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authorWeston Andros Adamson <dros@primarydata.com>2014-08-14 17:39:33 -0400
committerTrond Myklebust <trond.myklebust@primarydata.com>2014-08-22 18:04:44 -0400
commit78270e8fbc2916bfc8305b8f58f33474cce1ec0e (patch)
parentbba5c1887a925a9945d22217d38d58d8b3ba1043 (diff)
nfs: can_coalesce_requests must enforce contiguity
Commit 6094f83864c1d1296566a282cba05ba613f151ee "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>
1 files changed, 8 insertions, 0 deletions
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index a1d1de7b97c5..932c6cc27a76 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -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);