[PATCH] btrfs: wire up iter_file_splice_write

[Christoph Hellwig <hch@lst.de>]

btrfs implements the iter_write op and thus can use the more efficient
iov_iter based splice implementation.  For now falling back to the less
efficient default is pretty harmless, but I have a pending series that
removes the default, and thus would cause btrfs to not support splice
at all.

Reported-by: Andy Lavr <andy.lavr@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Andy Lavr <andy.lavr@gmail.com>
---
 fs/btrfs/file.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 2520605afc256e..b0d2c976587e52 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3509,6 +3509,7 @@ const struct file_operations btrfs_file_operations = {
 	.read_iter      = generic_file_read_iter,
 	.splice_read	= generic_file_splice_read,
 	.write_iter	= btrfs_file_write_iter,
+	.splice_write	= iter_file_splice_write,
 	.mmap		= btrfs_file_mmap,
 	.open		= btrfs_file_open,
 	.release	= btrfs_release_file,
-- 
2.26.2