Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 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 <asm/atomic.h> |
| 30 | |
| 31 | /* protects writes to fsnotify_groups and fsnotify_mask */ |
| 32 | static DEFINE_MUTEX(fsnotify_grp_mutex); |
| 33 | /* protects reads while running the fsnotify_groups list */ |
| 34 | struct srcu_struct fsnotify_grp_srcu; |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 35 | /* all groups registered to receive inode filesystem notifications */ |
Eric Paris | 19c2a0e | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 36 | LIST_HEAD(fsnotify_inode_groups); |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 37 | /* all groups registered to receive mount point filesystem notifications */ |
| 38 | LIST_HEAD(fsnotify_vfsmount_groups); |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 39 | /* bitwise OR of all events (FS_*) interesting to some group on this system */ |
Eric Paris | 19c2a0e | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 40 | __u32 fsnotify_inode_mask; |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 41 | /* bitwise OR of all events (FS_*) interesting to some group on this system */ |
| 42 | __u32 fsnotify_vfsmount_mask; |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 43 | |
| 44 | /* |
| 45 | * When a new group registers or changes it's set of interesting events |
| 46 | * this function updates the fsnotify_mask to contain all interesting events |
| 47 | */ |
| 48 | void fsnotify_recalc_global_mask(void) |
| 49 | { |
| 50 | struct fsnotify_group *group; |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 51 | __u32 inode_mask = 0; |
| 52 | __u32 vfsmount_mask = 0; |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 53 | int idx; |
| 54 | |
| 55 | idx = srcu_read_lock(&fsnotify_grp_srcu); |
Eric Paris | 19c2a0e | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 56 | list_for_each_entry_rcu(group, &fsnotify_inode_groups, inode_group_list) |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 57 | inode_mask |= group->mask; |
| 58 | list_for_each_entry_rcu(group, &fsnotify_vfsmount_groups, vfsmount_group_list) |
| 59 | vfsmount_mask |= group->mask; |
| 60 | |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 61 | srcu_read_unlock(&fsnotify_grp_srcu, idx); |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 62 | |
| 63 | fsnotify_inode_mask = inode_mask; |
| 64 | fsnotify_vfsmount_mask = vfsmount_mask; |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 65 | } |
| 66 | |
| 67 | /* |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 68 | * Update the group->mask by running all of the marks associated with this |
| 69 | * group and finding the bitwise | of all of the mark->mask. If we change |
| 70 | * the group->mask we need to update the global mask of events interesting |
| 71 | * to the system. |
| 72 | */ |
| 73 | void fsnotify_recalc_group_mask(struct fsnotify_group *group) |
| 74 | { |
| 75 | __u32 mask = 0; |
| 76 | __u32 old_mask = group->mask; |
| 77 | struct fsnotify_mark_entry *entry; |
| 78 | |
| 79 | spin_lock(&group->mark_lock); |
| 80 | list_for_each_entry(entry, &group->mark_entries, g_list) |
| 81 | mask |= entry->mask; |
| 82 | spin_unlock(&group->mark_lock); |
| 83 | |
| 84 | group->mask = mask; |
| 85 | |
| 86 | if (old_mask != mask) |
| 87 | fsnotify_recalc_global_mask(); |
| 88 | } |
| 89 | |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 90 | void fsnotify_add_vfsmount_group(struct fsnotify_group *group) |
| 91 | { |
| 92 | mutex_lock(&fsnotify_grp_mutex); |
| 93 | |
| 94 | if (!group->on_vfsmount_group_list) |
| 95 | list_add_tail_rcu(&group->vfsmount_group_list, &fsnotify_vfsmount_groups); |
| 96 | group->on_vfsmount_group_list = 1; |
| 97 | |
| 98 | mutex_unlock(&fsnotify_grp_mutex); |
| 99 | } |
| 100 | |
Eric Paris | 4ca7635 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 101 | void fsnotify_add_inode_group(struct fsnotify_group *group) |
Eric Paris | 19c2a0e | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 102 | { |
Eric Paris | 4ca7635 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 103 | mutex_lock(&fsnotify_grp_mutex); |
Eric Paris | 19c2a0e | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 104 | |
Eric Paris | 4ca7635 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 105 | if (!group->on_inode_group_list) |
| 106 | list_add_tail_rcu(&group->inode_group_list, &fsnotify_inode_groups); |
Eric Paris | 19c2a0e | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 107 | group->on_inode_group_list = 1; |
Eric Paris | 4ca7635 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 108 | |
| 109 | mutex_unlock(&fsnotify_grp_mutex); |
Eric Paris | 19c2a0e | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 110 | } |
| 111 | |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 112 | /* |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 113 | * Final freeing of a group |
| 114 | */ |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 115 | void fsnotify_final_destroy_group(struct fsnotify_group *group) |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 116 | { |
Eric Paris | a2d8bc6 | 2009-05-21 17:01:37 -0400 | [diff] [blame] | 117 | /* clear the notification queue of all events */ |
| 118 | fsnotify_flush_notify(group); |
| 119 | |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 120 | if (group->ops->free_group_priv) |
| 121 | group->ops->free_group_priv(group); |
| 122 | |
| 123 | kfree(group); |
| 124 | } |
| 125 | |
| 126 | /* |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 127 | * Trying to get rid of a group. We need to first get rid of any outstanding |
| 128 | * allocations and then free the group. Remember that fsnotify_clear_marks_by_group |
| 129 | * could miss marks that are being freed by inode and those marks could still |
| 130 | * hold a reference to this group (via group->num_marks) If we get into that |
| 131 | * situtation, the fsnotify_final_destroy_group will get called when that final |
| 132 | * mark is freed. |
| 133 | */ |
| 134 | static void fsnotify_destroy_group(struct fsnotify_group *group) |
| 135 | { |
| 136 | /* clear all inode mark entries for this group */ |
| 137 | fsnotify_clear_marks_by_group(group); |
| 138 | |
| 139 | /* past the point of no return, matches the initial value of 1 */ |
| 140 | if (atomic_dec_and_test(&group->num_marks)) |
| 141 | fsnotify_final_destroy_group(group); |
| 142 | } |
| 143 | |
| 144 | /* |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 145 | * Remove this group from the global list of groups that will get events |
| 146 | * this can be done even if there are still references and things still using |
| 147 | * this group. This just stops the group from getting new events. |
| 148 | */ |
| 149 | static void __fsnotify_evict_group(struct fsnotify_group *group) |
| 150 | { |
| 151 | BUG_ON(!mutex_is_locked(&fsnotify_grp_mutex)); |
| 152 | |
Eric Paris | 19c2a0e | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 153 | if (group->on_inode_group_list) |
| 154 | list_del_rcu(&group->inode_group_list); |
| 155 | group->on_inode_group_list = 0; |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 156 | if (group->on_vfsmount_group_list) |
| 157 | list_del_rcu(&group->vfsmount_group_list); |
| 158 | group->on_vfsmount_group_list = 0; |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 159 | } |
| 160 | |
| 161 | /* |
| 162 | * Called when a group is no longer interested in getting events. This can be |
| 163 | * used if a group is misbehaving or if for some reason a group should no longer |
| 164 | * get any filesystem events. |
| 165 | */ |
| 166 | void fsnotify_evict_group(struct fsnotify_group *group) |
| 167 | { |
| 168 | mutex_lock(&fsnotify_grp_mutex); |
| 169 | __fsnotify_evict_group(group); |
| 170 | mutex_unlock(&fsnotify_grp_mutex); |
| 171 | } |
| 172 | |
| 173 | /* |
| 174 | * Drop a reference to a group. Free it if it's through. |
| 175 | */ |
| 176 | void fsnotify_put_group(struct fsnotify_group *group) |
| 177 | { |
| 178 | if (!atomic_dec_and_mutex_lock(&group->refcnt, &fsnotify_grp_mutex)) |
| 179 | return; |
| 180 | |
| 181 | /* |
| 182 | * OK, now we know that there's no other users *and* we hold mutex, |
| 183 | * so no new references will appear |
| 184 | */ |
| 185 | __fsnotify_evict_group(group); |
| 186 | |
| 187 | /* |
| 188 | * now it's off the list, so the only thing we might care about is |
| 189 | * srcu access.... |
| 190 | */ |
| 191 | mutex_unlock(&fsnotify_grp_mutex); |
| 192 | synchronize_srcu(&fsnotify_grp_srcu); |
| 193 | |
| 194 | /* and now it is really dead. _Nothing_ could be seeing it */ |
| 195 | fsnotify_recalc_global_mask(); |
| 196 | fsnotify_destroy_group(group); |
| 197 | } |
| 198 | |
| 199 | /* |
Eric Paris | ffab834 | 2009-12-17 21:24:22 -0500 | [diff] [blame] | 200 | * Create a new fsnotify_group and hold a reference for the group returned. |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 201 | */ |
Eric Paris | 0d2e2a1 | 2009-12-17 21:24:22 -0500 | [diff] [blame] | 202 | struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops) |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 203 | { |
Eric Paris | 74be0cc | 2009-12-17 21:24:22 -0500 | [diff] [blame] | 204 | struct fsnotify_group *group; |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 205 | |
Eric Paris | f0553af | 2009-12-17 20:12:06 -0500 | [diff] [blame] | 206 | group = kzalloc(sizeof(struct fsnotify_group), GFP_KERNEL); |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 207 | if (!group) |
| 208 | return ERR_PTR(-ENOMEM); |
| 209 | |
Eric Paris | 36fddeb | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 210 | /* set to 0 when there a no external references to this group */ |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 211 | atomic_set(&group->refcnt, 1); |
Eric Paris | 36fddeb | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 212 | /* |
| 213 | * hits 0 when there are no external references AND no marks for |
| 214 | * this group |
| 215 | */ |
| 216 | atomic_set(&group->num_marks, 1); |
| 217 | |
Eric Paris | a2d8bc6 | 2009-05-21 17:01:37 -0400 | [diff] [blame] | 218 | mutex_init(&group->notification_mutex); |
| 219 | INIT_LIST_HEAD(&group->notification_list); |
| 220 | init_waitqueue_head(&group->notification_waitq); |
Eric Paris | a2d8bc6 | 2009-05-21 17:01:37 -0400 | [diff] [blame] | 221 | group->max_events = UINT_MAX; |
| 222 | |
Eric Paris | 4ca7635 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 223 | INIT_LIST_HEAD(&group->inode_group_list); |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 224 | INIT_LIST_HEAD(&group->vfsmount_group_list); |
Eric Paris | 4ca7635 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 225 | |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 226 | spin_lock_init(&group->mark_lock); |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 227 | INIT_LIST_HEAD(&group->mark_entries); |
| 228 | |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 229 | group->ops = ops; |
| 230 | |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 231 | return group; |
| 232 | } |