Make nfsd_splice_actor work with reads with a non-zero offset that doesn't end on a page boundary.
This was found when virtual machines with nfs-mounted qcow2 disks failed to boot properly (originally found on v6.0.5, fix also needed and tested on v6.0.9 and v6.1-rc6).
Signed-off-by: Anders Blomdell anders.blomdell@control.lth.se Link: https://bugzilla.redhat.com/show_bug.cgi?id=2142132 Fixes: bfbfb6182ad1 "nfsd_splice_actor(): handle compound pages" Cc: stable@vger.kernel.org # v6.0+
-- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -869,12 +869,13 @@ nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf, struct splice_desc *sd) { struct svc_rqst *rqstp = sd->u.data; - struct page *page = buf->page; // may be a compound one + // buf->page may be a compound one unsigned offset = buf->offset; + struct page *first = buf->page + offset / PAGE_SIZE; + struct page *last = buf->page + (offset + sd->len - 1) / PAGE_SIZE;
- page += offset / PAGE_SIZE; - for (int i = sd->len; i > 0; i -= PAGE_SIZE) - svc_rqst_replace_page(rqstp, page++); + for (struct page *page = first; page <= last; page++) + 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;