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  1. 12 9月, 2014 1 次提交
  3. 08 9月, 2014 2 次提交
  5. 22 8月, 2014 2 次提交
  7. 07 7月, 2014 1 次提交
  9. 01 7月, 2014 1 次提交
    • C
      qemu-img create: add 'nocow' option · 4ab15590
      由 Chunyan Liu 提交于 
      Add 'nocow' option so that users could have a chance to set NOCOW flag to
newly created files. It's useful on btrfs file system to enhance performance.

Btrfs has low performance when hosting VM images, even more when the guest
in those VM are also using btrfs as file system. One way to mitigate this bad
performance is to turn off COW attributes on VM files. Generally, there are
two ways to turn off NOCOW on btrfs: a) by mounting fs with nodatacow, then
all newly created files will be NOCOW. b) per file. Add the NOCOW file
attribute. It could only be done to empty or new files.

This patch tries the second way, according to the option, it could add NOCOW
per file.

For most block drivers, since the create file step is in raw-posix.c, so we
can do setting NOCOW flag ioctl in raw-posix.c only.

But there are some exceptions, like block/vpc.c and block/vdi.c, they are
creating file by calling qemu_open directly. For them, do the same setting
NOCOW flag ioctl work in them separately.

[Fixed up 082.out due to the new 'nocow' creation option
--Stefan]
Signed-off-by: NChunyan Liu <cyliu@suse.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
      4ab15590
  11. 04 6月, 2014 1 次提交
  13. 01 2月, 2014 1 次提交
    • D
      Describe flaws in qcow/qcow2 encryption in the docs · 136cd19d
      由 Daniel P. Berrange 提交于 
      The qemu-img.texi / qemu-doc.texi files currently describe the
qcow2/qcow2 encryption thus

  "Encryption uses the AES format which is very secure (128 bit
   keys). Use a long password (16 characters) to get maximum
   protection."

While AES is indeed a strong encryption system, the way that
QCow/QCow2 use it results in a poor/weak encryption system.
Due to the use of predictable IVs, based on the sector number
extended to 128 bits, it is vulnerable to chosen plaintext
attacks which can reveal the existence of encrypted data.

The direct use of the user passphrase as the encryption key
also leads to an inability to change the passphrase of an
image. If passphrase is ever compromised the image data will
all be vulnerable, since it cannot be re-encrypted. The admin
has to clone the image files with a new passphrase and then
use a program like shred to secure erase all the old files.

Recommend against any use of QCow/QCow2 encryption, directing
users to dm-crypt / LUKS which can meet modern cryptography
best practices.

[Changed "Qcow" to "qcow" for consistency.
--Stefan]
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
      136cd19d
  15. 24 1月, 2014 2 次提交
  17. 22 1月, 2014 1 次提交
  19. 20 12月, 2013 1 次提交
  21. 04 12月, 2013 1 次提交
  23. 28 11月, 2013 1 次提交
  25. 12 9月, 2013 1 次提交
  27. 06 9月, 2013 2 次提交
  29. 23 2月, 2013 3 次提交
  31. 30 11月, 2012 1 次提交
  33. 24 10月, 2012 2 次提交
  35. 14 9月, 2012 1 次提交
  37. 12 9月, 2012 1 次提交
    • B
      qemu-img: Add json output option to the info command. · c054b3fd
      由 Benoît Canet 提交于 
      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: NBenoit Canet <benoit@irqsave.net>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
      c054b3fd
  39. 18 8月, 2012 1 次提交
  41. 15 6月, 2012 2 次提交
  43. 26 5月, 2012 1 次提交
  45. 15 12月, 2011 1 次提交
  47. 29 8月, 2011 1 次提交
    • K
      qemu-img: Require larger zero areas for sparse handling · a22f123c
      由 Kevin Wolf 提交于 
      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: NKevin Wolf <kwolf@redhat.com>
      a22f123c
  49. 20 7月, 2011 1 次提交
  51. 05 7月, 2011 1 次提交
  53. 24 1月, 2011 1 次提交
  55. 22 10月, 2010 1 次提交
    • E
      Copy snapshots out of QCOW2 disk · 51ef6727
      由 edison 提交于 
      In order to backup snapshots, created from QCOW2 iamge, we want to copy snapshots out of QCOW2 disk to a seperate storage.
The following patch adds a new option in "qemu-img": qemu-img convert -f qcow2 -O qcow2 -s snapshot_name src_img bck_img.
Right now, it only supports to copy the full snapshot, delta snapshot is on the way.

Changes from V1: all the comments from Kevin are addressed:
Add read-only checking
Fix coding style
Change the name from bdrv_snapshot_load to bdrv_snapshot_load_tmp
Signed-off-by: NDisheng Su <edison@cloud.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
      51ef6727
  57. 03 5月, 2010 1 次提交
  59. 09 11月, 2009 3 次提交