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|
(* 'df' command for virtual domains.
(C) Copyright 2007 Richard W.M. Jones, Red Hat Inc.
http://libvirt.org/
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., 675 Mass Ave, Cambridge, MA 02139, USA.
Support for LVM2 PVs.
*)
open Printf
open ExtList
open Virt_df_gettext.Gettext
open Virt_df
open Virt_df_lvm2_metadata
let plugin_name = "LVM2"
let sector_size = 512
let sector_size64 = 512L
(* Probe to see if it's an LVM2 PV. *)
let rec probe_pv lvm_plugin_id dev =
try
let uuid, _ = read_pv_label dev in
if debug then
eprintf "LVM2 detected PV UUID %s\n%!" uuid;
{ lvm_plugin_id = lvm_plugin_id; pv_uuid = uuid }
with exn ->
if debug then prerr_endline (Printexc.to_string exn);
raise Not_found
and read_pv_label dev =
(* Load the first 8 sectors. I found by experimentation that
* the second sector contains the header ("LABELONE" etc) and
* the nineth sector contains some additional information about
* the location of the current metadata.
*)
let bits = dev#read_bitstring 0L (9 * sector_size) in
(*Bitmatch.hexdump_bitstring stdout bits;*)
bitmatch bits with
| sector0 : sector_size*8 : bitstring; (* sector 0 *)
labelone : 8*8 : bitstring; (* "LABELONE" *)
padding : 16*8 : bitstring; (* Seems to contain something. *)
lvm2_ver : 8*8 : bitstring; (* "LVM2 001" *)
uuid : 32*8 : bitstring; (* UUID *)
padding2 : (sector_size-64)*8 : bitstring; (* to end of second sector *)
sector234567 : sector_size*8 * 6 : bitstring; (* sectors 2-6 *)
padding3 : 0x28*8 : bitstring; (* start of sector 8 *)
metadata_offset : 32 : littleendian;(* metadata offset *)
padding4 : 4*8 : bitstring;
metadata_length : 32 : littleendian (* length of metadata (bytes) *)
when Bitmatch.string_of_bitstring labelone = "LABELONE" &&
Bitmatch.string_of_bitstring lvm2_ver = "LVM2 001" ->
(* Metadata offset is relative to end of PV label. *)
let metadata_offset = metadata_offset +* 0x1000_l in
(* Metadata length appears to include the trailing \000 which
* we don't want.
*)
let metadata_length = metadata_length -* 1_l in
let metadata = read_metadata dev metadata_offset metadata_length in
let uuid = Bitmatch.string_of_bitstring uuid in
uuid, metadata
| _ ->
invalid_arg
(sprintf "LVM2: read_pv_label: %s: not an LVM2 physical volume" dev#name)
and read_metadata dev offset32 len32 =
if debug then
eprintf "metadata: offset 0x%lx len %ld bytes\n%!" offset32 len32;
(* Check the offset and length are sensible. *)
let offset64 =
if offset32 <= Int32.max_int then Int64.of_int32 offset32
else invalid_arg "LVM2: read_metadata: metadata offset too large" in
let len64 =
if len32 <= 2_147_483_647_l then Int64.of_int32 len32
else invalid_arg "LVM2: read_metadata: metadata length too large" in
if offset64 <= 0x1200L || offset64 >= dev#size
|| len64 <= 0L || offset64 +^ len64 >= dev#size then
invalid_arg "LVM2: read_metadata: bad metadata offset or length";
(* If it is outside the disk boundaries, this will throw an exception,
* otherwise it will read and return the metadata string.
*)
dev#read offset64 (Int64.to_int len64)
(* We are passed a list of devices which we previously identified
* as PVs belonging to us. From these produce a list of all LVs
* (as devices) and return them. Note that we don't try to detect
* what is on these LVs - that will be done in the main code.
*)
let rec list_lvs devs =
(* Read the UUID and metadata (again) from each device to end up with
* an assoc list of PVs, keyed on the UUID.
*)
let pvs = List.map (
fun dev ->
let uuid, metadata = read_pv_label dev in
(uuid, (metadata, dev))
) devs in
(* Parse the metadata using the external lexer/parser. *)
let pvs = List.map (
fun (uuid, (metadata, dev)) ->
uuid, (Virt_df_lvm2_lexer.parse_lvm2_metadata_from_string metadata,
dev)
) pvs in
(* Print the parsed metadata.
List.iter (
fun (uuid, (metadata, dev)) ->
eprintf "metadata for UUID %s:\n" uuid;
output_metadata stderr metadata
) pvs;
*)
(* Scan for volume groups. The first entry in the metadata
* appears to be the volume group name. This gives us a
* list of VGs and the metadata for each underlying PV.
*)
let vgnames =
List.filter_map (
function
| pvuuid, (((vgname, Metadata vgmeta) :: _), dev) ->
Some (vgname, (pvuuid, vgmeta))
| _ -> None
) pvs in
let cmp ((a:string),_) ((b:string),_) = compare a b in
let vgnames = List.sort ~cmp vgnames in
let vgs = group_by vgnames in
(* Note that the metadata is supposed to be duplicated
* identically across all PVs (for redundancy purposes).
* In theory we should check this and use the 'seqno'
* field to find the latest metadata if it doesn't match,
* but in fact we don't check this.
*)
let vgs = List.map (
fun (vgname, metas) ->
let pvuuids = List.map fst metas in
let _, vgmeta = List.hd metas in (* just pick any metadata *)
vgname, (pvuuids, vgmeta)) vgs in
(* Print the VGs. *)
if debug then
List.iter (
fun (vgname, (pvuuids, vgmeta)) ->
eprintf "VG %s is on PVs: %s\n%!" vgname (String.concat "," pvuuids)
) vgs;
(* Some useful getter functions. If these can't get a value
* from the metadata or if the type is wrong they raise Not_found.
*)
let rec get_int64 field meta =
match List.assoc field meta with
| Int i -> i
| _ -> raise Not_found
and get_int field meta min max =
match List.assoc field meta with
| Int i when Int64.of_int min <= i && i <= Int64.of_int max ->
Int64.to_int i
| _ -> raise Not_found
and get_string field meta =
match List.assoc field meta with
| String s -> s
| _ -> raise Not_found
and get_meta field meta =
match List.assoc field meta with
| Metadata md -> md
| _ -> raise Not_found in
in
(* Scan for logical volumes. Each VG contains several LVs.
* This gives us a list of LVs within each VG (hence extends
* the vgs variable).
*)
let vgs = List.map (
fun (vgname, (pvuuids, vgmeta)) ->
let lvs =
try
let extent_size = get_int "extent_size" vgmeta 0 (256*1024) in
let lvs = get_meta "logical_volumes" vgmeta in
let lvs = List.filter_map (
function
| lvname, Metadata lvmeta ->
(try
let segment_count = get_int "segment_count" lvmeta 0 1024 in
(* Get the segments for this LV. *)
let segments = range 1 (segment_count+1) in
let segments =
List.map
(fun i -> get_meta ("segment" ^ string_of_int i) lvmeta)
segments in
let segments =
List.map (
fun segmeta ->
let start_extent =
get_int64 "start_extent" segmeta in
let extent_count =
get_int64 "extent_count" segmeta in
let segtype = get_string "type" segmeta in
if segtype <> "striped" then raise Not_found;
let stripe_count =
get_int "stripe_count" segmeta 0 1024 in
(* let stripes = in *)
(start_extent, extent_count, stripe_count)
) segments in
Some (lvname, (lvmeta, segments))
with
(* Something went wrong with segments - omit this LV. *)
Not_found -> None)
| _ -> None
) lvs in
lvs
with
Not_found ->
(* Something went wrong - assume no LVs found. *)
[] in
(vgname, (pvuuids, vgmeta, lvs))
) vgs in
(* Print the LVs. *)
if debug then
List.iter (
fun (vgname, (pvuuids, vgmeta, lvs)) ->
let lvnames = List.map fst lvs in
eprintf "VG %s contains LVs: %s\n%!" vgname (String.concat ", " lvnames)
) vgs;
[]
(* Register with main code. *)
let () =
lvm_type_register plugin_name probe_pv list_lvs
|
