linux-kernel - [PATCH v3 02/21] coda_flag_children(): cope with dentries turning negative

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Message-Id: <20231124060422.576198-2-viro@zeniv.linux.org.uk>
Date:   Fri, 24 Nov 2023 06:04:03 +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 02/21] coda_flag_children(): cope with dentries turning negative

->d_lock on parent does not stabilize ->d_inode of child.
We don't do much with that inode in there, but we need
at least to avoid struct inode getting freed under us...

Reviewed-by: Christian Brauner <brauner@...nel.org>
Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 fs/coda/cache.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/coda/cache.c b/fs/coda/cache.c
index 3b8c4513118f..bfbc03c6b632 100644
--- a/fs/coda/cache.c
+++ b/fs/coda/cache.c
@@ -92,13 +92,16 @@ static void coda_flag_children(struct dentry *parent, int flag)
 {
 	struct dentry *de;
 
+	rcu_read_lock();
 	spin_lock(&parent->d_lock);
 	list_for_each_entry(de, &parent->d_subdirs, d_child) {
+		struct inode *inode = d_inode_rcu(de);
 		/* don't know what to do with negative dentries */
-		if (d_inode(de) ) 
-			coda_flag_inode(d_inode(de), flag);
+		if (inode)
+			coda_flag_inode(inode, flag);
 	}
 	spin_unlock(&parent->d_lock);
+	rcu_read_unlock();
 	return; 
 }
 
-- 
2.39.2