[PATCHv2] NVMe: Spliting large i/o in the ioctl path [for-linus branch]

[sathya.m@samsung.com (Sathayavathi M)]

From: Sathyavathi M <sathya.m@samsung.com>

The NVME_IOCTL_SUBMIT_IO allows arbitrarily large i/o cmds if mdts is zero.
If the mdts has a limit, there is no check to verify if the cmd sent to device
is within the max transfer limit. This patch splits arbitrarily  large size i/o
to max_hw_sectors before submitting to device. If metadata (extended and
separate) is present then the i/o is split by considering both data+metadata.

Also addresses an issue where 128KB chunk i/o is split into 2(124KB+4KB) when
mdts is 0.

This also merges the previously submitted "Check for Extended metadata in ioctl
path" patch and addresses the comments for that patch.

This patch is generated against for-linus branch.

v1->v2
use of BLK_DEF_MAX_SECTORS macro is replaced with value.

Signed-off-by: Sathyavathi M <sathya.m at samsung.com>
---
 drivers/block/nvme-core.c | 209 ++++++++++++++++++++++++++++------------------
 include/linux/nvme.h      |   1 +
 include/uapi/linux/nvme.h |   4 +
 3 files changed, 132 insertions(+), 82 deletions(-)

diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
index ceb32dd..d812dee 100644
--- a/drivers/block/nvme-core.c
+++ b/drivers/block/nvme-core.c
@@ -1749,111 +1749,152 @@ static int nvme_submit_io(struct nvme_ns *ns, struct nvme_user_io __user *uio)
 	struct nvme_dev *dev = ns->dev;
 	struct nvme_user_io io;
 	struct nvme_command c;
-	unsigned length, meta_len;
-	int status, i;
-	struct nvme_iod *iod, *meta_iod = NULL;
+	unsigned tfr_len, meta_len = 0, split_length;
+	int status = 0, i, err = 0, count = 0;
+	u32 tfr_sectors;
+	u32 max_tfr_sectors, num_split_cmds, offset = 0;
+	u64 nxt_map_addr, nxt_meta_map_addr = 0;
+	struct nvme_iod *iod = NULL, *meta_iod = NULL;
 	dma_addr_t meta_dma_addr;
 	void *meta, *uninitialized_var(meta_mem);
+	bool ext_lba = ns->flbas & EXT_LBA;
 
 	if (copy_from_user(&io, uio, sizeof(io)))
 		return -EFAULT;
-	length = (io.nblocks + 1) << ns->lba_shift;
-	meta_len = (io.nblocks + 1) * ns->ms;
+	max_tfr_sectors = dev->max_hw_sectors;
 
-	if (meta_len && ((io.metadata & 3) || !io.metadata))
+	/* Check for unaligned or NULL metadata ptr for separate buffer */
+	if (ns->ms && !(ext_lba) && ((io.metadata & 3) || !io.metadata))
 		return -EINVAL;
 
-	switch (io.opcode) {
-	case nvme_cmd_write:
-	case nvme_cmd_read:
-	case nvme_cmd_compare:
-		iod = nvme_map_user_pages(dev, io.opcode & 1, io.addr, length);
-		break;
-	default:
+	if (io.opcode != nvme_cmd_write && io.opcode != nvme_cmd_read &&
+						io.opcode != nvme_cmd_compare)
 		return -EINVAL;
-	}
-
-	if (IS_ERR(iod))
-		return PTR_ERR(iod);
-
-	memset(&c, 0, sizeof(c));
-	c.rw.opcode = io.opcode;
-	c.rw.flags = io.flags;
-	c.rw.nsid = cpu_to_le32(ns->ns_id);
-	c.rw.slba = cpu_to_le64(io.slba);
-	c.rw.length = cpu_to_le16(io.nblocks);
-	c.rw.control = cpu_to_le16(io.control);
-	c.rw.dsmgmt = cpu_to_le32(io.dsmgmt);
-	c.rw.reftag = cpu_to_le32(io.reftag);
-	c.rw.apptag = cpu_to_le16(io.apptag);
-	c.rw.appmask = cpu_to_le16(io.appmask);
-
-	if (meta_len) {
-		meta_iod = nvme_map_user_pages(dev, io.opcode & 1, io.metadata,
-								meta_len);
-		if (IS_ERR(meta_iod)) {
-			status = PTR_ERR(meta_iod);
-			meta_iod = NULL;
-			goto unmap;
+	if (ext_lba || !ns->ms)
+		num_split_cmds = DIV_ROUND_UP((((io.nblocks + 1)
+			<< ns->lba_shift) + ((io.nblocks + 1) * ns->ms)),
+					(max_tfr_sectors << ns->lba_shift));
+	else
+		num_split_cmds = DIV_ROUND_UP(((io.nblocks + 1)
+			<< ns->lba_shift), (max_tfr_sectors << ns->lba_shift));
+
+	for (count = 0; count < num_split_cmds; count++) {
+		if (!ns->ms || !(ext_lba)) {
+			tfr_sectors = min(max_tfr_sectors, (io.nblocks + 1) -
+								offset);
+			tfr_len = tfr_sectors << ns->lba_shift;
+			nxt_map_addr = io.addr + ((1 << ns->lba_shift) *
+								offset);
+			if (ns->ms) {
+				nxt_meta_map_addr = io.metadata + (ns->ms
+						* offset);
+				meta_len = tfr_sectors * ns->ms;
+			}
 		}
-
-		meta_mem = dma_alloc_coherent(&dev->pci_dev->dev, meta_len,
-						&meta_dma_addr, GFP_KERNEL);
-		if (!meta_mem) {
-			status = -ENOMEM;
-			goto unmap;
+		/* ExtendedLBA */
+		else if (ns->ms && ext_lba) {
+			tfr_sectors = (max_tfr_sectors * (1 << ns->lba_shift))
+					/ ((1 << ns->lba_shift) + ns->ms);
+			tfr_sectors = min(tfr_sectors, (io.nblocks + 1) -
+								offset);
+			tfr_len = tfr_sectors * ((1 << ns->lba_shift) +
+								ns->ms);
+			nxt_map_addr = io.addr + (((1 << ns->lba_shift) +
+							ns->ms) * offset);
 		}
+		iod = nvme_map_user_pages(dev, io.opcode & 1, nxt_map_addr,
+								tfr_len);
+		if (IS_ERR(iod))
+			return PTR_ERR(iod);
 
-		if (io.opcode & 1) {
-			int meta_offset = 0;
+		memset(&c, 0, sizeof(c));
+		c.rw.opcode = io.opcode;
+		c.rw.flags = io.flags;
+		c.rw.nsid = cpu_to_le32(ns->ns_id);
+		c.rw.slba = cpu_to_le64(io.slba + offset);
+		c.rw.length = cpu_to_le16(tfr_sectors - 1);
+		c.rw.control = cpu_to_le16(io.control);
+		c.rw.dsmgmt = cpu_to_le32(io.dsmgmt);
+		c.rw.reftag = cpu_to_le32(io.reftag);
+		c.rw.apptag = cpu_to_le16(io.apptag);
+		c.rw.appmask = cpu_to_le16(io.appmask);
+
+		/* Mapping not needed for Extenede LBA */
+		if (ns->ms && !(ext_lba)) {
+			meta_iod = nvme_map_user_pages(dev, io.opcode & 1,
+					nxt_meta_map_addr, meta_len);
+			if (IS_ERR(meta_iod)) {
+				status = PTR_ERR(meta_iod);
+				meta_iod = NULL;
+				err = true;
+				goto unmap;
+			}
 
-			for (i = 0; i < meta_iod->nents; i++) {
-				meta = kmap_atomic(sg_page(&meta_iod->sg[i])) +
-						meta_iod->sg[i].offset;
-				memcpy(meta_mem + meta_offset, meta,
-						meta_iod->sg[i].length);
-				kunmap_atomic(meta);
-				meta_offset += meta_iod->sg[i].length;
+			meta_mem = dma_alloc_coherent(&dev->pci_dev->dev,
+					meta_len, &meta_dma_addr, GFP_KERNEL);
+			if (!meta_mem) {
+				status = -ENOMEM;
+				err = true;
+				goto unmap;
 			}
-		}
 
-		c.rw.metadata = cpu_to_le64(meta_dma_addr);
-	}
+			if (io.opcode & 1) {
+				int meta_offset = 0;
 
-	length = nvme_setup_prps(dev, iod, length, GFP_KERNEL);
-	c.rw.prp1 = cpu_to_le64(sg_dma_address(iod->sg));
-	c.rw.prp2 = cpu_to_le64(iod->first_dma);
+				for (i = 0; i < meta_iod->nents; i++) {
+					meta = kmap_atomic(sg_page(
+					&meta_iod->sg[i])) + meta_iod->sg[i].
+									offset;
+					memcpy(meta_mem + meta_offset, meta,
+						meta_iod->sg[i].length);
+					kunmap_atomic(meta);
+					meta_offset += meta_iod->sg[i].length;
+				}
+			}
 
-	if (length != (io.nblocks + 1) << ns->lba_shift)
-		status = -ENOMEM;
-	else
-		status = nvme_submit_io_cmd(dev, ns, &c, NULL);
+			c.rw.metadata = cpu_to_le64(meta_dma_addr);
+		}
 
-	if (meta_len) {
-		if (status == NVME_SC_SUCCESS && !(io.opcode & 1)) {
-			int meta_offset = 0;
+		split_length = nvme_setup_prps(dev, iod, tfr_len, GFP_KERNEL);
+		c.rw.prp1 = cpu_to_le64(sg_dma_address(iod->sg));
+		c.rw.prp2 = cpu_to_le64(iod->first_dma);
 
-			for (i = 0; i < meta_iod->nents; i++) {
-				meta = kmap_atomic(sg_page(&meta_iod->sg[i])) +
-						meta_iod->sg[i].offset;
-				memcpy(meta, meta_mem + meta_offset,
+		if (split_length != tfr_len)
+			status = -ENOMEM;
+		else {
+			status = nvme_submit_io_cmd(dev, ns, &c, NULL);
+			if (status != NVME_SC_SUCCESS)
+				err = true;
+		}
+		if (ns->ms && !(ext_lba)) {
+			if (status == NVME_SC_SUCCESS && !(io.opcode & 1)) {
+				int meta_offset = 0;
+
+				for (i = 0; i < meta_iod->nents; i++) {
+					meta = kmap_atomic(sg_page(
+					&meta_iod->sg[i])) + meta_iod->sg[i].
+									offset;
+					memcpy(meta, meta_mem + meta_offset,
 						meta_iod->sg[i].length);
-				kunmap_atomic(meta);
-				meta_offset += meta_iod->sg[i].length;
+					kunmap_atomic(meta);
+					meta_offset += meta_iod->sg[i].length;
+				}
 			}
-		}
-
-		dma_free_coherent(&dev->pci_dev->dev, meta_len, meta_mem,
-								meta_dma_addr);
-	}
 
- unmap:
-	nvme_unmap_user_pages(dev, io.opcode & 1, iod);
-	nvme_free_iod(dev, iod);
+			dma_free_coherent(&dev->pci_dev->dev, meta_len,
+						meta_mem, meta_dma_addr);
+		}
+		offset += tfr_sectors;
+unmap:
+		nvme_unmap_user_pages(dev, io.opcode & 1, iod);
+		nvme_free_iod(dev, iod);
 
-	if (meta_iod) {
-		nvme_unmap_user_pages(dev, io.opcode & 1, meta_iod);
-		nvme_free_iod(dev, meta_iod);
+		if (meta_iod) {
+			nvme_unmap_user_pages(dev, io.opcode & 1, meta_iod);
+			nvme_free_iod(dev, meta_iod);
+		}
+		if (err)
+			break;
 	}
 
 	return status;
@@ -2036,6 +2077,7 @@ static int nvme_revalidate_disk(struct gendisk *disk)
 	}
 
 	old_ms = ns->ms;
+	ns->flbas = id->flbas;
 	lbaf = id->flbas & NVME_NS_FLBAS_LBA_MASK;
 	ns->lba_shift = id->lbaf[lbaf].ds;
 	ns->ms = le16_to_cpu(id->lbaf[lbaf].ms);
@@ -2338,8 +2380,11 @@ static int nvme_dev_add(struct nvme_dev *dev)
 	memcpy(dev->serial, ctrl->sn, sizeof(ctrl->sn));
 	memcpy(dev->model, ctrl->mn, sizeof(ctrl->mn));
 	memcpy(dev->firmware_rev, ctrl->fr, sizeof(ctrl->fr));
+	/* Increase max transfer size if device reports MDTS=0 */
 	if (ctrl->mdts)
 		dev->max_hw_sectors = 1 << (ctrl->mdts + shift - 9);
+	else
+		dev->max_hw_sectors = 1024;
 	if ((pdev->vendor == PCI_VENDOR_ID_INTEL) &&
 			(pdev->device == 0x0953) && ctrl->vs[3]) {
 		unsigned int max_hw_sectors;
diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index 0adad4a..6e94947 100644
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -119,6 +119,7 @@ struct nvme_ns {
 	int lba_shift;
 	int ms;
 	int pi_type;
+	u8 flbas;
 	u64 mode_select_num_blocks;
 	u32 mode_select_block_len;
 };
diff --git a/include/uapi/linux/nvme.h b/include/uapi/linux/nvme.h
index aef9a81..666dd9f 100644
--- a/include/uapi/linux/nvme.h
+++ b/include/uapi/linux/nvme.h
@@ -98,6 +98,10 @@ struct nvme_lbaf {
 	__u8			rp;
 };
 
+enum {
+	EXT_LBA		= 0x10
+};
+
 struct nvme_id_ns {
 	__le64			nsze;
 	__le64			ncap;
-- 
1.8.3.2