(* 'df' command for virtual domains.
- * $Id$
- *
- * Support for LVM2 PVs.
- *)
+
+ (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
+
+(*----------------------------------------------------------------------*)
+(* Block device which can do linear maps, same as the kernel dm-linear.c *)
+class linear_map_device name extent_size segments =
+ (* The segments are passed containing (start_extent, extent_count, ...)
+ * but it's easier to deal with (start_extent, end_extent, ...) so
+ * rewrite them.
+ *)
+ let segments = List.map
+ (fun (start_extent, extent_count, dev, pvoffset) ->
+ (start_extent, start_extent +^ extent_count, dev, pvoffset)
+ ) segments in
+
+ (* Calculate the size of the device (in bytes). Note that because
+ * of the random nature of the mapping this doesn't imply that we can
+ * satisfy any read request up to the full size.
+ *)
+ let size_in_extents =
+ List.fold_left max 0L
+ (List.map (fun (_, end_extent, _, _) -> end_extent) segments) in
+ let size = size_in_extents *^ extent_size in
+object
+ inherit device
+ method name = name
+ method size = size
+
+ (* Read method checks which segment the request lies inside and
+ * maps it to the underlying device. If there is no mapping then
+ * we have to return an error.
+ *
+ * The request must lie inside a single extent, otherwise this is
+ * also an error (XXX - should lift this restriction, however default
+ * extent size is 4 MB so we probably won't hit this very often).
+ *)
+ method read offset len =
+ let offset_in_extents = offset /^ extent_size in
+
+ (* Check we don't cross an extent boundary. *)
+ if (offset +^ Int64.of_int (len-1)) /^ extent_size <> offset_in_extents
+ then invalid_arg "linear_map_device: request crosses extent boundary";
+
+ if offset_in_extents < 0L || offset_in_extents >= size_in_extents then
+ invalid_arg "linear_map_device: read outside device";
+
+ let rec loop = function
+ | [] ->
+ invalid_arg "linear_map_device: offset not mapped"
+ | (start_extent, end_extent, dev, pvoffset) :: rest ->
+ eprintf "pvoffset = %Ld\n" pvoffset;
+ if start_extent <= offset_in_extents &&
+ offset_in_extents < end_extent
+ then dev#read (offset +^ pvoffset *^ extent_size) len
+ else loop rest
+ in
+ loop segments
+end
+
+(*----------------------------------------------------------------------*)
+(* 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. *)
+ if !debug then
+ List.iter (
+ fun (uuid, (metadata, dev)) ->
+ eprintf "metadata for PV UUID %s on %s:\n" uuid dev#name;
+ 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
+ and get_stripes field meta = (* List of (string,int) pairs. *)
+ match List.assoc field meta with
+ | List xs ->
+ let rec loop = function
+ | [] -> []
+ | String pvname :: Int offset :: xs ->
+ (pvname, offset) :: loop xs
+ | _ -> raise Not_found
+ in
+ loop xs
+ | _ -> raise Not_found
+ in
+
+ (* The volume groups refer to the physical volumes using their
+ * own naming system ("pv0", "pv1", etc.) instead of PV UUIDs.
+ *
+ * Each PV also has a start (in sectors) & count (in extents)
+ * of the writable area (the bit after the superblock and metadata)
+ * which normally starts at sector 384.
+ *
+ * Create a PV device (simple offset + size) and a map from PV
+ * names to these devices.
+ *)
+ let vgs = List.map (
+ fun (vgname, (pvuuids, vgmeta)) ->
+ let pvdevs, extent_size =
+ try
+ (* NB: extent_size is in sectors here - we convert to bytes. *)
+ let extent_size = get_int "extent_size" vgmeta 0 (1024*1024) in
+ let extent_size = Int64.of_int extent_size *^ sector_size64 in
+
+ (* Get the physical_volumes section of the metadata. *)
+ let pvdevs = get_meta "physical_volumes" vgmeta in
+
+ List.filter_map (
+ function
+ | (pvname, Metadata meta) ->
+ (* Get the UUID. *)
+ let pvuuid = get_string "id" meta in
+ let pvuuid = canonical_uuid pvuuid in
+
+ (* Get the underlying physical device. *)
+ let _, dev = List.assoc pvuuid pvs in
+
+ (* Construct a PV device. *)
+ let pe_start = get_int64 "pe_start" meta in
+ let pe_start = pe_start *^ sector_size64 in
+ let pe_count = get_int64 "pe_count" meta in
+ let pe_count = pe_count *^ extent_size in
+ let pvdev = new offset_device pvuuid pe_start pe_count dev in
+
+ Some (pvname, pvdev)
+ | _ ->
+ None
+ ) pvdevs, extent_size
+ with
+ (* Something went wrong - just return an empty map. *)
+ Not_found -> [], 0L in
+ (vgname, (pvuuids, vgmeta, pvdevs, extent_size))
+ ) vgs 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, pvdevs, extent_size)) ->
+ let lvs =
+ try
+ 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
+
+ (* Can only handle striped segments at the
+ * moment. XXX
+ *)
+ if segtype <> "striped" then raise Not_found;
+
+ let stripe_count =
+ get_int "stripe_count" segmeta 0 1024 in
+ let stripes = get_stripes "stripes" segmeta in
+
+ if List.length stripes <> stripe_count then
+ raise Not_found;
+
+ (* Can only handle linear striped segments at
+ * the moment. XXX
+ *)
+ if stripe_count <> 1 then raise Not_found;
+ let pvname, pvoffset = List.hd stripes in
+
+ (start_extent, extent_count, pvname, pvoffset)
+ ) segments in
+
+ Some (lvname, 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, pvdevs, extent_size, lvs))
+ ) vgs in
+
+ (* Print the LVs. *)
+ if !debug then (
+ List.iter (
+ fun (vgname, (pvuuids, vgmeta, pvdevs, extent_size, lvs)) ->
+ eprintf "VG %s: (extent_size = %Ld bytes)\n" vgname extent_size;
+ List.iter (
+ fun (lvname, segments) ->
+ eprintf " %s/%s:\n" vgname lvname;
+ List.iter (
+ fun (start_extent, extent_count, pvname, pvoffset) ->
+ eprintf " start %Ld count %Ld at %s:%Ld\n"
+ start_extent extent_count pvname pvoffset
+ ) segments
+ ) lvs
+ ) vgs;
+ flush stderr
+ );
+
+ (* Finally we can set up devices for the LVs. *)
+ let lvs =
+ List.map (
+ fun (vgname, (pvuuid, vgmeta, pvdevs, extent_size, lvs)) ->
+ try
+ List.map (
+ fun (lvname, segments) ->
+ let name = vgname ^ "/" ^ lvname in
+ let segments = List.map (
+ fun (start_extent, extent_count, pvname, pvoffset) ->
+ (* Get the PV device. *)
+ let pvdev = List.assoc pvname pvdevs in
+
+ (* Extents mapped to: *)
+ (start_extent, extent_count, pvdev, pvoffset)
+ ) segments in
+
+ (* Create a linear mapping device. *)
+ let lv_dev = new linear_map_device name extent_size segments in
-(* Int64 operators for convenience. *)
-let (+^) = Int64.add
-let (-^) = Int64.sub
-let ( *^ ) = Int64.mul
-let (/^) = Int64.div
+ { lv_dev = lv_dev }
+ ) lvs
+ with
+ Not_found -> []
+ ) vgs in
+ let lvs = List.concat lvs in
-let probe_lvm2 target part_type fd start size =
- Virt_df.ProbeFailed "LVM2 not supported yet"
+ (* Return the list of LV devices. *)
+ lvs
+(*----------------------------------------------------------------------*)
(* Register with main code. *)
let () =
- Virt_df.fs_register
- [ 0x8e ] (* Partition type. *)
- probe_lvm2
+ lvm_type_register plugin_name probe_pv list_lvs
git.annexia.org / virt-top.git / blobdiff