[PATCH 4.9 08/41] ceph: ensure d_name stability in ceph_dentry_hash()

From: Greg Kroah-Hartman
Date: Tue Apr 30 2019 - 07:40:29 EST


From: Jeff Layton <jlayton@xxxxxxxxxx>

commit 76a495d666e5043ffc315695f8241f5e94a98849 upstream.

Take the d_lock here to ensure that d_name doesn't change.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
Reviewed-by: "Yan, Zheng" <zyan@xxxxxxxxxx>
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
fs/ceph/dir.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1471,6 +1471,7 @@ void ceph_dentry_lru_del(struct dentry *
unsigned ceph_dentry_hash(struct inode *dir, struct dentry *dn)
{
struct ceph_inode_info *dci = ceph_inode(dir);
+ unsigned hash;

switch (dci->i_dir_layout.dl_dir_hash) {
case 0: /* for backward compat */
@@ -1478,8 +1479,11 @@ unsigned ceph_dentry_hash(struct inode *
return dn->d_name.hash;

default:
- return ceph_str_hash(dci->i_dir_layout.dl_dir_hash,
+ spin_lock(&dn->d_lock);
+ hash = ceph_str_hash(dci->i_dir_layout.dl_dir_hash,
dn->d_name.name, dn->d_name.len);
+ spin_unlock(&dn->d_lock);
+ return hash;
}
}