[dm-devel] [PATCH v4 03/10] block: Introduce a new ioctl for copy

[Nitesh Shetty]

Add new BLKCOPY ioctl that offloads copying of one or more sources ranges
to one or more destination in a device. COPY ioctl accepts a 'copy_range'
structure that contains no of range, a reserved field , followed by an
array of ranges. Each source range is represented by 'range_entry' that
contains source start offset, destination start offset and length of
source ranges (in bytes)

MAX_COPY_NR_RANGE, limits the number of entries for the IOCTL and
MAX_COPY_TOTAL_LENGTH limits the total copy length, IOCTL can handle.

Example code, to issue BLKCOPY:
/* Sample example to copy three entries with [dest,src,len],
* [32768, 0, 4096] [36864, 4096, 4096] [40960,8192,4096] on same device */

int main(void)
{
	int i, ret, fd;
	unsigned long src = 0, dst = 32768, len = 4096;
	struct copy_range *cr;
	cr = (struct copy_range *)malloc(sizeof(*cr)+
					(sizeof(struct range_entry)*3));
	cr->nr_range = 3;
	cr->reserved = 0;
	for (i = 0; i< cr->nr_range; i++, src += len, dst += len) {
		cr->range_list[i].dst = dst;
		cr->range_list[i].src = src;
		cr->range_list[i].len = len;
		cr->range_list[i].comp_len = 0;
	}
	fd = open("/dev/nvme0n1", O_RDWR);
	if (fd < 0) return 1;
	ret = ioctl(fd, BLKCOPY, cr);
	if (ret != 0)
	       printf("copy failed, ret= %d\n", ret);
	for (i=0; i< cr->nr_range; i++)
		if (cr->range_list[i].len != cr->range_list[i].comp_len)
			printf("Partial copy for entry %d: requested %llu, completed %llu\n",
								i, cr->range_list[i].len,
								cr->range_list[i].comp_len);
	close(fd);
	free(cr);
	return ret;
}

Signed-off-by: Nitesh Shetty <nj.shetty at samsung.com>
Signed-off-by: Javier González <javier.gonz at samsung.com>
Signed-off-by: Arnav Dawn <arnav.dawn at samsung.com>
---
 block/ioctl.c           | 32 ++++++++++++++++++++++++++++++++
 include/uapi/linux/fs.h |  9 +++++++++
 2 files changed, 41 insertions(+)

diff --git a/block/ioctl.c b/block/ioctl.c
index 46949f1b0dba..58d93c20ff30 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -120,6 +120,36 @@ static int blk_ioctl_discard(struct block_device *bdev, fmode_t mode,
 	return err;
 }
 
+static int blk_ioctl_copy(struct block_device *bdev, fmode_t mode,
+		unsigned long arg)
+{
+	struct copy_range crange, *ranges = NULL;
+	size_t payload_size = 0;
+	int ret;
+
+	if (!(mode & FMODE_WRITE))
+		return -EBADF;
+
+	if (copy_from_user(&crange, (void __user *)arg, sizeof(crange)))
+		return -EFAULT;
+
+	if (unlikely(!crange.nr_range || crange.reserved || crange.nr_range >= MAX_COPY_NR_RANGE))
+		return -EINVAL;
+
+	payload_size = (crange.nr_range * sizeof(struct range_entry)) + sizeof(crange);
+
+	ranges = memdup_user((void __user *)arg, payload_size);
+	if (IS_ERR(ranges))
+		return PTR_ERR(ranges);
+
+	ret = blkdev_issue_copy(bdev, ranges->nr_range, ranges->range_list, bdev, GFP_KERNEL);
+	if (copy_to_user((void __user *)arg, ranges, payload_size))
+		ret = -EFAULT;
+
+	kfree(ranges);
+	return ret;
+}
+
 static int blk_ioctl_secure_erase(struct block_device *bdev, fmode_t mode,
 		void __user *argp)
 {
@@ -481,6 +511,8 @@ static int blkdev_common_ioctl(struct block_device *bdev, fmode_t mode,
 		return blk_ioctl_discard(bdev, mode, arg);
 	case BLKSECDISCARD:
 		return blk_ioctl_secure_erase(bdev, mode, argp);
+	case BLKCOPY:
+		return blk_ioctl_copy(bdev, mode, arg);
 	case BLKZEROOUT:
 		return blk_ioctl_zeroout(bdev, mode, arg);
 	case BLKGETDISKSEQ:
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 822c28cebf3a..a3b13406ffb8 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -78,6 +78,14 @@ struct range_entry {
 	__u64 comp_len;
 };
 
+struct copy_range {
+	__u64 nr_range;
+	__u64 reserved;
+
+	/* Range_list always must be at the end */
+	struct range_entry range_list[];
+};
+
 /* extent-same (dedupe) ioctls; these MUST match the btrfs ioctl definitions */
 #define FILE_DEDUPE_RANGE_SAME		0
 #define FILE_DEDUPE_RANGE_DIFFERS	1
@@ -199,6 +207,7 @@ struct fsxattr {
 #define BLKROTATIONAL _IO(0x12,126)
 #define BLKZEROOUT _IO(0x12,127)
 #define BLKGETDISKSEQ _IOR(0x12,128,__u64)
+#define BLKCOPY _IOWR(0x12, 129, struct copy_range)
 /*
  * A jump here: 130-136 are reserved for zoned block devices
  * (see uapi/linux/blkzoned.h)
-- 
2.35.1.500.gb896f729e2