1 (* 'df' command for virtual domains.
3 (C) Copyright 2007 Richard W.M. Jones, Red Hat Inc.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
27 open Diskimage_lvm2_metadata
31 let plugin_id = "LVM2"
33 let sector_size_int = 512
34 let sector_size = ~^sector_size_int
36 (*----------------------------------------------------------------------*)
37 (* Block device which can do linear maps, same as the kernel dm-linear.c *)
38 class linear_map_device name extent_size segments =
39 (* The segments are passed containing (start_extent, extent_count, ...)
40 * but it's easier to deal with (start_extent, end_extent, ...) so
43 let segments = List.map
44 (fun (start_extent, extent_count, dev, pvoffset) ->
45 (start_extent, start_extent +^ extent_count, dev, pvoffset)
48 (* Calculate the size of the device (in bytes). Note that because
49 * of the random nature of the mapping this doesn't imply that we can
50 * satisfy any read request up to the full size.
53 List.fold_left max ~^0
54 (List.map (fun (_, end_extent, _, _) -> end_extent) segments) in
55 let size = size_in_extents *^ extent_size in
61 (* The natural blocksize for LVM devices is the extent size.
62 * NB. Throws a runtime exception if the extent size is bigger
63 * than an int (only likely to matter on 32 bit).
65 method blocksize = extent_size
67 (* Map block (extent) i to the underlying device. *)
69 if i < ~^0 || i >= size_in_extents then
70 invalid_arg "linear_map_device: read outside device";
72 let rec loop = function
75 | (start_extent, end_extent, dev, pvoffset) :: rest ->
76 if start_extent <= i && i < end_extent then
77 [dev, (pvoffset +^ i) *^ extent_size]
83 (* NB. Use the superclass #read method. *)
86 (*----------------------------------------------------------------------*)
87 (* Probe to see if it's an LVM2 PV. *)
88 let rec probe lvm_plugin_id dev =
90 let uuid, _ = read_pv_label dev in
92 eprintf "LVM2 detected PV UUID %s\n%!" uuid;
93 { lvm_plugin_id = lvm_plugin_id; pv_uuid = uuid }
95 if !debug then prerr_endline (Printexc.to_string exn);
98 and read_pv_label dev =
99 (* Load the first 8 sectors. I found by experimentation that
100 * the second sector contains the header ("LABELONE" etc) and
101 * the nineth sector contains some additional information about
102 * the location of the current metadata.
104 let bits = dev#read_bitstring ~^0 (~^9 *^ sector_size) in
106 (*Bitmatch.hexdump_bitstring stdout bits;*)
111 sector0 : sector_size_int*8 : bitstring;
114 "LABELONE" : 64 : string; (* "LABELONE" *)
115 _ : 128 : bitstring; (* Seems to contain something. *)
116 "LVM2 001" : 64 : string; (* "LVM2 001" *)
117 uuid : 256 : string; (* UUID *)
118 endsect : (sector_size_int-64)*8 : bitstring;(* to end of second sector *)
121 sectors234567 : sector_size_int*8 * 6 : bitstring;
124 _ : 320 : bitstring; (* start of sector 8 *)
125 metadata_offset : 32 : littleendian; (* metadata offset *)
127 metadata_length : 32 : littleendian (* length of metadata (bytes) *)
130 (* Metadata offset is relative to end of PV label. *)
131 let metadata_offset = Int63.of_int32 metadata_offset +^ ~^0x1000 in
132 (* Metadata length appears to include the trailing \000 which
135 let metadata_length = Int63.of_int32 metadata_length -^ ~^1 in
137 let metadata = read_metadata dev metadata_offset metadata_length in
143 (sprintf "LVM2: read_pv_label: %s: not an LVM2 physical volume"
146 and read_metadata dev offset len =
148 eprintf "metadata: offset %s len %s bytes\n%!"
149 (Int63.to_string offset) (Int63.to_string len);
151 (* Check the offset and length are sensible. *)
152 if offset <= ~^0x1200 || offset >= dev#size
153 || len <= ~^0 || offset +^ len >= dev#size then
154 invalid_arg "LVM2: read_metadata: bad metadata offset or length";
156 (* If it is outside the disk boundaries, this will throw an exception,
157 * otherwise it will read and return the metadata string.
161 (*----------------------------------------------------------------------*)
162 (* We are passed a list of devices which we previously identified
163 * as PVs belonging to us. From these produce a list of all LVs
164 * (as devices) and return them. Note that we don't try to detect
165 * what is on these LVs - that will be done in the main code.
168 (* Read the UUID and metadata (again) from each device to end up with
169 * an assoc list of PVs, keyed on the UUID.
173 let uuid, metadata = read_pv_label dev in
174 (uuid, (metadata, dev))
177 (* Parse the metadata using the external lexer/parser. *)
179 fun (uuid, (metadata, dev)) ->
180 uuid, (Diskimage_lvm2_lexer.parse_lvm2_metadata_from_string metadata,
184 (* Print the parsed metadata. *)
187 fun (uuid, (metadata, dev)) ->
188 eprintf "metadata for PV UUID %s on %s:\n" uuid dev#name;
189 output_metadata stderr metadata
192 (* Scan for volume groups. The first entry in the metadata
193 * appears to be the volume group name. This gives us a
194 * list of VGs and the metadata for each underlying PV.
199 | pvuuid, (((vgname, Metadata vgmeta) :: _), dev) ->
200 Some (vgname, (pvuuid, vgmeta))
204 let cmp ((a:string),_) ((b:string),_) = compare a b in
205 let vgnames = List.sort ~cmp vgnames in
206 let vgs = group_by vgnames in
208 (* Note that the metadata is supposed to be duplicated
209 * identically across all PVs (for redundancy purposes).
210 * In theory we should check this and use the 'seqno'
211 * field to find the latest metadata if it doesn't match,
212 * but in fact we don't check this.
215 fun (vgname, metas) ->
216 let pvuuids = List.map fst metas in
217 let _, vgmeta = List.hd metas in (* just pick any metadata *)
218 vgname, (pvuuids, vgmeta)) vgs in
223 fun (vgname, (pvuuids, vgmeta)) ->
224 eprintf "VG %s is on PVs: %s\n%!" vgname (String.concat "," pvuuids)
227 (* Some useful getter functions. If these can't get a value
228 * from the metadata or if the type is wrong they raise Not_found.
230 let rec get_int63 field meta =
231 match List.assoc field meta with
233 | _ -> raise Not_found
234 and get_int_bounded field meta max =
235 match List.assoc field meta with
236 | Int i when i >= ~^0 && i <= Int63.of_int max -> Int63.to_int i
237 | _ -> raise Not_found
238 and get_string field meta =
239 match List.assoc field meta with
241 | _ -> raise Not_found
242 and get_meta field meta =
243 match List.assoc field meta with
245 | _ -> raise Not_found
246 and get_stripes field meta = (* List of (string,int) pairs. *)
247 match List.assoc field meta with
249 let rec loop = function
251 | String pvname :: Int offset :: xs ->
252 (pvname, offset) :: loop xs
253 | _ -> raise Not_found
256 | _ -> raise Not_found
259 (* The volume groups refer to the physical volumes using their
260 * own naming system ("pv0", "pv1", etc.) instead of PV UUIDs.
262 * Each PV also has a start (in sectors) & count (in extents)
263 * of the writable area (the bit after the superblock and metadata)
264 * which normally starts at sector 384.
266 * Create a PV device (simple offset + size) and a map from PV
267 * names to these devices.
270 fun (vgname, (pvuuids, vgmeta)) ->
271 let pvdevs, extent_size =
273 (* NB: extent_size is in sectors here - we convert to bytes. *)
275 get_int_bounded "extent_size" vgmeta (1024*1024) in
276 let extent_size = Int63.of_int extent_size in
277 let extent_size = extent_size *^ sector_size in
279 (* Get the physical_volumes section of the metadata. *)
280 let pvdevs = get_meta "physical_volumes" vgmeta in
284 | (pvname, Metadata meta) ->
286 let pvuuid = get_string "id" meta in
287 let pvuuid = canonical_uuid pvuuid in
289 (* Get the underlying physical device. *)
290 let _, dev = List.assoc pvuuid pvs in
292 (* Construct a PV device. *)
293 let pe_start = get_int63 "pe_start" meta in
294 let pe_start = pe_start *^ sector_size in
295 let pe_count = get_int63 "pe_count" meta in
296 let pe_count = pe_count *^ extent_size in
300 pe_start pe_count (* start, size in bytes *)
301 (* don't really have a natural block size ... *)
303 dev (* underlying device *) in
308 ) pvdevs, extent_size
310 (* Something went wrong - just return an empty map. *)
311 Not_found -> [], ~^0 in
312 (vgname, (pvuuids, vgmeta, pvdevs, extent_size))
315 (* Scan for logical volumes. Each VG contains several LVs.
316 * This gives us a list of LVs within each VG (hence extends
320 fun (vgname, (pvuuids, vgmeta, pvdevs, extent_size)) ->
323 let lvs = get_meta "logical_volumes" vgmeta in
324 let lvs = List.filter_map (
326 | lvname, Metadata lvmeta ->
329 get_int_bounded "segment_count" lvmeta 1024 in
331 (* Get the segments for this LV. *)
332 let segments = range 1 (segment_count+1) in
335 (fun i -> get_meta ("segment" ^ string_of_int i) lvmeta)
342 get_int63 "start_extent" segmeta in
344 get_int63 "extent_count" segmeta in
345 let segtype = get_string "type" segmeta in
347 (* Can only handle striped segments at the
350 if segtype <> "striped" then raise Not_found;
353 get_int_bounded "stripe_count" segmeta 1024 in
354 let stripes = get_stripes "stripes" segmeta in
356 if List.length stripes <> stripe_count then
359 (* Can only handle linear striped segments at
362 if stripe_count <> 1 then raise Not_found;
363 let pvname, pvoffset = List.hd stripes in
365 (start_extent, extent_count, pvname, pvoffset)
368 Some (lvname, segments)
370 (* Something went wrong with segments - omit this LV. *)
378 (* Something went wrong - assume no LVs found. *)
380 (vgname, (pvuuids, vgmeta, pvdevs, extent_size, lvs))
386 fun (vgname, (pvuuids, vgmeta, pvdevs, extent_size, lvs)) ->
387 eprintf "VG %s: (extent_size = %s bytes)\n" vgname
388 (Int63.to_string extent_size);
390 fun (lvname, segments) ->
391 eprintf " %s/%s:\n" vgname lvname;
393 fun (start_extent, extent_count, pvname, pvoffset) ->
394 eprintf " start %s count %s at %s:%s\n"
395 (Int63.to_string start_extent)
396 (Int63.to_string extent_count)
397 pvname (Int63.to_string pvoffset)
404 (* Finally we can set up devices for the LVs. *)
407 fun (vgname, (pvuuid, vgmeta, pvdevs, extent_size, lvs)) ->
410 fun (lvname, segments) ->
411 let name = vgname ^ "/" ^ lvname in
412 let segments = List.map (
413 fun (start_extent, extent_count, pvname, pvoffset) ->
414 (* Get the PV device. *)
415 let pvdev = List.assoc pvname pvdevs in
417 (* Extents mapped to: *)
418 (start_extent, extent_count, pvdev, pvoffset)
421 (* Create a linear mapping device. *)
422 let lv_dev = new linear_map_device name extent_size segments in
429 let lvs = List.concat lvs in
431 (* Return the list of LV devices. *)