1 // SPDX-License-Identifier: GPL-2.0-only
5  * Copyright (C) 2006-2008 Nokia Corporation.
19  * If the root of a TNC sub-tree is clean and old enough, then the children are
21  * dumps entire sub-trees.
23  * The age of znodes is just the time-stamp when they were last looked at.
27  * un-mounts, which is done by the 'ubifs_infos_lock' and 'c->umount_mutex'.
32 /* List of all UBIFS file-system instances */
49  * shrink_tnc - shrink TNC tree.
50  * @c: UBIFS file-system description object
64 	ubifs_assert(c, mutex_is_locked(&c->umount_mutex));  in shrink_tnc()
65 	ubifs_assert(c, mutex_is_locked(&c->tnc_mutex));  in shrink_tnc()
67 	if (!c->zroot.znode || atomic_long_read(&c->clean_zn_cnt) == 0)  in shrink_tnc()
72 	 * to destroy large sub-trees. Indeed, if a znode is old, then all its  in shrink_tnc()
75 	 * Note, we are holding 'c->tnc_mutex', so we do not have to lock the  in shrink_tnc()
76 	 * 'c->space_lock' when _reading_ 'c->clean_zn_cnt', because it is  in shrink_tnc()
77 	 * changed only when the 'c->tnc_mutex' is held.  in shrink_tnc()
80 	znode = ubifs_tnc_levelorder_next(c, c->zroot.znode, NULL);  in shrink_tnc()
82 	       atomic_long_read(&c->clean_zn_cnt) > 0) {  in shrink_tnc()
86 		 * If the znode is clean, but it is in the 'c->cnext' list, this  in shrink_tnc()
96 		 * the znodes which are in the 'c->cnext' list as freeable.  in shrink_tnc()
98 		 * Also note, if the root of a sub-tree is not in 'c->cnext',  in shrink_tnc()
99 		 * then the whole sub-tree is not in 'c->cnext' as well, so it  in shrink_tnc()
100 		 * is safe to dump whole sub-tree.  in shrink_tnc()
103 		if (znode->cnext) {  in shrink_tnc()
110 			   abs(time - znode->time) >= age) {  in shrink_tnc()
111 			if (znode->parent)  in shrink_tnc()
112 				znode->parent->zbranch[znode->iip].znode = NULL;  in shrink_tnc()
114 				c->zroot.znode = NULL;  in shrink_tnc()
118 			atomic_long_sub(freed, &c->clean_zn_cnt);  in shrink_tnc()
123 		if (unlikely(!c->zroot.znode))  in shrink_tnc()
127 		znode = ubifs_tnc_levelorder_next(c, c->zroot.znode, znode);  in shrink_tnc()
135  * shrink_tnc_trees - shrink UBIFS TNC trees.
140  * This function walks the list of mounted UBIFS file-systems and frees clean
155 	/* Iterate over all mounted UBIFS file-systems and try to shrink them */  in shrink_tnc_trees()
163 		if (c->shrinker_run_no == run_no)  in shrink_tnc_trees()
165 		if (!mutex_trylock(&c->umount_mutex)) {  in shrink_tnc_trees()
166 			/* Some un-mount is in progress, try next FS */  in shrink_tnc_trees()
168 			p = p->next;  in shrink_tnc_trees()
172 		 * We're holding 'c->umount_mutex', so the file-system won't go  in shrink_tnc_trees()
175 		if (!mutex_trylock(&c->tnc_mutex)) {  in shrink_tnc_trees()
176 			mutex_unlock(&c->umount_mutex);  in shrink_tnc_trees()
178 			p = p->next;  in shrink_tnc_trees()
183 		 * OK, now we have TNC locked, the file-system cannot go away -  in shrink_tnc_trees()
186 		c->shrinker_run_no = run_no;  in shrink_tnc_trees()
188 		mutex_unlock(&c->tnc_mutex);  in shrink_tnc_trees()
191 		p = p->next;  in shrink_tnc_trees()
196 		list_move_tail(&c->infos_list, &ubifs_infos);  in shrink_tnc_trees()
197 		mutex_unlock(&c->umount_mutex);  in shrink_tnc_trees()
206  * kick_a_thread - kick a background thread to start commit.
209  * %-1 if a thread was kicked or there is another reason to assume the memory
219 	 * Iterate over all mounted UBIFS file-systems and find out if there is  in kick_a_thread()
228 			if (!mutex_trylock(&c->umount_mutex)) {  in kick_a_thread()
230 				 * Some un-mount is in progress, it will  in kick_a_thread()
234 				return -1;  in kick_a_thread()
237 			dirty_zn_cnt = atomic_long_read(&c->dirty_zn_cnt);  in kick_a_thread()
239 			if (!dirty_zn_cnt || c->cmt_state == COMMIT_BROKEN ||  in kick_a_thread()
240 			    c->ro_mount || c->ro_error) {  in kick_a_thread()
241 				mutex_unlock(&c->umount_mutex);  in kick_a_thread()
245 			if (c->cmt_state != COMMIT_RESTING) {  in kick_a_thread()
247 				mutex_unlock(&c->umount_mutex);  in kick_a_thread()
248 				return -1;  in kick_a_thread()
252 				list_move_tail(&c->infos_list, &ubifs_infos);  in kick_a_thread()
256 				mutex_unlock(&c->umount_mutex);  in kick_a_thread()
257 				return -1;  in kick_a_thread()
259 			mutex_unlock(&c->umount_mutex);  in kick_a_thread()
282 	unsigned long nr = sc->nr_to_scan;  in ubifs_shrink_scan()
292 		 * And we return -1 which means will make VM call us again  in ubifs_shrink_scan()
304 	freed += shrink_tnc_trees(nr - freed, YOUNG_ZNODE_AGE, &contention);  in ubifs_shrink_scan()
309 	freed += shrink_tnc_trees(nr - freed, 0, &contention);  in ubifs_shrink_scan()