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authorEric Paris <eparis@redhat.com>2009-05-21 17:01:37 -0400
committerEric Paris <eparis@redhat.com>2009-06-11 14:57:53 -0400
commita2d8bc6cb4a3024661baf877242f123787d0c054 (patch)
tree4ff3f93877a8992d5383c14fb6012ab9b1954660 /include/linux/fsnotify_backend.h
parent3c5119c05d624f95f4967d16b38c9624b816bdb9 (diff)
fsnotify: generic notification queue and waitq
inotify needs to do asyc notification in which event information is stored on a queue until the listener is ready to receive it. This patch implements a generic notification queue for inotify (and later fanotify) to store events to be sent at a later time. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'include/linux/fsnotify_backend.h')
-rw-r--r--include/linux/fsnotify_backend.h37
1 files changed, 37 insertions, 0 deletions
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 9ea800e840f..15f8f82a5c5 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -119,6 +119,13 @@ struct fsnotify_group {
const struct fsnotify_ops *ops; /* how this group handles things */
+ /* needed to send notification to userspace */
+ struct mutex notification_mutex; /* protect the notification_list */
+ struct list_head notification_list; /* list of event_holder this group needs to send to userspace */
+ wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */
+ unsigned int q_len; /* events on the queue */
+ unsigned int max_events; /* maximum events allowed on the list */
+
/* stores all fastapth entries assoc with this group so they can be cleaned on unregister */
spinlock_t mark_lock; /* protect mark_entries list */
atomic_t num_marks; /* 1 for each mark entry and 1 for not being
@@ -136,11 +143,32 @@ struct fsnotify_group {
};
/*
+ * A single event can be queued in multiple group->notification_lists.
+ *
+ * each group->notification_list will point to an event_holder which in turns points
+ * to the actual event that needs to be sent to userspace.
+ *
+ * Seemed cheaper to create a refcnt'd event and a small holder for every group
+ * than create a different event for every group
+ *
+ */
+struct fsnotify_event_holder {
+ struct fsnotify_event *event;
+ struct list_head event_list;
+};
+
+/*
* all of the information about the original object we want to now send to
* a group. If you want to carry more info from the accessing task to the
* listener this structure is where you need to be adding fields.
*/
struct fsnotify_event {
+ /*
+ * If we create an event we are also likely going to need a holder
+ * to link to a group. So embed one holder in the event. Means only
+ * one allocation for the common case where we only have one group
+ */
+ struct fsnotify_event_holder holder;
spinlock_t lock; /* protection for the associated event_holder and private_list */
/* to_tell may ONLY be dereferenced during handle_event(). */
struct inode *to_tell; /* either the inode the event happened to or its parent */
@@ -264,6 +292,15 @@ extern void fsnotify_put_event(struct fsnotify_event *event);
extern struct fsnotify_event_private_data *fsnotify_get_priv_from_event(struct fsnotify_group *group,
struct fsnotify_event *event);
+/* attach the event to the group notification queue */
+extern int fsnotify_add_notify_event(struct fsnotify_group *group, struct fsnotify_event *event);
+/* true if the group notification queue is empty */
+extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group);
+/* return, but do not dequeue the first event on the notification queue */
+extern struct fsnotify_event *fsnotify_peek_notify_event(struct fsnotify_group *group);
+/* reutnr AND dequeue the first event on the notification queue */
+extern struct fsnotify_event *fsnotify_remove_notify_event(struct fsnotify_group *group);
+
/* functions used to manipulate the marks attached to inodes */
/* run all marks associated with an inode and update inode->i_fsnotify_mask */