Commit Graph

179 Commits

Author SHA1 Message Date
Kevin Wolf
98289620e0 block: Don't parse protocol from file.filename
One of the major reasons for doing something new for -blockdev and
blockdev-add was that the old block layer code parses filenames instead
of just taking them literally. So we should really leave it untouched
when it's passing using the new interfaces (like -drive
file.filename=...).

This allows opening relative file names that contain a colon.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
2013-07-15 09:49:00 +02:00
Stefan Weil
7c30f65703 qemu-img: Add missing GCC_FMT_ATTR
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
2013-06-21 22:52:50 +04:00
Wenchao Xia
43526ec8d1 block: add image info query function bdrv_query_image_info()
This patch adds function bdrv_query_image_info(), which will
retrieve image info in qmp object format. The implementation is
based on the code moved from qemu-img.c, but uses block layer
function to get snapshot info.

Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-06-07 13:37:45 +02:00
Wenchao Xia
fb0ed4539c block: add snapshot info query function bdrv_query_snapshot_info_list()
This patch adds function bdrv_query_snapshot_info_list(), which will
retrieve snapshot info of an image in qmp object format. The implementation
is based on the code moved from qemu-img.c with modification to fit more
for qmp based block layer API.

Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-06-07 13:37:45 +02:00
Kevin Wolf
5e00984aef cutils: Support 'P' and 'E' suffixes in strtosz()
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-06-06 11:27:03 +02:00
Wenchao Xia
5b91704469 block: dump snapshot and image info to specified output
bdrv_snapshot_dump() and bdrv_image_info_dump() do not dump to a buffer now,
some internal buffers are still used for format control, which have no
chance to be truncated. As a result, these two functions have no more issue
of truncation, and they can be used by both qemu and qemu-img with correct
parameter specified.

Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-06-04 13:56:30 +02:00
Wenchao Xia
f364ec65b5 block: move qmp and info dump related code to block/qapi.c
This patch is a pure code move patch, except following modification:
1 get_human_readable_size() is changed to static function.
2 dump_human_image_info() is renamed to bdrv_image_info_dump().
3 in qmp_query_block() and qmp_query_blockstats, use bdrv_next(bs)
instead of direct traverse of global array 'bdrv_states'.
4 collect_snapshots() and collect_image_info() are renamed, unused parameter
*fmt in collect_image_info() is removed.
5 code style fix.

To avoid conflict and tip better, macro in header file is BLOCK_QAPI_H
instead of QAPI_H. Now block.h and snapshot.h are at the same level in
include path, block_int.h and qapi.h will both include them.

Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-06-04 13:56:30 +02:00
Stefan Hajnoczi
54f106d5fd qemu-img: do not zero-pad the compressed write buffer
bdrv_write_compressed() does not allow requests that span the end of the
device.  Therefore it is useless to zero-pad the last cluster and
thereby exceed the end of the device.

Let image formats handle zero-padding the final compressed cluster, if
necessary.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-04-22 10:27:58 +02:00
Kevin Wolf
de9c0cec6c block: Add options QDict to bdrv_open() prototype
It doesn't do anything yet except storing the options QDict in the
BlockDriverState.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-03-15 16:07:49 +01:00
Miroslav Rezanina
d14ed18c8d qemu-img: Add compare subcommand
This patch adds new qemu-img subcommand that compares content of two disk
images.

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-02-22 21:21:10 +01:00
Miroslav Rezanina
f382d43a91 qemu-img: Add "Quiet mode" option
There can be a need to turn output to stdout off. This patch adds a -q option
that enable "Quiet mode". In Quiet mode, only errors are printed out.

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-02-22 21:21:09 +01:00
Stefan Hajnoczi
e6439d783c qemu-img: add compressed clusters to BlockFragInfo
Show how many clusters are compressed.  This can be used to monitor how
many compressed clusters remain and whether to recompress the image.

Suggested-by: Cole Robinson <crobinso@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-02-22 21:21:09 +01:00
Stefan Hajnoczi
c9fc508398 qemu-img: fix missing space in qemu-img check output
The qemu-img check fragmentation printf() is missing a space before the
'=' sign.  The human output is not guaranteed to be stable and we are
not aware of screen scrapers, so add the missing space.

Also fix the missing indentation of the printf() arguments.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-02-22 21:21:09 +01:00
Federico Simoncelli
8599ea4c42 qemu-img: add json output option to the check command
This option --output=[human|json] makes qemu-img check output a human
or JSON representation at the choice of the user.

Signed-off-by: Federico Simoncelli <fsimonce@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-02-22 21:21:08 +01:00
Federico Simoncelli
c6bb9ad198 qemu-img: find the image end offset during check
This patch adds the support for reporting the image end offset (in
bytes). This is particularly useful after a conversion (or a rebase)
where the destination is a block device in order to find the first
unused byte at the end of the image.

Signed-off-by: Federico Simoncelli <fsimonce@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-02-22 21:21:08 +01:00
liguang
7944339726 qemu-img: report size overflow error message
qemu-img will complain when qcow or qcow2
size overflow for 64 bits, report the right
message in this condition.

$./qemu-img create -f qcow2 /tmp/foo 0x10000000000000000
before change:
qemu-img: Invalid image size specified! You may use k, M, G or T suffixes for
qemu-img: kilobytes, megabytes, gigabytes and terabytes.

after change:
qemu-img: Image size must be less than 8 EiB!

[Resolved conflict with a9300911 goto removal -- Stefan]

Signed-off-by: liguang <lig.fnst@cn.fujitsu.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-01-02 16:08:56 +01:00
Paolo Bonzini
9c17d615a6 softmmu: move include files to include/sysemu/
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-12-19 08:32:45 +01:00
Paolo Bonzini
1de7afc984 misc: move include files to include/qemu/
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-12-19 08:32:39 +01:00
Paolo Bonzini
737e150e89 block: move include files to include/block/
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-12-19 08:31:31 +01:00
Paolo Bonzini
7b1b5d1913 qapi: move include files to include/qobject/
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-12-19 08:31:31 +01:00
Dong Xu Wang
e478b448d7 use qemu_opts_create_nofail
We will use qemu_opts_create_nofail function, it can make code
more readable.

Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-12-11 16:35:47 +01:00
Luiz Capitulino
a930091189 qemu-img: img_create(): drop unneeded goto and ret variable
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-12-11 11:05:10 +01:00
Luiz Capitulino
9b37525a7d qemu-img: img_create(): pass Error object to bdrv_img_create()
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-12-11 11:05:10 +01:00
Luiz Capitulino
71c79813d8 block: bdrv_img_create(): add Error ** argument
This commit adds an Error ** argument to bdrv_img_create() and set it
appropriately on error.

Callers of bdrv_img_create() pass NULL for the new argument and still
rely on bdrv_img_create()'s return value. Next commits will change
callers to use the Error object instead.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-12-11 11:05:10 +01:00
Paolo Bonzini
2592c59a66 tools: initialize main loop before block layer
Tools were broken because they initialized the block layer while
qemu_aio_context was still NULL.

Reported-by: malc <av1474@comtv.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: malc <av1474@comtv.ru>
2012-11-06 04:37:57 +04:00
Stefan Hajnoczi
9699bf0d06 qemu-img: Add --backing-chain option to info command
The qemu-img info --backing-chain option enumerates the backing file
chain.  For example, for base.qcow2 <- snap1.qcow2 <- snap2.qcow2 the
output becomes:

  $ qemu-img info --backing-chain snap2.qcow2
  image: snap2.qcow2
  file format: qcow2
  virtual size: 100M (104857600 bytes)
  disk size: 196K
  cluster_size: 65536
  backing file: snap1.qcow2
  backing file format: qcow2

  image: snap1.qcow2
  file format: qcow2
  virtual size: 100M (104857600 bytes)
  disk size: 196K
  cluster_size: 65536
  backing file: base.qcow2
  backing file format: qcow2

  image: base.qcow2
  file format: qcow2
  virtual size: 100M (104857600 bytes)
  disk size: 136K
  cluster_size: 65536

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-10-24 10:26:19 +02:00
Alex Bligh
a616673dd1 qemu-img rebase: use empty string to rebase without backing file
This patch allows an empty filename to be passed as the new base image name
for qemu-img rebase to mean base the image on no backing file (i.e.
independent of any backing file). According to Eric Blake, qemu-img rebase
already supports this when '-u' is used; this adds support when -u is not
used.

Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-10-24 10:26:18 +02:00
Kevin Wolf
1f71049523 qemu-img: Fix division by zero for zero size images
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
2012-10-24 10:26:18 +02:00
Anthony Liguori
109820df4a Merge remote-tracking branch 'kwolf/for-anthony' into staging
* kwolf/for-anthony:
  block: Don't forget to delete temporary file
  Don't require encryption password for 'qemu-img info' command
  qemu-img: Add json output option to the info command.
  qapi: Add SnapshotInfo and ImageInfo.
  ahci: properly reset PxCMD on HBA reset
  block: fix block tray status
  vdi: Fix warning from clang
  block/curl: Fix wrong free statement
  ide: Fix error messages from static code analysis (no real error)
  ATAPI: STARTSTOPUNIT only eject/load media if powercondition is 0
  sheepdog: fix savevm and loadvm
2012-09-17 10:23:15 -05:00
Stefan Weil
0546b8c2f0 Spelling fixes in comments and documentation
These wrong spellings were detected by codespell:

* successully -> successfully

* alot -> a lot

* wanna -> want to

* infomation -> information

* occured -> occurred

["also is" -> "is also" and "ressources" -> "resources" suggested by
Peter Maydell <peter.maydell@linaro.org>]

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2012-09-14 08:21:28 +01:00
Daniel P. Berrange
f0536bb848 Don't require encryption password for 'qemu-img info' command
The encryption password is only required if I/O is going to be
performed on a disk image. The 'qemu-img info' command merely
reports metadata, so it should not ask for a decryption password

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-09-12 15:50:09 +02:00
Benoît Canet
c054b3fd78 qemu-img: Add json output option to the info command.
This option --output=[human|json] make qemu-img info output on
human or JSON representation at the choice of the user.

example:
{
    "snapshots": [
        {
            "vm-clock-nsec": 637102488,
            "name": "vm-20120821145509",
            "date-sec": 1345553709,
            "date-nsec": 220289000,
            "vm-clock-sec": 20,
            "id": "1",
            "vm-state-size": 96522745
        },
        {
            "vm-clock-nsec": 28210866,
            "name": "vm-20120821154059",
            "date-sec": 1345556459,
            "date-nsec": 171392000,
            "vm-clock-sec": 46,
            "id": "2",
            "vm-state-size": 101208714
        }
    ],
    "virtual-size": 1073741824,
    "filename": "snap.qcow2",
    "cluster-size": 65536,
    "format": "qcow2",
    "actual-size": 985587712,
    "dirty-flag": false
}

Signed-off-by: Benoit Canet <benoit@irqsave.net>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-09-12 15:50:09 +02:00
Stefan Hajnoczi
058f8f16db block: add BLOCK_O_CHECK for qemu-img check
Image formats with a dirty bit, like qed and qcow2, repair dirty image
files upon open with BDRV_O_RDWR.  Performing automatic repair when
qemu-img check runs is not ideal because the bdrv_open() call repairs
the image before the actual bdrv_check() call from qemu-img.c.

Fix this "double repair" since it leads to confusing output from
qemu-img check.  Tell the block driver that this image is being opened
just for bdrv_check().  This skips automatic repair and qemu-img.c can
invoke it manually with bdrv_check().

Update the golden output for qemu-iotests 039 to reflect the new
qemu-img check output.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-10 10:25:12 +02:00
Dong Xu Wang
20caf0f766 qemu-img: use QemuOpts instead of QEMUOptionParameter in resize function
Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-06 22:39:14 +02:00
Peter Maydell
c8057f951d Support 'help' as a synonym for '?' in command line options
For command line options which permit '?' meaning 'please list the
permitted values', add support for 'help' as a synonym, by abstracting
the check out into a helper function.

This change means that in some cases where we were being lazy in
our string parsing, "?junk" will now be rejected as an invalid option
rather than being (undocumentedly) treated the same way as "?".

Update the documentation to use 'help' rather than '?', since '?'
is a shell metacharacter and thus prone to fail confusingly if there
is a single character filename in the current working directory and
the '?' has not been escaped. It's therefore better to steer users
towards 'help', though '?' is retained for backwards compatibility.

We do not, however, update the output of the system emulator's -help
(or any documentation autogenerated from the qemu-options.hx which
is the source of the -help text) because libvirt parses our -help
output and will break. At a later date when QEMU provides a better
interface so libvirt can avoid having to do this, we can update the
-help text too.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2012-08-02 13:16:42 -05:00
Markus Armbruster
f8d6bba1c1 block: Replace bdrv_get_format() by bdrv_get_format_name()
So callers don't need to know anything about maximum name length.
Returning a pointer is safe, because the name string lives as long as
the block driver it names, and block drivers don't die.

Requested by Peter Maydell.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-06-15 14:03:43 +02:00
Kevin Wolf
ccf34716ee qemu-img check: Print fixed clusters and recheck
When any inconsistencies have been fixed, print the statistics and run
another check to make sure everything is correct now.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-06-15 14:03:42 +02:00
Kevin Wolf
4534ff5426 qemu-img check -r for repairing images
The QED block driver already provides the functionality to not only
detect inconsistencies in images, but also fix them. However, this
functionality cannot be manually invoked with qemu-img, but the
check happens only automatically during bdrv_open().

This adds a -r switch to qemu-img check that allows manual invocation
of an image repair.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-06-15 14:03:42 +02:00
Charles Arnold
fa170c148b qemu-img: Fix segmentation fault
The following command generates a segmentation fault.
qemu-img convert -O vpc -o ? test test2
This is because the 'goto out;' statement calls qemu_progress_end
before qemu_progress_init is called resulting in a NULL pointer
invocation.

Signed-off-by: Charles Arnold <carnold@suse.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-05-14 17:02:19 +02:00
Paolo Bonzini
dc5a137125 qemu-img: make "info" backing file output correct and easier to use
qemu-img info should use the same logic as qemu when printing the
backing file path, or debugging becomes quite tricky.  We can also
simplify the output in case the backing file has an absolute path
or a protocol.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-05-10 10:32:12 +02:00
Liu Yuan
80ccf93b88 qemu-img: let 'qemu-img convert' flush data
The 'qemu-img convert -h' advertise that the default cache mode is
'writeback', while in fact it is 'unsafe'.

This patch 1) fix the help manual and 2) let bdrv_close() call bdrv_flush()

2) is needed because some backend storage doesn't have a self-flush
mechanism(for e.g., sheepdog), so we need to call bdrv_flush() to make
sure the image is really writen to the storage instead of hanging around
writeback cache forever.

Signed-off-by: Liu Yuan <tailai.ly@taobao.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-20 11:42:41 +02:00
Dong Xu Wang
64c79160b4 qemu-img: add dirty flag status
Some block drivers can verify their image files are clean or not. So we can show
it while using "qemu-img info".

Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-05 14:54:41 +02:00
Dong Xu Wang
f8111c241a qemu-img: add image fragmentation statistics
Discussion can be found at:
http://patchwork.ozlabs.org/patch/128730/

This patch add image fragmentation statistics while using qemu-img check.

Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-05 14:54:40 +02:00
Kevin Wolf
259b217310 qcow2: Add error messages in qcow2_truncate
qemu-img resize has some limitations with qcow2, but the user is only
told that "this image format does not support resize". Quite confusing,
so add some more detailed error_report() calls and change "this image
format" into "this image".

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2012-03-12 15:14:06 +01:00
Zhi Yong Wu
67d384e804 qemu-img: fix segment fault when the image format is qed
[root@f15 qemu]# qemu-img info /home/zwu/work/misc/rh6.img
image: /home/zwu/work/misc/rh6.img
file format: qed
virtual size: 4.0G (4294967296 bytes)
disk size: 1.2G
cluster_size: 65536
Segmentation fault (core dumped)

Today when i were fixing another issue, i found this issue; After simple
investigation, i found that the required clock vm_clock is not created
for qemu tool.

Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-02-29 16:05:07 +01:00
Stefan Hajnoczi
1a6d39fd71 cutils: extract buffer_is_zero() from qemu-img.c
The qemu-img.c:is_not_zero() function checks if a buffer contains all
zeroes.  This function will come in handy for zero-detection in the
block layer, so clean it up and move it to cutils.c.

Note that the function now returns true if the buffer is all zeroes.
This avoids the double-negatives (i.e. !is_not_zero()) that the old
function can cause in callers.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-02-09 16:17:50 +01:00
Kevin Wolf
87a1b3e381 qemu-img rebase: Fix for undersized backing files
Backing files may be smaller than the corresponding COW file. When
reading directly from the backing file, qemu-img rebase must consider
this and assume zero sectors after the end of backing files.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2011-12-15 12:40:08 +01:00
Markus Armbruster
e36b369577 qemu-img: Tighten parsing of size arguments
strtosz_suffix() fails unless the size is followed by 0, whitespace or
','.  Useless here, because we need to fail for any junk following the
size, even if it starts with whitespace or ','.  Check manually.
Things like "qemu-img create xxx 1024," and "qemu-img convert -S '1024
junk'" are now caught.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2011-11-28 16:20:52 -06:00
Kevin Wolf
41521fa4a6 qemu-img: Don't allow preallocation and compression at the same time
Only qcow and qcow2 can do compression at all, and they require unallocated
clusters when writing the compressed data.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2011-10-21 17:34:13 +02:00
Kevin Wolf
a22f123ca3 qemu-img: Require larger zero areas for sparse handling
By default, require 4k of consecutive zero bytes for qemu-img to make the
output file sparse by not issuing a write request for the zeroed parts. Add an
-S option to allow users to tune this setting.

This helps to avoid situations where a lot of zero sectors and data sectors are
mixed and qemu-img tended to issue many tiny 512 byte writes.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-08-29 14:42:39 +02:00