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-rw-r--r--fs/afs/flock.c126
1 files changed, 79 insertions, 47 deletions
diff --git a/fs/afs/flock.c b/fs/afs/flock.c
index 4f77f3caee97..af6952e39a18 100644
--- a/fs/afs/flock.c
+++ b/fs/afs/flock.c
@@ -19,6 +19,7 @@ static void afs_fl_copy_lock(struct file_lock *new, struct file_lock *fl);
19static void afs_fl_release_private(struct file_lock *fl); 19static void afs_fl_release_private(struct file_lock *fl);
20 20
21static struct workqueue_struct *afs_lock_manager; 21static struct workqueue_struct *afs_lock_manager;
22static DEFINE_MUTEX(afs_lock_manager_mutex);
22 23
23static struct file_lock_operations afs_lock_ops = { 24static struct file_lock_operations afs_lock_ops = {
24 .fl_copy_lock = afs_fl_copy_lock, 25 .fl_copy_lock = afs_fl_copy_lock,
@@ -30,12 +31,20 @@ static struct file_lock_operations afs_lock_ops = {
30 */ 31 */
31static int afs_init_lock_manager(void) 32static int afs_init_lock_manager(void)
32{ 33{
34 int ret;
35
36 ret = 0;
33 if (!afs_lock_manager) { 37 if (!afs_lock_manager) {
34 afs_lock_manager = create_singlethread_workqueue("kafs_lockd"); 38 mutex_lock(&afs_lock_manager_mutex);
35 if (!afs_lock_manager) 39 if (!afs_lock_manager) {
36 return -ENOMEM; 40 afs_lock_manager =
41 create_singlethread_workqueue("kafs_lockd");
42 if (!afs_lock_manager)
43 ret = -ENOMEM;
44 }
45 mutex_unlock(&afs_lock_manager_mutex);
37 } 46 }
38 return 0; 47 return ret;
39} 48}
40 49
41/* 50/*
@@ -68,6 +77,29 @@ static void afs_schedule_lock_extension(struct afs_vnode *vnode)
68} 77}
69 78
70/* 79/*
80 * grant one or more locks (readlocks are allowed to jump the queue if the
81 * first lock in the queue is itself a readlock)
82 * - the caller must hold the vnode lock
83 */
84static void afs_grant_locks(struct afs_vnode *vnode, struct file_lock *fl)
85{
86 struct file_lock *p, *_p;
87
88 list_move_tail(&fl->fl_u.afs.link, &vnode->granted_locks);
89 if (fl->fl_type == F_RDLCK) {
90 list_for_each_entry_safe(p, _p, &vnode->pending_locks,
91 fl_u.afs.link) {
92 if (p->fl_type == F_RDLCK) {
93 p->fl_u.afs.state = AFS_LOCK_GRANTED;
94 list_move_tail(&p->fl_u.afs.link,
95 &vnode->granted_locks);
96 wake_up(&p->fl_wait);
97 }
98 }
99 }
100}
101
102/*
71 * do work for a lock, including: 103 * do work for a lock, including:
72 * - probing for a lock we're waiting on but didn't get immediately 104 * - probing for a lock we're waiting on but didn't get immediately
73 * - extending a lock that's close to timing out 105 * - extending a lock that's close to timing out
@@ -172,8 +204,7 @@ void afs_lock_work(struct work_struct *work)
172 struct file_lock, fl_u.afs.link) == fl) { 204 struct file_lock, fl_u.afs.link) == fl) {
173 fl->fl_u.afs.state = ret; 205 fl->fl_u.afs.state = ret;
174 if (ret == AFS_LOCK_GRANTED) 206 if (ret == AFS_LOCK_GRANTED)
175 list_move_tail(&fl->fl_u.afs.link, 207 afs_grant_locks(vnode, fl);
176 &vnode->granted_locks);
177 else 208 else
178 list_del_init(&fl->fl_u.afs.link); 209 list_del_init(&fl->fl_u.afs.link);
179 wake_up(&fl->fl_wait); 210 wake_up(&fl->fl_wait);
@@ -258,49 +289,50 @@ static int afs_do_setlk(struct file *file, struct file_lock *fl)
258 289
259 spin_lock(&vnode->lock); 290 spin_lock(&vnode->lock);
260 291
261 if (list_empty(&vnode->pending_locks)) { 292 /* if we've already got a readlock on the server then we can instantly
262 /* if there's no-one else with a lock on this vnode, then we 293 * grant another readlock, irrespective of whether there are any
263 * need to ask the server for a lock */ 294 * pending writelocks */
264 if (list_empty(&vnode->granted_locks)) { 295 if (type == AFS_LOCK_READ &&
265 _debug("not locked"); 296 vnode->flags & (1 << AFS_VNODE_READLOCKED)) {
266 ASSERTCMP(vnode->flags & 297 _debug("instant readlock");
267 ((1 << AFS_VNODE_LOCKING) | 298 ASSERTCMP(vnode->flags &
268 (1 << AFS_VNODE_READLOCKED) | 299 ((1 << AFS_VNODE_LOCKING) |
269 (1 << AFS_VNODE_WRITELOCKED)), ==, 0); 300 (1 << AFS_VNODE_WRITELOCKED)), ==, 0);
270 list_add_tail(&fl->fl_u.afs.link, &vnode->pending_locks); 301 ASSERT(!list_empty(&vnode->granted_locks));
271 set_bit(AFS_VNODE_LOCKING, &vnode->flags); 302 goto sharing_existing_lock;
272 spin_unlock(&vnode->lock); 303 }
273 304
274 ret = afs_vnode_set_lock(vnode, key, type); 305 /* if there's no-one else with a lock on this vnode, then we need to
275 clear_bit(AFS_VNODE_LOCKING, &vnode->flags); 306 * ask the server for a lock */
276 switch (ret) { 307 if (list_empty(&vnode->pending_locks) &&
277 case 0: 308 list_empty(&vnode->granted_locks)) {
278 goto acquired_server_lock; 309 _debug("not locked");
279 case -EWOULDBLOCK: 310 ASSERTCMP(vnode->flags &
280 spin_lock(&vnode->lock); 311 ((1 << AFS_VNODE_LOCKING) |
281 ASSERT(list_empty(&vnode->granted_locks)); 312 (1 << AFS_VNODE_READLOCKED) |
282 ASSERTCMP(vnode->pending_locks.next, ==, 313 (1 << AFS_VNODE_WRITELOCKED)), ==, 0);
283 &fl->fl_u.afs.link); 314 list_add_tail(&fl->fl_u.afs.link, &vnode->pending_locks);
284 goto wait; 315 set_bit(AFS_VNODE_LOCKING, &vnode->flags);
285 default: 316 spin_unlock(&vnode->lock);
286 spin_lock(&vnode->lock);
287 list_del_init(&fl->fl_u.afs.link);
288 spin_unlock(&vnode->lock);
289 goto error;
290 }
291 }
292 317
293 /* if we've already got a readlock on the server and no waiting 318 ret = afs_vnode_set_lock(vnode, key, type);
294 * writelocks, then we might be able to instantly grant another 319 clear_bit(AFS_VNODE_LOCKING, &vnode->flags);
295 * readlock */ 320 switch (ret) {
296 if (type == AFS_LOCK_READ && 321 case 0:
297 vnode->flags & (1 << AFS_VNODE_READLOCKED)) { 322 _debug("acquired");
298 _debug("instant readlock"); 323 goto acquired_server_lock;
299 ASSERTCMP(vnode->flags & 324 case -EWOULDBLOCK:
300 ((1 << AFS_VNODE_LOCKING) | 325 _debug("would block");
301 (1 << AFS_VNODE_WRITELOCKED)), ==, 0); 326 spin_lock(&vnode->lock);
302 ASSERT(!list_empty(&vnode->granted_locks)); 327 ASSERT(list_empty(&vnode->granted_locks));
303 goto sharing_existing_lock; 328 ASSERTCMP(vnode->pending_locks.next, ==,
329 &fl->fl_u.afs.link);
330 goto wait;
331 default:
332 spin_lock(&vnode->lock);
333 list_del_init(&fl->fl_u.afs.link);
334 spin_unlock(&vnode->lock);
335 goto error;
304 } 336 }
305 } 337 }
306 338