fs, block: copy_file_range for def_blk_ops for direct block device

For direct block device opened with O_DIRECT, use blkdev_copy_offload to
issue device copy offload, or use splice_copy_file_range in case
device copy offload capability is absent or the device files are not open
with O_DIRECT.

Reviewed-by: Hannes Reinecke <[email protected]>
Signed-off-by: Anuj Gupta <[email protected]>
Signed-off-by: Nitesh Shetty <[email protected]>

block/fops.c

@@ -18,6 +18,7 @@
 #include <linux/iomap.h>
 #include <linux/module.h>
 #include <linux/io_uring/cmd.h>
+#include <linux/splice.h>
 #include "blk.h"
 
 static inline struct inode *bdev_file_inode(struct file *file)
@@ -775,6 +776,30 @@ static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
 	return ret;
 }
 
+static ssize_t blkdev_copy_file_range(struct file *file_in, loff_t pos_in,
+				      struct file *file_out, loff_t pos_out,
+				      size_t len, unsigned int flags)
+{
+	struct block_device *in_bdev = I_BDEV(bdev_file_inode(file_in));
+	struct block_device *out_bdev = I_BDEV(bdev_file_inode(file_out));
+	ssize_t copied = 0;
+
+	if ((in_bdev == out_bdev) && bdev_max_copy_sectors(in_bdev) &&
+	    (file_in->f_iocb_flags & IOCB_DIRECT) &&
+	    (file_out->f_iocb_flags & IOCB_DIRECT)) {
+		copied = blkdev_copy_offload(in_bdev, pos_in, pos_out, len,
+					     NULL, NULL, GFP_KERNEL);
+		if (copied < 0)
+			copied = 0;
+	} else {
+		copied = splice_copy_file_range(file_in, pos_in + copied,
+						 file_out, pos_out + copied,
+						 len - copied);
+	}
+
+	return copied;
+}
+
 #define	BLKDEV_FALLOC_FL_SUPPORTED					\
 		(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |		\
 		 FALLOC_FL_ZERO_RANGE)
@@ -873,6 +898,7 @@ const struct file_operations def_blk_fops = {
 	.fallocate	= blkdev_fallocate,
 	.uring_cmd	= blkdev_uring_cmd,
 	.fop_flags	= FOP_BUFFER_RASYNC,
+	.copy_file_range = blkdev_copy_file_range,
 };
 
 static __init int blkdev_init(void)