X-Git-Url: http://git.annexia.org/?p=virt-top.git;a=blobdiff_plain;f=virt-df%2Fvirt_df_lvm2.ml;h=6a8f573faa2c2e1ee05c1852d9425c805542e1fb;hp=a1f77e395e6fd39ff09e04772e0167e64fb6a9d8;hb=0bdb08c61ec66a16a81c2778a2a76cac77b08fda;hpb=5616e76a5a01656aa0dcc323fcd1fcd77764e638

diff --git a/virt-df/virt_df_lvm2.ml b/virt-df/virt_df_lvm2.ml
index a1f77e3..6a8f573 100644
--- a/virt-df/virt_df_lvm2.ml
+++ b/virt-df/virt_df_lvm2.ml
@@ -1,22 +1,432 @@
 (* '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