splice: check f_mode for seekable file

check f_mode for seekable file

As a seekable file is allowed without a llseek function, so the old way isn't
work any more.
Signed-off-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
----
 fs/splice.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

fs/splice.c

@@ -1372,8 +1372,7 @@ static long do_splice(struct file *in, loff_t __user *off_in,
 		if (off_in)
 			return -ESPIPE;
 		if (off_out) {
-			if (!out->f_op || !out->f_op->llseek ||
-			    out->f_op->llseek == no_llseek)
+			if (!(out->f_mode & FMODE_PWRITE))
 				return -EINVAL;
 			if (copy_from_user(&offset, off_out, sizeof(loff_t)))
 				return -EFAULT;
@@ -1393,8 +1392,7 @@ static long do_splice(struct file *in, loff_t __user *off_in,
 		if (off_out)
 			return -ESPIPE;
 		if (off_in) {
-			if (!in->f_op || !in->f_op->llseek ||
-			    in->f_op->llseek == no_llseek)
+			if (!(in->f_mode & FMODE_PREAD))
 				return -EINVAL;
 			if (copy_from_user(&offset, off_in, sizeof(loff_t)))
 				return -EFAULT;