fs/afs/validation.c

2 /* vnode and volume validity verification.
19  *  (2) On a RW volume, in response to certain vnode (inode)-accessing RPC
27  *  (3) On a RO (or Backup) volume, in response to certain vnode-accessing RPC
28  *      calls, each server maintains a time-limited per-volume promise that it
29  *      will send us a CB.CallBack request if the RO volume is updated to a
30  *      snapshot of the RW volume ("vos release").  This is an atomic event
31  *      that cuts over all instances of the RO volume across multiple servers
34  *	Note that a volume-level callbacks may also be sent for other reasons,
35  *	such as the volumeserver taking over control of the volume from the
41  *  (4) Certain RPC calls include a volume information record "VolSync" in
42  *      their reply.  This contains a creation date for the volume that should
43  *      remain unchanged for a RW volume (but will be changed if the volume is
45  *      when a RO volume is released.
50  *	a volume have been altered since we last checked a vnode.
60  *      recognised that a RO volume has been updated.
70  *  (1) When a volume-level CB.CallBack occurs, we increment ->cb_v_break on
71  *      the volume and reset ->cb_expires_at (ie. set AFS_NO_CB_PROMISE) on the
72  *      volume and volume's server record.
74  *  (2) When a CB.InitCallBackState occurs, we treat this as a volume-level
75  *	callback break on all the volumes that have been using that volume
85  *	->cb_v_break match, and if they don't, we lock volume->cb_check_lock
88  *	After checking the volume, we check the vnode.  If there's a mismatch
89  *	between the volume counters and the vnode's mirrors of those counters,
95  *	(A) If the Creation timestamp has changed on a RW volume or regressed
96  *	    on a RO volume, we try to increment ->cb_scrub; if it advances on a
97  *	    RO volume, we assume "vos release" happened and try to increment
107  *	volume->cb_v_check is then set to ->cb_v_break.
111  *	the volume and the volume's server record.
118  * Check the validity of a vnode/inode and its parent volume.
122 	const struct afs_volume *volume = vnode->volume;
128 	if (atomic_read(&volume->cb_v_check) != atomic_read(&volume->cb_v_break) ||
130 	    volume->cb_expires_at <= deadline ||
131 	    vnode->cb_ro_snapshot != atomic_read(&volume->cb_ro_snapshot) ||
132 	    vnode->cb_scrub	  != atomic_read(&volume->cb_scrub) ||
144 static bool __afs_is_server_excluded(struct afs_operation *op, struct afs_volume *volume)
153 	slist = rcu_dereference(volume->servers);
167  * Update the volume's server list when the creation time changes and see if
170 static int afs_is_server_excluded(struct afs_operation *op, struct afs_volume *volume)
174 	if (__afs_is_server_excluded(op, volume))
177 	set_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);
178 	ret = afs_check_volume_status(op->volume, op);
182 	return __afs_is_server_excluded(op, volume);
186  * Handle a change to the volume creation time in the VolSync record.
188 static int afs_update_volume_creation_time(struct afs_operation *op, struct afs_volume *volume)
191 	time64_t cur = volume->creation_time;
196 	_enter("%llx,%llx,%llx->%llx", volume->vid, cur, old, new);
199 		volume->creation_time = new;
215 	 * our caches.  For a RW vol, this will only change if the volume is
217 	 * the volume is updated to a new snapshot (eg. "vos release").
219 	if (volume->type == AFSVL_RWVOL)
221 	if (volume->type == AFSVL_BACKVOL) {
227 	/* We have an RO volume, we need to query the VL server and look at the
230 	ret = afs_is_server_excluded(op, volume);
234 		snap = atomic_read(&volume->cb_ro_snapshot);
235 		trace_afs_cb_v_break(volume->vid, snap, afs_cb_break_volume_excluded);
240 	snap = atomic_inc_return(&volume->cb_ro_snapshot);
241 	trace_afs_cb_v_break(volume->vid, snap, afs_cb_break_for_vos_release);
242 	volume->creation_time = new;
246 	atomic_inc(&volume->cb_scrub);
247 	trace_afs_cb_v_break(volume->vid, 0, afs_cb_break_for_creation_regress);
248 	volume->creation_time = new;
253  * Handle a change to the volume update time in the VolSync record.
255 static void afs_update_volume_update_time(struct afs_operation *op, struct afs_volume *volume)
258 	time64_t cur = volume->update_time;
262 	_enter("%llx,%llx,%llx->%llx", volume->vid, cur, old, new);
265 		volume->update_time = new;
272 	/* If the volume update time changes in an unexpected way, we need to
275 	 * volume is updated to a new snapshot (eg. "vos release").
287 			atomic_inc(&volume->cb_scrub);
288 			trace_afs_cb_v_break(volume->vid, 0, reason);
290 		volume->update_time = new;
294 static int afs_update_volume_times(struct afs_operation *op, struct afs_volume *volume)
298 	if (likely(op->volsync.creation == volume->creation_time &&
299 		   op->volsync.update == volume->update_time))
302 	mutex_lock(&volume->volsync_lock);
303 	if (op->volsync.creation != volume->creation_time) {
304 		ret = afs_update_volume_creation_time(op, volume);
308 	if (op->volsync.update != volume->update_time)
309 		afs_update_volume_update_time(op, volume);
311 	mutex_unlock(&volume->volsync_lock);
316  * Update the state of a volume, including recording the expiration time of the
324 	struct afs_volume *volume = op->volume;
325 	unsigned int cb_v_break = atomic_read(&volume->cb_v_break);
326 	unsigned int cb_v_check = atomic_read(&volume->cb_v_check);
329 	_enter("%llx", op->volume->vid);
332 		ret = afs_update_volume_times(op, volume);
347 		volume->cb_expires_at = expires_at;
350 		atomic_cmpxchg(&volume->cb_v_check, cb_v_check, op->cb_v_break);
384 	struct afs_volume *volume = vnode->volume;
406 	/* Validate a volume after the v_break has changed or the volume
407 	 * callback expired.  We only want to do this once per volume per
411 	if (volume->cb_expires_at <= deadline ||
412 	    atomic_read(&volume->cb_v_check) != atomic_read(&volume->cb_v_break)) {
413 		ret = mutex_lock_interruptible(&volume->cb_check_lock);
419 	cb_ro_snapshot = atomic_read(&volume->cb_ro_snapshot);
420 	cb_scrub = atomic_read(&volume->cb_scrub);
427 	    volume->cb_expires_at <= deadline ||
428 	    atomic_read(&volume->cb_v_check) != atomic_read(&volume->cb_v_break) ||
443 	/* We can drop the volume lock now as. */
445 		mutex_unlock(&volume->cb_check_lock);
449 	cb_ro_snapshot = atomic_read(&volume->cb_ro_snapshot);
450 	cb_scrub = atomic_read(&volume->cb_scrub);
470 		mutex_unlock(&volume->cb_check_lock);