Re: [Qemu-devel] [PATCH v5 03/11] block: add basic backup support to block driver

[Stefan Hajnoczi <stefanha@redhat.com>]

On Tue, Jun 18, 2013 at 04:52:11PM +0200, Kevin Wolf wrote:
> Am 30.05.2013 um 14:34 hat Stefan Hajnoczi geschrieben:
> > From: Dietmar Maurer <dietmar@proxmox.com>
> > 
> > backup_start() creates a block job that copies a point-in-time snapshot
> > of a block device to a target block device.
> > 
> > We call backup_do_cow() for each write during backup. That function
> > reads the original data from the block device before it gets
> > overwritten.  The data is then written to the target device.
> > 
> > Currently backup cluster size is hardcoded to 65536 bytes.
> > 
> > [I made a number of changes to Dietmar's original patch and folded them
> > in to make code review easy.  Here is the full list:
> > 
> >  * Drop BackupDumpFunc interface in favor of a target block device
> >  * Detect zero clusters with buffer_is_zero() and use bdrv_co_write_zeroes()
> >  * Use 0 delay instead of 1us, like other block jobs
> >  * Unify creation/start functions into backup_start()
> >  * Simplify cleanup, free bitmap in backup_run() instead of cb
> >  * function
> >  * Use HBitmap to avoid duplicating bitmap code
> >  * Use bdrv_getlength() instead of accessing ->total_sectors
> >  * directly
> >  * Delete the backup.h header file, it is no longer necessary
> >  * Move ./backup.c to block/backup.c
> >  * Remove #ifdefed out code
> >  * Coding style and whitespace cleanups
> >  * Use bdrv_add_before_write_notifier() instead of blockjob-specific hooks
> >  * Keep our own in-flight CowRequest list instead of using block.c
> >    tracked requests.  This means a little code duplication but is much
> >    simpler than trying to share the tracked requests list and use the
> >    backup block size.
> >  * Add on_source_error and on_target_error error handling.
> > 
> > -- stefanha]
> > 
> > Signed-off-by: Dietmar Maurer <dietmar@proxmox.com>
> > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> > 
> > backup size fixes
> > 
> > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> 
> You probably didn't want to have the second part in the final commit
> message?

Thanks for pointing this out.  I overlooked it when squashing.  Will
fix.

Stefan