SUNRPC: Make slot allocation more reliable

In xprt_alloc_slot(), the spin lock is only needed to provide atomicity
between the atomic_add_unless() failure and the call to xprt_add_backlog().
We do not actually need to hold it across the memory allocation itself.

By dropping the lock, we can use a more resilient GFP_NOFS allocation,
just as we now do in the rest of the RPC client code.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 3e63c5e97ebe67875f98836eae254f7d3c3460ba..4654a99342697e729d1c4e61242a421b72d98cf7 100644 (file)
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -1047,13 +1047,15 @@ out:
        return ret;
 }
 
-static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt, gfp_t gfp_flags)
+static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt)
 {
        struct rpc_rqst *req = ERR_PTR(-EAGAIN);
 
        if (!atomic_add_unless(&xprt->num_reqs, 1, xprt->max_reqs))
                goto out;
-       req = kzalloc(sizeof(struct rpc_rqst), gfp_flags);
+       spin_unlock(&xprt->reserve_lock);
+       req = kzalloc(sizeof(struct rpc_rqst), GFP_NOFS);
+       spin_lock(&xprt->reserve_lock);
        if (req != NULL)
                goto out;
        atomic_dec(&xprt->num_reqs);
@@ -1081,7 +1083,7 @@ void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
                list_del(&req->rq_list);
                goto out_init_req;
        }
-       req = xprt_dynamic_alloc_slot(xprt, GFP_NOWAIT|__GFP_NOWARN);
+       req = xprt_dynamic_alloc_slot(xprt);
        if (!IS_ERR(req))
                goto out_init_req;
        switch (PTR_ERR(req)) {