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Merge pull request #46 from jonludlam/host-create-idempotency2
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Host create idempotency2
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Jon Ludlam committed Apr 27, 2015
2 parents 0a09382 + 4bc050f commit 6321dc5
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Showing 2 changed files with 72 additions and 55 deletions.
2 changes: 2 additions & 0 deletions idl/xenvm_interface.ml
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Original file line number Diff line number Diff line change
@@ -1,5 +1,7 @@
(* XenVM LVM type thing *)

exception HostNotCreated

let _journal_name = "xenvm_journal"

external get_lv: name:string -> (Vg_wrapper.t * Lv_wrapper.t) = ""
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125 changes: 70 additions & 55 deletions xenvmd/xenvmd.ml
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Original file line number Diff line number Diff line change
Expand Up @@ -161,50 +161,65 @@ module VolumeManager = struct

module Host = struct
let create name =
let size = Int64.(mul 4L (mul 1024L 1024L)) in
let freeLVM = freeLVM name in
let toLVM = toLVM name in
let fromLVM = fromLVM name in
let freeLVM = freeLVM name in
write (fun vg ->
Lvm.Vg.create vg toLVM size
) >>= fun () ->
write (fun vg ->
Lvm.Vg.create vg fromLVM size
) >>= fun () ->
write (fun vg ->
Lvm.Vg.create vg freeLVM size
) >>= fun () ->
(* The local allocator needs to see the volumes now *)
sync () >>= fun () ->
myvg >>= fun vg ->
( match Vg_IO.find vg toLVM with
| Some lv -> return lv
| None -> assert false ) >>= fun v ->
Vg_IO.Volume.connect v
>>= function
| `Error _ -> fail (Failure (Printf.sprintf "Failed to open %s" toLVM))
| `Ok disk ->
ToLVM.create ~disk ()
>>= fun () ->
Vg_IO.Volume.disconnect disk
>>= fun () ->
( match Vg_IO.find vg fromLVM with
| Some lv -> return lv
| None -> assert false ) >>= fun v ->
Vg_IO.Volume.connect v
>>= function
| `Error _ -> fail (Failure (Printf.sprintf "Failed to open %s" fromLVM))
| `Ok disk ->
FromLVM.create ~disk ()
>>= fun () ->
Vg_IO.Volume.disconnect disk

match Vg_IO.find vg freeLVM with
| Some lv ->
debug "Found freeLVM exists already";
return () (* We've already done this *)
| None -> begin
debug "No freeLVM volume";
let size = Int64.(mul 4L (mul 1024L 1024L)) in
write (fun vg ->
Lvm.Vg.create vg toLVM size
) >>= fun () ->
write (fun vg ->
Lvm.Vg.create vg fromLVM size
) >>= fun () ->
(* The local allocator needs to see the volumes now *)
sync () >>= fun () ->
myvg >>= fun vg ->
( match Vg_IO.find vg toLVM with
| Some lv -> return lv
| None -> assert false ) >>= fun v ->
Vg_IO.Volume.connect v
>>= function
| `Error _ -> fail (Failure (Printf.sprintf "Failed to open %s" toLVM))
| `Ok disk ->
ToLVM.create ~disk ()
>>= fun () ->
Vg_IO.Volume.disconnect disk
>>= fun () ->
( match Vg_IO.find vg fromLVM with
| Some lv -> return lv
| None -> assert false ) >>= fun v ->
Vg_IO.Volume.connect v
>>= function
| `Error _ -> fail (Failure (Printf.sprintf "Failed to open %s" fromLVM))
| `Ok disk ->
FromLVM.create ~disk ()
>>= fun () ->
Vg_IO.Volume.disconnect disk >>= fun () ->
(* Create the freeLVM LV at the end - we can use the existence
of this as a flag to show that we've finished host creation *)
write (fun vg ->
Lvm.Vg.create vg freeLVM size
) >>= fun () ->
sync ()
end

let connect name =
myvg >>= fun vg ->
info "Registering host %s" name;
let toLVM = toLVM name in
let fromLVM = fromLVM name in
let freeLVM = freeLVM name in
( try
Lwt.return (Lvm.Vg.LVs.find_by_name freeLVM (Vg_IO.metadata_of vg).Lvm.Vg.lvs).Lvm.Lv.id
with _ ->
fail Xenvm_interface.HostNotCreated ) >>= fun freeLVMid ->
( match Vg_IO.find vg toLVM with
| Some lv -> return lv
| None -> assert false ) >>= fun v ->
Expand All @@ -216,7 +231,6 @@ module VolumeManager = struct
>>= fun to_LVM ->
ToLVM.resume to_LVM
>>= fun () ->

( match Vg_IO.find vg fromLVM with
| Some lv -> return lv
| None -> assert false ) >>= fun v ->
Expand All @@ -228,7 +242,7 @@ module VolumeManager = struct
>>= fun from_LVM ->
to_LVMs := (name, to_LVM) :: !to_LVMs;
from_LVMs := (name, from_LVM) :: !from_LVMs;
free_LVs := (name, freeLVM) :: !free_LVs;
free_LVs := (name, (freeLVM,freeLVMid)) :: !free_LVs;
return ()

let flush name =
Expand All @@ -240,11 +254,12 @@ module VolumeManager = struct
>>= fun (pos, items) ->
Lwt_list.iter_s (function { ExpandVolume.volume; segments } ->
write (fun vg ->
Lvm.Vg.do_op vg (Lvm.Redo.Op.(LvExpand(volume, { lvex_segments = segments })))
let id = (Lvm.Vg.LVs.find_by_name volume vg.Lvm.Vg.lvs).Lvm.Lv.id in
Lvm.Vg.do_op vg (Lvm.Redo.Op.(LvExpand(id, { lvex_segments = segments })))
) >>= fun () ->
write (fun vg ->
let free = (List.assoc name !free_LVs) in
Lvm.Vg.do_op vg (Lvm.Redo.Op.(LvCrop(free, { lvc_segments = segments })))
let (_,freeid) = (List.assoc name !free_LVs) in
Lvm.Vg.do_op vg (Lvm.Redo.Op.(LvCrop(freeid, { lvc_segments = segments })))
)
) items
>>= fun () ->
Expand Down Expand Up @@ -301,7 +316,7 @@ module VolumeManager = struct
let fromLVM = { Xenvm_interface.lv; suspended } in
read (fun vg ->
try
let lv = Lvm.Vg.LVs.find (freeLVM name) vg.Lvm.Vg.lvs in
let lv = Lvm.Vg.LVs.find_by_name (freeLVM name) vg.Lvm.Vg.lvs in
return (Lvm.Lv.size_in_extents lv)
with Not_found -> return 0L
) >>= fun freeExtents ->
Expand Down Expand Up @@ -340,16 +355,16 @@ module FreePool = struct
let q = try Some(List.assoc host !VolumeManager.from_LVMs) with Not_found -> None in
let host' = try Some(List.assoc host !VolumeManager.free_LVs) with Not_found -> None in
begin match q, host' with
| Some from_lvm, Some free ->
| Some from_lvm, Some (freename,freeid) ->
VolumeManager.write
(fun vg ->
match (try Some(Lvm.Vg.LVs.find free vg.Lvm.Vg.lvs) with Not_found -> None) with
match (try Some(Lvm.Vg.LVs.find freeid vg.Lvm.Vg.lvs) with Not_found -> None) with
| None ->
`Error (`Msg (Printf.sprintf "Failed to find volume %s" free))
`Error (`Msg (Printf.sprintf "Failed to find volume %s" freename))
| Some lv ->
let size = Lvm.Lv.size_in_extents lv in
let segments = Lvm.Lv.Segment.linear size allocation in
Lvm.Vg.do_op vg (Lvm.Redo.Op.(LvExpand(free, { lvex_segments = segments })))
Lvm.Vg.do_op vg (Lvm.Redo.Op.(LvExpand(freeid, { lvex_segments = segments })))
)
>>= fun () ->
FromLVM.push from_lvm allocation
Expand Down Expand Up @@ -400,7 +415,7 @@ module FreePool = struct
>>= fun lvm ->

Lwt_list.iter_s
(fun (host, free) ->
(fun (host, (freename,freeid)) ->
(* XXX: need to lock the host somehow. Ideally we would still service
other queues while one host is locked. *)
let from_lvm = List.assoc host !VolumeManager.from_LVMs in
Expand All @@ -419,9 +434,9 @@ module FreePool = struct
wait ()
>>= fun () ->
fatal_error "resend_free_volumes"
( match try Some(Lvm.Vg.LVs.find free lvm.Lvm.Vg.lvs) with _ -> None with
( match try Some(Lvm.Vg.LVs.find freeid lvm.Lvm.Vg.lvs) with _ -> None with
| Some lv -> return (`Ok (Lvm.Lv.to_allocation lv))
| None -> return (`Error (`Msg (Printf.sprintf "Failed to find LV %s" free))) )
| None -> return (`Error (`Msg (Printf.sprintf "Failed to find LV %s" freename))) )
>>= fun allocation ->
FromLVM.push from_lvm allocation
>>= fun pos ->
Expand All @@ -440,18 +455,18 @@ module FreePool = struct
let extent_size_mib = Int64.(div (mul extent_size (of_int sector_size)) (mul 1024L 1024L)) in
(* XXX: avoid double-allocating the same free blocks *)
Lwt_list.iter_s
(fun (host, free) ->
match try Some(Lvm.Vg.LVs.find free x.Lvm.Vg.lvs) with _ -> None with
(fun (host, (freename,freeid)) ->
match try Some(Lvm.Vg.LVs.find freeid x.Lvm.Vg.lvs) with _ -> None with
| Some lv ->
let size_mib = Int64.mul (Lvm.Lv.size_in_extents lv) extent_size_mib in
if size_mib < config.Config.host_low_water_mark then begin
info "LV %s is %Ld MiB < low_water_mark %Ld MiB; allocating %Ld MiB"
free size_mib config.Config.host_low_water_mark config.Config.host_allocation_quantum;
freename size_mib config.Config.host_low_water_mark config.Config.host_allocation_quantum;
(* find free space in the VG *)
begin match !journal, Lvm.Pv.Allocator.find x.Lvm.Vg.free_space Int64.(div config.Config.host_allocation_quantum extent_size_mib) with
| _, `Error (`OnlyThisMuchFree free_extents) ->
info "LV %s is %Ld MiB but total space free (%Ld MiB) is less than allocation quantum (%Ld MiB)"
free size_mib Int64.(mul free_extents extent_size_mib) config.Config.host_allocation_quantum;
freename size_mib Int64.(mul free_extents extent_size_mib) config.Config.host_allocation_quantum;
(* try again later *)
return ()
| Some j, `Ok allocated_extents ->
Expand All @@ -461,12 +476,12 @@ module FreePool = struct
wait ()
(* The operation has been performed *)
| None, `Ok _ ->
error "Unable to extend LV %s because the journal is not configured" free;
error "Unable to extend LV %s because the journal is not configured" freename;
return ()
end
end else return ()
| None ->
error "Failed to find host %s free LV %s" host free;
error "Failed to find host %s free LV %s" host freename;
return ()
) !VolumeManager.free_LVs
end
Expand Down Expand Up @@ -512,7 +527,7 @@ module Impl = struct
let open Lvm in
fatal_error "get_lv"
(VolumeManager.read (fun vg ->
let lv = Lvm.Vg.LVs.find name vg.Vg.lvs in
let lv = Lvm.Vg.LVs.find_by_name name vg.Vg.lvs in
return (`Ok ({ vg with Vg.lvs = Vg.LVs.empty }, lv))
))

Expand Down

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