From: Trond Myklebust trond.myklebust@hammerspace.com
[ 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@vger.kernel.org # v5.5+ Signed-off-by: Trond Myklebust trond.myklebust@hammerspace.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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)