[PATCH] fat: enable .splice_write to support splice on O_DIRECT file

[Hou Tao]

Now splice() on O_DIRECT-opened fat file will return -EFAULT, that is
because the default .splice_write, namely default_file_splice_write(),
will construct an ITER_KVEC iov_iter and dio_refill_pages() in dio path
can not handle it.

Fix it by implementing .splice_write through iter_file_splice_write().

Spotted by xfs-tests generic/091.

Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
---
 fs/fat/file.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/fat/file.c b/fs/fat/file.c
index 13935ee99e1e..b3bed32946b1 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -214,6 +214,7 @@ const struct file_operations fat_file_operations = {
 #endif
 	.fsync		= fat_file_fsync,
 	.splice_read	= generic_file_splice_read,
+	.splice_write	= iter_file_splice_write,
 	.fallocate	= fat_fallocate,
 };
 
-- 
2.16.2.dirty