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NFSD: Fix reads with a non-zero offset that don't end on a page boundary 

This was found when virtual machines with nfs-mounted qcow2 disks
failed to boot properly.

Reported-by: Anders Blomdell <anders.blomdell@control.lth.se>
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2142132
Fixes: bfbfb6182a ("nfsd_splice_actor(): handle compound pages")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Chuck Lever 2022-11-23 14:14:32 -05:00
parent 5a01c80544
commit ac8db824ea
1 changed files with 4 additions and 3 deletions
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7
fs/nfsd/vfs.c
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@ -871,10 +871,11 @@ nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
struct svc_rqst *rqstp = sd->u.data;
struct page *page = buf->page; // may be a compound one
unsigned offset = buf->offset;
struct page *last_page;
page += offset / PAGE_SIZE;
for (int i = sd->len; i > 0; i -= PAGE_SIZE)
svc_rqst_replace_page(rqstp, page++);
last_page = page + (offset + sd->len - 1) / PAGE_SIZE;
for (page += offset / PAGE_SIZE; page <= last_page; 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;