Merge tag 'nfs-for-4.18-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

Pull NFS client bugfixes from Trond Myklebust:
 "Hightlights include:

   - fix an rcu deadlock in nfs_delegation_find_inode()

   - fix NFSv4 deadlocks due to not freeing the session slot in
     layoutget

   - don't send layoutreturn if the layout is already invalid

   - prevent duplicate XID allocation

   - flexfiles: Don't tie up all the rpciod threads in resends"

* tag 'nfs-for-4.18-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  pNFS/flexfiles: Process writeback resends from nfsiod context as well
  pNFS/flexfiles: Don't tie up all the rpciod threads in resends
  sunrpc: Prevent duplicate XID allocation
  pNFS: Don't send layoutreturn if the layout is already invalid
  pNFS: Always free the session slot on error in nfs4_layoutget_handle_exception
  NFS: Fix an rcu deadlock in nfs_delegation_find_inode()

1 files changed, 7 insertions, 3 deletions

diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 3c85af058227..3fabf9f6a0f9 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -987,8 +987,6 @@ bool xprt_prepare_transmit(struct rpc_task *task)
                 task->tk_status = -EAGAIN;
                 goto out_unlock;
         }
-        if (!bc_prealloc(req) && !req->rq_xmit_bytes_sent)
-                req->rq_xid = xprt_alloc_xid(xprt);
         ret = true;
 out_unlock:
         spin_unlock_bh(&xprt->transport_lock);
@@ -1298,7 +1296,12 @@ void xprt_retry_reserve(struct rpc_task *task)
 
 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
 {
-        return (__force __be32)xprt->xid++;
+        __be32 xid;
+
+        spin_lock(&xprt->reserve_lock);
+        xid = (__force __be32)xprt->xid++;
+        spin_unlock(&xprt->reserve_lock);
+        return xid;
 }
 
 static inline void xprt_init_xid(struct rpc_xprt *xprt)
@@ -1316,6 +1319,7 @@ void xprt_request_init(struct rpc_task *task)
         req->rq_task    = task;
         req->rq_xprt    = xprt;
         req->rq_buffer  = NULL;
+        req->rq_xid     = xprt_alloc_xid(xprt);
         req->rq_connect_cookie = xprt->connect_cookie - 1;
         req->rq_bytes_sent = 0;
         req->rq_snd_buf.len = 0;