Implement sync.btrfssnap recursive=true

* factorize the command passing
* store snaps in each <subvol>/.snap/<rfc3339 utc datetime>[,<name>]
  so users can access the snaps even if shown only the subvol
* skip snaps for ro subvolumes (can't create a .snap, and makes no
  sense to snapshot a immutable dataset)

opensvc/drivers/resource/sync/btrfssnap/__init__.py

@@ -8,6 +8,7 @@
 from env import Env
 from core.objects.svcdict import KEYS
 from utilities.proc import justcall
+from utilities.files import makedirs
 
 DRIVER_GROUP = "sync"
 DRIVER_BASENAME = "btrfssnap"
@@ -34,6 +35,14 @@
         "example": "3",
         "text": "The maximum number of snapshots to retain."
     },
+    {
+        "keyword": "recursive",
+        "at": True,
+        "default": False,
+        "convert": "boolean",
+        "candidates": [True, False],
+        "text": "Also replicate subvolumes in the src tree."
+    },
 ]
 
 KEYS.register_driver(
@@ -55,6 +64,7 @@ def __init__(self,
                  name=None,
                  subvol=None,
                  keep=1,
+                 recursive=False,
                  **kwargs):
         super(SyncBtrfssnap, self).__init__(type="sync.btrfssnap", **kwargs)
 
@@ -67,6 +77,7 @@ def __init__(self,
         self.subvol = subvol
         self.keep = keep
         self.name = name
+        self.recursive = recursive
         self.btrfs = {}
 
     def on_add(self):
@@ -118,52 +129,80 @@ def get_btrfs(self, label):
             raise ex.Error(str(e))
         return self.btrfs[label]
 
+    def src(self, label, path):
+        return os.path.join(self.btrfs[label].rootdir, path)
+
+    def subvols(self, label, path):
+        """
+        sort by path so the subvols are sorted by path depth
+        """
+        btr = self.get_btrfs(label)
+        src = self.src(label, path)
+        if not src:
+            return []
+        if not self.recursive:
+            sub = btr.get_subvol(src)
+            if not sub:
+                return []
+            return [sub]
+        subvols = []
+        for subvol in btr.get_subvols().values():
+            if subvol["path"] == path:
+                subvols.append(subvol)
+            elif subvol["path"].startswith(path + "/"):
+                subvols.append(subvol)
+        subvols = sorted(subvols, key=lambda x: x["path"])
+        return subvols
+
+    def create_snaps(self, label, subvol):
+        cmds = []
+        for sv in self.subvols(label, subvol):
+            if "/.snap/" in sv["path"]:
+                continue
+            cmds += self.create_snap(label, sv["path"])
+        return cmds
+
     def create_snap(self, label, subvol):
         btrfs = self.get_btrfs(label)
         orig = os.path.join(btrfs.rootdir, subvol)
         snap = os.path.join(btrfs.rootdir, subvol)
+        snap += "/.snap/"
+        snap += datetime.datetime.utcnow().isoformat("T")+"Z"
         if self.name:
-            suffix = "."+self.name
-        else:
-            suffix = ""
-        suffix += ".snap.%Y-%m-%d.%H:%M:%S"
-        snap += datetime.datetime.now().strftime(suffix)
+            snap += "," + self.name
         try:
-            btrfs.snapshot(orig, snap, readonly=True)
-        except utilities.subsystems.btrfs.ExistError:
-            raise ex.Error('%s should not exist'%snap)
-        except utilities.subsystems.btrfs.ExecError:
-            raise ex.Error
+            makedirs(os.path.dirname(snap))
+        except OSError as e:
+            self.log.debug("skip %s snap: readonly", subvol)
+            return []
+        cmd = btrfs.snapshot_cmd(orig, snap, readonly=True)
+        if not cmd:
+            return []
+        return [" ".join(cmd)]
 
-    def remove_snap(self, label, subvol):
+    def remove_snaps(self, label, subvol):
         btrfs = self.get_btrfs(label)
-        btrfs.get_subvols(refresh=True)
+        btrfs.get_subvols()
         snaps = {}
-        for sv in btrfs.subvols.values():
-            if not sv["path"].startswith(subvol):
-                continue
-            s = sv["path"].replace(subvol, "")
-            l = s.split('.')
-            if len(l) < 2:
-                continue
-            if l[1] not in ("snap", self.name):
-                continue
+        for sv in self.subvols(label, subvol+"/.snap"):
+            ds = sv["path"].replace(subvol+"/.snap/", "")
+            ds = ds.split(",")[0] # discard optional name
             try:
-                ds = sv["path"].split(".snap.")[-1]
-                d = datetime.datetime.strptime(ds, "%Y-%m-%d.%H:%M:%S")
+                d = datetime.datetime.strptime(ds, "%Y-%m-%dT%H:%M:%S.%fZ")
                 snaps[ds] = sv["path"]
             except Exception as e:
                 pass
         if len(snaps) <= self.keep:
-            return
+            return []
         sorted_snaps = []
         for ds in sorted(snaps.keys(), reverse=True):
             sorted_snaps.append(snaps[ds])
+        cmds = []
         for path in sorted_snaps[self.keep:]:
-            try:
-                btrfs.subvol_delete(os.path.join(btrfs.rootdir, path))
-            except utilities.subsystems.btrfs.ExecError:
-                raise ex.Error
+            cmd = btrfs.subvol_delete_cmd(os.path.join(btrfs.rootdir, path))
+            if cmd:
+                cmds.append(" ".join(cmd))
+        return cmds
 
     def _status_one(self, label, subvol):
         if self.test_btrfs(label) != 0:
@@ -174,23 +213,14 @@ def _status_one(self, label, subvol):
         except Exception as e:
             self.status_log("%s:%s %s" % (label, subvol, str(e)))
             return
-        try:
-            btrfs.get_subvols()
-        except:
-            return
         snaps = []
-        for sv in btrfs.subvols.values():
-            if not sv["path"].startswith(subvol + '.'):
-                continue
-            s = sv["path"].replace(subvol, "")
-            l = s.split('.')
-            if len(l) < 2:
-                continue
-            if l[1] not in ("snap", self.name):
+        for sv in self.subvols(label, subvol):
+            if "/.snap/" not in subvol["path"]:
                 continue
+            ds = sv["path"].replace(subvol+"/.snap/", "")
+            ds = ds.split(",")[0] # discard optional name
             try:
-                ds = sv["path"].split(".snap.")[-1]
-                d = datetime.datetime.strptime(ds, "%Y-%m-%d.%H:%M:%S")
+                d = datetime.datetime.strptime(ds, "%Y-%m-%dT%H:%M:%S.%fZ")
                 snaps.append(d)
             except Exception as e:
                 pass
@@ -202,7 +232,7 @@ def _status_one(self, label, subvol):
         last = sorted(snaps, reverse=True)[0]
         limit = datetime.datetime.now() - datetime.timedelta(seconds=self.sync_max_delay)
         if last < limit:
-            self.status_log("%s:%s last snap is too old (%s)" % (label, subvol, last.strftime("%Y-%m-%d %H:%M:%S")))
+            self.status_log("%s:%s last snap is too old (%s)" % (label, subvol, last.strftime("%Y-%m-%dT%H:%M:%S.%fZ")))
 
     def _status(self, verbose=False):
         for s in self.subvol:
@@ -231,8 +261,18 @@ def _sync_update(self, s):
         if self.test_btrfs(label) != 0:
             self.log.info("skip snap of %s while the btrfs is no writable"%label)
             return
-        self.create_snap(label, subvol)
-        self.remove_snap(label, subvol)
+        cmds = []
+        cmds += self.create_snaps(label, subvol)
+        cmds += self.remove_snaps(label, subvol)
+        if not cmds:
+            return
+        self.do_cmds(label, cmds)
+
+    def do_cmds(self, label, cmds):
+        o = self.get_btrfs(label)
+        ret, out, err = o.vcall(" && ".join(cmds), shell=True)
+        if ret != 0:
+            raise ex.Error
 
     @notify
     def sync_update(self):