change system file

hc

2024-10-09 244b2c5ca8b14627e4a17755e5922221e121c771

 kernel/fs/autofs/expire.c
..
..
@@ -1,11 +1,8 @@
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+// SPDX-License-Identifier: GPL-2.0-or-later
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 /*
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  * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
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  * Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
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  * Copyright 2001-2006 Ian Kent <raven@themaw.net>
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- *
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- * This file is part of the Linux kernel and is made available under
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- * the terms of the GNU General Public License, version 2, or at your
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- * option, any later version, incorporated herein by reference.
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  */
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7
 
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 #include "autofs_i.h"
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@@ -73,6 +70,27 @@
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 	return status;
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 }
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72
 
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+/* p->d_lock held */
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+static struct dentry *positive_after(struct dentry *p, struct dentry *child)
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+{
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+	if (child)
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+		child = list_next_entry(child, d_child);
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+	else
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+		child = list_first_entry(&p->d_subdirs, struct dentry, d_child);
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+
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+	list_for_each_entry_from(child, &p->d_subdirs, d_child) {
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+		spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
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+		if (simple_positive(child)) {
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+			dget_dlock(child);
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+			spin_unlock(&child->d_lock);
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+			return child;
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+		}
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+		spin_unlock(&child->d_lock);
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+	}
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+
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+	return NULL;
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+}
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+
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 /*
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  * Calculate and dget next entry in the subdirs list under root.
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  */
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@@ -80,43 +98,14 @@
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 					       struct dentry *root)
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 {
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 	struct autofs_sb_info *sbi = autofs_sbi(root->d_sb);
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-	struct list_head *next;
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 	struct dentry *q;
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 	spin_lock(&sbi->lookup_lock);
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 	spin_lock(&root->d_lock);
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-
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-	if (prev)
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-		next = prev->d_child.next;
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-	else {
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-		prev = dget_dlock(root);
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-		next = prev->d_subdirs.next;
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-	}
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-
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-cont:
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-	if (next == &root->d_subdirs) {
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-		spin_unlock(&root->d_lock);
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-		spin_unlock(&sbi->lookup_lock);
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-		dput(prev);
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-		return NULL;
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-	}
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-
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-	q = list_entry(next, struct dentry, d_child);
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-
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-	spin_lock_nested(&q->d_lock, DENTRY_D_LOCK_NESTED);
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-	/* Already gone or negative dentry (under construction) - try next */
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-	if (!d_count(q) || !simple_positive(q)) {
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-		spin_unlock(&q->d_lock);
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-		next = q->d_child.next;
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-		goto cont;
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-	}
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-	dget_dlock(q);
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-	spin_unlock(&q->d_lock);
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+	q = positive_after(root, prev);
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 	spin_unlock(&root->d_lock);
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 	spin_unlock(&sbi->lookup_lock);
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-
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 	dput(prev);
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-
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 	return q;
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 }
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@@ -127,59 +116,28 @@
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 					       struct dentry *root)
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 {
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 	struct autofs_sb_info *sbi = autofs_sbi(root->d_sb);
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-	struct list_head *next;
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-	struct dentry *p, *ret;
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+	struct dentry *p = prev, *ret = NULL, *d = NULL;
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 	if (prev == NULL)
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 		return dget(root);
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 	spin_lock(&sbi->lookup_lock);
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-relock:
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-	p = prev;
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 	spin_lock(&p->d_lock);
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-again:
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-	next = p->d_subdirs.next;
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-	if (next == &p->d_subdirs) {
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-		while (1) {
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-			struct dentry *parent;
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+	while (1) {
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+		struct dentry *parent;
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-			if (p == root) {
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-				spin_unlock(&p->d_lock);
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-				spin_unlock(&sbi->lookup_lock);
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-				dput(prev);
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-				return NULL;
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-			}
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-
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-			parent = p->d_parent;
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-			if (!spin_trylock(&parent->d_lock)) {
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-				spin_unlock(&p->d_lock);
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-				cpu_relax();
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-				goto relock;
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-			}
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-			spin_unlock(&p->d_lock);
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-			next = p->d_child.next;
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-			p = parent;
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-			if (next != &parent->d_subdirs)
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-				break;
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-		}
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-	}
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-	ret = list_entry(next, struct dentry, d_child);
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-
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-	spin_lock_nested(&ret->d_lock, DENTRY_D_LOCK_NESTED);
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-	/* Negative dentry - try next */
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-	if (!simple_positive(ret)) {
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+		ret = positive_after(p, d);
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+		if (ret || p == root)
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+			break;
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+		parent = p->d_parent;
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 		spin_unlock(&p->d_lock);
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-		lock_set_subclass(&ret->d_lock.dep_map, 0, _RET_IP_);
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-		p = ret;
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-		goto again;
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+		spin_lock(&parent->d_lock);
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+		d = p;
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+		p = parent;
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 	}
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-	dget_dlock(ret);
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-	spin_unlock(&ret->d_lock);
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 	spin_unlock(&p->d_lock);
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 	spin_unlock(&sbi->lookup_lock);
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-
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 	dput(prev);
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-
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 	return ret;
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 }
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..
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@@ -253,7 +211,7 @@
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 			}
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 		} else {
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 			struct autofs_info *ino = autofs_dentry_ino(p);
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-			unsigned int ino_count = atomic_read(&ino->count);
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+			unsigned int ino_count = READ_ONCE(ino->count);
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 			/* allow for dget above and top is already dgot */
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 			if (p == top)
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@@ -421,7 +379,7 @@
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 		/* Not a forced expire? */
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 		if (!(how & AUTOFS_EXP_FORCED)) {
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 			/* ref-walk currently on this dentry? */
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-			ino_count = atomic_read(&ino->count) + 1;
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+			ino_count = READ_ONCE(ino->count) + 1;
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 			if (d_count(dentry) > ino_count)
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 				return NULL;
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 		}
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@@ -438,7 +396,7 @@
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 		/* Not a forced expire? */
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 		if (!(how & AUTOFS_EXP_FORCED)) {
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 			/* ref-walk currently on this dentry? */
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-			ino_count = atomic_read(&ino->count) + 1;
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+			ino_count = READ_ONCE(ino->count) + 1;
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 			if (d_count(dentry) > ino_count)
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 				return NULL;
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 		}