Initial import

1 files changed, 405 insertions, 0 deletions

diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
new file mode 100644
index 000000000..0f313f93c
--- /dev/null
+++ b/include/linux/fsnotify_backend.h
@@ -0,0 +1,405 @@
+/*
+ * Filesystem access notification for Linux
+ *
+ *  Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
+ */
+
+#ifndef __LINUX_FSNOTIFY_BACKEND_H
+#define __LINUX_FSNOTIFY_BACKEND_H
+
+#ifdef __KERNEL__
+
+#include <linux/idr.h> /* inotify uses this */
+#include <linux/fs.h> /* struct inode */
+#include <linux/list.h>
+#include <linux/path.h> /* struct path */
+#include <linux/spinlock.h>
+#include <linux/types.h>
+#include <linux/atomic.h>
+
+/*
+ * IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily
+ * convert between them.  dnotify only needs conversion at watch creation
+ * so no perf loss there.  fanotify isn't defined yet, so it can use the
+ * wholes if it needs more events.
+ */
+#define FS_ACCESS		0x00000001	/* File was accessed */
+#define FS_MODIFY		0x00000002	/* File was modified */
+#define FS_ATTRIB		0x00000004	/* Metadata changed */
+#define FS_CLOSE_WRITE		0x00000008	/* Writtable file was closed */
+#define FS_CLOSE_NOWRITE	0x00000010	/* Unwrittable file closed */
+#define FS_OPEN			0x00000020	/* File was opened */
+#define FS_MOVED_FROM		0x00000040	/* File was moved from X */
+#define FS_MOVED_TO		0x00000080	/* File was moved to Y */
+#define FS_CREATE		0x00000100	/* Subfile was created */
+#define FS_DELETE		0x00000200	/* Subfile was deleted */
+#define FS_DELETE_SELF		0x00000400	/* Self was deleted */
+#define FS_MOVE_SELF		0x00000800	/* Self was moved */
+
+#define FS_UNMOUNT		0x00002000	/* inode on umount fs */
+#define FS_Q_OVERFLOW		0x00004000	/* Event queued overflowed */
+#define FS_IN_IGNORED		0x00008000	/* last inotify event here */
+
+#define FS_OPEN_PERM		0x00010000	/* open event in an permission hook */
+#define FS_ACCESS_PERM		0x00020000	/* access event in a permissions hook */
+
+#define FS_EXCL_UNLINK		0x04000000	/* do not send events if object is unlinked */
+#define FS_ISDIR		0x40000000	/* event occurred against dir */
+#define FS_IN_ONESHOT		0x80000000	/* only send event once */
+
+#define FS_DN_RENAME		0x10000000	/* file renamed */
+#define FS_DN_MULTISHOT		0x20000000	/* dnotify multishot */
+
+/* This inode cares about things that happen to its children.  Always set for
+ * dnotify and inotify. */
+#define FS_EVENT_ON_CHILD	0x08000000
+
+/* This is a list of all events that may get sent to a parernt based on fs event
+ * happening to inodes inside that directory */
+#define FS_EVENTS_POSS_ON_CHILD   (FS_ACCESS | FS_MODIFY | FS_ATTRIB |\
+				   FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\
+				   FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\
+				   FS_DELETE | FS_OPEN_PERM | FS_ACCESS_PERM)
+
+#define FS_MOVE			(FS_MOVED_FROM | FS_MOVED_TO)
+
+#define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM)
+
+#define ALL_FSNOTIFY_EVENTS (FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
+			     FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN | \
+			     FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE | \
+			     FS_DELETE | FS_DELETE_SELF | FS_MOVE_SELF | \
+			     FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \
+			     FS_OPEN_PERM | FS_ACCESS_PERM | FS_EXCL_UNLINK | \
+			     FS_ISDIR | FS_IN_ONESHOT | FS_DN_RENAME | \
+			     FS_DN_MULTISHOT | FS_EVENT_ON_CHILD)
+
+struct fsnotify_group;
+struct fsnotify_event;
+struct fsnotify_mark;
+struct fsnotify_event_private_data;
+struct fsnotify_fname;
+
+/*
+ * Each group much define these ops.  The fsnotify infrastructure will call
+ * these operations for each relevant group.
+ *
+ * should_send_event - given a group, inode, and mask this function determines
+ *		if the group is interested in this event.
+ * handle_event - main call for a group to handle an fs event
+ * free_group_priv - called when a group refcnt hits 0 to clean up the private union
+ * freeing_mark - called when a mark is being destroyed for some reason.  The group
+ * 		MUST be holding a reference on each mark and that reference must be
+ * 		dropped in this function.  inotify uses this function to send
+ * 		userspace messages that marks have been removed.
+ */
+struct fsnotify_ops {
+	int (*handle_event)(struct fsnotify_group *group,
+			    struct inode *inode,
+			    struct fsnotify_mark *inode_mark,
+			    struct fsnotify_mark *vfsmount_mark,
+			    u32 mask, void *data, int data_type,
+			    const unsigned char *file_name, u32 cookie);
+	void (*free_group_priv)(struct fsnotify_group *group);
+	void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group);
+	void (*free_event)(struct fsnotify_event *event);
+};
+
+/*
+ * 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 {
+	struct list_head list;
+	/* inode may ONLY be dereferenced during handle_event(). */
+	struct inode *inode;	/* either the inode the event happened to or its parent */
+	u32 mask;		/* the type of access, bitwise OR for FS_* event types */
+};
+
+/*
+ * A group is a "thing" that wants to receive notification about filesystem
+ * events.  The mask holds the subset of event types this group cares about.
+ * refcnt on a group is up to the implementor and at any moment if it goes 0
+ * everything will be cleaned up.
+ */
+struct fsnotify_group {
+	/*
+	 * How the refcnt is used is up to each group.  When the refcnt hits 0
+	 * fsnotify will clean up all of the resources associated with this group.
+	 * As an example, the dnotify group will always have a refcnt=1 and that
+	 * will never change.  Inotify, on the other hand, has a group per
+	 * inotify_init() and the refcnt will hit 0 only when that fd has been
+	 * closed.
+	 */
+	atomic_t refcnt;		/* things with interest in this 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 */
+	/*
+	 * Valid fsnotify group priorities.  Events are send in order from highest
+	 * priority to lowest priority.  We default to the lowest priority.
+	 */
+	#define FS_PRIO_0	0 /* normal notifiers, no permissions */
+	#define FS_PRIO_1	1 /* fanotify content based access control */
+	#define FS_PRIO_2	2 /* fanotify pre-content access */
+	unsigned int priority;
+
+	/* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
+	struct mutex mark_mutex;	/* protect marks_list */
+	atomic_t num_marks;		/* 1 for each mark and 1 for not being
+					 * past the point of no return when freeing
+					 * a group */
+	struct list_head marks_list;	/* all inode marks for this group */
+
+	struct fasync_struct *fsn_fa;    /* async notification */
+
+	struct fsnotify_event *overflow_event;	/* Event we queue when the
+						 * notification list is too
+						 * full */
+
+	/* groups can define private fields here or use the void *private */
+	union {
+		void *private;
+#ifdef CONFIG_INOTIFY_USER
+		struct inotify_group_private_data {
+			spinlock_t	idr_lock;
+			struct idr      idr;
+			struct user_struct      *user;
+		} inotify_data;
+#endif
+#ifdef CONFIG_FANOTIFY
+		struct fanotify_group_private_data {
+#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
+			/* allows a group to block waiting for a userspace response */
+			spinlock_t access_lock;
+			struct list_head access_list;
+			wait_queue_head_t access_waitq;
+			atomic_t bypass_perm;
+#endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */
+			int f_flags;
+			unsigned int max_marks;
+			struct user_struct *user;
+		} fanotify_data;
+#endif /* CONFIG_FANOTIFY */
+	};
+};
+
+/* when calling fsnotify tell it if the data is a path or inode */
+#define FSNOTIFY_EVENT_NONE	0
+#define FSNOTIFY_EVENT_PATH	1
+#define FSNOTIFY_EVENT_INODE	2
+
+/*
+ * a mark is simply an object attached to an in core inode which allows an
+ * fsnotify listener to indicate they are either no longer interested in events
+ * of a type matching mask or only interested in those events.
+ *
+ * these are flushed when an inode is evicted from core and may be flushed
+ * when the inode is modified (as seen by fsnotify_access).  Some fsnotify users
+ * (such as dnotify) will flush these when the open fd is closed and not at
+ * inode eviction or modification.
+ */
+struct fsnotify_mark {
+	__u32 mask;			/* mask this mark is for */
+	/* we hold ref for each i_list and g_list.  also one ref for each 'thing'
+	 * in kernel that found and may be using this mark. */
+	atomic_t refcnt;		/* active things looking at this mark */
+	struct fsnotify_group *group;	/* group this mark is for */
+	struct list_head g_list;	/* list of marks by group->i_fsnotify_marks
+					 * Also reused for queueing mark into
+					 * destroy_list when it's waiting for
+					 * the end of SRCU period before it can
+					 * be freed */
+	spinlock_t lock;		/* protect group and inode */
+	struct hlist_node obj_list;	/* list of marks for inode / vfsmount */
+	struct list_head free_list;	/* tmp list used when freeing this mark */
+	union {
+		struct inode *inode;	/* inode this mark is associated with */
+		struct vfsmount *mnt;	/* vfsmount this mark is associated with */
+	};
+	__u32 ignored_mask;		/* events types to ignore */
+#define FSNOTIFY_MARK_FLAG_INODE		0x01
+#define FSNOTIFY_MARK_FLAG_VFSMOUNT		0x02
+#define FSNOTIFY_MARK_FLAG_OBJECT_PINNED	0x04
+#define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY	0x08
+#define FSNOTIFY_MARK_FLAG_ALIVE		0x10
+	unsigned int flags;		/* vfsmount or inode mark? */
+	void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */
+};
+
+#ifdef CONFIG_FSNOTIFY
+
+/* called from the vfs helpers */
+
+/* main fsnotify call to send events */
+extern int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
+		    const unsigned char *name, u32 cookie);
+extern int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask);
+extern void __fsnotify_inode_delete(struct inode *inode);
+extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
+extern u32 fsnotify_get_cookie(void);
+
+static inline int fsnotify_inode_watches_children(struct inode *inode)
+{
+	/* FS_EVENT_ON_CHILD is set if the inode may care */
+	if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD))
+		return 0;
+	/* this inode might care about child events, does it care about the
+	 * specific set of events that can happen on a child? */
+	return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD;
+}
+
+/*
+ * Update the dentry with a flag indicating the interest of its parent to receive
+ * filesystem events when those events happens to this dentry->d_inode.
+ */
+static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
+{
+	struct dentry *parent;
+
+	assert_spin_locked(&dentry->d_lock);
+
+	/*
+	 * Serialisation of setting PARENT_WATCHED on the dentries is provided
+	 * by d_lock. If inotify_inode_watched changes after we have taken
+	 * d_lock, the following __fsnotify_update_child_dentry_flags call will
+	 * find our entry, so it will spin until we complete here, and update
+	 * us with the new state.
+	 */
+	parent = dentry->d_parent;
+	if (parent->d_inode && fsnotify_inode_watches_children(parent->d_inode))
+		dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
+	else
+		dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
+}
+
+/*
+ * fsnotify_d_instantiate - instantiate a dentry for inode
+ */
+static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode)
+{
+	if (!inode)
+		return;
+
+	spin_lock(&dentry->d_lock);
+	__fsnotify_update_dcache_flags(dentry);
+	spin_unlock(&dentry->d_lock);
+}
+
+/* called from fsnotify listeners, such as fanotify or dnotify */
+
+/* create a new group */
+extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops);
+/* get reference to a group */
+extern void fsnotify_get_group(struct fsnotify_group *group);
+/* drop reference on a group from fsnotify_alloc_group */
+extern void fsnotify_put_group(struct fsnotify_group *group);
+/* destroy group */
+extern void fsnotify_destroy_group(struct fsnotify_group *group);
+/* fasync handler function */
+extern int fsnotify_fasync(int fd, struct file *file, int on);
+/* Free event from memory */
+extern void fsnotify_destroy_event(struct fsnotify_group *group,
+				   struct fsnotify_event *event);
+/* attach the event to the group notification queue */
+extern int fsnotify_add_event(struct fsnotify_group *group,
+			      struct fsnotify_event *event,
+			      int (*merge)(struct list_head *,
+					   struct fsnotify_event *));
+/* Remove passed event from groups notification queue */
+extern void fsnotify_remove_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_first_event(struct fsnotify_group *group);
+/* return AND dequeue the first event on the notification queue */
+extern struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group);
+
+/* functions used to manipulate the marks attached to inodes */
+
+/* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */
+extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt);
+/* run all marks associated with an inode and update inode->i_fsnotify_mask */
+extern void fsnotify_recalc_inode_mask(struct inode *inode);
+extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark));
+/* find (and take a reference) to a mark associated with group and inode */
+extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode);
+/* find (and take a reference) to a mark associated with group and vfsmount */
+extern struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt);
+/* copy the values from old into new */
+extern void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old);
+/* set the ignored_mask of a mark */
+extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask);
+/* set the mask of a mark (might pin the object into memory */
+extern void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask);
+/* attach the mark to both the group and the inode */
+extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group,
+			     struct inode *inode, struct vfsmount *mnt, int allow_dups);
+extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark, struct fsnotify_group *group,
+				    struct inode *inode, struct vfsmount *mnt, int allow_dups);
+/* given a group and a mark, flag mark to be freed when all references are dropped */
+extern void fsnotify_destroy_mark(struct fsnotify_mark *mark,
+				  struct fsnotify_group *group);
+extern void fsnotify_destroy_mark_locked(struct fsnotify_mark *mark,
+					 struct fsnotify_group *group);
+/* run all the marks in a group, and clear all of the vfsmount marks */
+extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group);
+/* run all the marks in a group, and clear all of the inode marks */
+extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group);
+/* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/
+extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags);
+/* run all the marks in a group, and flag them to be freed */
+extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group);
+extern void fsnotify_get_mark(struct fsnotify_mark *mark);
+extern void fsnotify_put_mark(struct fsnotify_mark *mark);
+extern void fsnotify_unmount_inodes(struct list_head *list);
+
+/* put here because inotify does some weird stuff when destroying watches */
+extern void fsnotify_init_event(struct fsnotify_event *event,
+				struct inode *to_tell, u32 mask);
+
+#else
+
+static inline int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
+			   const unsigned char *name, u32 cookie)
+{
+	return 0;
+}
+
+static inline int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
+{
+	return 0;
+}
+
+static inline void __fsnotify_inode_delete(struct inode *inode)
+{}
+
+static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
+{}
+
+static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
+{}
+
+static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode)
+{}
+
+static inline u32 fsnotify_get_cookie(void)
+{
+	return 0;
+}
+
+static inline void fsnotify_unmount_inodes(struct list_head *list)
+{}
+
+#endif	/* CONFIG_FSNOTIFY */
+
+#endif	/* __KERNEL __ */
+
+#endif	/* __LINUX_FSNOTIFY_BACKEND_H */