[Libguestfs] [PATCH v3 09/10] sparsify: Add virt-sparsify --in-place mode.
Richard W.M. Jones
rjones at redhat.com
Wed Mar 12 14:26:16 UTC 2014
---
po/POTFILES-ml | 1 +
sparsify/Makefile.am | 2 +
sparsify/cmdline.ml | 77 +++++++++++++++++-------
sparsify/in_place.ml | 143 +++++++++++++++++++++++++++++++++++++++++++++
sparsify/sparsify.ml | 3 +
sparsify/virt-sparsify.pod | 63 +++++++++++++++++---
6 files changed, 259 insertions(+), 30 deletions(-)
create mode 100644 sparsify/in_place.ml
diff --git a/po/POTFILES-ml b/po/POTFILES-ml
index 899a460..ed96697 100644
--- a/po/POTFILES-ml
+++ b/po/POTFILES-ml
@@ -35,6 +35,7 @@ mllib/urandom.ml
resize/resize.ml
sparsify/cmdline.ml
sparsify/copying.ml
+sparsify/in_place.ml
sparsify/sparsify.ml
sysprep/main.ml
sysprep/sysprep_operation.ml
diff --git a/sparsify/Makefile.am b/sparsify/Makefile.am
index 2f32093..811c131 100644
--- a/sparsify/Makefile.am
+++ b/sparsify/Makefile.am
@@ -28,6 +28,7 @@ CLEANFILES = *~ *.cmi *.cmo *.cmx *.cmxa *.o virt-sparsify
SOURCES = \
cmdline.ml \
copying.ml \
+ in_place.ml \
sparsify.ml \
statvfs-c.c
@@ -46,6 +47,7 @@ deps = \
statvfs-c.o \
cmdline.cmx \
copying.cmx \
+ in_place.cmx \
sparsify.cmx
if HAVE_OCAMLOPT
diff --git a/sparsify/cmdline.ml b/sparsify/cmdline.ml
index b714a9e..d25e9e9 100644
--- a/sparsify/cmdline.ml
+++ b/sparsify/cmdline.ml
@@ -27,7 +27,8 @@ let prog = Filename.basename Sys.executable_name
let error fs = error ~prog fs
type mode_t =
- Mode_copying of string * check_t * bool * string option * string option
+| Mode_copying of string * check_t * bool * string option * string option
+| Mode_in_place
and check_t = [`Ignore|`Continue|`Warn|`Fail]
let parse_cmdline () =
@@ -54,6 +55,7 @@ let parse_cmdline () =
let debug_gc = ref false in
let format = ref "" in
let ignores = ref [] in
+ let in_place = ref false in
let machine_readable = ref false in
let option = ref "" in
let quiet = ref false in
@@ -69,6 +71,8 @@ let parse_cmdline () =
"--debug-gc", Arg.Set debug_gc, " " ^ s_"Debug GC and memory allocations";
"--format", Arg.Set_string format, s_"format" ^ " " ^ s_"Format of input disk";
"--ignore", Arg.String (add ignores), s_"fs" ^ " " ^ s_"Ignore filesystem";
+ "--in-place", Arg.Set in_place, " " ^ s_"Modify the disk image in-place";
+ "--inplace", Arg.Set in_place, ditto;
"--long-options", Arg.Unit display_long_options, " " ^ s_"List long options";
"--machine-readable", Arg.Set machine_readable, " " ^ s_"Make output machine readable";
"-o", Arg.Set_string option, s_"option" ^ " " ^ s_"Add qemu-img options";
@@ -90,6 +94,8 @@ let parse_cmdline () =
virt-sparsify [--options] indisk outdisk
+ virt-sparsify [--options] --in-place disk
+
A short summary of the options is given below. For detailed help please
read the man page virt-sparsify(1).
")
@@ -103,6 +109,7 @@ read the man page virt-sparsify(1).
let debug_gc = !debug_gc in
let format = match !format with "" -> None | str -> Some str in
let ignores = List.rev !ignores in
+ let in_place = !in_place in
let machine_readable = !machine_readable in
let option = match !option with "" -> None | str -> Some str in
let quiet = !quiet in
@@ -118,6 +125,7 @@ read the man page virt-sparsify(1).
printf "linux-swap\n";
printf "zero\n";
printf "check-tmpdir\n";
+ printf "in-place\n";
let g = new G.guestfs () in
g#add_drive "/dev/null";
g#launch ();
@@ -128,12 +136,14 @@ read the man page virt-sparsify(1).
exit 0
);
- (* Verify we got exactly 2 disks. *)
+ (* Verify we got exactly 1 or 2 disks, depending on the mode. *)
let indisk, outdisk =
- match List.rev !disks with
- | [indisk; outdisk] -> indisk, outdisk
+ match in_place, List.rev !disks with
+ | false, [indisk; outdisk] -> indisk, outdisk
+ | true, [disk] -> disk, ""
| _ ->
- error "usage is: %s [--options] indisk outdisk" prog in
+ error "usage is: %s [--options] indisk outdisk OR %s --in-place disk"
+ prog prog in
(* Simple-minded check that the user isn't trying to use the
* same disk for input and output.
@@ -141,24 +151,49 @@ read the man page virt-sparsify(1).
if indisk = outdisk then
error (f_"you cannot use the same disk image for input and output");
- (* The input disk must be an absolute path, so we can store the name
- * in the overlay disk.
- *)
let indisk =
- if not (Filename.is_relative indisk) then
+ if not in_place then (
+ (* The input disk must be an absolute path, so we can store the name
+ * in the overlay disk.
+ *)
+ let indisk =
+ if not (Filename.is_relative indisk) then
+ indisk
+ else
+ Sys.getcwd () // indisk in
+
+ (* Check the output is not a block or char special (RHBZ#1056290). *)
+ if is_block_device outdisk then
+ error (f_"output '%s' cannot be a block device, it must be a regular file")
+ outdisk;
+
+ if is_char_device outdisk then
+ error (f_"output '%s' cannot be a character device, it must be a regular file")
+ outdisk;
+
indisk
+ )
+ else ( (* --in-place checks *)
+ if check_tmpdir <> `Warn then
+ error (f_"you cannot use --in-place and --check-tmpdir options together");
+
+ if compress then
+ error (f_"you cannot use --in-place and --compress options together");
+
+ if convert <> None then
+ error (f_"you cannot use --in-place and --convert options together");
+
+ if option <> None then
+ error (f_"you cannot use --in-place and -o options together");
+
+ indisk
+ ) in
+
+ let mode =
+ if not in_place then
+ Mode_copying (outdisk, check_tmpdir, compress, convert, option)
else
- Sys.getcwd () // indisk in
-
- (* Check the output is not a block or char special (RHBZ#1056290). *)
- if is_block_device outdisk then
- error (f_"output '%s' cannot be a block device, it must be a regular file")
- outdisk;
-
- if is_char_device outdisk then
- error (f_"output '%s' cannot be a character device, it must be a regular file")
- outdisk;
+ Mode_in_place in
indisk, debug_gc, format, ignores, machine_readable,
- quiet, verbose, trace, zeroes,
- Mode_copying (outdisk, check_tmpdir, compress, convert, option)
+ quiet, verbose, trace, zeroes, mode
diff --git a/sparsify/in_place.ml b/sparsify/in_place.ml
new file mode 100644
index 0000000..9f46ad3
--- /dev/null
+++ b/sparsify/in_place.ml
@@ -0,0 +1,143 @@
+(* virt-sparsify
+ * Copyright (C) 2011-2014 Red Hat Inc.
+ *
+ * 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *)
+
+(* This is the virt-sparsify --in-place mode. *)
+
+open Unix
+open Printf
+
+open Common_gettext.Gettext
+
+module G = Guestfs
+
+open Common_utils
+open Cmdline
+
+let run disk format ignores machine_readable quiet verbose trace zeroes =
+ (* Connect to libguestfs. *)
+ let g = new G.guestfs () in
+ if trace then g#set_trace true;
+ if verbose then g#set_verbose true;
+
+ (* XXX Current limitation of the API. Can remove this hunk in future. *)
+ let format =
+ match format with
+ | Some _ -> format
+ | None -> Some (g#disk_format disk) in
+
+ g#add_drive ?format ~discard:"enable" disk;
+
+ if not quiet then Progress.set_up_progress_bar ~machine_readable g;
+ g#launch ();
+
+ (* Discard non-ignored filesystems that we are able to mount, and
+ * selected swap partitions.
+ *)
+ let filesystems = g#list_filesystems () in
+ let filesystems = List.map fst filesystems in
+ let filesystems = List.sort compare filesystems in
+
+ let is_ignored fs =
+ let fs = g#canonical_device_name fs in
+ List.exists (fun fs' -> fs = g#canonical_device_name fs') ignores
+ in
+
+ List.iter (
+ fun fs ->
+ if not (is_ignored fs) then (
+ if List.mem fs zeroes then (
+ if not quiet then
+ printf (f_"Zeroing %s ...\n%!") fs;
+
+ if not (g#blkdiscardzeroes fs) then
+ g#zero_device fs;
+ g#blkdiscard fs
+ ) else (
+ let mounted =
+ try g#mount_options "discard" fs "/"; true
+ with _ -> false in
+
+ if mounted then (
+ if not quiet then
+ printf (f_"Trimming %s ...\n%!") fs;
+
+ g#fstrim "/"
+ ) else (
+ let is_linux_x86_swap =
+ (* Look for the signature for Linux swap on i386.
+ * Location depends on page size, so it definitely won't
+ * work on non-x86 architectures (eg. on PPC, page size is
+ * 64K). Also this avoids hibernated swap space: in those,
+ * the signature is moved to a different location.
+ *)
+ try g#pread_device fs 10 4086L = "SWAPSPACE2"
+ with _ -> false in
+
+ if is_linux_x86_swap then (
+ if not quiet then
+ printf (f_"Clearing Linux swap on %s ...\n%!") fs;
+
+ (* Don't use mkswap. Just preserve the header containing
+ * the label, UUID and swap format version (libguestfs
+ * mkswap may differ from guest's own).
+ *)
+ let header = g#pread_device fs 4096 0L in
+ g#blkdiscard fs;
+ if g#pwrite_device fs header 0L <> 4096 then
+ error (f_"pwrite: short write restoring swap partition header")
+ )
+ )
+ );
+
+ g#umount_all ()
+ )
+ ) filesystems;
+
+ (* Discard unused space in volume groups. *)
+ let vgs = g#vgs () in
+ let vgs = Array.to_list vgs in
+ let vgs = List.sort compare vgs in
+ List.iter (
+ fun vg ->
+ if not (List.mem vg ignores) then (
+ let lvname = string_random8 () in
+ let lvdev = "/dev/" ^ vg ^ "/" ^ lvname in
+
+ let created =
+ try g#lvcreate_free lvname vg 100; true
+ with _ -> false in
+
+ if created then (
+ if not quiet then
+ printf (f_"Discard space in volgroup %s ...\n%!") vg;
+
+ g#blkdiscard lvdev;
+ g#sync ();
+ g#lvremove lvdev
+ )
+ )
+ ) vgs;
+
+ g#shutdown ();
+ g#close ();
+
+ (* Finished. *)
+ if not quiet then (
+ print_newline ();
+ wrap (s_"Sparsify in-place operation completed with no errors.\n");
+ )
diff --git a/sparsify/sparsify.ml b/sparsify/sparsify.ml
index faefb23..f148296 100644
--- a/sparsify/sparsify.ml
+++ b/sparsify/sparsify.ml
@@ -37,6 +37,9 @@ let rec main () =
| Mode_copying (outdisk, check_tmpdir, compress, convert, option) ->
Copying.run indisk outdisk check_tmpdir compress convert
format ignores machine_readable option quiet verbose trace zeroes
+ | Mode_in_place ->
+ In_place.run indisk format ignores machine_readable
+ quiet verbose trace zeroes
);
if debug_gc then
diff --git a/sparsify/virt-sparsify.pod b/sparsify/virt-sparsify.pod
index 84e94c5..c12a15f 100644
--- a/sparsify/virt-sparsify.pod
+++ b/sparsify/virt-sparsify.pod
@@ -8,6 +8,8 @@ virt-sparsify - Make a virtual machine disk sparse
virt-sparsify [--options] indisk outdisk
+ virt-sparsify [--options] --in-place disk
+
=head1 DESCRIPTION
Virt-sparsify is a tool which can make a virtual machine disk (or any
@@ -45,13 +47,6 @@ such as C<du -sh>. It can make a huge difference:
=item *
-Virt-sparsify does not do in-place modifications. It copies from a
-source image to a destination image, leaving the source unchanged.
-I<Check that the sparsification was successful before deleting the
-source image>.
-
-=item *
-
The virtual machine I<must be shut down> before using this tool.
=item *
@@ -60,6 +55,9 @@ Virt-sparsify may require up to 2x the virtual size of the source disk
image (1 temporary copy + 1 destination image). This is in the worst
case and usually much less space is required.
+If you are using the I<--in-place> option, then large amounts of
+temporary space are B<not> required.
+
=item *
Virt-sparsify cannot resize disk images. To do that, use
@@ -105,6 +103,11 @@ to ignore (don't zero free space on) certain filesystems by doing:
See L<virt-filesystems(1)> to get a list of filesystems within a disk
image.
+Since virt-sparsify E<ge> 1.26, you can now sparsify a disk image
+in place by doing:
+
+ virt-sparsify --in-place disk.img
+
=head1 OPTIONS
=over 4
@@ -147,11 +150,15 @@ B<fail> and exit.
=back
+You cannot use this option and I<--in-place> together.
+
=item B<--compress>
Compress the output file. This I<only> works if the output format is
C<qcow2>.
+You cannot use this option and I<--in-place> together.
+
=item B<--convert> raw
=item B<--convert> qcow2
@@ -171,6 +178,8 @@ then virt-sparsify doesn't need to try to guess the input format.
For fine-tuning the output format, see: I<--compress>, I<-o>.
+You cannot use this option and I<--in-place> together.
+
=item B<--debug-gc>
Debug garbage collection and memory allocation. This is only useful
@@ -191,14 +200,23 @@ ensure the format is always specified.
=item B<--ignore> volgroup
-Ignore the named filesystem. Free space on the filesystem will not be
+Ignore the named filesystem.
+
+When not using I<--in-place>: Free space on the filesystem will not be
zeroed, but existing blocks of zeroes will still be sparsified.
+When using I<--in-place>, the filesystem is ignored completely.
+
In the second form, this ignores the named volume group. Use the
volume group name without the C</dev/> prefix, eg. I<--ignore vg_foo>
You can give this option multiple times.
+=item B<--in-place>
+
+Do in-place sparsification instead of copying sparsification.
+See L</IN-PLACE SPARSIFICATION> below.
+
=item B<--machine-readable>
This option is used to make the output more machine friendly
@@ -217,6 +235,8 @@ them with commas, eg:
virt-sparsify --convert qcow2 \
-o cluster_size=512,preallocation=metadata ...
+You cannot use this option and I<--in-place> together.
+
=item B<-q>
=item B<--quiet>
@@ -249,6 +269,28 @@ excellent! You can give this option multiple times.
=back
+=head1 IN-PLACE SPARSIFICATION
+
+Since virt-sparsify E<ge> 1.26, the tool is able to do in-place
+sparsification (instead of copying from an input disk to an output
+disk). This is more efficient. However it requires special support
+in libguestfs, the kernel and qemu, and it is not able to recover
+quite as much space as copying sparsification. So in-place
+sparsification is considered to be experimental at this time.
+
+To use this mode, specify a disk image which will be modified in
+place:
+
+ virt-sparsify --in-place disk.img
+
+Some options are not compatible with this mode: I<--convert>,
+I<--compress> and I<-o> because they require wholesale disk format
+changes; I<--check-tmpdir> because large amounts of temporary space
+are not required.
+
+In-place sparsification works using discard (a.k.a trim or unmap)
+support.
+
=head1 MACHINE READABLE OUTPUT
The I<--machine-readable> option can be used to make the output more
@@ -332,6 +374,9 @@ size of the tmpfs mountpoint, eg:
mount -o remount,size=10G /tmp
+If you are using the I<--in-place> option, then large amounts of
+temporary space are B<not> required.
+
=back
For other environment variables, see L<guestfs(3)/ENVIRONMENT VARIABLES>.
@@ -355,4 +400,4 @@ Richard W.M. Jones L<http://people.redhat.com/~rjones/>
=head1 COPYRIGHT
-Copyright (C) 2011-2012 Red Hat Inc.
+Copyright (C) 2011-2014 Red Hat Inc.
--
1.8.5.3
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