1 /* 2 * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation; either version 2, or (at your option) 7 * any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; see the file COPYING. If not, write to 16 * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. 17 */ 18 19 #include <linux/list.h> 20 #include <linux/mutex.h> 21 #include <linux/slab.h> 22 #include <linux/srcu.h> 23 #include <linux/rculist.h> 24 #include <linux/wait.h> 25 26 #include <linux/fsnotify_backend.h> 27 #include "fsnotify.h" 28 29 #include <linux/atomic.h> 30 31 /* 32 * Final freeing of a group 33 */ 34 static void fsnotify_final_destroy_group(struct fsnotify_group *group) 35 { 36 if (group->ops->free_group_priv) 37 group->ops->free_group_priv(group); 38 39 kfree(group); 40 } 41 42 /* 43 * Trying to get rid of a group. Remove all marks, flush all events and release 44 * the group reference. 45 * Note that another thread calling fsnotify_clear_marks_by_group() may still 46 * hold a ref to the group. 47 */ 48 void fsnotify_destroy_group(struct fsnotify_group *group) 49 { 50 /* clear all inode marks for this group */ 51 fsnotify_clear_marks_by_group(group); 52 53 synchronize_srcu(&fsnotify_mark_srcu); 54 55 /* clear the notification queue of all events */ 56 fsnotify_flush_notify(group); 57 58 /* 59 * Destroy overflow event (we cannot use fsnotify_destroy_event() as 60 * that deliberately ignores overflow events. 61 */ 62 if (group->overflow_event) 63 group->ops->free_event(group->overflow_event); 64 65 fsnotify_put_group(group); 66 } 67 68 /* 69 * Get reference to a group. 70 */ 71 void fsnotify_get_group(struct fsnotify_group *group) 72 { 73 atomic_inc(&group->refcnt); 74 } 75 76 /* 77 * Drop a reference to a group. Free it if it's through. 78 */ 79 void fsnotify_put_group(struct fsnotify_group *group) 80 { 81 if (atomic_dec_and_test(&group->refcnt)) 82 fsnotify_final_destroy_group(group); 83 } 84 85 /* 86 * Create a new fsnotify_group and hold a reference for the group returned. 87 */ 88 struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops) 89 { 90 struct fsnotify_group *group; 91 92 group = kzalloc(sizeof(struct fsnotify_group), GFP_KERNEL); 93 if (!group) 94 return ERR_PTR(-ENOMEM); 95 96 /* set to 0 when there a no external references to this group */ 97 atomic_set(&group->refcnt, 1); 98 atomic_set(&group->num_marks, 0); 99 100 mutex_init(&group->notification_mutex); 101 INIT_LIST_HEAD(&group->notification_list); 102 init_waitqueue_head(&group->notification_waitq); 103 group->max_events = UINT_MAX; 104 105 mutex_init(&group->mark_mutex); 106 INIT_LIST_HEAD(&group->marks_list); 107 108 group->ops = ops; 109 110 return group; 111 } 112 113 int fsnotify_fasync(int fd, struct file *file, int on) 114 { 115 struct fsnotify_group *group = file->private_data; 116 117 return fasync_helper(fd, file, on, &group->fsn_fa) >= 0 ? 0 : -EIO; 118 } 119