From 88d830c7b7215525791a5ca7938add25278b68a9 Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Mon, 26 Feb 2018 16:58:02 +0000
Subject: [PATCH] vfs: create cache.opens and use it in place of cache.get to
 avoid potential race

---
 vfs/cache.go | 14 ++++++++++++++
 vfs/file.go  |  4 ++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/vfs/cache.go b/vfs/cache.go
index 302d98dd9..b8a3a103c 100644
--- a/vfs/cache.go
+++ b/vfs/cache.go
@@ -161,6 +161,20 @@ func (c *cache) _get(isFile bool, name string) (item *cacheItem, found bool) {
 	return item, found
 }
 
+// opens returns the number of opens that are on the file
+//
+// name should be a remote path not an osPath
+func (c *cache) opens(name string) int {
+	name = clean(name)
+	c.itemMu.Lock()
+	defer c.itemMu.Unlock()
+	item := c.item[name]
+	if item == nil {
+		return 0
+	}
+	return item.opens
+}
+
 // get gets name from the cache or creates a new one
 //
 // name should be a remote path not an osPath
diff --git a/vfs/file.go b/vfs/file.go
index 8ac9aaac7..a50abad1f 100644
--- a/vfs/file.go
+++ b/vfs/file.go
@@ -431,8 +431,8 @@ func (f *File) Open(flags int) (fd Handle, err error) {
 
 	// Open the correct sort of handle
 	CacheMode := f.d.vfs.Opt.CacheMode
-	CacheItem := f.d.vfs.cache.get(f.Path())
-	if CacheMode >= CacheModeMinimal && CacheItem.opens > 0 {
+	opens := f.d.vfs.cache.opens(f.Path())
+	if CacheMode >= CacheModeMinimal && opens > 0 {
 		fd, err = f.openRW(flags)
 	} else if read && write {
 		if CacheMode >= CacheModeMinimal {