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 /* SPDX-License-Identifier: GPL-2.0 */
 /*
  * 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>
 #include <linux/user_namespace.h>
 #include <linux/refcount.h>
 #include <linux/mempool.h>
 #include <linux/sched/mm.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_OPEN_EXEC        0x00001000  /* File was opened for exec */
 
 #define FS_UNMOUNT      0x00002000  /* inode on umount fs */
 #define FS_Q_OVERFLOW       0x00004000  /* Event queued overflowed */
 #define FS_ERROR        0x00008000  /* Filesystem Error (fanotify) */
 
 /*
  * FS_IN_IGNORED overloads FS_ERROR.  It is only used internally by inotify
  * which does not support FS_ERROR.
  */
 #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_OPEN_EXEC_PERM   0x00040000  /* open/exec event in a permission hook */
 
 /*
  * Set on inode mark that cares about things that happen to its children.
  * Always set for dnotify and inotify.
  * Set on inode/sb/mount marks that care about parent/name info.
  */
 #define FS_EVENT_ON_CHILD   0x08000000
 
 #define FS_RENAME       0x10000000  /* File was renamed */
 #define FS_DN_MULTISHOT     0x20000000  /* dnotify multishot */
 #define FS_ISDIR        0x40000000  /* event occurred against dir */
 
 #define FS_MOVE         (FS_MOVED_FROM | FS_MOVED_TO)
 
 /*
  * Directory entry modification events - reported only to directory
  * where entry is modified and not to a watching parent.
  * The watching parent may get an FS_ATTRIB|FS_EVENT_ON_CHILD event
  * when a directory entry inside a child subdir changes.
  */
 #define ALL_FSNOTIFY_DIRENT_EVENTS (FS_CREATE | FS_DELETE | FS_MOVE | FS_RENAME)
 
 #define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM | \
                   FS_OPEN_EXEC_PERM)
 
 /*
  * This is a list of all events that may get sent to a parent that is watching
  * with flag FS_EVENT_ON_CHILD based on fs event on a child of that directory.
  */
 #define FS_EVENTS_POSS_ON_CHILD   (ALL_FSNOTIFY_PERM_EVENTS | \
                    FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
                    FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | \
                    FS_OPEN | FS_OPEN_EXEC)
 
 /*
  * This is a list of all events that may get sent with the parent inode as the
  * @to_tell argument of fsnotify().
  * It may include events that can be sent to an inode/sb/mount mark, but cannot
  * be sent to a parent watching children.
  */
 #define FS_EVENTS_POSS_TO_PARENT (FS_EVENTS_POSS_ON_CHILD)
 
 /* Events that can be reported to backends */
 #define ALL_FSNOTIFY_EVENTS (ALL_FSNOTIFY_DIRENT_EVENTS | \
                  FS_EVENTS_POSS_ON_CHILD | \
                  FS_DELETE_SELF | FS_MOVE_SELF | \
                  FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \
                  FS_ERROR)
 
 /* Extra flags that may be reported with event or control handling of events */
 #define ALL_FSNOTIFY_FLAGS  (FS_ISDIR | FS_EVENT_ON_CHILD | FS_DN_MULTISHOT)
 
 #define ALL_FSNOTIFY_BITS   (ALL_FSNOTIFY_EVENTS | ALL_FSNOTIFY_FLAGS)
 
 struct fsnotify_group;
 struct fsnotify_event;
 struct fsnotify_mark;
 struct fsnotify_event_private_data;
 struct fsnotify_fname;
 struct fsnotify_iter_info;
 
 struct mem_cgroup;
 
 /*
  * 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
  * @group:  group to notify
  * @mask:   event type and flags
  * @data:   object that event happened on
  * @data_type:  type of object for fanotify_data_XXX() accessors
  * @dir:    optional directory associated with event -
  *      if @file_name is not NULL, this is the directory that
  *      @file_name is relative to
  * @file_name:  optional file name associated with event
  * @cookie: inotify rename cookie
  * @iter_info:  array of marks from this group that are interested in the event
  *
  * handle_inode_event - simple variant of handle_event() for groups that only
  *      have inode marks and don't have ignore mask
  * @mark:   mark to notify
  * @mask:   event type and flags
  * @inode:  inode that event happened on
  * @dir:    optional directory associated with event -
  *      if @file_name is not NULL, this is the directory that
  *      @file_name is relative to.
  *      Either @inode or @dir must be non-NULL.
  * @file_name:  optional file name associated with event
  * @cookie: inotify rename cookie
  *
  * 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, u32 mask,
                 const void *data, int data_type, struct inode *dir,
                 const struct qstr *file_name, u32 cookie,
                 struct fsnotify_iter_info *iter_info);
     int (*handle_inode_event)(struct fsnotify_mark *mark, u32 mask,
                 struct inode *inode, struct inode *dir,
                 const struct qstr *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_group *group, struct fsnotify_event *event);
     /* called on final put+free to free memory */
     void (*free_mark)(struct fsnotify_mark *mark);
 };
 
 /*
  * 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;
 };
 
 /*
  * 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 {
     const struct fsnotify_ops *ops; /* how this group handles things */
 
     /*
      * 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.
      */
     refcount_t refcnt;      /* things with interest in this group */
 
     /* needed to send notification to userspace */
     spinlock_t notification_lock;       /* 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;
     bool shutdown;      /* group is being shut down, don't queue more events */
 
 #define FSNOTIFY_GROUP_USER 0x01 /* user allocated group */
 #define FSNOTIFY_GROUP_DUPS 0x02 /* allow multiple marks per object */
 #define FSNOTIFY_GROUP_NOFS 0x04 /* group lock is not direct reclaim safe */
     int flags;
     unsigned int owner_flags;   /* stored flags of mark_mutex owner */
 
     /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
     struct mutex mark_mutex;    /* protect marks_list */
     atomic_t user_waits;        /* Number of tasks waiting for user
                      * response */
     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 */
 
     struct mem_cgroup *memcg;   /* memcg to charge allocations */
 
     /* 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 ucounts *ucounts;
         } inotify_data;
 #endif
 #ifdef CONFIG_FANOTIFY
         struct fanotify_group_private_data {
             /* Hash table of events for merge */
             struct hlist_head *merge_hash;
             /* allows a group to block waiting for a userspace response */
             struct list_head access_list;
             wait_queue_head_t access_waitq;
             int flags;           /* flags from fanotify_init() */
             int f_flags; /* event_f_flags from fanotify_init() */
             struct ucounts *ucounts;
             mempool_t error_events_pool;
         } fanotify_data;
 #endif /* CONFIG_FANOTIFY */
     };
 };
 
 /*
  * These helpers are used to prevent deadlock when reclaiming inodes with
  * evictable marks of the same group that is allocating a new mark.
  */
 static inline void fsnotify_group_lock(struct fsnotify_group *group)
 {
     mutex_lock(&group->mark_mutex);
     if (group->flags & FSNOTIFY_GROUP_NOFS)
         group->owner_flags = memalloc_nofs_save();
 }
 
 static inline void fsnotify_group_unlock(struct fsnotify_group *group)
 {
     if (group->flags & FSNOTIFY_GROUP_NOFS)
         memalloc_nofs_restore(group->owner_flags);
     mutex_unlock(&group->mark_mutex);
 }
 
 static inline void fsnotify_group_assert_locked(struct fsnotify_group *group)
 {
     WARN_ON_ONCE(!mutex_is_locked(&group->mark_mutex));
     if (group->flags & FSNOTIFY_GROUP_NOFS)
         WARN_ON_ONCE(!(current->flags & PF_MEMALLOC_NOFS));
 }
 
 /* When calling fsnotify tell it if the data is a path or inode */
 enum fsnotify_data_type {
     FSNOTIFY_EVENT_NONE,
     FSNOTIFY_EVENT_PATH,
     FSNOTIFY_EVENT_INODE,
     FSNOTIFY_EVENT_DENTRY,
     FSNOTIFY_EVENT_ERROR,
 };
 
 struct fs_error_report {
     int error;
     struct inode *inode;
     struct super_block *sb;
 };
 
 static inline struct inode *fsnotify_data_inode(const void *data, int data_type)
 {
     switch (data_type) {
     case FSNOTIFY_EVENT_INODE:
         return (struct inode *)data;
     case FSNOTIFY_EVENT_DENTRY:
         return d_inode(data);
     case FSNOTIFY_EVENT_PATH:
         return d_inode(((const struct path *)data)->dentry);
     case FSNOTIFY_EVENT_ERROR:
         return ((struct fs_error_report *)data)->inode;
     default:
         return NULL;
     }
 }
 
 static inline struct dentry *fsnotify_data_dentry(const void *data, int data_type)
 {
     switch (data_type) {
     case FSNOTIFY_EVENT_DENTRY:
         /* Non const is needed for dget() */
         return (struct dentry *)data;
     case FSNOTIFY_EVENT_PATH:
         return ((const struct path *)data)->dentry;
     default:
         return NULL;
     }
 }
 
 static inline const struct path *fsnotify_data_path(const void *data,
                             int data_type)
 {
     switch (data_type) {
     case FSNOTIFY_EVENT_PATH:
         return data;
     default:
         return NULL;
     }
 }
 
 static inline struct super_block *fsnotify_data_sb(const void *data,
                            int data_type)
 {
     switch (data_type) {
     case FSNOTIFY_EVENT_INODE:
         return ((struct inode *)data)->i_sb;
     case FSNOTIFY_EVENT_DENTRY:
         return ((struct dentry *)data)->d_sb;
     case FSNOTIFY_EVENT_PATH:
         return ((const struct path *)data)->dentry->d_sb;
     case FSNOTIFY_EVENT_ERROR:
         return ((struct fs_error_report *) data)->sb;
     default:
         return NULL;
     }
 }
 
 static inline struct fs_error_report *fsnotify_data_error_report(
                             const void *data,
                             int data_type)
 {
     switch (data_type) {
     case FSNOTIFY_EVENT_ERROR:
         return (struct fs_error_report *) data;
     default:
         return NULL;
     }
 }
 
 /*
  * Index to merged marks iterator array that correlates to a type of watch.
  * The type of watched object can be deduced from the iterator type, but not
  * the other way around, because an event can match different watched objects
  * of the same object type.
  * For example, both parent and child are watching an object of type inode.
  */
 enum fsnotify_iter_type {
     FSNOTIFY_ITER_TYPE_INODE,
     FSNOTIFY_ITER_TYPE_VFSMOUNT,
     FSNOTIFY_ITER_TYPE_SB,
     FSNOTIFY_ITER_TYPE_PARENT,
     FSNOTIFY_ITER_TYPE_INODE2,
     FSNOTIFY_ITER_TYPE_COUNT
 };
 
 /* The type of object that a mark is attached to */
 enum fsnotify_obj_type {
     FSNOTIFY_OBJ_TYPE_ANY = -1,
     FSNOTIFY_OBJ_TYPE_INODE,
     FSNOTIFY_OBJ_TYPE_VFSMOUNT,
     FSNOTIFY_OBJ_TYPE_SB,
     FSNOTIFY_OBJ_TYPE_COUNT,
     FSNOTIFY_OBJ_TYPE_DETACHED = FSNOTIFY_OBJ_TYPE_COUNT
 };
 
 static inline bool fsnotify_valid_obj_type(unsigned int obj_type)
 {
     return (obj_type < FSNOTIFY_OBJ_TYPE_COUNT);
 }
 
 struct fsnotify_iter_info {
     struct fsnotify_mark *marks[FSNOTIFY_ITER_TYPE_COUNT];
     struct fsnotify_group *current_group;
     unsigned int report_mask;
     int srcu_idx;
 };
 
 static inline bool fsnotify_iter_should_report_type(
         struct fsnotify_iter_info *iter_info, int iter_type)
 {
     return (iter_info->report_mask & (1U << iter_type));
 }
 
 static inline void fsnotify_iter_set_report_type(
         struct fsnotify_iter_info *iter_info, int iter_type)
 {
     iter_info->report_mask |= (1U << iter_type);
 }
 
 static inline struct fsnotify_mark *fsnotify_iter_mark(
         struct fsnotify_iter_info *iter_info, int iter_type)
 {
     if (fsnotify_iter_should_report_type(iter_info, iter_type))
         return iter_info->marks[iter_type];
     return NULL;
 }
 
 static inline int fsnotify_iter_step(struct fsnotify_iter_info *iter, int type,
                      struct fsnotify_mark **markp)
 {
     while (type < FSNOTIFY_ITER_TYPE_COUNT) {
         *markp = fsnotify_iter_mark(iter, type);
         if (*markp)
             break;
         type++;
     }
     return type;
 }
 
 #define FSNOTIFY_ITER_FUNCS(name, NAME) \
 static inline struct fsnotify_mark *fsnotify_iter_##name##_mark( \
         struct fsnotify_iter_info *iter_info) \
 { \
     return fsnotify_iter_mark(iter_info, FSNOTIFY_ITER_TYPE_##NAME); \
 }
 
 FSNOTIFY_ITER_FUNCS(inode, INODE)
 FSNOTIFY_ITER_FUNCS(parent, PARENT)
 FSNOTIFY_ITER_FUNCS(vfsmount, VFSMOUNT)
 FSNOTIFY_ITER_FUNCS(sb, SB)
 
 #define fsnotify_foreach_iter_type(type) \
     for (type = 0; type < FSNOTIFY_ITER_TYPE_COUNT; type++)
 #define fsnotify_foreach_iter_mark_type(iter, mark, type) \
     for (type = 0; \
          type = fsnotify_iter_step(iter, type, &mark), \
          type < FSNOTIFY_ITER_TYPE_COUNT; \
          type++)
 
 /*
  * fsnotify_connp_t is what we embed in objects which connector can be attached
  * to. fsnotify_connp_t * is how we refer from connector back to object.
  */
 struct fsnotify_mark_connector;
 typedef struct fsnotify_mark_connector __rcu *fsnotify_connp_t;
 
 /*
  * Inode/vfsmount/sb point to this structure which tracks all marks attached to
  * the inode/vfsmount/sb. The reference to inode/vfsmount/sb is held by this
  * structure. We destroy this structure when there are no more marks attached
  * to it. The structure is protected by fsnotify_mark_srcu.
  */
 struct fsnotify_mark_connector {
     spinlock_t lock;
     unsigned short type;    /* Type of object [lock] */
 #define FSNOTIFY_CONN_FLAG_HAS_FSID 0x01
 #define FSNOTIFY_CONN_FLAG_HAS_IREF 0x02
     unsigned short flags;   /* flags [lock] */
     __kernel_fsid_t fsid;   /* fsid of filesystem containing object */
     union {
         /* Object pointer [lock] */
         fsnotify_connp_t *obj;
         /* Used listing heads to free after srcu period expires */
         struct fsnotify_mark_connector *destroy_next;
     };
     struct hlist_head list;
 };
 
 /*
  * 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.
  *
  * 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.
  */
 struct fsnotify_mark {
     /* 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'
      * in kernel that found and may be using this mark. */
     refcount_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->marks_list. 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 [connector->lock, mark ref] */
     struct hlist_node obj_list;
     /* Head of list of marks for an object [mark ref] */
     struct fsnotify_mark_connector *connector;
     /* Events types and flags to ignore [mark->lock, group->mark_mutex] */
     __u32 ignore_mask;
     /* General fsnotify mark flags */
 #define FSNOTIFY_MARK_FLAG_ALIVE        0x0001
 #define FSNOTIFY_MARK_FLAG_ATTACHED     0x0002
     /* inotify mark flags */
 #define FSNOTIFY_MARK_FLAG_EXCL_UNLINK      0x0010
 #define FSNOTIFY_MARK_FLAG_IN_ONESHOT       0x0020
     /* fanotify mark flags */
 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY  0x0100
 #define FSNOTIFY_MARK_FLAG_NO_IREF      0x0200
 #define FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS 0x0400
     unsigned int flags;     /* flags [mark->lock] */
 };
 
 #ifdef CONFIG_FSNOTIFY
 
 /* called from the vfs helpers */
 
 /* main fsnotify call to send events */
 extern int fsnotify(__u32 mask, const void *data, int data_type,
             struct inode *dir, const struct qstr *name,
             struct inode *inode, u32 cookie);
 extern int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data,
                int data_type);
 extern void __fsnotify_inode_delete(struct inode *inode);
 extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
 extern void fsnotify_sb_delete(struct super_block *sb);
 extern u32 fsnotify_get_cookie(void);
 
 static inline __u32 fsnotify_parent_needed_mask(__u32 mask)
 {
     /* FS_EVENT_ON_CHILD is set on marks that want parent/name info */
     if (!(mask & FS_EVENT_ON_CHILD))
         return 0;
     /*
      * This object might be watched by a mark that cares about parent/name
      * info, does it care about the specific set of events that can be
      * reported with parent/name info?
      */
     return mask & FS_EVENTS_POSS_TO_PARENT;
 }
 
 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_flags(struct dentry *dentry)
 {
     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.
      */
     if (fsnotify_inode_watches_children(dentry->d_parent->d_inode))
         dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
     else
         dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
 }
 
 /* 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,
                 int flags);
 /* 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);
 /* group destruction begins, stop queuing new events */
 extern void fsnotify_group_stop_queueing(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_insert_event(struct fsnotify_group *group,
                  struct fsnotify_event *event,
                  int (*merge)(struct fsnotify_group *,
                           struct fsnotify_event *),
                  void (*insert)(struct fsnotify_group *,
                         struct fsnotify_event *));
 
 static inline int fsnotify_add_event(struct fsnotify_group *group,
                      struct fsnotify_event *event,
                      int (*merge)(struct fsnotify_group *,
                           struct fsnotify_event *))
 {
     return fsnotify_insert_event(group, event, merge, NULL);
 }
 
 /* Queue overflow event to a notification group */
 static inline void fsnotify_queue_overflow(struct fsnotify_group *group)
 {
     fsnotify_add_event(group, group->overflow_event, NULL);
 }
 
 static inline bool fsnotify_is_overflow_event(u32 mask)
 {
     return mask & FS_Q_OVERFLOW;
 }
 
 static inline bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group)
 {
     assert_spin_locked(&group->notification_lock);
 
     return list_empty(&group->notification_list);
 }
 
 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);
 /* Remove event queued in the notification list */
 extern void fsnotify_remove_queued_event(struct fsnotify_group *group,
                      struct fsnotify_event *event);
 
 /* functions used to manipulate the marks attached to inodes */
 
 /*
  * Canonical "ignore mask" including event flags.
  *
  * Note the subtle semantic difference from the legacy ->ignored_mask.
  * ->ignored_mask traditionally only meant which events should be ignored,
  * while ->ignore_mask also includes flags regarding the type of objects on
  * which events should be ignored.
  */
 static inline __u32 fsnotify_ignore_mask(struct fsnotify_mark *mark)
 {
     __u32 ignore_mask = mark->ignore_mask;
 
     /* The event flags in ignore mask take effect */
     if (mark->flags & FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS)
         return ignore_mask;
 
     /*
      * Legacy behavior:
      * - Always ignore events on dir
      * - Ignore events on child if parent is watching children
      */
     ignore_mask |= FS_ISDIR;
     ignore_mask &= ~FS_EVENT_ON_CHILD;
     ignore_mask |= mark->mask & FS_EVENT_ON_CHILD;
 
     return ignore_mask;
 }
 
 /* Legacy ignored_mask - only event types to ignore */
 static inline __u32 fsnotify_ignored_events(struct fsnotify_mark *mark)
 {
     return mark->ignore_mask & ALL_FSNOTIFY_EVENTS;
 }
 
 /*
  * Check if mask (or ignore mask) should be applied depending if victim is a
  * directory and whether it is reported to a watching parent.
  */
 static inline bool fsnotify_mask_applicable(__u32 mask, bool is_dir,
                         int iter_type)
 {
     /* Should mask be applied to a directory? */
     if (is_dir && !(mask & FS_ISDIR))
         return false;
 
     /* Should mask be applied to a child? */
     if (iter_type == FSNOTIFY_ITER_TYPE_PARENT &&
         !(mask & FS_EVENT_ON_CHILD))
         return false;
 
     return true;
 }
 
 /*
  * Effective ignore mask taking into account if event victim is a
  * directory and whether it is reported to a watching parent.
  */
 static inline __u32 fsnotify_effective_ignore_mask(struct fsnotify_mark *mark,
                            bool is_dir, int iter_type)
 {
     __u32 ignore_mask = fsnotify_ignored_events(mark);
 
     if (!ignore_mask)
         return 0;
 
     /* For non-dir and non-child, no need to consult the event flags */
     if (!is_dir && iter_type != FSNOTIFY_ITER_TYPE_PARENT)
         return ignore_mask;
 
     ignore_mask = fsnotify_ignore_mask(mark);
     if (!fsnotify_mask_applicable(ignore_mask, is_dir, iter_type))
         return 0;
 
     return ignore_mask & ALL_FSNOTIFY_EVENTS;
 }
 
 /* Get mask for calculating object interest taking ignore mask into account */
 static inline __u32 fsnotify_calc_mask(struct fsnotify_mark *mark)
 {
     __u32 mask = mark->mask;
 
     if (!fsnotify_ignored_events(mark))
         return mask;
 
     /* Interest in FS_MODIFY may be needed for clearing ignore mask */
     if (!(mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
         mask |= FS_MODIFY;
 
     /*
      * If mark is interested in ignoring events on children, the object must
      * show interest in those events for fsnotify_parent() to notice it.
      */
     return mask | mark->ignore_mask;
 }
 
 /* Get mask of events for a list of marks */
 extern __u32 fsnotify_conn_mask(struct fsnotify_mark_connector *conn);
 /* Calculate mask of events for a list of marks */
 extern void fsnotify_recalc_mask(struct fsnotify_mark_connector *conn);
 extern void fsnotify_init_mark(struct fsnotify_mark *mark,
                    struct fsnotify_group *group);
 /* Find mark belonging to given group in the list of marks */
 extern struct fsnotify_mark *fsnotify_find_mark(fsnotify_connp_t *connp,
                         struct fsnotify_group *group);
 /* Get cached fsid of filesystem containing object */
 extern int fsnotify_get_conn_fsid(const struct fsnotify_mark_connector *conn,
                   __kernel_fsid_t *fsid);
 /* attach the mark to the object */
 extern int fsnotify_add_mark(struct fsnotify_mark *mark,
                  fsnotify_connp_t *connp, unsigned int obj_type,
                  int add_flags, __kernel_fsid_t *fsid);
 extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark,
                     fsnotify_connp_t *connp,
                     unsigned int obj_type, int add_flags,
                     __kernel_fsid_t *fsid);
 
 /* attach the mark to the inode */
 static inline int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
                       struct inode *inode,
                       int add_flags)
 {
     return fsnotify_add_mark(mark, &inode->i_fsnotify_marks,
                  FSNOTIFY_OBJ_TYPE_INODE, add_flags, NULL);
 }
 static inline int fsnotify_add_inode_mark_locked(struct fsnotify_mark *mark,
                          struct inode *inode,
                          int add_flags)
 {
     return fsnotify_add_mark_locked(mark, &inode->i_fsnotify_marks,
                     FSNOTIFY_OBJ_TYPE_INODE, add_flags,
                     NULL);
 }
 
 /* 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);
 /* 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);
 /* Wait until all marks queued for destruction are destroyed */
 extern void fsnotify_wait_marks_destroyed(void);
 /* Clear all of the marks of a group attached to a given object type */
 extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group,
                       unsigned int obj_type);
 /* run all the marks in a group, and clear all of the vfsmount marks */
 static inline void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group)
 {
     fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_TYPE_VFSMOUNT);
 }
 /* run all the marks in a group, and clear all of the inode marks */
 static inline void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group)
 {
     fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_TYPE_INODE);
 }
 /* run all the marks in a group, and clear all of the sn marks */
 static inline void fsnotify_clear_sb_marks_by_group(struct fsnotify_group *group)
 {
     fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_TYPE_SB);
 }
 extern void fsnotify_get_mark(struct fsnotify_mark *mark);
 extern void fsnotify_put_mark(struct fsnotify_mark *mark);
 extern void fsnotify_finish_user_wait(struct fsnotify_iter_info *iter_info);
 extern bool fsnotify_prepare_user_wait(struct fsnotify_iter_info *iter_info);
 
 static inline void fsnotify_init_event(struct fsnotify_event *event)
 {
     INIT_LIST_HEAD(&event->list);
 }
 
 #else
 
 static inline int fsnotify(__u32 mask, const void *data, int data_type,
                struct inode *dir, const struct qstr *name,
                struct inode *inode, u32 cookie)
 {
     return 0;
 }
 
 static inline int __fsnotify_parent(struct dentry *dentry, __u32 mask,
                   const void *data, int data_type)
 {
     return 0;
 }
 
 static inline void __fsnotify_inode_delete(struct inode *inode)
 {}
 
 static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
 {}
 
 static inline void fsnotify_sb_delete(struct super_block *sb)
 {}
 
 static inline void fsnotify_update_flags(struct dentry *dentry)
 {}
 
 static inline u32 fsnotify_get_cookie(void)
 {
     return 0;
 }
 
 static inline void fsnotify_unmount_inodes(struct super_block *sb)
 {}
 
 #endif  /* CONFIG_FSNOTIFY */
 
 #endif  /* __KERNEL __ */
 
 #endif  /* __LINUX_FSNOTIFY_BACKEND_H */

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