[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 <hout...@huawei.com>
---
 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