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include/linux/fsnotify_backend.h
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/* * 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__ |
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#include <linux/idr.h> /* inotify uses this */ |
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#include <linux/fs.h> /* struct inode */ #include <linux/list.h> #include <linux/path.h> /* struct path */ #include <linux/spinlock.h> #include <linux/types.h> |
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#include <linux/atomic.h> |
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/* * 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 */ |
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#define FS_OPEN_PERM 0x00010000 /* open event in an permission hook */ #define FS_ACCESS_PERM 0x00020000 /* access event in a permissions hook */ |
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#define FS_EXCL_UNLINK 0x04000000 /* do not send events if object is unlinked */ |
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#define FS_ISDIR 0x40000000 /* event occurred against dir */ |
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#define FS_IN_ONESHOT 0x80000000 /* only send event once */ #define FS_DN_RENAME 0x10000000 /* file renamed */ #define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */ |
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/* 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 |\ |
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FS_DELETE | FS_OPEN_PERM | FS_ACCESS_PERM) |
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#define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO) |
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#define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM) |
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#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 | \ |
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FS_ISDIR | FS_IN_ONESHOT | FS_DN_RENAME | \ |
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FS_DN_MULTISHOT | FS_EVENT_ON_CHILD) |
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struct fsnotify_group; struct fsnotify_event; |
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struct fsnotify_mark; |
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struct fsnotify_event_private_data; |
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struct fsnotify_fname; |
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/* * Each group much define these ops. The fsnotify infrastructure will call * these operations for each relevant group. * * 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 |
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* 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. |
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*/ struct fsnotify_ops { |
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int (*handle_event)(struct fsnotify_group *group, |
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struct inode *inode, |
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struct fsnotify_mark *inode_mark, struct fsnotify_mark *vfsmount_mark, |
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u32 mask, void *data, int data_type, |
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const unsigned char *file_name, u32 cookie); |
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void (*free_group_priv)(struct fsnotify_group *group); |
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void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group); |
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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 */ |
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}; /* * 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 { /* |
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* 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 */ |
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const struct fsnotify_ops *ops; /* how this group handles things */ |
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/* 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 */ |
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/* * 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; |
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/* stores all fastpath marks assoc with this group so they can be cleaned on unregister */ |
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struct mutex mark_mutex; /* protect marks_list */ |
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atomic_t num_marks; /* 1 for each mark and 1 for not being |
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* past the point of no return when freeing * a group */ |
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struct list_head marks_list; /* all inode marks for this group */ |
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struct fasync_struct *fsn_fa; /* async notification */ |
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struct fsnotify_event *overflow_event; /* Event we queue when the |
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* notification list is too * full */ |
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/* groups can define private fields here or use the void *private */ union { void *private; |
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#ifdef CONFIG_INOTIFY_USER struct inotify_group_private_data { spinlock_t idr_lock; struct idr idr; |
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struct user_struct *user; } inotify_data; #endif |
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#ifdef CONFIG_FANOTIFY |
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struct fanotify_group_private_data { |
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#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS |
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/* allows a group to block waiting for a userspace response */ |
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spinlock_t access_lock; |
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struct list_head access_list; wait_queue_head_t access_waitq; |
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atomic_t bypass_perm; |
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#endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */ int f_flags; |
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unsigned int max_marks; |
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struct user_struct *user; |
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} fanotify_data; |
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#endif /* CONFIG_FANOTIFY */ |
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}; }; |
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/* when calling fsnotify tell it if the data is a path or inode */ #define FSNOTIFY_EVENT_NONE 0 |
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#define FSNOTIFY_EVENT_PATH 1 |
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#define FSNOTIFY_EVENT_INODE 2 |
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/* |
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* A mark is simply an object attached to an in core inode which allows an |
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* fsnotify listener to indicate they are either no longer interested in events * of a type matching mask or only interested in those events. * |
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* 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. * * Text in brackets is showing the lock(s) protecting modifications of a * particular entry. obj_lock means either inode->i_lock or * mnt->mnt_root->d_lock depending on the mark type. |
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*/ |
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struct fsnotify_mark { |
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/* Mask this mark is for [mark->lock, group->mark_mutex] */ __u32 mask; /* We hold one for presence in g_list. Also one ref for each 'thing' |
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* in kernel that found and may be using this mark. */ |
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atomic_t refcnt; /* Group this mark is for. Set on mark creation, stable until last ref * is dropped */ struct fsnotify_group *group; /* 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. [group->mark_mutex] */ struct list_head g_list; /* Protects inode / mnt pointers, flags, masks */ spinlock_t lock; /* List of marks for inode / vfsmount [obj_lock] */ struct hlist_node obj_list; |
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union { /* Object pointer [mark->lock, group->mark_mutex] */ |
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struct inode *inode; /* inode this mark is associated with */ struct vfsmount *mnt; /* vfsmount this mark is associated with */ |
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}; |
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/* Events types to ignore [mark->lock, group->mark_mutex] */ __u32 ignored_mask; |
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#define FSNOTIFY_MARK_FLAG_INODE 0x01 #define FSNOTIFY_MARK_FLAG_VFSMOUNT 0x02 #define FSNOTIFY_MARK_FLAG_OBJECT_PINNED 0x04 |
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#define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08 |
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#define FSNOTIFY_MARK_FLAG_ALIVE 0x10 |
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#define FSNOTIFY_MARK_FLAG_ATTACHED 0x20 |
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unsigned int flags; /* flags [mark->lock] */ |
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void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */ |
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}; |
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#ifdef CONFIG_FSNOTIFY /* called from the vfs helpers */ /* main fsnotify call to send events */ |
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extern int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, const unsigned char *name, u32 cookie); |
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extern int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask); |
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extern void __fsnotify_inode_delete(struct inode *inode); |
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extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt); |
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extern u32 fsnotify_get_cookie(void); |
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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; |
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assert_spin_locked(&dentry->d_lock); |
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/* * 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. */ |
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parent = dentry->d_parent; |
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if (parent->d_inode && fsnotify_inode_watches_children(parent->d_inode)) |
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dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; else dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; } /* * fsnotify_d_instantiate - instantiate a dentry for inode |
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*/ static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) { if (!inode) return; |
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spin_lock(&dentry->d_lock); __fsnotify_update_dcache_flags(dentry); spin_unlock(&dentry->d_lock); } |
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/* called from fsnotify listeners, such as fanotify or dnotify */ |
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/* create a new group */ |
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extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops); |
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/* get reference to a group */ extern void fsnotify_get_group(struct fsnotify_group *group); |
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/* drop reference on a group from fsnotify_alloc_group */ |
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extern void fsnotify_put_group(struct fsnotify_group *group); |
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/* destroy group */ extern void fsnotify_destroy_group(struct fsnotify_group *group); |
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/* fasync handler function */ extern int fsnotify_fasync(int fd, struct file *file, int on); |
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/* Free event from memory */ extern void fsnotify_destroy_event(struct fsnotify_group *group, struct fsnotify_event *event); |
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/* attach the event to the group notification queue */ |
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extern int fsnotify_add_event(struct fsnotify_group *group, struct fsnotify_event *event, int (*merge)(struct list_head *, struct fsnotify_event *)); |
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/* Remove passed event from groups notification queue */ extern void fsnotify_remove_event(struct fsnotify_group *group, struct fsnotify_event *event); |
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/* 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 */ |
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extern struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group); |
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/* return AND dequeue the first event on the notification queue */ |
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extern struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group); |
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/* functions used to manipulate the marks attached to inodes */ |
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/* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */ extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt); |
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/* run all marks associated with an inode and update inode->i_fsnotify_mask */ extern void fsnotify_recalc_inode_mask(struct inode *inode); |
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extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark)); |
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/* find (and take a reference) to a mark associated with group and inode */ |
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extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode); |
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/* 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); |
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/* copy the values from old into new */ |
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extern void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old); |
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/* set the ignored_mask of a mark */ extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask); |
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/* 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); |
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/* attach the mark to both the group and the inode */ |
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extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group, struct inode *inode, struct vfsmount *mnt, int allow_dups); |
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extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark, struct fsnotify_group *group, struct inode *inode, struct vfsmount *mnt, int allow_dups); |
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/* 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); |
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/* detach mark from inode / mount list, group list, drop inode reference */ extern void fsnotify_detach_mark(struct fsnotify_mark *mark); /* free mark */ extern void fsnotify_free_mark(struct fsnotify_mark *mark); |
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/* 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); |
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/* run all the marks in a group, and flag them to be freed */ extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group); |
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extern void fsnotify_get_mark(struct fsnotify_mark *mark); extern void fsnotify_put_mark(struct fsnotify_mark *mark); |
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extern void fsnotify_unmount_inodes(struct super_block *sb); |
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/* put here because inotify does some weird stuff when destroying watches */ |
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extern void fsnotify_init_event(struct fsnotify_event *event, struct inode *to_tell, u32 mask); |
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#else |
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static inline int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, const unsigned char *name, u32 cookie) { return 0; } |
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static inline int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask) { return 0; } |
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static inline void __fsnotify_inode_delete(struct inode *inode) {} |
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static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt) {} |
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static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) {} static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) {} |
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static inline u32 fsnotify_get_cookie(void) { return 0; } |
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static inline void fsnotify_unmount_inodes(struct super_block *sb) |
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{} |
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#endif /* CONFIG_FSNOTIFY */ #endif /* __KERNEL __ */ #endif /* __LINUX_FSNOTIFY_BACKEND_H */ |