[PATCH 4/7] block: Introduce a new ioctl for simple copy

[SelvaKumar S <selvakuma.s1@xxxxxxxxxxx>]

From: Nitesh Shetty <nj.shetty@xxxxxxxxxxx>

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

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 source-ranges [0, 8] [16, 8] [32,8] to
 * [64,24], on the same device */

int main(void)
{
	int ret, fd;
	struct range_entry source_range[] = {{.src = 0, .len = 8},
		{.src = 16, .len = 8}, {.src = 32, .len = 8},};
	struct copy_range cr;

	cr.dest = 64;
	cr.nr_range = 3;
	cr.range_list = (__u64)&source_range;

	fd = open("/dev/nvme0n1", O_RDWR);
	if (fd < 0) return 1;

	ret = ioctl(fd, BLKCOPY, &cr);
	if (ret < 0) printf("copy failure\n");

	close(fd);

	return ret;
}

Signed-off-by: Nitesh Shetty <nj.shetty@xxxxxxxxxxx>
Signed-off-by: SelvaKumar S <selvakuma.s1@xxxxxxxxxxx>
Signed-off-by: Kanchan Joshi <joshi.k@xxxxxxxxxxx>
---
 block/ioctl.c           | 33 +++++++++++++++++++++++++++++++++
 include/uapi/linux/fs.h |  8 ++++++++
 2 files changed, 41 insertions(+)

diff --git a/block/ioctl.c b/block/ioctl.c
index eb0491e90b9a..2af56d01e9fe 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -143,6 +143,37 @@ static int blk_ioctl_discard(struct block_device *bdev, fmode_t mode,
 				    GFP_KERNEL, flags);
 }
 
+static int blk_ioctl_copy(struct block_device *bdev, fmode_t mode,
+		unsigned long arg)
+{
+	struct copy_range crange;
+	struct range_entry *rlist;
+	int ret;
+
+	if (!(mode & FMODE_WRITE))
+		return -EBADF;
+
+	if (copy_from_user(&crange, (void __user *)arg, sizeof(crange)))
+		return -EFAULT;
+
+	rlist = kmalloc_array(crange.nr_range, sizeof(*rlist),
+			GFP_KERNEL);
+	if (!rlist)
+		return -ENOMEM;
+
+	if (copy_from_user(rlist, (void __user *)crange.range_list,
+				sizeof(*rlist) * crange.nr_range)) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+	ret = blkdev_issue_copy(bdev, crange.nr_range, rlist, bdev, crange.dest,
+			GFP_KERNEL, 0);
+out:
+	kfree(rlist);
+	return ret;
+}
+
 static int blk_ioctl_zeroout(struct block_device *bdev, fmode_t mode,
 		unsigned long arg)
 {
@@ -468,6 +499,8 @@ static int blkdev_common_ioctl(struct block_device *bdev, fmode_t mode,
 	case BLKSECDISCARD:
 		return blk_ioctl_discard(bdev, mode, arg,
 				BLKDEV_DISCARD_SECURE);
+	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 7a97b588d892..4183688ff398 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -76,6 +76,13 @@ struct range_entry {
 	__u64 len;
 };
 
+struct copy_range {
+	__u64 dest;
+	__u64 nr_range;
+	__u64 range_list;
+	__u64 rsvd;
+};
+
 /* extent-same (dedupe) ioctls; these MUST match the btrfs ioctl definitions */
 #define FILE_DEDUPE_RANGE_SAME		0
 #define FILE_DEDUPE_RANGE_DIFFERS	1
@@ -197,6 +204,7 @@ 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)
-- 
2.25.1