(* '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