linux-kernel - [PATCH v3 10/21] make retain_dentry() neutral with respect to refcounting

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20231124060422.576198-10-viro@zeniv.linux.org.uk>
Date:   Fri, 24 Nov 2023 06:04:11 +0000
From:   Al Viro <viro@...iv.linux.org.uk>
To:     linux-fsdevel@...r.kernel.org
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Christian Brauner <brauner@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3 10/21] make retain_dentry() neutral with respect to refcounting

retain_dentry() used to decrement refcount if and only if it returned
true.  Lift those decrements into the callers.

Reviewed-by: Christian Brauner <brauner@...nel.org>
Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 fs/dcache.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index 0718b3895c12..2e74f3f2ce2e 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -680,7 +680,6 @@ static inline bool retain_dentry(struct dentry *dentry)
 		return false;
 
 	/* retain; LRU fodder */
-	dentry->d_lockref.count--;
 	if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST)))
 		d_lru_add(dentry);
 	else if (unlikely(!(dentry->d_flags & DCACHE_REFERENCED)))
@@ -744,6 +743,8 @@ static struct dentry *dentry_kill(struct dentry *dentry)
 	} else if (likely(!retain_dentry(dentry))) {
 		__dentry_kill(dentry);
 		return parent;
+	} else {
+		dentry->d_lockref.count--;
 	}
 	/* we are keeping it, after all */
 	if (inode)
@@ -893,6 +894,7 @@ void dput(struct dentry *dentry)
 		rcu_read_unlock();
 
 		if (likely(retain_dentry(dentry))) {
+			dentry->d_lockref.count--;
 			spin_unlock(&dentry->d_lock);
 			return;
 		}
@@ -925,6 +927,8 @@ void dput_to_list(struct dentry *dentry, struct list_head *list)
 	if (!retain_dentry(dentry)) {
 		--dentry->d_lockref.count;
 		to_shrink_list(dentry, list);
+	} else {
+		--dentry->d_lockref.count;
 	}
 	spin_unlock(&dentry->d_lock);
 }
-- 
2.39.2