Commit 47446d74 authored by Vasily Averin's avatar Vasily Averin Committed by Chuck Lever
Browse files

nfsd4: add refcount for nfsd4_blocked_lock 



nbl allocated in nfsd4_lock can be released by a several ways:
directly in nfsd4_lock(), via nfs4_laundromat(), via another nfs
command RELEASE_LOCKOWNER or via nfsd4_callback.
This structure should be refcounted to be used and released correctly
in all these cases.

Refcount is initialized to 1 during allocation and is incremented
when nbl is added into nbl_list/nbl_lru lists.

Usually nbl is linked into both lists together, so only one refcount
is used for both lists.

However nfsd4_lock() should keep in mind that nbl can be present
in one of lists only. This can happen if nbl was handled already
by nfs4_laundromat/nfsd4_callback/etc.

Refcount is decremented if vfs_lock_file() returns FILE_LOCK_DEFERRED,
because nbl can be handled already by nfs4_laundromat/nfsd4_callback/etc.

Refcount is not changed in find_blocked_lock() because of it reuses counter
released after removing nbl from lists.

Signed-off-by: default avatarVasily Averin <vvs@virtuozzo.com>
Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent 40595cdc

fs/nfsd/nfs4state.c

+22 −3
Original line number Diff line number Diff line
@@ -246,6 +246,7 @@ find_blocked_lock(struct nfs4_lockowner *lo, struct knfsd_fh *fh, 
	list_for_each_entry(cur, &lo->lo_blocked, nbl_list) {

		if (fh_match(fh, &cur->nbl_fh)) {

			list_del_init(&cur->nbl_list);

			WARN_ON(list_empty(&cur->nbl_lru));

			list_del_init(&cur->nbl_lru);

			found = cur;

			break;
@@ -271,6 +272,7 @@ find_or_allocate_block(struct nfs4_lockowner *lo, struct knfsd_fh *fh, 
			INIT_LIST_HEAD(&nbl->nbl_lru);

			fh_copy_shallow(&nbl->nbl_fh, fh);

			locks_init_lock(&nbl->nbl_lock);

			kref_init(&nbl->nbl_kref);

			nfsd4_init_cb(&nbl->nbl_cb, lo->lo_owner.so_client,

					&nfsd4_cb_notify_lock_ops,

					NFSPROC4_CLNT_CB_NOTIFY_LOCK);
@@ -279,12 +281,21 @@ find_or_allocate_block(struct nfs4_lockowner *lo, struct knfsd_fh *fh, 
	return nbl;

}



static void

free_nbl(struct kref *kref)

{

	struct nfsd4_blocked_lock *nbl;



	nbl = container_of(kref, struct nfsd4_blocked_lock, nbl_kref);

	kfree(nbl);

}



static void

free_blocked_lock(struct nfsd4_blocked_lock *nbl)

{

	locks_delete_block(&nbl->nbl_lock);

	locks_release_private(&nbl->nbl_lock);

	kfree(nbl);

	kref_put(&nbl->nbl_kref, free_nbl);

}



static void
@@ -302,6 +313,7 @@ remove_blocked_locks(struct nfs4_lockowner *lo) 
					struct nfsd4_blocked_lock,

					nbl_list);

		list_del_init(&nbl->nbl_list);

		WARN_ON(list_empty(&nbl->nbl_lru));

		list_move(&nbl->nbl_lru, &reaplist);

	}

	spin_unlock(&nn->blocked_locks_lock);
@@ -6987,6 +6999,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, 
		spin_lock(&nn->blocked_locks_lock);

		list_add_tail(&nbl->nbl_list, &lock_sop->lo_blocked);

		list_add_tail(&nbl->nbl_lru, &nn->blocked_locks_lru);

		kref_get(&nbl->nbl_kref);

		spin_unlock(&nn->blocked_locks_lock);

	}
@@ -6999,6 +7012,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, 
			nn->somebody_reclaimed = true;

		break;

	case FILE_LOCK_DEFERRED:

		kref_put(&nbl->nbl_kref, free_nbl);

		nbl = NULL;

		fallthrough;

	case -EAGAIN:		/* conflock holds conflicting lock */
@@ -7019,8 +7033,13 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, 
		/* dequeue it if we queued it before */

		if (fl_flags & FL_SLEEP) {

			spin_lock(&nn->blocked_locks_lock);

			if (!list_empty(&nbl->nbl_list) &&

			    !list_empty(&nbl->nbl_lru)) {

				list_del_init(&nbl->nbl_list);

				list_del_init(&nbl->nbl_lru);

				kref_put(&nbl->nbl_kref, free_nbl);

			}

			/* nbl can use one of lists to be linked to reaplist */

			spin_unlock(&nn->blocked_locks_lock);

		}

		free_blocked_lock(nbl);

fs/nfsd/state.h

+1 −0
Original line number Diff line number Diff line
@@ -633,6 +633,7 @@ struct nfsd4_blocked_lock { 
	struct file_lock	nbl_lock;

	struct knfsd_fh		nbl_fh;

	struct nfsd4_callback	nbl_cb;

	struct kref		nbl_kref;

};



struct nfsd4_compound_state;