Commit bfbfb618 authored by Al Viro's avatar Al Viro
Browse files

nfsd_splice_actor(): handle compound pages 



pipe_buffer might refer to a compound page (and contain more than a PAGE_SIZE
worth of data).  Theoretically it had been possible since way back, but
nfsd_splice_actor() hadn't run into that until copy_page_to_iter() change.
Fortunately, the only thing that changes for compound pages is that we
need to stuff each relevant subpage in and convert the offset into offset
in the first subpage.

Acked-by: default avatarChuck Lever <chuck.lever@oracle.com>
Tested-by: default avatarBenjamin Coddington <bcodding@redhat.com>
Fixes: f0f6b614 "copy_page_to_iter(): don't split high-order page in case of ITER_PIPE"
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 568035b0

fs/nfsd/vfs.c

+8 −4
Original line number Diff line number Diff line
@@ -846,10 +846,14 @@ nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf, 
		  struct splice_desc *sd)

{

	struct svc_rqst *rqstp = sd->u.data;



	svc_rqst_replace_page(rqstp, buf->page);

	if (rqstp->rq_res.page_len == 0)

		rqstp->rq_res.page_base = buf->offset;

	struct page *page = buf->page;	// may be a compound one

	unsigned offset = buf->offset;



	page += offset / PAGE_SIZE;

	for (int i = sd->len; i > 0; i -= PAGE_SIZE)

		svc_rqst_replace_page(rqstp, page++);

	if (rqstp->rq_res.page_len == 0)	// first call

		rqstp->rq_res.page_base = offset % PAGE_SIZE;

	rqstp->rq_res.page_len += sd->len;

	return sd->len;

}