NFS: Prevent another deadlock in nfs_release_page()

We should not attempt to free the page if __GFP_FS is not set. Otherwise we
can deadlock as per

  http://bugzilla.kernel.org/show_bug.cgi?id=15578

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@kernel.org

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index ae8d022..ae0d927 100644 (file)
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -491,7 +491,8 @@ static int nfs_release_page(struct page *page, gfp_t gfp)
 {
        dfprintk(PAGECACHE, "NFS: release_page(%p)\n", page);
 
-       if (gfp & __GFP_WAIT)
+       /* Only do I/O if gfp is a superset of GFP_KERNEL */
+       if ((gfp & GFP_KERNEL) == GFP_KERNEL)
                nfs_wb_page(page->mapping->host, page);
        /* If PagePrivate() is set, then the page is not freeable */
        if (PagePrivate(page))