fs: get inodes via pure go instead of find

This also makes the count more accurate since hardlinks no longer
double-count.

fs/fs.go

@@ -19,7 +19,6 @@ package fs
 
 import (
 	"bufio"
-	"bytes"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -474,24 +473,22 @@ func (self *RealFsInfo) GetDirInodeUsage(dir string, timeout time.Duration) (uin
 	if dir == "" {
 		return 0, fmt.Errorf("invalid directory")
 	}
-	var counter byteCounter
-	var stderr bytes.Buffer
-	claimToken()
-	defer releaseToken()
-	findCmd := exec.Command("find", dir, "-xdev", "-printf", ".")
-	findCmd.Stdout, findCmd.Stderr = &counter, &stderr
-	if err := findCmd.Start(); err != nil {
-		return 0, fmt.Errorf("failed to exec cmd %v - %v; stderr: %v", findCmd.Args, err, stderr.String())
-	}
-	timer := time.AfterFunc(timeout, func() {
-		glog.Infof("killing cmd %v due to timeout(%s)", findCmd.Args, timeout.String())
-		findCmd.Process.Kill()
+
+	inodes := map[uint64]struct{}{}
+
+	err := filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return fmt.Errorf("unable to count inodes for part of dir %s: %s", dir, err)
+		}
+		s, ok := info.Sys().(*syscall.Stat_t)
+		if !ok {
+			return fmt.Errorf("unsupported fileinfo; could not convert to stat_t")
+		}
+		inodes[s.Ino] = struct{}{}
+		return nil
 	})
-	if err := findCmd.Wait(); err != nil {
-		return 0, fmt.Errorf("cmd %v failed. stderr: %s; err: %v", findCmd.Args, stderr.String(), err)
-	}
-	timer.Stop()
-	return counter.bytesWritten, nil
+
+	return uint64(len(inodes)), err
 }
 
 func getVfsStats(path string) (total uint64, free uint64, avail uint64, inodes uint64, inodesFree uint64, err error) {
@@ -603,11 +600,3 @@ func getZfstats(poolName string) (uint64, uint64, uint64, error) {
 
 	return total, dataset.Avail, dataset.Avail, nil
 }
-
-// Simple io.Writer implementation that counts how many bytes were written.
-type byteCounter struct{ bytesWritten uint64 }
-
-func (b *byteCounter) Write(p []byte) (int, error) {
-	b.bytesWritten += uint64(len(p))
-	return len(p), nil
-}