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2024-10-09 244b2c5ca8b14627e4a17755e5922221e121c771 
 kernel/fs/quota/dquot.c
....@@ -225,12 +225,21 @@
225225 
226226 /*
227227  * Dquot List Management:
228
- * The quota code uses four lists for dquot management: the inuse_list,
229
- * free_dquots, dqi_dirty_list, and dquot_hash[] array. A single dquot
230
- * structure may be on some of those lists, depending on its current state.
228
+ * The quota code uses five lists for dquot management: the inuse_list,
229
+ * releasing_dquots, free_dquots, dqi_dirty_list, and dquot_hash[] array.
230
+ * A single dquot structure may be on some of those lists, depending on
231
+ * its current state.
231232  *
232233  * All dquots are placed to the end of inuse_list when first created, and this
233234  * list is used for invalidate operation, which must look at every dquot.
235
+ *
236
+ * When the last reference of a dquot will be dropped, the dquot will be
237
+ * added to releasing_dquots. We'd then queue work item which would call
238
+ * synchronize_srcu() and after that perform the final cleanup of all the
239
+ * dquots on the list. Both releasing_dquots and free_dquots use the
240
+ * dq_free list_head in the dquot struct. When a dquot is removed from
241
+ * releasing_dquots, a reference count is always subtracted, and if
242
+ * dq_count == 0 at that point, the dquot will be added to the free_dquots.
234243  *
235244  * Unused dquots (dq_count == 0) are added to the free_dquots list when freed,
236245  * and this list is searched whenever we need an available dquot.  Dquots are
....@@ -250,6 +259,7 @@
250259 
251260 static LIST_HEAD(inuse_list);
252261 static LIST_HEAD(free_dquots);
262
+static LIST_HEAD(releasing_dquots);
253263 static unsigned int dq_hash_bits, dq_hash_mask;
254264 static struct hlist_head *dquot_hash;
255265 
....@@ -259,6 +269,9 @@
259269 static qsize_t inode_get_rsv_space(struct inode *inode);
260270 static qsize_t __inode_get_rsv_space(struct inode *inode);
261271 static int __dquot_initialize(struct inode *inode, int type);
272
+
273
+static void quota_release_workfn(struct work_struct *work);
274
+static DECLARE_DELAYED_WORK(quota_release_work, quota_release_workfn);
262275 
263276 static inline unsigned int
264277 hashfn(const struct super_block *sb, struct kqid qid)
....@@ -307,12 +320,18 @@
307320 	dqstats_inc(DQST_FREE_DQUOTS);
308321 }
309322 
323
+static inline void put_releasing_dquots(struct dquot *dquot)
324
+{
325
+	list_add_tail(&dquot->dq_free, &releasing_dquots);
326
+}
327
+
310328 static inline void remove_free_dquot(struct dquot *dquot)
311329 {
312330 	if (list_empty(&dquot->dq_free))
313331 		return;
314332 	list_del_init(&dquot->dq_free);
315
-	dqstats_dec(DQST_FREE_DQUOTS);
333
+	if (!atomic_read(&dquot->dq_count))
334
+		dqstats_dec(DQST_FREE_DQUOTS);
316335 }
317336 
318337 static inline void put_inuse(struct dquot *dquot)
....@@ -338,6 +357,11 @@
338357 	mutex_unlock(&dquot->dq_lock);
339358 }
340359 
360
+static inline int dquot_active(struct dquot *dquot)
361
+{
362
+	return test_bit(DQ_ACTIVE_B, &dquot->dq_flags);
363
+}
364
+
341365 static inline int dquot_dirty(struct dquot *dquot)
342366 {
343367 	return test_bit(DQ_MOD_B, &dquot->dq_flags);
....@@ -353,14 +377,14 @@
353377 {
354378 	int ret = 1;
355379 
356
-	if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags))
380
+	if (!dquot_active(dquot))
357381 		return 0;
358382 
359383 	if (sb_dqopt(dquot->dq_sb)->flags & DQUOT_NOLIST_DIRTY)
360384 		return test_and_set_bit(DQ_MOD_B, &dquot->dq_flags);
361385 
362386 	/* If quota is dirty already, we don't have to acquire dq_list_lock */
363
-	if (test_bit(DQ_MOD_B, &dquot->dq_flags))
387
+	if (dquot_dirty(dquot))
364388 		return 1;
365389 
366390 	spin_lock(&dq_list_lock);
....@@ -442,7 +466,7 @@
442466 	smp_mb__before_atomic();
443467 	set_bit(DQ_READ_B, &dquot->dq_flags);
444468 	/* Instantiate dquot if needed */
445
-	if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags) && !dquot->dq_off) {
469
+	if (!dquot_active(dquot) && !dquot->dq_off) {
446470 		ret = dqopt->ops[dquot->dq_id.type]->commit_dqblk(dquot);
447471 		/* Write the info if needed */
448472 		if (info_dirty(&dqopt->info[dquot->dq_id.type])) {
....@@ -484,7 +508,7 @@
484508 		goto out_lock;
485509 	/* Inactive dquot can be only if there was error during read/init
486510 	 * => we have better not writing it */
487
-	if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags))
511
+	if (dquot_active(dquot))
488512 		ret = dqopt->ops[dquot->dq_id.type]->commit_dqblk(dquot);
489513 	else
490514 		ret = -EIO;
....@@ -549,6 +573,8 @@
549573 	struct dquot *dquot, *tmp;
550574 
551575 restart:
576
+	flush_delayed_work(&quota_release_work);
577
+
552578 	spin_lock(&dq_list_lock);
553579 	list_for_each_entry_safe(dquot, tmp, &inuse_list, dq_inuse) {
554580 		if (dquot->dq_sb != sb)
....@@ -557,7 +583,13 @@
557583 			continue;
558584 		/* Wait for dquot users */
559585 		if (atomic_read(&dquot->dq_count)) {
560
-			dqgrab(dquot);
586
+			/* dquot in releasing_dquots, flush and retry */
587
+			if (!list_empty(&dquot->dq_free)) {
588
+				spin_unlock(&dq_list_lock);
589
+				goto restart;
590
+			}
591
+
592
+			atomic_inc(&dquot->dq_count);
561593 			spin_unlock(&dq_list_lock);
562594 			/*
563595 			 * Once dqput() wakes us up, we know it's time to free
....@@ -599,7 +631,7 @@
599631 
600632 	spin_lock(&dq_list_lock);
601633 	list_for_each_entry(dquot, &inuse_list, dq_inuse) {
602
-		if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags))
634
+		if (!dquot_active(dquot))
603635 			continue;
604636 		if (dquot->dq_sb != sb)
605637 			continue;
....@@ -614,7 +646,7 @@
614646 		 * outstanding call and recheck the DQ_ACTIVE_B after that.
615647 		 */
616648 		wait_on_dquot(dquot);
617
-		if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
649
+		if (dquot_active(dquot)) {
618650 			ret = fn(dquot, priv);
619651 			if (ret < 0)
620652 				goto out;
....@@ -629,6 +661,18 @@
629661 	return ret;
630662 }
631663 EXPORT_SYMBOL(dquot_scan_active);
664
+
665
+static inline int dquot_write_dquot(struct dquot *dquot)
666
+{
667
+	int ret = dquot->dq_sb->dq_op->write_dquot(dquot);
668
+	if (ret < 0) {
669
+		quota_error(dquot->dq_sb, "Can't write quota structure "
670
+			    "(error %d). Quota may get out of sync!", ret);
671
+		/* Clear dirty bit anyway to avoid infinite loop. */
672
+		clear_dquot_dirty(dquot);
673
+	}
674
+	return ret;
675
+}
632676 
633677 /* Write all dquot structures to quota files */
634678 int dquot_writeback_dquots(struct super_block *sb, int type)
....@@ -653,23 +697,16 @@
653697 			dquot = list_first_entry(&dirty, struct dquot,
654698 						 dq_dirty);
655699 
656
-			WARN_ON(!test_bit(DQ_ACTIVE_B, &dquot->dq_flags));
700
+			WARN_ON(!dquot_active(dquot));
657701 
658702 			/* Now we have active dquot from which someone is
659703  			 * holding reference so we can safely just increase
660704 			 * use count */
661705 			dqgrab(dquot);
662706 			spin_unlock(&dq_list_lock);
663
-			err = sb->dq_op->write_dquot(dquot);
664
-			if (err) {
665
-				/*
666
-				 * Clear dirty bit anyway to avoid infinite
667
-				 * loop here.
668
-				 */
669
-				clear_dquot_dirty(dquot);
670
-				if (!ret)
671
-					ret = err;
672
-			}
707
+			err = dquot_write_dquot(dquot);
708
+			if (err && !ret)
709
+				ret = err;
673710 			dqput(dquot);
674711 			spin_lock(&dq_list_lock);
675712 		}
....@@ -763,12 +800,53 @@
763800 };
764801 
765802 /*
803
+ * Safely release dquot and put reference to dquot.
804
+ */
805
+static void quota_release_workfn(struct work_struct *work)
806
+{
807
+	struct dquot *dquot;
808
+	struct list_head rls_head;
809
+
810
+	spin_lock(&dq_list_lock);
811
+	/* Exchange the list head to avoid livelock. */
812
+	list_replace_init(&releasing_dquots, &rls_head);
813
+	spin_unlock(&dq_list_lock);
814
+
815
+restart:
816
+	synchronize_srcu(&dquot_srcu);
817
+	spin_lock(&dq_list_lock);
818
+	while (!list_empty(&rls_head)) {
819
+		dquot = list_first_entry(&rls_head, struct dquot, dq_free);
820
+		/* Dquot got used again? */
821
+		if (atomic_read(&dquot->dq_count) > 1) {
822
+			remove_free_dquot(dquot);
823
+			atomic_dec(&dquot->dq_count);
824
+			continue;
825
+		}
826
+		if (dquot_dirty(dquot)) {
827
+			spin_unlock(&dq_list_lock);
828
+			/* Commit dquot before releasing */
829
+			dquot_write_dquot(dquot);
830
+			goto restart;
831
+		}
832
+		if (dquot_active(dquot)) {
833
+			spin_unlock(&dq_list_lock);
834
+			dquot->dq_sb->dq_op->release_dquot(dquot);
835
+			goto restart;
836
+		}
837
+		/* Dquot is inactive and clean, now move it to free list */
838
+		remove_free_dquot(dquot);
839
+		atomic_dec(&dquot->dq_count);
840
+		put_dquot_last(dquot);
841
+	}
842
+	spin_unlock(&dq_list_lock);
843
+}
844
+
845
+/*
766846  * Put reference to dquot
767847  */
768848 void dqput(struct dquot *dquot)
769849 {
770
-	int ret;
771
-
772850 	if (!dquot)
773851 		return;
774852 #ifdef CONFIG_QUOTA_DEBUG
....@@ -780,7 +858,7 @@
780858 	}
781859 #endif
782860 	dqstats_inc(DQST_DROPS);
783
-we_slept:
861
+
784862 	spin_lock(&dq_list_lock);
785863 	if (atomic_read(&dquot->dq_count) > 1) {
786864 		/* We have more than one user... nothing to do */
....@@ -792,35 +870,15 @@
792870 		spin_unlock(&dq_list_lock);
793871 		return;
794872 	}
873
+
795874 	/* Need to release dquot? */
796
-	if (dquot_dirty(dquot)) {
797
-		spin_unlock(&dq_list_lock);
798
-		/* Commit dquot before releasing */
799
-		ret = dquot->dq_sb->dq_op->write_dquot(dquot);
800
-		if (ret < 0) {
801
-			quota_error(dquot->dq_sb, "Can't write quota structure"
802
-				    " (error %d). Quota may get out of sync!",
803
-				    ret);
804
-			/*
805
-			 * We clear dirty bit anyway, so that we avoid
806
-			 * infinite loop here
807
-			 */
808
-			clear_dquot_dirty(dquot);
809
-		}
810
-		goto we_slept;
811
-	}
812
-	if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
813
-		spin_unlock(&dq_list_lock);
814
-		dquot->dq_sb->dq_op->release_dquot(dquot);
815
-		goto we_slept;
816
-	}
817
-	atomic_dec(&dquot->dq_count);
818875 #ifdef CONFIG_QUOTA_DEBUG
819876 	/* sanity check */
820877 	BUG_ON(!list_empty(&dquot->dq_free));
821878 #endif
822
-	put_dquot_last(dquot);
879
+	put_releasing_dquots(dquot);
823880 	spin_unlock(&dq_list_lock);
881
+	queue_delayed_work(system_unbound_wq, &quota_release_work, 1);
824882 }
825883 EXPORT_SYMBOL(dqput);
826884 
....@@ -910,7 +968,7 @@
910968 	 * already finished or it will be canceled due to dq_count > 1 test */
911969 	wait_on_dquot(dquot);
912970 	/* Read the dquot / allocate space in quota file */
913
-	if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
971
+	if (!dquot_active(dquot)) {
914972 		int err;
915973 
916974 		err = sb->dq_op->acquire_dquot(dquot);
....@@ -1427,7 +1485,7 @@
14271485 	return QUOTA_NL_NOWARN;
14281486 }
14291487 
1430
-static int dquot_active(const struct inode *inode)
1488
+static int inode_quota_active(const struct inode *inode)
14311489 {
14321490 	struct super_block *sb = inode->i_sb;
14331491 
....@@ -1450,7 +1508,7 @@
14501508 	qsize_t rsv;
14511509 	int ret = 0;
14521510 
1453
-	if (!dquot_active(inode))
1511
+	if (!inode_quota_active(inode))
14541512 		return 0;
14551513 
14561514 	dquots = i_dquot(inode);
....@@ -1558,7 +1616,7 @@
15581616 	struct dquot **dquots;
15591617 	int i;
15601618 
1561
-	if (!dquot_active(inode))
1619
+	if (!inode_quota_active(inode))
15621620 		return false;
15631621 
15641622 	dquots = i_dquot(inode);
....@@ -1669,7 +1727,7 @@
16691727 	int reserve = flags & DQUOT_SPACE_RESERVE;
16701728 	struct dquot **dquots;
16711729 
1672
-	if (!dquot_active(inode)) {
1730
+	if (!inode_quota_active(inode)) {
16731731 		if (reserve) {
16741732 			spin_lock(&inode->i_lock);
16751733 			*inode_reserved_space(inode) += number;
....@@ -1739,7 +1797,7 @@
17391797 	struct dquot_warn warn[MAXQUOTAS];
17401798 	struct dquot * const *dquots;
17411799 
1742
-	if (!dquot_active(inode))
1800
+	if (!inode_quota_active(inode))
17431801 		return 0;
17441802 	for (cnt = 0; cnt < MAXQUOTAS; cnt++)
17451803 		warn[cnt].w_type = QUOTA_NL_NOWARN;
....@@ -1782,7 +1840,7 @@
17821840 	struct dquot **dquots;
17831841 	int cnt, index;
17841842 
1785
-	if (!dquot_active(inode)) {
1843
+	if (!inode_quota_active(inode)) {
17861844 		spin_lock(&inode->i_lock);
17871845 		*inode_reserved_space(inode) -= number;
17881846 		__inode_add_bytes(inode, number);
....@@ -1824,7 +1882,7 @@
18241882 	struct dquot **dquots;
18251883 	int cnt, index;
18261884 
1827
-	if (!dquot_active(inode)) {
1885
+	if (!inode_quota_active(inode)) {
18281886 		spin_lock(&inode->i_lock);
18291887 		*inode_reserved_space(inode) += number;
18301888 		__inode_sub_bytes(inode, number);
....@@ -1868,7 +1926,7 @@
18681926 	struct dquot **dquots;
18691927 	int reserve = flags & DQUOT_SPACE_RESERVE, index;
18701928 
1871
-	if (!dquot_active(inode)) {
1929
+	if (!inode_quota_active(inode)) {
18721930 		if (reserve) {
18731931 			spin_lock(&inode->i_lock);
18741932 			*inode_reserved_space(inode) -= number;
....@@ -1923,7 +1981,7 @@
19231981 	struct dquot * const *dquots;
19241982 	int index;
19251983 
1926
-	if (!dquot_active(inode))
1984
+	if (!inode_quota_active(inode))
19271985 		return;
19281986 
19291987 	dquots = i_dquot(inode);
....@@ -2094,7 +2152,7 @@
20942152 	struct super_block *sb = inode->i_sb;
20952153 	int ret;
20962154 
2097
-	if (!dquot_active(inode))
2155
+	if (!inode_quota_active(inode))
20982156 		return 0;
20992157 
21002158 	if (iattr->ia_valid & ATTR_UID && !uid_eq(iattr->ia_uid, inode->i_uid)){
....@@ -2319,6 +2377,8 @@
23192377 	struct super_block *sb = inode->i_sb;
23202378 	struct quota_info *dqopt = sb_dqopt(sb);
23212379 
2380
+	if (is_bad_inode(inode))
2381
+		return -EUCLEAN;
23222382 	if (!S_ISREG(inode->i_mode))
23232383 		return -EACCES;
23242384 	if (IS_RDONLY(inode))
....@@ -2413,7 +2473,8 @@
24132473 
24142474 	error = add_dquot_ref(sb, type);
24152475 	if (error)
2416
-		dquot_disable(sb, type, flags);
2476
+		dquot_disable(sb, type,
2477
+			      DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED);
24172478 
24182479 	return error;
24192480 out_fmt: