10:11 a.m.
On Friday, 14 July 2017 15:39:26 CEST Richard W.M. Jones wrote:
+(* In order to examine subvolumes, quota and other things, the
btrfs
+ * filesystem has to be mounted. However we're passed a mountable
+ * in these cases, so we must mount the filesystem. But we cannot
+ * mount it under the sysroot, as something else might be mounted
+ * there so this function mounts the filesystem on a temporary
+ * directory and ensures it is always unmounted afterwards.
+ *)
+let with_mounted mountable f =
+ let tmpdir = sprintf "/tmp/%s" (String.random8 ()) in
let tmpdir = Mkdtemp.temp_dir ~base_dir:"/tmp" "btrfs." ""
in
(or even without ~base_dir, I guess the default should be fine.)
This will also avoid the mkdir calls later on.
+ (* This is the cleanup function which is called to unmount and
+ * remove the temporary directory. This is called on error and
+ * ordinary exit paths.
+ *)
+ let finally () =
+ ignore (Sys.command (sprintf "umount %s" (quote tmpdir)));
+ rmdir tmpdir
+ in
+
+ match mountable.m_type with
+ | MountablePath ->
+ (* This corner-case happens for Mountable_or_Path parameters, where
+ * a path was supplied by the caller. The path (the m_device
+ * field) is relative to the sysroot.
+ *)
+ f (Sysroot.sysroot () // mountable.m_device)
After using Mkdtemp.temp_dir above, "rmdir tmpdir" will be needed here.
+
+ | MountableDevice ->
+ protect ~finally ~f:(
+ fun () ->
+ mkdir tmpdir 0o700;
+ ignore (command "mount" [mountable.m_device; tmpdir]);
+ f tmpdir
+ )
+
+ | MountableBtrfsVol subvol ->
+ protect ~finally ~f:(
+ fun () ->
+ mkdir tmpdir 0o700;
+ ignore (command "mount" ["-o"; "subvol=" ^ subvol
(* XXX quoting? *);
+ mountable.m_device; tmpdir]);
+ f tmpdir
+ )
+
+let re_btrfs_subvolume_list =
+ Str.regexp ("ID[ \t]+\\([0-9]+\\).*[ \t]" ^
+ "top level[ \t]+\\([0-9]+\\).*[ \t]" ^
+ "path[ \t]+\\(.*\\)")
Sigh, Str does not support simple character classes like \s :( No wonder
there are at least two or three "re" OCaml modules providing sane regular
expression engines (with a less awkward syntax for captures, etc).
+let btrfs_subvolume_list mountable =
+ (* Execute 'btrfs subvolume list <fs>', and split the output into lines
*)
+ let lines =
+ with_mounted mountable (
+ fun mp -> command "btrfs" ["subvolume"; "list";
mp]
+ ) in
+ let lines = String.nsplit "\n" lines in
If here we do:
let lines = List.filter ((<>) "") lines in
then later on we can use List.map instead of filter_map.
diff --git a/daemon/btrfs.mli b/daemon/btrfs.mli
new file mode 100644
index 000000000..55a38e42d
--- /dev/null
+++ b/daemon/btrfs.mli
@@ -0,0 +1,26 @@
+(* guestfs-inspection
+ * Copyright (C) 2009-2017 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *)
+
+type btrfssubvolume = {
+ btrfssubvolume_id : int64;
+ btrfssubvolume_top_level_id : int64;
+ btrfssubvolume_path : string;
+}
Is this needed? Could Structs.btrfssubvolume be used below?
--
Pino Toscano