Merge tag 'nfs-for-3.7-4' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

Pull NFS client bugfixes from Trond Myklebust:

 - Fix a bunch of deadlock situations:
   * State recovery can deadlock if we fail to release sequence ids
     before scheduling the recovery thread.
   * Calling deactivate_super() from an RPC workqueue thread can
     deadlock because of the call to rpc_shutdown_client.

 - Display the device name correctly in /proc/*/mounts

 - Fix a number of incorrect error return values:
   * When NFSv3 mounts fail due to a timeout.
   * On NFSv4.1 backchannel setup failure
   * On NFSv4 open access checks

 - pnfs_find_alloc_layout() must check the layout pointer for NULL

 - Fix a regression in the legacy DNS resolved

* tag 'nfs-for-3.7-4' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  NFS4: nfs4_opendata_access should return errno
  NFSv4: Initialise the NFSv4.1 slot table highest_used_slotid correctly
  SUNRPC: return proper errno from backchannel_rqst
  NFS: add nfs_sb_deactive_async to avoid deadlock
  nfs: Show original device name verbatim in /proc/*/mount{s,info}
  nfsv3: Make v3 mounts fail with ETIMEDOUTs instead EIO on mountd timeouts
  nfs: Check whether a layout pointer is NULL before free it
  NFS: fix bug in legacy DNS resolver.
  NFSv4: nfs4_locku_done must release the sequence id
  NFSv4.1: We must release the sequence id when we fail to get a session slot
  NFS: Wait for session recovery to finish before returning

1 files changed, 50 insertions, 1 deletions

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index e831bce4976..652d3f7176a 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -54,6 +54,7 @@
 #include <linux/parser.h>
 #include <linux/nsproxy.h>
 #include <linux/rcupdate.h>
+#include <linux/kthread.h>
 
 #include <asm/uaccess.h>
 
@@ -415,6 +416,54 @@ void nfs_sb_deactive(struct super_block *sb)
 }
 EXPORT_SYMBOL_GPL(nfs_sb_deactive);
 
+static int nfs_deactivate_super_async_work(void *ptr)
+{
+	struct super_block *sb = ptr;
+
+	deactivate_super(sb);
+	module_put_and_exit(0);
+	return 0;
+}
+
+/*
+ * same effect as deactivate_super, but will do final unmount in kthread
+ * context
+ */
+static void nfs_deactivate_super_async(struct super_block *sb)
+{
+	struct task_struct *task;
+	char buf[INET6_ADDRSTRLEN + 1];
+	struct nfs_server *server = NFS_SB(sb);
+	struct nfs_client *clp = server->nfs_client;
+
+	if (!atomic_add_unless(&sb->s_active, -1, 1)) {
+		rcu_read_lock();
+		snprintf(buf, sizeof(buf),
+			rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_ADDR));
+		rcu_read_unlock();
+
+		__module_get(THIS_MODULE);
+		task = kthread_run(nfs_deactivate_super_async_work, sb,
+				"%s-deactivate-super", buf);
+		if (IS_ERR(task)) {
+			pr_err("%s: kthread_run: %ld\n",
+				__func__, PTR_ERR(task));
+			/* make synchronous call and hope for the best */
+			deactivate_super(sb);
+			module_put(THIS_MODULE);
+		}
+	}
+}
+
+void nfs_sb_deactive_async(struct super_block *sb)
+{
+	struct nfs_server *server = NFS_SB(sb);
+
+	if (atomic_dec_and_test(&server->active))
+		nfs_deactivate_super_async(sb);
+}
+EXPORT_SYMBOL_GPL(nfs_sb_deactive_async);
+
 /*
  * Deliver file system statistics to userspace
  */
@@ -771,7 +820,7 @@ int nfs_show_devname(struct seq_file *m, struct dentry *root)
 	int err = 0;
 	if (!page)
 		return -ENOMEM;
-	devname = nfs_path(&dummy, root, page, PAGE_SIZE);
+	devname = nfs_path(&dummy, root, page, PAGE_SIZE, 0);
 	if (IS_ERR(devname))
 		err = PTR_ERR(devname);
 	else