PATCH: sendfile() checks f_op.sendpage() instead of f_op.splice_write()wrongly

[Changli Gao]

sendfile(2) checks f_op.sendpage() instead of f_op.splice_write() wrongly.

sendfile(2) was reworked with the splice infrastructure, but it still
checks f_op.sendpage() instead of f_op.splice_write() wrongly. Although
if f_op.sendpage() exists, f_op.splice_write() always exists at the same
time currently, the assumption will be broken in future silently. This
patch also brings a side effect: sendfile(2) can work with any output
file, which supports splice_write() not only mmap(2).

Signed-off-by: Changli Gao <xiaosuo@xxxxxxxxx>
----
fs/read_write.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -826,7 +826,7 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
 	if (!(out_file->f_mode & FMODE_WRITE))
 		goto fput_out;
 	retval = -EINVAL;
-	if (!out_file->f_op || !out_file->f_op->sendpage)
+	if (!out_file->f_op || !out_file->f_op->splice_write)
 		goto fput_out;
 	in_inode = in_file->f_path.dentry->d_inode;
 	out_inode = out_file->f_path.dentry->d_inode;


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