Re: [Qemu-devel] [PATCH v6 03/12] block: add basic backup support to block driver

[Kevin Wolf]

Am 24.06.2013 um 17:13 hat Stefan Hajnoczi geschrieben:
> From: Dietmar Maurer <address@hidden>
> 
> 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.
>  * Use trace events instead of DPRINTF()
> 
> -- stefanha]
> 
> Signed-off-by: Dietmar Maurer <address@hidden>
> Signed-off-by: Stefan Hajnoczi <address@hidden>

> +static BlockJobType backup_job_type = {
> +    .instance_size  = sizeof(BackupBlockJob),
> +    .job_type       = "backup",
> +    .set_speed      = backup_set_speed,
> +    .iostatus_reset = backup_iostatus_reset,
> +};

const is still missing.

Kevin