From b5f563fb0ffb5ea2f88a1700715559152a9dc52f Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Tue, 12 Feb 2019 17:27:04 +0000
Subject: [PATCH] vfs: Ignore Truncate if called with no readers and already
 the correct size

This fixes FreeBSD which seems to call SetAttr with a size even on
read only files.

This is probably a bug in the FreeBSD FUSE implementation as it
happens with mount and cmount.

See: https://forum.rclone.org/t/freebsd-question/8662/12
---
 vfs/file.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/vfs/file.go b/vfs/file.go
index eec001b86..a20c6d525 100644
--- a/vfs/file.go
+++ b/vfs/file.go
@@ -601,6 +601,12 @@ func (f *File) Truncate(size int64) (err error) {
 		}
 		return err
 	}
+
+	// If no writers, and size is already correct then all done
+	if f.o.Size() == size {
+		return nil
+	}
+
 	fs.Debugf(f.o, "Truncating file")
 
 	// Otherwise if no writers then truncate the file by opening