From f2b4d57068d13b6dc3de2ccc6550675d11d34cfa Mon Sep 17 00:00:00 2001
From: Jakob Unterwurzacher
Date: Fri, 1 Jul 2016 23:29:31 +0200
Subject: fusefrontend: coalesce grows in Truncate()

We were growing the file block-by-block which was pretty
inefficient. We now coalesce all the grows into a single
Ftruncate. Also simplifies the code!

Simplistic benchmark: Before:

  $ time truncate -s 1000M foo
  real	0m0.568s

After:

  $ time truncate -s 1000M foo
  real	0m0.205s
---
 internal/fusefrontend/file_holes.go | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'internal/fusefrontend/file_holes.go')

diff --git a/internal/fusefrontend/file_holes.go b/internal/fusefrontend/file_holes.go
index 46a5865..1d9a5fb 100644
--- a/internal/fusefrontend/file_holes.go
+++ b/internal/fusefrontend/file_holes.go
@@ -22,6 +22,10 @@ func (f *file) createsHole(plainSize uint64, off int64) bool {
 func (f *file) zeroPad(plainSize uint64) fuse.Status {
 	lastBlockLen := plainSize % f.contentEnc.PlainBS()
 	missing := f.contentEnc.PlainBS() - lastBlockLen
+	if missing == 0 {
+		// Already block-aligned
+		return fuse.OK
+	}
 	pad := make([]byte, missing)
 	tlog.Debug.Printf("zeroPad: Writing %d bytes\n", missing)
 	_, status := f.doWrite(pad, int64(plainSize))
-- 
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