NFS client bugfixes for Linux 4.1

Highlights include:
 
 - Fix a Linux-4.1 regression affecting stat()
 - Take an extra reference to fl->fl_file when running a setlk
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Merge tag 'nfs-for-4.1-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

Pull two NFS client bugfixes from Trond Myklebust:
 "Highlights include:

   - fix a Linux-4.1 regression affecting stat()

   - take an extra reference to fl->fl_file when running a setlk"

* tag 'nfs-for-4.1-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  nfs: take extra reference to fl->fl_file when running a setlk
  nfs: stat(2) fails during cthon04 basic test5 on NFSv4.0

fs/nfs/nfs4proc.c

@@ -38,6 +38,7 @@
 #include <linux/mm.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
+#include <linux/file.h>
 #include <linux/string.h>
 #include <linux/ratelimit.h>
 #include <linux/printk.h>
@@ -5604,6 +5605,7 @@ static struct nfs4_lockdata *nfs4_alloc_lockdata(struct file_lock *fl,
 	p->server = server;
 	atomic_inc(&lsp->ls_count);
 	p->ctx = get_nfs_open_context(ctx);
+	get_file(fl->fl_file);
 	memcpy(&p->fl, fl, sizeof(p->fl));
 	return p;
 out_free_seqid:
@@ -5716,6 +5718,7 @@ static void nfs4_lock_release(void *calldata)
 		nfs_free_seqid(data->arg.lock_seqid);
 	nfs4_put_lock_state(data->lsp);
 	put_nfs_open_context(data->ctx);
+	fput(data->fl.fl_file);
 	kfree(data);
 	dprintk("%s: done!\n", __func__);
 }

fs/nfs/write.c

@@ -1845,12 +1845,15 @@ int nfs_wb_all(struct inode *inode)
 	trace_nfs_writeback_inode_enter(inode);
 
 	ret = filemap_write_and_wait(inode->i_mapping);
-	if (!ret) {
+	if (ret)
+		goto out;
 	ret = nfs_commit_inode(inode, FLUSH_SYNC);
-		if (!ret)
+	if (ret < 0)
+		goto out;
 	pnfs_sync_inode(inode, true);
-	}
+	ret = 0;
 
+out:
 	trace_nfs_writeback_inode_exit(inode, ret);
 	return ret;
 }