From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
[ Upstream commit 75da98586af75eb80664714a67a9895bf0a5517e ]
We must not return from nfs_d_automount() without holding 2 references
to the mount record. Doing so, will trigger the BUG() in finish_automount().
Also ensure that we don't try to reschedule the automount timer with
a negative or zero timeout value.
Fixes: 22a1ae9a93fb ("NFS: If nfs_mountpoint_expiry_timeout < 0, do not expire submounts")
Cc: stable@xxxxxxxxxxxxxxx # v5.5+
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/nfs/namespace.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c
index 5e0e9d29f5c57..0c5db17607411 100644
--- a/fs/nfs/namespace.c
+++ b/fs/nfs/namespace.c
@@ -143,6 +143,7 @@ struct vfsmount *nfs_d_automount(struct path *path)
struct nfs_server *server = NFS_SERVER(d_inode(path->dentry));
struct nfs_fh *fh = NULL;
struct nfs_fattr *fattr = NULL;
+ int timeout = READ_ONCE(nfs_mountpoint_expiry_timeout);
if (IS_ROOT(path->dentry))
return ERR_PTR(-ESTALE);
@@ -157,12 +158,12 @@ struct vfsmount *nfs_d_automount(struct path *path)
if (IS_ERR(mnt))
goto out;
- if (nfs_mountpoint_expiry_timeout < 0)
+ mntget(mnt); /* prevent immediate expiration */
+ if (timeout <= 0)
goto out;
- mntget(mnt); /* prevent immediate expiration */
mnt_set_expiry(mnt, &nfs_automount_list);
- schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
+ schedule_delayed_work(&nfs_automount_task, timeout);
out:
nfs_free_fattr(fattr);
@@ -201,10 +202,11 @@ const struct inode_operations nfs_referral_inode_operations = {
static void nfs_expire_automounts(struct work_struct *work)
{
struct list_head *list = &nfs_automount_list;
+ int timeout = READ_ONCE(nfs_mountpoint_expiry_timeout);
mark_mounts_for_expiry(list);
- if (!list_empty(list))
- schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
+ if (!list_empty(list) && timeout > 0)
+ schedule_delayed_work(&nfs_automount_task, timeout);
}
void nfs_release_automount_timer(void)
--
2.20.1
