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authorLinus Torvalds <torvalds@linux-foundation.org>2010-08-10 14:39:13 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2010-08-10 14:39:13 -0400
commit8c8946f509a494769a8c602b5ed189df01917d39 (patch)
treedfd96bd6ca5ea6803c6d77f65ba37e04f78b2d3b /fs/notify/group.c
parent5f248c9c251c60af3403902b26e08de43964ea0b (diff)
parent1968f5eed54ce47bde488fd9a450912e4a2d7138 (diff)
Merge branch 'for-linus' of git://git.infradead.org/users/eparis/notify
* 'for-linus' of git://git.infradead.org/users/eparis/notify: (132 commits) fanotify: use both marks when possible fsnotify: pass both the vfsmount mark and inode mark fsnotify: walk the inode and vfsmount lists simultaneously fsnotify: rework ignored mark flushing fsnotify: remove global fsnotify groups lists fsnotify: remove group->mask fsnotify: remove the global masks fsnotify: cleanup should_send_event fanotify: use the mark in handler functions audit: use the mark in handler functions dnotify: use the mark in handler functions inotify: use the mark in handler functions fsnotify: send fsnotify_mark to groups in event handling functions fsnotify: Exchange list heads instead of moving elements fsnotify: srcu to protect read side of inode and vfsmount locks fsnotify: use an explicit flag to indicate fsnotify_destroy_mark has been called fsnotify: use _rcu functions for mark list traversal fsnotify: place marks on object in order of group memory address vfs/fsnotify: fsnotify_close can delay the final work in fput fsnotify: store struct file not struct path ... Fix up trivial delete/modify conflict in fs/notify/inotify/inotify.c.
Diffstat (limited to 'fs/notify/group.c')
-rw-r--r--fs/notify/group.c182
1 files changed, 16 insertions, 166 deletions
diff --git a/fs/notify/group.c b/fs/notify/group.c
index 0e1677144bc5..d309f38449cb 100644
--- a/fs/notify/group.c
+++ b/fs/notify/group.c
@@ -28,64 +28,6 @@
28 28
29#include <asm/atomic.h> 29#include <asm/atomic.h>
30 30
31/* protects writes to fsnotify_groups and fsnotify_mask */
32static DEFINE_MUTEX(fsnotify_grp_mutex);
33/* protects reads while running the fsnotify_groups list */
34struct srcu_struct fsnotify_grp_srcu;
35/* all groups registered to receive filesystem notifications */
36LIST_HEAD(fsnotify_groups);
37/* bitwise OR of all events (FS_*) interesting to some group on this system */
38__u32 fsnotify_mask;
39
40/*
41 * When a new group registers or changes it's set of interesting events
42 * this function updates the fsnotify_mask to contain all interesting events
43 */
44void fsnotify_recalc_global_mask(void)
45{
46 struct fsnotify_group *group;
47 __u32 mask = 0;
48 int idx;
49
50 idx = srcu_read_lock(&fsnotify_grp_srcu);
51 list_for_each_entry_rcu(group, &fsnotify_groups, group_list)
52 mask |= group->mask;
53 srcu_read_unlock(&fsnotify_grp_srcu, idx);
54 fsnotify_mask = mask;
55}
56
57/*
58 * Update the group->mask by running all of the marks associated with this
59 * group and finding the bitwise | of all of the mark->mask. If we change
60 * the group->mask we need to update the global mask of events interesting
61 * to the system.
62 */
63void fsnotify_recalc_group_mask(struct fsnotify_group *group)
64{
65 __u32 mask = 0;
66 __u32 old_mask = group->mask;
67 struct fsnotify_mark_entry *entry;
68
69 spin_lock(&group->mark_lock);
70 list_for_each_entry(entry, &group->mark_entries, g_list)
71 mask |= entry->mask;
72 spin_unlock(&group->mark_lock);
73
74 group->mask = mask;
75
76 if (old_mask != mask)
77 fsnotify_recalc_global_mask();
78}
79
80/*
81 * Take a reference to a group so things found under the fsnotify_grp_mutex
82 * can't get freed under us
83 */
84static void fsnotify_get_group(struct fsnotify_group *group)
85{
86 atomic_inc(&group->refcnt);
87}
88
89/* 31/*
90 * Final freeing of a group 32 * Final freeing of a group
91 */ 33 */
@@ -110,145 +52,53 @@ void fsnotify_final_destroy_group(struct fsnotify_group *group)
110 */ 52 */
111static void fsnotify_destroy_group(struct fsnotify_group *group) 53static void fsnotify_destroy_group(struct fsnotify_group *group)
112{ 54{
113 /* clear all inode mark entries for this group */ 55 /* clear all inode marks for this group */
114 fsnotify_clear_marks_by_group(group); 56 fsnotify_clear_marks_by_group(group);
115 57
58 synchronize_srcu(&fsnotify_mark_srcu);
59
116 /* past the point of no return, matches the initial value of 1 */ 60 /* past the point of no return, matches the initial value of 1 */
117 if (atomic_dec_and_test(&group->num_marks)) 61 if (atomic_dec_and_test(&group->num_marks))
118 fsnotify_final_destroy_group(group); 62 fsnotify_final_destroy_group(group);
119} 63}
120 64
121/* 65/*
122 * Remove this group from the global list of groups that will get events
123 * this can be done even if there are still references and things still using
124 * this group. This just stops the group from getting new events.
125 */
126static void __fsnotify_evict_group(struct fsnotify_group *group)
127{
128 BUG_ON(!mutex_is_locked(&fsnotify_grp_mutex));
129
130 if (group->on_group_list)
131 list_del_rcu(&group->group_list);
132 group->on_group_list = 0;
133}
134
135/*
136 * Called when a group is no longer interested in getting events. This can be
137 * used if a group is misbehaving or if for some reason a group should no longer
138 * get any filesystem events.
139 */
140void fsnotify_evict_group(struct fsnotify_group *group)
141{
142 mutex_lock(&fsnotify_grp_mutex);
143 __fsnotify_evict_group(group);
144 mutex_unlock(&fsnotify_grp_mutex);
145}
146
147/*
148 * Drop a reference to a group. Free it if it's through. 66 * Drop a reference to a group. Free it if it's through.
149 */ 67 */
150void fsnotify_put_group(struct fsnotify_group *group) 68void fsnotify_put_group(struct fsnotify_group *group)
151{ 69{
152 if (!atomic_dec_and_mutex_lock(&group->refcnt, &fsnotify_grp_mutex)) 70 if (atomic_dec_and_test(&group->refcnt))
153 return; 71 fsnotify_destroy_group(group);
154
155 /*
156 * OK, now we know that there's no other users *and* we hold mutex,
157 * so no new references will appear
158 */
159 __fsnotify_evict_group(group);
160
161 /*
162 * now it's off the list, so the only thing we might care about is
163 * srcu access....
164 */
165 mutex_unlock(&fsnotify_grp_mutex);
166 synchronize_srcu(&fsnotify_grp_srcu);
167
168 /* and now it is really dead. _Nothing_ could be seeing it */
169 fsnotify_recalc_global_mask();
170 fsnotify_destroy_group(group);
171}
172
173/*
174 * Simply run the fsnotify_groups list and find a group which matches
175 * the given parameters. If a group is found we take a reference to that
176 * group.
177 */
178static struct fsnotify_group *fsnotify_find_group(unsigned int group_num, __u32 mask,
179 const struct fsnotify_ops *ops)
180{
181 struct fsnotify_group *group_iter;
182 struct fsnotify_group *group = NULL;
183
184 BUG_ON(!mutex_is_locked(&fsnotify_grp_mutex));
185
186 list_for_each_entry_rcu(group_iter, &fsnotify_groups, group_list) {
187 if (group_iter->group_num == group_num) {
188 if ((group_iter->mask == mask) &&
189 (group_iter->ops == ops)) {
190 fsnotify_get_group(group_iter);
191 group = group_iter;
192 } else
193 group = ERR_PTR(-EEXIST);
194 }
195 }
196 return group;
197} 72}
198 73
199/* 74/*
200 * Either finds an existing group which matches the group_num, mask, and ops or 75 * Create a new fsnotify_group and hold a reference for the group returned.
201 * creates a new group and adds it to the global group list. In either case we
202 * take a reference for the group returned.
203 */ 76 */
204struct fsnotify_group *fsnotify_obtain_group(unsigned int group_num, __u32 mask, 77struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops)
205 const struct fsnotify_ops *ops)
206{ 78{
207 struct fsnotify_group *group, *tgroup; 79 struct fsnotify_group *group;
208 80
209 /* very low use, simpler locking if we just always alloc */ 81 group = kzalloc(sizeof(struct fsnotify_group), GFP_KERNEL);
210 group = kmalloc(sizeof(struct fsnotify_group), GFP_KERNEL);
211 if (!group) 82 if (!group)
212 return ERR_PTR(-ENOMEM); 83 return ERR_PTR(-ENOMEM);
213 84
85 /* set to 0 when there a no external references to this group */
214 atomic_set(&group->refcnt, 1); 86 atomic_set(&group->refcnt, 1);
215 87 /*
216 group->on_group_list = 0; 88 * hits 0 when there are no external references AND no marks for
217 group->group_num = group_num; 89 * this group
218 group->mask = mask; 90 */
91 atomic_set(&group->num_marks, 1);
219 92
220 mutex_init(&group->notification_mutex); 93 mutex_init(&group->notification_mutex);
221 INIT_LIST_HEAD(&group->notification_list); 94 INIT_LIST_HEAD(&group->notification_list);
222 init_waitqueue_head(&group->notification_waitq); 95 init_waitqueue_head(&group->notification_waitq);
223 group->q_len = 0;
224 group->max_events = UINT_MAX; 96 group->max_events = UINT_MAX;
225 97
226 spin_lock_init(&group->mark_lock); 98 spin_lock_init(&group->mark_lock);
227 atomic_set(&group->num_marks, 0); 99 INIT_LIST_HEAD(&group->marks_list);
228 INIT_LIST_HEAD(&group->mark_entries);
229 100
230 group->ops = ops; 101 group->ops = ops;
231 102
232 mutex_lock(&fsnotify_grp_mutex);
233 tgroup = fsnotify_find_group(group_num, mask, ops);
234 if (tgroup) {
235 /* group already exists */
236 mutex_unlock(&fsnotify_grp_mutex);
237 /* destroy the new one we made */
238 fsnotify_put_group(group);
239 return tgroup;
240 }
241
242 /* group not found, add a new one */
243 list_add_rcu(&group->group_list, &fsnotify_groups);
244 group->on_group_list = 1;
245 /* being on the fsnotify_groups list holds one num_marks */
246 atomic_inc(&group->num_marks);
247
248 mutex_unlock(&fsnotify_grp_mutex);
249
250 if (mask)
251 fsnotify_recalc_global_mask();
252
253 return group; 103 return group;
254} 104}