inotify: provide function for name length rounding

Rounding of name length when passing it to userspace was done in several
places.  Provide a function to do it and use it in all places.

Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Eric Paris <eparis@parisplace.org>
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, 21 insertions, 20 deletions

diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index 60f954a891ab..1bb6dc8eaf1c 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -124,6 +124,13 @@ static unsigned int inotify_poll(struct file *file, poll_table *wait)
         return ret;
 }
 
+static int round_event_name_len(struct fsnotify_event *event)
+{
+        if (!event->name_len)
+                return 0;
+        return roundup(event->name_len + 1, sizeof(struct inotify_event));
+}
+
 /*
  * Get an inotify_kernel_event if one exists and is small
  * enough to fit in "count". Return an error pointer if
@@ -144,9 +151,7 @@ static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
 
         pr_debug("%s: group=%p event=%p\n", __func__, group, event);
 
-        if (event->name_len)
-                event_size += roundup(event->name_len + 1, event_size);
-
+        event_size += round_event_name_len(event);
         if (event_size > count)
                 return ERR_PTR(-EINVAL);
 
@@ -171,7 +176,8 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
         struct fsnotify_event_private_data *fsn_priv;
         struct inotify_event_private_data *priv;
         size_t event_size = sizeof(struct inotify_event);
-        size_t name_len = 0;
+        size_t name_len;
+        size_t pad_name_len;
 
         pr_debug("%s: group=%p event=%p\n", __func__, group, event);
 
@@ -189,14 +195,13 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
                 inotify_free_event_priv(fsn_priv);
         }
 
+        name_len = event->name_len;
         /*
-         * round up event->name_len so it is a multiple of event_size
+         * round up name length so it is a multiple of event_size
          * plus an extra byte for the terminating '\0'.
          */
-        if (event->name_len)
-                name_len = roundup(event->name_len + 1, event_size);
-        inotify_event.len = name_len;
-
+        pad_name_len = round_event_name_len(event);
+        inotify_event.len = pad_name_len;
         inotify_event.mask = inotify_mask_to_arg(event->mask);
         inotify_event.cookie = event->sync_cookie;
 
@@ -209,20 +214,18 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
         /*
          * fsnotify only stores the pathname, so here we have to send the pathname
          * and then pad that pathname out to a multiple of sizeof(inotify_event)
-         * with zeros.  I get my zeros from the nul_inotify_event.
+         * with zeros.
          */
-        if (name_len) {
-                unsigned int len_to_zero = name_len - event->name_len;
+        if (pad_name_len) {
                 /* copy the path name */
-                if (copy_to_user(buf, event->file_name, event->name_len))
+                if (copy_to_user(buf, event->file_name, name_len))
                         return -EFAULT;
-                buf += event->name_len;
+                buf += name_len;
 
                 /* fill userspace with 0's */
-                if (clear_user(buf, len_to_zero))
+                if (clear_user(buf, pad_name_len - name_len))
                         return -EFAULT;
-                buf += len_to_zero;
-                event_size += name_len;
+                event_size += pad_name_len;
         }
 
         return event_size;
@@ -314,9 +317,7 @@ static long inotify_ioctl(struct file *file, unsigned int cmd,
                 list_for_each_entry(holder, &group->notification_list, event_list) {
                         event = holder->event;
                         send_len += sizeof(struct inotify_event);
-                        if (event->name_len)
-                                send_len += roundup(event->name_len + 1,
-                                                sizeof(struct inotify_event));
+                        send_len += round_event_name_len(event);
                 }
                 mutex_unlock(&group->notification_mutex);
                 ret = put_user(send_len, (int __user *) p);