From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> In order for the wait in nfs_uuid_put() to be safe, it is necessary to ensure that nfs_uuid_add_file() doesn't add a new entry once the nfs_uuid->net has been NULLed out. Also fix up the wake_up_var_locked() / wait_var_event_spinlock() to both use the nfs_uuid address, since nfl, and &nfl->uuid could be used elsewhere. Acked-by: Mike Snitzer <snitzer@xxxxxxxxxx> Tested-by: Mike Snitzer <snitzer@xxxxxxxxxx> Link: https://lore.kernel.org/all/175262893035.2234665.1735173020338594784@xxxxxxxxxxxxxxxxxxxxx/ Fixes: 21fb44034695 ("nfs_localio: protect race between nfs_uuid_put() and nfs_close_local_fh()") Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> --- fs/nfs_common/nfslocalio.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/fs/nfs_common/nfslocalio.c b/fs/nfs_common/nfslocalio.c index 64949c46c174..f1f1592ac134 100644 --- a/fs/nfs_common/nfslocalio.c +++ b/fs/nfs_common/nfslocalio.c @@ -177,7 +177,7 @@ static bool nfs_uuid_put(nfs_uuid_t *nfs_uuid) /* nfs_close_local_fh() is doing the * close and we must wait. until it unlinks */ - wait_var_event_spinlock(nfl, + wait_var_event_spinlock(nfs_uuid, list_first_entry_or_null( &nfs_uuid->files, struct nfs_file_localio, @@ -243,15 +243,20 @@ void nfs_localio_invalidate_clients(struct list_head *nn_local_clients, } EXPORT_SYMBOL_GPL(nfs_localio_invalidate_clients); -static void nfs_uuid_add_file(nfs_uuid_t *nfs_uuid, struct nfs_file_localio *nfl) +static int nfs_uuid_add_file(nfs_uuid_t *nfs_uuid, struct nfs_file_localio *nfl) { + int ret = 0; + /* Add nfl to nfs_uuid->files if it isn't already */ spin_lock(&nfs_uuid->lock); - if (list_empty(&nfl->list)) { + if (rcu_access_pointer(nfs_uuid->net) == NULL) { + ret = -ENXIO; + } else if (list_empty(&nfl->list)) { rcu_assign_pointer(nfl->nfs_uuid, nfs_uuid); list_add_tail(&nfl->list, &nfs_uuid->files); } spin_unlock(&nfs_uuid->lock); + return ret; } /* @@ -285,11 +290,13 @@ struct nfsd_file *nfs_open_local_fh(nfs_uuid_t *uuid, } rcu_read_unlock(); /* We have an implied reference to net thanks to nfsd_net_try_get */ - localio = nfs_to->nfsd_open_local_fh(net, uuid->dom, rpc_clnt, - cred, nfs_fh, pnf, fmode); + localio = nfs_to->nfsd_open_local_fh(net, uuid->dom, rpc_clnt, cred, + nfs_fh, pnf, fmode); + if (!IS_ERR(localio) && nfs_uuid_add_file(uuid, nfl) < 0) { + /* Delete the cached file when racing with nfs_uuid_put() */ + nfs_to_nfsd_file_put_local(pnf); + } nfs_to_nfsd_net_put(net); - if (!IS_ERR(localio)) - nfs_uuid_add_file(uuid, nfl); return localio; } @@ -338,7 +345,7 @@ void nfs_close_local_fh(struct nfs_file_localio *nfl) */ spin_lock(&nfs_uuid->lock); list_del_init(&nfl->list); - wake_up_var_locked(&nfl->nfs_uuid, &nfs_uuid->lock); + wake_up_var_locked(nfs_uuid, &nfs_uuid->lock); spin_unlock(&nfs_uuid->lock); } EXPORT_SYMBOL_GPL(nfs_close_local_fh); -- 2.50.1
