redonkable
/
alistair23-linux
1
0
Fork 0
Code Releases Activity

nfs: can_coalesce_requests must enforce contiguity 

Commit 6094f83864
"nfs: allow coalescing of subpage requests" got rid of the requirement
that requests cover whole pages, but it made some incorrect assumptions.

It turns out that callers of this interface can map adjacent requests
(by file position as seen by req_offset + req->wb_bytes) to different pages,
even when they could share a page. An example is the direct I/O interface -
iov_iter_get_pages_alloc may return one segment with a partial page filled
and the next segment (which is adjacent in the file position) starts with a
new page.

Reported-by: Toralf Förster <toralf.foerster@gmx.de>
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
hifive-unleashed-5.1
Weston Andros Adamson 2014-08-14 17:39:33 -04:00 committed by Trond Myklebust
parent bba5c1887a
commit 78270e8fbc
1 changed files with 8 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
fs/nfs/pagelist.c
View File

@ -823,6 +823,14 @@ static bool nfs_can_coalesce_requests(struct nfs_page *prev,
return false;
if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
return false;
if (req->wb_page == prev->wb_page) {
if (req->wb_pgbase != prev->wb_pgbase + prev->wb_bytes)
return false;
} else {
if (req->wb_pgbase != 0 ||
prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
return false;
}
}
size = pgio->pg_ops->pg_test(pgio, prev, req);
WARN_ON_ONCE(size > req->wb_bytes);