Commit 75da9858 authored by Trond Myklebust's avatar Trond Myklebust
Browse files

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: 22a1ae9a ("NFS: If nfs_mountpoint_expiry_timeout < 0, do not expire submounts")
Cc: stable@vger.kernel.org # v5.5+
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
parent 529af905

fs/nfs/namespace.c

+7 −5
Original line number Diff line number Diff line
@@ -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)

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