X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/740d71d2b7a797bb2dd2e1e427c12e84c86b9ce6..32e4350b4ea4c111ae95d9a99712fb86bf0ecb86:/services/keepstore/volume_unix.go

diff --git a/services/keepstore/volume_unix.go b/services/keepstore/volume_unix.go
index ddddd5abf9..75a75229a6 100644
--- a/services/keepstore/volume_unix.go
+++ b/services/keepstore/volume_unix.go
@@ -97,6 +97,30 @@ func (v *UnixVolume) Put(loc string, block []byte) error {
 	return response.err
 }
 
+func (v *UnixVolume) Touch(loc string) error {
+	p := v.blockPath(loc)
+	f, err := os.OpenFile(p, os.O_RDWR|os.O_APPEND, 0644)
+	if err != nil {
+		return err
+	}
+	if e := lockfile(f); e != nil {
+		return e
+	}
+	defer unlockfile(f)
+	now := time.Now().Unix()
+	utime := syscall.Utimbuf{now, now}
+	return syscall.Utime(p, &utime)
+}
+
+func (v *UnixVolume) Mtime(loc string) (time.Time, error) {
+	p := v.blockPath(loc)
+	if fi, err := os.Stat(p); err != nil {
+		return time.Time{}, err
+	} else {
+		return fi.ModTime(), nil
+	}
+}
+
 // Read retrieves a block identified by the locator string "loc", and
 // returns its contents as a byte slice.
 //
@@ -230,7 +254,29 @@ func (v *UnixVolume) Index(prefix string) (output string) {
 }
 
 func (v *UnixVolume) Delete(loc string) error {
-	return os.Remove(v.blockPath(loc))
+	p := v.blockPath(loc)
+	f, err := os.OpenFile(p, os.O_RDWR|os.O_APPEND, 0644)
+	if err != nil {
+		return err
+	}
+	if e := lockfile(f); e != nil {
+		return e
+	}
+	defer unlockfile(f)
+
+	// If the block has been PUT more recently than -permission_ttl,
+	// return success without removing the block.  This guards against
+	// a race condition where a block is old enough that Data Manager
+	// has added it to the trash list, but the user submitted a PUT
+	// for the block since then.
+	if fi, err := os.Stat(p); err != nil {
+		return err
+	} else {
+		if time.Since(fi.ModTime()) < permission_ttl {
+			return nil
+		}
+	}
+	return os.Remove(p)
 }
 
 // blockDir returns the fully qualified directory name for the directory
@@ -293,3 +339,12 @@ func (v *UnixVolume) FreeDiskSpace() (free uint64, err error) {
 func (v *UnixVolume) String() string {
 	return fmt.Sprintf("[UnixVolume %s]", v.root)
 }
+
+// lockfile and unlockfile use flock(2) to manage kernel file locks.
+func lockfile(f *os.File) error {
+	return syscall.Flock(int(f.Fd()), syscall.LOCK_EX)
+}
+
+func unlockfile(f *os.File) error {
+	return syscall.Flock(int(f.Fd()), syscall.LOCK_UN)
+}