4  * Copyright (C) 2006-2008 Nokia Corporation.
17  * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
31  * If the root of a TNC sub-tree is clean and old enough, then the children are
33  * dumps entire sub-trees.
35  * The age of znodes is just the time-stamp when they were last looked at.
39  * un-mounts, which is done by the 'ubifs_infos_lock' and 'c->umount_mutex'.
44 /* List of all UBIFS file-system instances */
61  * shrink_tnc - shrink TNC tree.
62  * @c: UBIFS file-system description object
76 	ubifs_assert(c, mutex_is_locked(&c->umount_mutex));  in shrink_tnc()
77 	ubifs_assert(c, mutex_is_locked(&c->tnc_mutex));  in shrink_tnc()
79 	if (!c->zroot.znode || atomic_long_read(&c->clean_zn_cnt) == 0)  in shrink_tnc()
84 	 * to destroy large sub-trees. Indeed, if a znode is old, then all its  in shrink_tnc()
87 	 * Note, we are holding 'c->tnc_mutex', so we do not have to lock the  in shrink_tnc()
88 	 * 'c->space_lock' when _reading_ 'c->clean_zn_cnt', because it is  in shrink_tnc()
89 	 * changed only when the 'c->tnc_mutex' is held.  in shrink_tnc()
92 	znode = ubifs_tnc_levelorder_next(c, c->zroot.znode, NULL);  in shrink_tnc()
94 	       atomic_long_read(&c->clean_zn_cnt) > 0) {  in shrink_tnc()
98 		 * If the znode is clean, but it is in the 'c->cnext' list, this  in shrink_tnc()
108 		 * the znodes which are in the 'c->cnext' list as freeable.  in shrink_tnc()
110 		 * Also note, if the root of a sub-tree is not in 'c->cnext',  in shrink_tnc()
111 		 * then the whole sub-tree is not in 'c->cnext' as well, so it  in shrink_tnc()
112 		 * is safe to dump whole sub-tree.  in shrink_tnc()
115 		if (znode->cnext) {  in shrink_tnc()
122 			   abs(time - znode->time) >= age) {  in shrink_tnc()
123 			if (znode->parent)  in shrink_tnc()
124 				znode->parent->zbranch[znode->iip].znode = NULL;  in shrink_tnc()
126 				c->zroot.znode = NULL;  in shrink_tnc()
130 			atomic_long_sub(freed, &c->clean_zn_cnt);  in shrink_tnc()
135 		if (unlikely(!c->zroot.znode))  in shrink_tnc()
139 		znode = ubifs_tnc_levelorder_next(c, c->zroot.znode, znode);  in shrink_tnc()
147  * shrink_tnc_trees - shrink UBIFS TNC trees.
152  * This function walks the list of mounted UBIFS file-systems and frees clean
167 	/* Iterate over all mounted UBIFS file-systems and try to shrink them */  in shrink_tnc_trees()
175 		if (c->shrinker_run_no == run_no)  in shrink_tnc_trees()
177 		if (!mutex_trylock(&c->umount_mutex)) {  in shrink_tnc_trees()
178 			/* Some un-mount is in progress, try next FS */  in shrink_tnc_trees()
180 			p = p->next;  in shrink_tnc_trees()
184 		 * We're holding 'c->umount_mutex', so the file-system won't go  in shrink_tnc_trees()
187 		if (!mutex_trylock(&c->tnc_mutex)) {  in shrink_tnc_trees()
188 			mutex_unlock(&c->umount_mutex);  in shrink_tnc_trees()
190 			p = p->next;  in shrink_tnc_trees()
195 		 * OK, now we have TNC locked, the file-system cannot go away -  in shrink_tnc_trees()
198 		c->shrinker_run_no = run_no;  in shrink_tnc_trees()
200 		mutex_unlock(&c->tnc_mutex);  in shrink_tnc_trees()
203 		p = p->next;  in shrink_tnc_trees()
208 		list_move_tail(&c->infos_list, &ubifs_infos);  in shrink_tnc_trees()
209 		mutex_unlock(&c->umount_mutex);  in shrink_tnc_trees()
218  * kick_a_thread - kick a background thread to start commit.
221  * %-1 if a thread was kicked or there is another reason to assume the memory
231 	 * Iterate over all mounted UBIFS file-systems and find out if there is  in kick_a_thread()
240 			if (!mutex_trylock(&c->umount_mutex)) {  in kick_a_thread()
242 				 * Some un-mount is in progress, it will  in kick_a_thread()
246 				return -1;  in kick_a_thread()
249 			dirty_zn_cnt = atomic_long_read(&c->dirty_zn_cnt);  in kick_a_thread()
251 			if (!dirty_zn_cnt || c->cmt_state == COMMIT_BROKEN ||  in kick_a_thread()
252 			    c->ro_mount || c->ro_error) {  in kick_a_thread()
253 				mutex_unlock(&c->umount_mutex);  in kick_a_thread()
257 			if (c->cmt_state != COMMIT_RESTING) {  in kick_a_thread()
259 				mutex_unlock(&c->umount_mutex);  in kick_a_thread()
260 				return -1;  in kick_a_thread()
264 				list_move_tail(&c->infos_list, &ubifs_infos);  in kick_a_thread()
268 				mutex_unlock(&c->umount_mutex);  in kick_a_thread()
269 				return -1;  in kick_a_thread()
271 			mutex_unlock(&c->umount_mutex);  in kick_a_thread()
294 	unsigned long nr = sc->nr_to_scan;  in ubifs_shrink_scan()
304 		 * And we return -1 which means will make VM call us again  in ubifs_shrink_scan()
316 	freed += shrink_tnc_trees(nr - freed, YOUNG_ZNODE_AGE, &contention);  in ubifs_shrink_scan()
321 	freed += shrink_tnc_trees(nr - freed, 0, &contention);  in ubifs_shrink_scan()