On Wed, Apr 12, 2017 at 12:51:58AM +0100, Al Viro wrote:
> On Tue, Apr 11, 2017 at 07:45:58PM -0400, Dave Jones wrote:
> > > if (file->f_op->splice_write == generic_splice_sendpage) {
> > > struct socket *sock = file->private_data;
> > > printk(KERN_ERR "socket [%d, %p]\n", sock->type, sock->ops);
> > > }
> > > printk(KERN_ERR "in->f_op = %p\n", in->f_op);
> >
> > Ugh, this explodes with a million errors when I try to compile it.
> > It misses socket definition, and include <linux/net.h> causes another
> > cascade of errors about linkage.h and nonsense.
>
> Ignore the socket part - you've already triggered it with NFS file as
> destination, so this is not particularly interesting. I would still like
> to see in->f_op and even more - the checks in default_file_splice_read().
... and the latter had a braino - WARN_ON(size != ret), not len != ret.
Diff follows:
diff --git a/fs/splice.c b/fs/splice.c
index 006ba50f4ece..43dd9b3140ee 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -448,6 +448,18 @@ static ssize_t default_file_splice_read(struct file *in,
loff_t *ppos,
put_page(pages[i]);
kvfree(pages);
iov_iter_advance(&to, copied); /* truncates and discards */
+ if (res > 0 && pipe == current->splice_pipe) {
+ int idx = pipe->curbuf;
+ int n = pipe->nrbufs;
+ size_t size = 0;
+ while (n--) {
+ size += pipe->bufs[idx++].len;
+ if (idx == pipe->buffers)
+ idx = 0;
+ }
+ WARN_ON(size != res);
+ }
+
return res;
}
@@ -970,6 +982,11 @@ ssize_t splice_direct_to_actor(struct file *in, struct
splice_desc *sd,
while (len) {
size_t read_len;
loff_t pos = sd->pos, prev_pos = pos;
+ if (WARN_ON(pipe->buffers)) {
+ printk(KERN_ERR "in->f_op = %p, ->splice_write = %p\n",
+ in->f_op,
+ sd->u.file->f_op->splice_write);
+ }
ret = do_splice_to(in, &pos, pipe, len, flags);
if (unlikely(ret <= 0))
