proc: mounts_poll() make consistent to mdstat_poll

In recently sysfs_poll discussion, Neil Brown pointed out /proc/mounts
also should be fixed.

SUSv3 says "Regular files shall always poll TRUE for reading and
writing".  see
http://www.opengroup.org/onlinepubs/009695399/functions/poll.html

Then, mounts_poll()'s default should be "POLLIN | POLLRDNORM".  it mean
always readable.

In addition, event trigger should use "POLLERR | POLLPRI" instead
POLLERR.  it makes consistent to mdstat_poll() and sysfs_poll(). and,
select(2) can handle POLLPRI easily.


Reported-by: Neil Brown <neilb@suse.de>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index f71559784bfb..aa763ab00777 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -648,14 +648,14 @@ static unsigned mounts_poll(struct file *file, poll_table *wait)
 {
         struct proc_mounts *p = file->private_data;
         struct mnt_namespace *ns = p->ns;
-        unsigned res = 0;
+        unsigned res = POLLIN | POLLRDNORM;
 
         poll_wait(file, &ns->poll, wait);
 
         spin_lock(&vfsmount_lock);
         if (p->event != ns->event) {
                 p->event = ns->event;
-                res = POLLERR;
+                res |= POLLERR | POLLPRI;
         }
         spin_unlock(&vfsmount_lock);