From 2cfe2354dfe19ad6d77fcf921f38fe9103bedef4 Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Fri, 21 Dec 2018 13:55:06 +0000
Subject: [PATCH] vfs: fix deadlock between RWFileHandle.close and File.Remove
 - fixes #2857

Before this change we took the locks file.mu and file.muRW in an
inconsistent order - after the change we always take them in the same
order to fix the deadlock.
---
 vfs/file.go | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/vfs/file.go b/vfs/file.go
index 8e9f91ecc..47fdf22ab 100644
--- a/vfs/file.go
+++ b/vfs/file.go
@@ -444,19 +444,19 @@ func (f *File) Remove() error {
 	if f.d.vfs.Opt.ReadOnly {
 		return EROFS
 	}
-	f.mu.Lock()
-	f.muRW.Lock()
+	f.muRW.Lock() // muRW must be locked before mu to avoid
+	f.mu.Lock()   // deadlock in RWFileHandle.openPending and .close
 	if f.o != nil {
 		err := f.o.Remove()
 		if err != nil {
 			fs.Errorf(f, "File.Remove file error: %v", err)
-			f.muRW.Unlock()
 			f.mu.Unlock()
+			f.muRW.Unlock()
 			return err
 		}
 	}
-	f.muRW.Unlock()
 	f.mu.Unlock()
+	f.muRW.Unlock()
 
 	// Remove the item from the directory listing
 	f.d.delObject(f.Name())