[PATCH] inotify (1/5): split kernel API from userspace support
The following series of patches introduces a kernel API for inotify,
making it possible for kernel modules to benefit from inotify's
mechanism for watching inodes. With these patches, inotify will
maintain for each caller a list of watches (via an embedded struct
inotify_watch), where each inotify_watch is associated with a
corresponding struct inode. The caller registers an event handler and
specifies for which filesystem events their event handler should be
called per inotify_watch.
Signed-off-by: Amy Griffis <amy.griffis@hp.com>
Acked-by: Robert Love <rml@novell.com>
Acked-by: John McCutchan <john@johnmccutchan.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/inotify.h b/include/linux/inotify.h
index 71aa155..68b6e01 100644
--- a/include/linux/inotify.h
+++ b/include/linux/inotify.h
@@ -68,8 +68,37 @@
#include <linux/dcache.h>
#include <linux/fs.h>
+/*
+ * struct inotify_watch - represents a watch request on a specific inode
+ *
+ * h_list is protected by ih->mutex of the associated inotify_handle.
+ * i_list, mask are protected by inode->inotify_mutex of the associated inode.
+ * ih, inode, and wd are never written to once the watch is created.
+ *
+ * Callers must use the established inotify interfaces to access inotify_watch
+ * contents. The content of this structure is private to the inotify
+ * implementation.
+ */
+struct inotify_watch {
+ struct list_head h_list; /* entry in inotify_handle's list */
+ struct list_head i_list; /* entry in inode's list */
+ atomic_t count; /* reference count */
+ struct inotify_handle *ih; /* associated inotify handle */
+ struct inode *inode; /* associated inode */
+ __s32 wd; /* watch descriptor */
+ __u32 mask; /* event mask for this watch */
+};
+
+struct inotify_operations {
+ void (*handle_event)(struct inotify_watch *, u32, u32, u32,
+ const char *);
+ void (*destroy_watch)(struct inotify_watch *);
+};
+
#ifdef CONFIG_INOTIFY
+/* Kernel API for producing events */
+
extern void inotify_d_instantiate(struct dentry *, struct inode *);
extern void inotify_d_move(struct dentry *);
extern void inotify_inode_queue_event(struct inode *, __u32, __u32,
@@ -80,6 +109,18 @@
extern void inotify_inode_is_dead(struct inode *);
extern u32 inotify_get_cookie(void);
+/* Kernel Consumer API */
+
+extern struct inotify_handle *inotify_init(const struct inotify_operations *);
+extern void inotify_destroy(struct inotify_handle *);
+extern __s32 inotify_find_update_watch(struct inotify_handle *, struct inode *,
+ u32);
+extern __s32 inotify_add_watch(struct inotify_handle *, struct inotify_watch *,
+ struct inode *, __u32);
+extern int inotify_rm_wd(struct inotify_handle *, __u32);
+extern void get_inotify_watch(struct inotify_watch *);
+extern void put_inotify_watch(struct inotify_watch *);
+
#else
static inline void inotify_d_instantiate(struct dentry *dentry,
@@ -116,6 +157,41 @@
return 0;
}
+static inline struct inotify_handle *inotify_init(const struct inotify_operations *ops)
+{
+ return ERR_PTR(-EOPNOTSUPP);
+}
+
+static inline void inotify_destroy(struct inotify_handle *ih)
+{
+}
+
+static inline __s32 inotify_find_update_watch(struct inotify_handle *ih,
+ struct inode *inode, u32 mask)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline __s32 inotify_add_watch(struct inotify_handle *ih,
+ struct inotify_watch *watch,
+ struct inode *inode, __u32 mask)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int inotify_rm_wd(struct inotify_handle *ih, __u32 wd)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline void get_inotify_watch(struct inotify_watch *watch)
+{
+}
+
+static inline void put_inotify_watch(struct inotify_watch *watch)
+{
+}
+
#endif /* CONFIG_INOTIFY */
#endif /* __KERNEL __ */