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

From: Al Viro
Date: Fri Nov 24 2023 - 01:04:48 EST


->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@xxxxxxxxxx>
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
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