Commit b401be22 authored by Jeff Layton's avatar Jeff Layton Committed by J. Bruce Fields
Browse files

nfsd: don't allow CLOSE to proceed until refcount on stateid drops 



Once we remove client_mutex protection, it'll be possible to have an
in-flight operation using an openstateid when a CLOSE call comes in.
If that happens, we can't just put the sc_file reference and clear its
pointer without risking an oops.

Fix this by ensuring that v4.0 CLOSE operations wait for the refcount
to drop before proceeding to do so.

Signed-off-by: default avatarJeff Layton <jlayton@primarydata.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent d3134b10

fs/nfsd/nfs4state.c

+20 −1
Original line number Diff line number Diff line
@@ -85,6 +85,12 @@ static DEFINE_MUTEX(client_mutex); 
 */

static DEFINE_SPINLOCK(state_lock);



/*

 * A waitqueue for all in-progress 4.0 CLOSE operations that are waiting for

 * the refcount on the open stateid to drop.

 */

static DECLARE_WAIT_QUEUE_HEAD(close_wq);



static struct kmem_cache *openowner_slab;

static struct kmem_cache *lockowner_slab;

static struct kmem_cache *file_slab;
@@ -640,8 +646,10 @@ nfs4_put_stid(struct nfs4_stid *s) 


	might_lock(&clp->cl_lock);



	if (!atomic_dec_and_lock(&s->sc_count, &clp->cl_lock))

	if (!atomic_dec_and_lock(&s->sc_count, &clp->cl_lock)) {

		wake_up_all(&close_wq);

		return;

	}

	idr_remove(&clp->cl_stateids, s->sc_stateid.si_opaque.so_id);

	spin_unlock(&clp->cl_lock);

	s->sc_free(s);
@@ -3070,6 +3078,17 @@ move_to_close_lru(struct nfs4_ol_stateid *s, struct net *net) 


	dprintk("NFSD: move_to_close_lru nfs4_openowner %p\n", oo);



	/*

	 * We know that we hold one reference via nfsd4_close, and another

	 * "persistent" reference for the client. If the refcount is higher

	 * than 2, then there are still calls in progress that are using this

	 * stateid. We can't put the sc_file reference until they are finished.

	 * Wait for the refcount to drop to 2. Since it has been unhashed,

	 * there should be no danger of the refcount going back up again at

	 * this point.

	 */

	wait_event(close_wq, atomic_read(&s->st_stid.sc_count) == 2);



	release_all_access(s);

	if (s->st_stid.sc_file) {

		put_nfs4_file(s->st_stid.sc_file);

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