nfs: cap request size to fit a kmalloced page array
pNFS servers may return arbitrarily large layouts. Trim back the I/O size
to one that we can at least allocate the page array for.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index be7cbce..94e16ec 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -481,6 +481,14 @@
return 0;
}
+ /*
+ * Limit the request size so that we can still allocate a page array
+ * for it without upsetting the slab allocator.
+ */
+ if (((desc->pg_count + req->wb_bytes) >> PAGE_SHIFT) *
+ sizeof(struct page) > PAGE_SIZE)
+ return 0;
+
return min(desc->pg_bsize - desc->pg_count, (size_t)req->wb_bytes);
}
EXPORT_SYMBOL_GPL(nfs_generic_pg_test);