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path: root/fs/notify/inotify/inotify_user.c
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Diffstat (limited to 'fs/notify/inotify/inotify_user.c')
-rw-r--r--fs/notify/inotify/inotify_user.c135
1 files changed, 74 insertions, 61 deletions
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index d53a1838d6e8..bed766e435b5 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -427,10 +427,61 @@ static unsigned int inotify_poll(struct file *file, poll_table *wait)
return ret;
}
+/*
+ * Get an inotify_kernel_event if one exists and is small
+ * enough to fit in "count". Return an error pointer if
+ * not large enough.
+ *
+ * Called with the device ev_mutex held.
+ */
+static struct inotify_kernel_event *get_one_event(struct inotify_device *dev,
+ size_t count)
+{
+ size_t event_size = sizeof(struct inotify_event);
+ struct inotify_kernel_event *kevent;
+
+ if (list_empty(&dev->events))
+ return NULL;
+
+ kevent = inotify_dev_get_event(dev);
+ if (kevent->name)
+ event_size += kevent->event.len;
+
+ if (event_size > count)
+ return ERR_PTR(-EINVAL);
+
+ remove_kevent(dev, kevent);
+ return kevent;
+}
+
+/*
+ * Copy an event to user space, returning how much we copied.
+ *
+ * We already checked that the event size is smaller than the
+ * buffer we had in "get_one_event()" above.
+ */
+static ssize_t copy_event_to_user(struct inotify_kernel_event *kevent,
+ char __user *buf)
+{
+ size_t event_size = sizeof(struct inotify_event);
+
+ if (copy_to_user(buf, &kevent->event, event_size))
+ return -EFAULT;
+
+ if (kevent->name) {
+ buf += event_size;
+
+ if (copy_to_user(buf, kevent->name, kevent->event.len))
+ return -EFAULT;
+
+ event_size += kevent->event.len;
+ }
+ return event_size;
+}
+
static ssize_t inotify_read(struct file *file, char __user *buf,
size_t count, loff_t *pos)
{
- size_t event_size = sizeof (struct inotify_event);
struct inotify_device *dev;
char __user *start;
int ret;
@@ -440,81 +491,43 @@ static ssize_t inotify_read(struct file *file, char __user *buf,
dev = file->private_data;
while (1) {
+ struct inotify_kernel_event *kevent;
prepare_to_wait(&dev->wq, &wait, TASK_INTERRUPTIBLE);
mutex_lock(&dev->ev_mutex);
- if (!list_empty(&dev->events)) {
- ret = 0;
- break;
- }
+ kevent = get_one_event(dev, count);
mutex_unlock(&dev->ev_mutex);
- if (file->f_flags & O_NONBLOCK) {
- ret = -EAGAIN;
- break;
- }
-
- if (signal_pending(current)) {
- ret = -EINTR;
- break;
+ if (kevent) {
+ ret = PTR_ERR(kevent);
+ if (IS_ERR(kevent))
+ break;
+ ret = copy_event_to_user(kevent, buf);
+ free_kevent(kevent);
+ if (ret < 0)
+ break;
+ buf += ret;
+ count -= ret;
+ continue;
}
- schedule();
- }
-
- finish_wait(&dev->wq, &wait);
- if (ret)
- return ret;
-
- while (1) {
- struct inotify_kernel_event *kevent;
-
- ret = buf - start;
- if (list_empty(&dev->events))
+ ret = -EAGAIN;
+ if (file->f_flags & O_NONBLOCK)
break;
-
- kevent = inotify_dev_get_event(dev);
- if (event_size + kevent->event.len > count) {
- if (ret == 0 && count > 0) {
- /*
- * could not get a single event because we
- * didn't have enough buffer space.
- */
- ret = -EINVAL;
- }
+ ret = -EINTR;
+ if (signal_pending(current))
break;
- }
- remove_kevent(dev, kevent);
- /*
- * Must perform the copy_to_user outside the mutex in order
- * to avoid a lock order reversal with mmap_sem.
- */
- mutex_unlock(&dev->ev_mutex);
-
- if (copy_to_user(buf, &kevent->event, event_size)) {
- ret = -EFAULT;
+ if (start != buf)
break;
- }
- buf += event_size;
- count -= event_size;
-
- if (kevent->name) {
- if (copy_to_user(buf, kevent->name, kevent->event.len)){
- ret = -EFAULT;
- break;
- }
- buf += kevent->event.len;
- count -= kevent->event.len;
- }
-
- free_kevent(kevent);
- mutex_lock(&dev->ev_mutex);
+ schedule();
}
- mutex_unlock(&dev->ev_mutex);
+ finish_wait(&dev->wq, &wait);
+ if (start != buf && ret != -EFAULT)
+ ret = buf - start;
return ret;
}