For direct block device opened with O_DIRECT, use copy_file_range to
issue device copy offload, or use generic_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 <h...@suse.de>
Signed-off-by: Anuj Gupta <anuj2...@samsung.com>
Signed-off-by: Nitesh Shetty <nj.she...@samsung.com>
---
 block/fops.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/block/fops.c b/block/fops.c
index acff3d5d22d4..6aa537c0e24f 100644
--- a/block/fops.c
+++ b/block/fops.c
@@ -735,6 +735,30 @@ 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 = generic_copy_file_range(file_in, pos_in + copied,
+                                                file_out, pos_out + copied,
+                                                len - copied, flags);
+       }
+
+       return copied;
+}
+
 #define        BLKDEV_FALLOC_FL_SUPPORTED                                      
\
                (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |           \
                 FALLOC_FL_ZERO_RANGE | FALLOC_FL_NO_HIDE_STALE)
@@ -828,6 +852,7 @@ const struct file_operations def_blk_fops = {
        .splice_read    = filemap_splice_read,
        .splice_write   = iter_file_splice_write,
        .fallocate      = blkdev_fallocate,
+       .copy_file_range = blkdev_copy_file_range,
 };
 
 static __init int blkdev_init(void)
-- 
2.35.1.500.gb896f729e2

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