On Wed, 2022-05-11 at 17:52 -0400, Chuck Lever wrote:
> nfsd4_release_lockowner() mustn't hold clp->cl_lock when
> check_for_locks() invokes nfsd_file_put(), which can sleep.
>
> Reported-by: Dai Ngo <dai.ngo@xxxxxxxxxx>
> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> ---
> fs/nfsd/nfs4state.c | 56 +++++++++++++++++++++++----------------------------
> 1 file changed, 25 insertions(+), 31 deletions(-)
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 234e852fcdfa..e2eb6d031643 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -6611,8 +6611,8 @@ nfs4_set_lock_denied(struct file_lock *fl, struct nfsd4_lock_denied *deny)
> deny->ld_type = NFS4_WRITE_LT;
> }
>
> -static struct nfs4_lockowner *
> -find_lockowner_str_locked(struct nfs4_client *clp, struct xdr_netobj *owner)
> +static struct nfs4_stateowner *
> +find_stateowner_str_locked(struct nfs4_client *clp, struct xdr_netobj *owner)
> {
> unsigned int strhashval = ownerstr_hashval(owner);
> struct nfs4_stateowner *so;
> @@ -6624,11 +6624,22 @@ find_lockowner_str_locked(struct nfs4_client *clp, struct xdr_netobj *owner)
> if (so->so_is_open_owner)
> continue;
> if (same_owner_str(so, owner))
> - return lockowner(nfs4_get_stateowner(so));
> + return nfs4_get_stateowner(so);
> }
> return NULL;
> }
>
> +static struct nfs4_lockowner *
> +find_lockowner_str_locked(struct nfs4_client *clp, struct xdr_netobj *owner)
> +{
> + struct nfs4_stateowner *so;
> +
> + so = find_stateowner_str_locked(clp, owner);
> + if (!so)
> + return NULL;
> + return lockowner(so);
> +}
> +
> static struct nfs4_lockowner *
> find_lockowner_str(struct nfs4_client *clp, struct xdr_netobj *owner)
> {
> @@ -7305,10 +7316,8 @@ nfsd4_release_lockowner(struct svc_rqst *rqstp,
> struct nfsd4_release_lockowner *rlockowner = &u->release_lockowner;
> clientid_t *clid = &rlockowner->rl_clientid;
> struct nfs4_stateowner *sop;
> - struct nfs4_lockowner *lo = NULL;
> + struct nfs4_lockowner *lo;
> struct nfs4_ol_stateid *stp;
> - struct xdr_netobj *owner = &rlockowner->rl_owner;
> - unsigned int hashval = ownerstr_hashval(owner);
> __be32 status;
> struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
> struct nfs4_client *clp;
> @@ -7322,32 +7331,18 @@ nfsd4_release_lockowner(struct svc_rqst *rqstp,
> return status;
>
> clp = cstate->clp;
> - /* Find the matching lock stateowner */
> spin_lock(&clp->cl_lock);
> - list_for_each_entry(sop, &clp->cl_ownerstr_hashtbl[hashval],
> - so_strhash) {
> -
> - if (sop->so_is_open_owner || !same_owner_str(sop, owner))
> - continue;
> -
> - /* see if there are still any locks associated with it */
> - lo = lockowner(sop);
> - list_for_each_entry(stp, &sop->so_stateids, st_perstateowner) {
> - if (check_for_locks(stp->st_stid.sc_file, lo)) {
> - status = nfserr_locks_held;
> - spin_unlock(&clp->cl_lock);
> - return status;
> - }
> - }
> + sop = find_stateowner_str_locked(clp, &rlockowner->rl_owner);
> + spin_unlock(&clp->cl_lock);
> + if (!sop)
> + return nfs_ok;
>
> - nfs4_get_stateowner(sop);
> - break;
> - }
> - if (!lo) {
> - spin_unlock(&clp->cl_lock);
> - return status;
> - }
> + lo = lockowner(sop);
> + list_for_each_entry(stp, &sop->so_stateids, st_perstateowner)
> + if (check_for_locks(stp->st_stid.sc_file, lo))
> + return nfserr_locks_held;
>
It has been a while since I was in this code, but is it safe to walk the
above list without holding the cl_lock?
> + spin_lock(&clp->cl_lock);
> unhash_lockowner_locked(lo);
> while (!list_empty(&lo->lo_owner.so_stateids)) {
> stp = list_first_entry(&lo->lo_owner.so_stateids,
> @@ -7360,8 +7355,7 @@ nfsd4_release_lockowner(struct svc_rqst *rqstp,
> free_ol_stateid_reaplist(&reaplist);
> remove_blocked_locks(lo);
> nfs4_put_stateowner(&lo->lo_owner);
> -
> - return status;
> + return nfs_ok;
> }
>
> static inline struct nfs4_client_reclaim *
>
>
--
Jeff Layton <jlayton@xxxxxxxxxx>
