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# Date Author Comment
77a5a000 05/18/2011 03:39 pm Stefan Hajnoczi

qed: support for growing images

The .bdrv_truncate() operation resizes images and growing is easy to
implement in QED. Simply check that the new size is valid and then
update the image_size header field to reflect the new size.

Signed-off-by: Stefan Hajnoczi <>...
6f321e93 05/18/2011 03:38 pm Stefan Hajnoczi

qed: Periodically flush and clear need check bit

One strategy to limit the startup delay of consistency check when
opening image files is to ensure that the file is marked dirty for as
little time as possible.

QED currently marks the image dirty when the first allocating write...
21df65b6 04/13/2011 01:06 pm Anthony Liguori

qed: Add support for zero clusters

Zero clusters are similar to unallocated clusters except instead of reading
their value from a backing file when one is available, the cluster is always
read as zero.

This implements read support only. At this stage, QED will never write a...
10b758e8 02/10/2011 02:23 pm Kevin Wolf

qed: Report error for unsupported features

Instead of just returning -ENOTSUP, generate a more detailed error.

Unfortunately we don't have a helpful text for features that we don't know yet,
so just print the feature mask. It might be useful at least if someone asks for...
0d09c797 01/31/2011 11:03 am Stefan Hajnoczi

qed: Images with backing file do not require QED_F_NEED_CHECK

The consistency check on open is necessary in order to fix inconsistent
table offsets left as a result of a crash mid-operation. Images with a
backing file actually flush before updating table offsets and are...
c743849b 01/24/2011 05:41 pm Stefan Hajnoczi

qed: Refuse to create images on block devices

QED relies on the underlying filesystem to extend the file and maintain
its size. Check that images are not created on a block device.

Signed-off-by: Stefan Hajnoczi <>
Signed-off-by: Kevin Wolf <>
75411d23 12/17/2010 05:11 pm Stefan Hajnoczi

qed: Add QEMU Enhanced Disk image format

This patch introduces the qed on-disk layout and implements image
creation. Later patches add read/write and other functionality.

Signed-off-by: Stefan Hajnoczi <>
Signed-off-by: Kevin Wolf <>
298800ca 12/17/2010 05:11 pm Stefan Hajnoczi

qed: Table, L2 cache, and cluster functions

This patch adds code to look up data cluster offsets in the image via
the L1/L2 tables. The L2 tables are writethrough cached in memory for
performance (each read/write requires a lookup so it is essential to
cache the tables)....
eabba580 12/17/2010 05:11 pm Stefan Hajnoczi

qed: Read/write support

This patch implements the read/write state machine. Operations are
fully asynchronous and multiple operations may be active at any time.

Allocating writes lock tables to ensure metadata updates do not
interfere with each other. If two allocating writes need to update the...
01979a98 12/17/2010 05:11 pm Stefan Hajnoczi

qed: Consistency check support

This patch adds support for the qemu-img check command. It also
introduces a dirty bit in the qed header to mark modified images as
needing a check. This bit is cleared when the image file is closed
cleanly.

If an image file is opened and it has the dirty bit set, a consistency...