NFS: Add an nfsiod workqueue

NFS post-rpciod cleanups often involve tasks that cannot be safely
performed within the rpciod context (due to deadlock concerns). We
therefore add a dedicated NFS workqueue that can perform tasks like
cleaning up state after an interrupted NFSv4 open() call, or calling
put_nfs_open_context() after an asynchronous read or write call.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

2 files changed, 38 insertions, 0 deletions

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index a499fb58d858..36cb99985d22 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1219,6 +1219,36 @@ static void nfs_destroy_inodecache(void)
         kmem_cache_destroy(nfs_inode_cachep);
 }
 
+struct workqueue_struct *nfsiod_workqueue;
+
+/*
+ * start up the nfsiod workqueue
+ */
+static int nfsiod_start(void)
+{
+        struct workqueue_struct *wq;
+        dprintk("RPC:       creating workqueue nfsiod\n");
+        wq = create_singlethread_workqueue("nfsiod");
+        if (wq == NULL)
+                return -ENOMEM;
+        nfsiod_workqueue = wq;
+        return 0;
+}
+
+/*
+ * Destroy the nfsiod workqueue
+ */
+static void nfsiod_stop(void)
+{
+        struct workqueue_struct *wq;
+
+        wq = nfsiod_workqueue;
+        if (wq == NULL)
+                return;
+        nfsiod_workqueue = NULL;
+        destroy_workqueue(wq);
+}
+
 /*
  * Initialize NFS
  */
@@ -1226,6 +1256,10 @@ static int __init init_nfs_fs(void)
 {
         int err;
 
+        err = nfsiod_start();
+        if (err)
+                goto out6;
+
         err = nfs_fs_proc_init();
         if (err)
                 goto out5;
@@ -1272,6 +1306,8 @@ out3:
 out4:
         nfs_fs_proc_exit();
 out5:
+        nfsiod_stop();
+out6:
         return err;
 }
 
@@ -1287,6 +1323,7 @@ static void __exit exit_nfs_fs(void)
 #endif
         unregister_nfs_fs();
         nfs_fs_proc_exit();
+        nfsiod_stop();
 }
 
 /* Not quite true; I just maintain it */
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 0f5619611b8d..985dc2931031 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -143,6 +143,7 @@ extern struct rpc_procinfo nfs4_procedures[];
 extern int nfs_access_cache_shrinker(int nr_to_scan, gfp_t gfp_mask);
 
 /* inode.c */
+extern struct workqueue_struct *nfsiod_workqueue;
 extern struct inode *nfs_alloc_inode(struct super_block *sb);
 extern void nfs_destroy_inode(struct inode *);
 extern int nfs_write_inode(struct inode *,int);