-allocate. The default is 2048.");
+
 /* Max number of requests before requeueing the job.
  * Using this limit prevents one virtqueue from starving others with
  * request.
@@ -80,9 +124,10 @@ struct vhost_scsi_cmd {
 	u32 copied_iov:1;
 	const void *saved_iter_addr;
 	struct iov_iter saved_iter;
-	/* Pointer to the SGL formatted memory from virtio-scsi */
-	struct scatterlist *tvc_sgl;
-	struct scatterlist *tvc_prot_sgl;
+	struct scatterlist *sgl;
+	struct sg_table table;
+	struct scatterlist *prot_sgl;
+	struct sg_table prot_table;
 	/* Pointer to response header iovec */
 	struct iovec *tvc_resp_iov;
 	/* Pointer to vhost_scsi for our device */
@@ -206,6 +251,8 @@ struct vhost_scsi {
 
 	bool vs_events_missed; /* any missed events, protected by vq->mutex */
 	int vs_events_nr; /* num of pending events, protected by vq->mutex */
+
+	unsigned int inline_sg_cnt;
 };
 
 struct vhost_scsi_tmf {
@@ -328,23 +375,35 @@ static void vhost_scsi_release_cmd_res(struct se_cmd *se_cmd)
 {
 	struct vhost_scsi_cmd *tv_cmd = container_of(se_cmd,
 				struct vhost_scsi_cmd, tvc_se_cmd);
+	struct vhost_scsi *vs = tv_cmd->tvc_vhost;
 	struct vhost_scsi_virtqueue *svq = container_of(tv_cmd->tvc_vq,
 				struct vhost_scsi_virtqueue, vq);
 	struct vhost_scsi_inflight *inflight = tv_cmd->inflight;
+	struct scatterlist *sg;
+	struct page *page;
 	int i;
 
 	if (tv_cmd->tvc_sgl_count) {
-		for (i = 0; i < tv_cmd->tvc_sgl_count; i++) {
+		for_each_sgtable_sg(&tv_cmd->table, sg, i) {
+			page = sg_page(sg);
+			if (!page)
+				continue;
+
 			if (tv_cmd->copied_iov)
-				__free_page(sg_page(&tv_cmd->tvc_sgl[i]));
+				__free_page(page);
 			else
-				put_page(sg_page(&tv_cmd->tvc_sgl[i]));
+				put_page(page);
 		}
 		kfree(tv_cmd->saved_iter_addr);
+		sg_free_table_chained(&tv_cmd->table, vs->inline_sg_cnt);
 	}
 	if (tv_cmd->tvc_prot_sgl_count) {
-		for (i = 0; i < tv_cmd->tvc_prot_sgl_count; i++)
-			put_page(sg_page(&tv_cmd->tvc_prot_sgl[i]));
+		for_each_sgtable_sg(&tv_cmd->prot_table, sg, i) {
+			page = sg_page(sg);
+			if (page)
+				put_page(page);
+		}
+		sg_free_table_chained(&tv_cmd->prot_table, vs->inline_sg_cnt);
 	}
 
 	sbitmap_clear_bit(&svq->scsi_tags, se_cmd->map_tag);
@@ -534,14 +593,17 @@ static void vhost_scsi_evt_work(struct vhost_work *work)
 static int vhost_scsi_copy_sgl_to_iov(struct vhost_scsi_cmd *cmd)
 {
 	struct iov_iter *iter = &cmd->saved_iter;
-	struct scatterlist *sg = cmd->tvc_sgl;
+	struct scatterlist *sg;
 	struct page *page;
 	size_t len;
 	int i;
 
-	for (i = 0; i < cmd->tvc_sgl_count; i++) {
-		page = sg_page(&sg[i]);
-		len = sg[i].length;
+	for_each_sgtable_sg(&cmd->table, sg, i) {
+		page = sg_page(sg);
+		if (!page)
+			continue;
+
+		len = sg->length;
 
 		if (copy_page_to_iter(page, 0, len, iter) != len) {
 			pr_err("Could not copy data while handling misaligned cmd. Error %zu\n",
@@ -617,7 +679,7 @@ vhost_scsi_get_cmd(struct vhost_virtqueue *vq, struct vhost_scsi_tpg *tpg,
 					struct vhost_scsi_virtqueue, vq);
 	struct vhost_scsi_cmd *cmd;
 	struct vhost_scsi_nexus *tv_nexus;
-	struct scatterlist *sg, *prot_sg;
+	struct scatterlist *sgl, *prot_sgl;
 	struct iovec *tvc_resp_iov;
 	int tag;
 
@@ -634,12 +696,12 @@ vhost_scsi_get_cmd(struct vhost_virtqueue *vq, struct vhost_scsi_tpg *tpg,
 	}
 
 	cmd = &svq->scsi_cmds[tag];
-	sg = cmd->tvc_sgl;
-	prot_sg = cmd->tvc_prot_sgl;
+	sgl = cmd->sgl;
+	prot_sgl = cmd->prot_sgl;
 	tvc_resp_iov = cmd->tvc_resp_iov;
 	memset(cmd, 0, sizeof(*cmd));
-	cmd->tvc_sgl = sg;
-	cmd->tvc_prot_sgl = prot_sg;
+	cmd->sgl = sgl;
+	cmd->prot_sgl = prot_sgl;
 	cmd->tvc_se_cmd.map_tag = tag;
 	cmd->tvc_tag = scsi_tag;
 	cmd->tvc_lun = lun;
@@ -655,6 +717,27 @@ vhost_scsi_get_cmd(struct vhost_virtqueue *vq, struct vhost_scsi_tpg *tpg,
 	return cmd;
 }
 
+static void vhost_scsi_revert_map_iov_to_sgl(struct iov_iter *iter,
+					     struct scatterlist *curr,
+					     struct scatterlist *end)
+{
+	size_t revert_bytes = 0;
+	struct page *page;
+
+	while (curr != end) {
+		page = sg_page(curr);
+
+		if (page) {
+			put_page(page);
+			revert_bytes += curr->length;
+		}
+		/* Clear so we can re-use it for the copy path */
+		sg_set_page(curr, NULL, 0, 0);
+		curr = sg_next(curr);
+	}
+	iov_iter_revert(iter, revert_bytes);
+}
+
 /*
  * Map a user memory range into a scatterlist
  *
@@ -663,16 +746,17 @@ vhost_scsi_get_cmd(struct vhost_virtqueue *vq, struct vhost_scsi_tpg *tpg,
 static int
 vhost_scsi_map_to_sgl(struct vhost_scsi_cmd *cmd,
 		      struct iov_iter *iter,
-		      struct scatterlist *sgl,
+		      struct sg_table *sg_table,
+		      struct scatterlist **sgl,
 		      bool is_prot)
 {
 	struct vhost_scsi_virtqueue *svq = container_of(cmd->tvc_vq,
 					struct vhost_scsi_virtqueue, vq);
 	struct page **pages = svq->upages;
-	struct scatterlist *sg = sgl;
-	ssize_t bytes, mapped_bytes;
-	size_t offset, mapped_offset;
-	unsigned int npages = 0;
+	struct scatterlist *sg = *sgl;
+	ssize_t bytes;
+	size_t offset;
+	unsigned int n, npages = 0;
 
 	bytes = iov_iter_get_pages2(iter, pages, LONG_MAX,
 				VHOST_SCSI_PREALLOC_UPAGES, &offset);
@@ -680,11 +764,8 @@ vhost_scsi_map_to_sgl(struct vhost_scsi_cmd *cmd,
 	if (bytes <= 0)
 		return bytes < 0 ? bytes : -EFAULT;
 
-	mapped_bytes = bytes;
-	mapped_offset = offset;
-
 	while (bytes) {
-		unsigned n = min_t(unsigned, PAGE_SIZE - offset, bytes);
+		n = min_t(unsigned int, PAGE_SIZE - offset, bytes);
 		/*
 		 * The block layer requires bios/requests to be a multiple of
 		 * 512 bytes, but Windows can send us vecs that are misaligned.
@@ -705,25 +786,24 @@ vhost_scsi_map_to_sgl(struct vhost_scsi_cmd *cmd,
 			goto revert_iter_get_pages;
 		}
 
-		sg_set_page(sg++, pages[npages++], n, offset);
+		sg_set_page(sg, pages[npages++], n, offset);
+		sg = sg_next(sg);
 		bytes -= n;
 		offset = 0;
 	}
 
+	*sgl = sg;
 	return npages;
 
 revert_iter_get_pages:
-	iov_iter_revert(iter, mapped_bytes);
+	vhost_scsi_revert_map_iov_to_sgl(iter, *sgl, sg);
 
-	npages = 0;
-	while (mapped_bytes) {
-		unsigned int n = min_t(unsigned int, PAGE_SIZE - mapped_offset,
-				       mapped_bytes);
+	iov_iter_revert(iter, bytes);
+	while (bytes) {
+		n = min_t(unsigned int, PAGE_SIZE, bytes);
 
 		put_page(pages[npages++]);
-
-		mapped_bytes -= n;
-		mapped_offset = 0;
+		bytes -= n;
 	}
 
 	return -EINVAL;
@@ -751,10 +831,11 @@ vhost_scsi_calc_sgls(struct iov_iter *iter, size_t bytes, int max_sgls)
 
 static int
 vhost_scsi_copy_iov_to_sgl(struct vhost_scsi_cmd *cmd, struct iov_iter *iter,
-			   struct scatterlist *sg, int sg_count)
+			   struct sg_table *sg_table, int sg_count)
 {
 	size_t len = iov_iter_count(iter);
 	unsigned int nbytes = 0;
+	struct scatterlist *sg;
 	struct page *page;
 	int i, ret;
 
@@ -765,16 +846,15 @@ vhost_scsi_copy_iov_to_sgl(struct vhost_scsi_cmd *cmd, struct iov_iter *iter,
 			return -ENOMEM;
 	}
 
-	for (i = 0; i < sg_count; i++) {
+	for_each_sgtable_sg(sg_table, sg, i) {
 		page = alloc_page(GFP_KERNEL);
 		if (!page) {
-			i--;
 			ret = -ENOMEM;
 			goto err;
 		}
 
 		nbytes = min_t(unsigned int, PAGE_SIZE, len);
-		sg_set_page(&sg[i], page, nbytes, 0);
+		sg_set_page(sg, page, nbytes, 0);
 
 		if (cmd->tvc_data_direction == DMA_TO_DEVICE &&
 		    copy_page_from_iter(page, 0, nbytes, iter) != nbytes) {
@@ -792,39 +872,29 @@ err:
 	pr_err("Could not read %u bytes while handling misaligned cmd\n",
 	       nbytes);
 
-	for (; i >= 0; i--)
-		__free_page(sg_page(&sg[i]));
+	for_each_sgtable_sg(sg_table, sg, i) {
+		page = sg_page(sg);
+		if (page)
+			__free_page(page);
+	}
 	kfree(cmd->saved_iter_addr);
 	return ret;
 }
 
 static int
 vhost_scsi_map_iov_to_sgl(struct vhost_scsi_cmd *cmd, struct iov_iter *iter,
-			  struct scatterlist *sg, int sg_count, bool is_prot)
+			  struct sg_table *sg_table, int sg_count, bool is_prot)
 {
-	struct scatterlist *p = sg;
-	size_t revert_bytes;
+	struct scatterlist *sg = sg_table->sgl;
 	int ret;
 
 	while (iov_iter_count(iter)) {
-		ret = vhost_scsi_map_to_sgl(cmd, iter, sg, is_prot);
+		ret = vhost_scsi_map_to_sgl(cmd, iter, sg_table, &sg, is_prot);
 		if (ret < 0) {
-			revert_bytes = 0;
-
-			while (p < sg) {
-				struct page *page = sg_page(p);
-
-				if (page) {
-					put_page(page);
-					revert_bytes += p->length;
-				}
-				p++;
-			}
-
-			iov_iter_revert(iter, revert_bytes);
+			vhost_scsi_revert_map_iov_to_sgl(iter, sg_table->sgl,
+							 sg);
 			return ret;
 		}
-		sg += ret;
 	}
 
 	return 0;
@@ -835,23 +905,29 @@ vhost_scsi_mapal(struct vhost_scsi_cmd *cmd,
 		 size_t prot_bytes, struct iov_iter *prot_iter,
 		 size_t data_bytes, struct iov_iter *data_iter)
 {
+	struct vhost_scsi *vs = cmd->tvc_vhost;
 	int sgl_count, ret;
 
 	if (prot_bytes) {
 		sgl_count = vhost_scsi_calc_sgls(prot_iter, prot_bytes,
 						 VHOST_SCSI_PREALLOC_PROT_SGLS);
-		if (sgl_count < 0)
-			return sgl_count;
+		cmd->prot_table.sgl = cmd->prot_sgl;
+		ret = sg_alloc_table_chained(&cmd->prot_table, sgl_count,
+					     cmd->prot_table.sgl,
+					     vs->inline_sg_cnt);
+		if (ret)
+			return ret;
 
-		sg_init_table(cmd->tvc_prot_sgl, sgl_count);
 		cmd->tvc_prot_sgl_count = sgl_count;
 		pr_debug("%s prot_sg %p prot_sgl_count %u\n", __func__,
-			 cmd->tvc_prot_sgl, cmd->tvc_prot_sgl_count);
+			 cmd->prot_table.sgl, cmd->tvc_prot_sgl_count);
 
 		ret = vhost_scsi_map_iov_to_sgl(cmd, prot_iter,
-						cmd->tvc_prot_sgl,
+						&cmd->prot_table,
 						cmd->tvc_prot_sgl_count, true);
 		if (ret < 0) {
+			sg_free_table_chained(&cmd->prot_table,
+					      vs->inline_sg_cnt);
 			cmd->tvc_prot_sgl_count = 0;
 			return ret;
 		}
@@ -861,20 +937,23 @@ vhost_scsi_mapal(struct vhost_scsi_cmd *cmd,
 	if (sgl_count < 0)
 		return sgl_count;
 
-	sg_init_table(cmd->tvc_sgl, sgl_count);
+	cmd->table.sgl = cmd->sgl;
+	ret = sg_alloc_table_chained(&cmd->table, sgl_count, cmd->table.sgl,
+				     vs->inline_sg_cnt);
+	if (ret)
+		return ret;
+
 	cmd->tvc_sgl_count = sgl_count;
 	pr_debug("%s data_sg %p data_sgl_count %u\n", __func__,
-		  cmd->tvc_sgl, cmd->tvc_sgl_count);
+		  cmd->table.sgl, cmd->tvc_sgl_count);
 
-	ret = vhost_scsi_map_iov_to_sgl(cmd, data_iter, cmd->tvc_sgl,
+	ret = vhost_scsi_map_iov_to_sgl(cmd, data_iter, &cmd->table,
 					cmd->tvc_sgl_count, false);
-	if (ret == -EINVAL) {
-		sg_init_table(cmd->tvc_sgl, cmd->tvc_sgl_count);
-		ret = vhost_scsi_copy_iov_to_sgl(cmd, data_iter, cmd->tvc_sgl,
+	if (ret == -EINVAL)
+		ret = vhost_scsi_copy_iov_to_sgl(cmd, data_iter, &cmd->table,
 						 cmd->tvc_sgl_count);
-	}
-
 	if (ret < 0) {
+		sg_free_table_chained(&cmd->table, vs->inline_sg_cnt);
 		cmd->tvc_sgl_count = 0;
 		return ret;
 	}
@@ -906,10 +985,10 @@ static void vhost_scsi_target_queue_cmd(struct vhost_scsi_cmd *cmd)
 
 	/* FIXME: BIDI operation */
 	if (cmd->tvc_sgl_count) {
-		sg_ptr = cmd->tvc_sgl;
+		sg_ptr = cmd->table.sgl;
 
 		if (cmd->tvc_prot_sgl_count)
-			sg_prot_ptr = cmd->tvc_prot_sgl;
+			sg_prot_ptr = cmd->prot_table.sgl;
 		else
 			se_cmd->prot_pto = true;
 	} else {
@@ -1620,8 +1699,8 @@ static void vhost_scsi_destroy_vq_cmds(struct vhost_virtqueue *vq)
 	for (i = 0; i < svq->max_cmds; i++) {
 		tv_cmd = &svq->scsi_cmds[i];
 
-		kfree(tv_cmd->tvc_sgl);
-		kfree(tv_cmd->tvc_prot_sgl);
+		kfree(tv_cmd->sgl);
+		kfree(tv_cmd->prot_sgl);
 		kfree(tv_cmd->tvc_resp_iov);
 	}
 
@@ -1635,6 +1714,7 @@ static int vhost_scsi_setup_vq_cmds(struct vhost_virtqueue *vq, int max_cmds)
 {
 	struct vhost_scsi_virtqueue *svq = container_of(vq,
 					struct vhost_scsi_virtqueue, vq);
+	struct vhost_scsi *vs = svq->vs;
 	struct vhost_scsi_cmd *tv_cmd;
 	unsigned int i;
 
@@ -1660,12 +1740,14 @@ static int vhost_scsi_setup_vq_cmds(struct vhost_virtqueue *vq, int max_cmds)
 	for (i = 0; i < max_cmds; i++) {
 		tv_cmd = &svq->scsi_cmds[i];
 
-		tv_cmd->tvc_sgl = kcalloc(VHOST_SCSI_PREALLOC_SGLS,
-					  sizeof(struct scatterlist),
-					  GFP_KERNEL);
-		if (!tv_cmd->tvc_sgl) {
-			pr_err("Unable to allocate tv_cmd->tvc_sgl\n");
-			goto out;
+		if (vs->inline_sg_cnt) {
+			tv_cmd->sgl = kcalloc(vs->inline_sg_cnt,
+					      sizeof(struct scatterlist),
+					      GFP_KERNEL);
+			if (!tv_cmd->sgl) {
+				pr_err("Unable to allocate tv_cmd->sgl\n");
+				goto out;
+			}
 		}
 
 		tv_cmd->tvc_resp_iov = kcalloc(UIO_MAXIOV,
@@ -1676,12 +1758,13 @@ static int vhost_scsi_setup_vq_cmds(struct vhost_virtqueue *vq, int max_cmds)
 			goto out;
 		}
 
-		if (vhost_has_feature(vq, VIRTIO_SCSI_F_T10_PI)) {
-			tv_cmd->tvc_prot_sgl = kcalloc(VHOST_SCSI_PREALLOC_PROT_SGLS,
-						sizeof(struct scatterlist),
-						GFP_KERNEL);
-			if (!tv_cmd->tvc_prot_sgl) {
-				pr_err("Unable to allocate tv_cmd->tvc_prot_sgl\n");
+		if (vhost_has_feature(vq, VIRTIO_SCSI_F_T10_PI) &&
+		    vs->inline_sg_cnt) {
+			tv_cmd->prot_sgl = kcalloc(vs->inline_sg_cnt,
+						   sizeof(struct scatterlist),
+						   GFP_KERNEL);
+			if (!tv_cmd->prot_sgl) {
+				pr_err("Unable to allocate tv_cmd->prot_sgl\n");
 				goto out;
 			}
 		}
@@ -1972,6 +2055,7 @@ static int vhost_scsi_open(struct inode *inode, struct file *f)
 	vs = kvzalloc(sizeof(*vs), GFP_KERNEL);
 	if (!vs)
 		goto err_vs;
+	vs->inline_sg_cnt = vhost_scsi_inline_sg_cnt;
 
 	if (nvqs > VHOST_SCSI_MAX_IO_VQ) {
 		pr_err("Invalid max_io_vqs of %d. Using %d.\n", nvqs,