[PATCH for 4.11] userfaultfd: report actual registered features in fdinfo

[Mike Rapoport <rppt@linux.vnet.ibm.com>]

fdinfo for userfault file descriptor reports UFFD_API_FEATURES. Up until
recently, the UFFD_API_FEATURES was defined as 0, therefore corresponding
field in fdinfo always contained zero. Now, with introduction of several
additional features, UFFD_API_FEATURES is not longer 0 and it seems better
to report actual features requested for the userfaultfd object described by
the fdinfo. First, the applications that were using userfault will still
see zero at the features field in fdinfo. Next, reporting actual features
rather than available features, gives clear indication of what userfault
features are used by an application.

Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
---
 fs/userfaultfd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 1d227b0..f7555fc 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1756,7 +1756,7 @@ static void userfaultfd_show_fdinfo(struct seq_file *m, struct file *f)
 	 *	protocols: aa:... bb:...
 	 */
 	seq_printf(m, "pending:\t%lu\ntotal:\t%lu\nAPI:\t%Lx:%x:%Lx\n",
-		   pending, total, UFFD_API, UFFD_API_FEATURES,
+		   pending, total, UFFD_API, ctx->features,
 		   UFFD_API_IOCTLS|UFFD_API_RANGE_IOCTLS);
 }
 #endif
-- 
1.9.1

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