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userfaultfd: report actual registered features in fdinfo

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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.

Link: http://lkml.kernel.org/r/1491140181-22121-1-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mike Rapoport 2017-04-07 16:04:42 -07:00 committed by Linus Torvalds
parent d75450ff40
commit 045098e944
1 changed files with 1 additions and 1 deletions
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2
fs/userfaultfd.c
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@ -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