The patch below does not apply to the 5.5-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 75da98586af75eb80664714a67a9895bf0a5517e Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Date: Thu, 2 Apr 2020 10:34:36 -0400
Subject: [PATCH] NFS: finish_automount() requires us to hold 2 refs to the
mount record
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>
diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c
index da67820462f2..fe19ae280262 100644
--- a/fs/nfs/namespace.c
+++ b/fs/nfs/namespace.c
@@ -145,6 +145,7 @@ struct vfsmount *nfs_d_automount(struct path *path)
struct vfsmount *mnt = ERR_PTR(-ENOMEM);
struct nfs_server *server = NFS_SERVER(d_inode(path->dentry));
struct nfs_client *client = server->nfs_client;
+ int timeout = READ_ONCE(nfs_mountpoint_expiry_timeout);
int ret;
if (IS_ROOT(path->dentry))
@@ -190,12 +191,12 @@ struct vfsmount *nfs_d_automount(struct path *path)
if (IS_ERR(mnt))
goto out_fc;
- if (nfs_mountpoint_expiry_timeout < 0)
+ mntget(mnt); /* prevent immediate expiration */
+ if (timeout <= 0)
goto out_fc;
- 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_fc:
put_fs_context(fc);
@@ -233,10 +234,11 @@ 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)
