NFSv4.1: Fix a deadlock in layoutget

commit 8ac092519ad91931c96d306c4bfae2c6587c325f upstream.

We cannot call nfs4_handle_exception() without first ensuring that the
slot has been freed. If not, we end up deadlocking with the process
waiting for recovery to complete, and recovery waiting for the slot
table to drain.

Fixes: 2e80dbe7ac51 ("NFSv4.1: Close callback races for OPEN, LAYOUTGET...")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 241da19b7da4a54a45b1a2bd6cae4cab8cab4dde..e475a3d13f273db2b73040d879aa84aeee71a4d8 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -8371,6 +8371,7 @@ nfs4_layoutget_handle_exception(struct rpc_task *task,
                goto out;
        }
 
+       nfs4_sequence_free_slot(&lgp->res.seq_res);
        err = nfs4_handle_exception(server, nfs4err, exception);
        if (!status) {
                if (exception->retry)