fsnotify: convert notification_mutex to a spinlock

notification_mutex is used to protect the list of pending events.  As such
there's no reason to use a sleeping lock for it.  Convert it to a
spinlock.

[jack@suse.cz: fixed version]
  Link: http://lkml.kernel.org/r/1474031567-1831-1-git-send-email-jack@suse.cz
Link: http://lkml.kernel.org/r/1473797711-14111-5-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 8 deletions

diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index b8d08d0d0a4d..69d1ea3d292a 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -115,10 +115,10 @@ static unsigned int inotify_poll(struct file *file, poll_table *wait)
 	int ret = 0;
 
 	poll_wait(file, &group->notification_waitq, wait);
-	mutex_lock(&group->notification_mutex);
+	spin_lock(&group->notification_lock);
 	if (!fsnotify_notify_queue_is_empty(group))
 		ret = POLLIN | POLLRDNORM;
-	mutex_unlock(&group->notification_mutex);
+	spin_unlock(&group->notification_lock);
 
 	return ret;
 }
@@ -138,7 +138,7 @@ static int round_event_name_len(struct fsnotify_event *fsn_event)
  * enough to fit in "count". Return an error pointer if
  * not large enough.
  *
- * Called with the group->notification_mutex held.
+ * Called with the group->notification_lock held.
  */
 static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
 					    size_t count)
@@ -157,7 +157,7 @@ static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
 	if (event_size > count)
 		return ERR_PTR(-EINVAL);
 
-	/* held the notification_mutex the whole time, so this is the
+	/* held the notification_lock the whole time, so this is the
 	 * same event we peeked above */
 	fsnotify_remove_first_event(group);
 
@@ -234,9 +234,9 @@ static ssize_t inotify_read(struct file *file, char __user *buf,
 
 	add_wait_queue(&group->notification_waitq, &wait);
 	while (1) {
-		mutex_lock(&group->notification_mutex);
+		spin_lock(&group->notification_lock);
 		kevent = get_one_event(group, count);
-		mutex_unlock(&group->notification_mutex);
+		spin_unlock(&group->notification_lock);
 
 		pr_debug("%s: group=%p kevent=%p\n", __func__, group, kevent);
 
@@ -300,13 +300,13 @@ static long inotify_ioctl(struct file *file, unsigned int cmd,
 
 	switch (cmd) {
 	case FIONREAD:
-		mutex_lock(&group->notification_mutex);
+		spin_lock(&group->notification_lock);
 		list_for_each_entry(fsn_event, &group->notification_list,
 				    list) {
 			send_len += sizeof(struct inotify_event);
 			send_len += round_event_name_len(fsn_event);
 		}
-		mutex_unlock(&group->notification_mutex);
+		spin_unlock(&group->notification_lock);
 		ret = put_user(send_len, (int __user *) p);
 		break;
 	}