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nfsd_splice_actor(): handle compound pages

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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: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Benjamin Coddington <bcodding@redhat.com>
Fixes: f0f6b614f8 "copy_page_to_iter(): don't split high-order page in case of ITER_PIPE"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2022-09-10 22:14:02 +01:00
parent 568035b01c
commit bfbfb6182a
1 changed files with 7 additions and 3 deletions
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10
fs/nfsd/vfs.c
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@ -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;
struct page *page = buf->page; // may be a compound one
unsigned offset = buf->offset;
svc_rqst_replace_page(rqstp, buf->page);
if (rqstp->rq_res.page_len == 0)
rqstp->rq_res.page_base = 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;
}