On 7/30/19 12:32 PM, Vladimir Sementsov-Ogievskiy wrote:
> We have detect_zeroes option, so at least for blockdev-backup user
> should define it if zero-detection is needed. For drive-backup leave
> detection enabled by default but do it through existing option instead
> of open-coding.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
> ---
> block/backup.c | 15 ++++++---------
> blockdev.c | 8 ++++----
> 2 files changed, 10 insertions(+), 13 deletions(-)
>
> diff --git a/block/backup.c b/block/backup.c
> index 715e1d3be8..f4aaf08df3 100644
> --- a/block/backup.c
> +++ b/block/backup.c
> @@ -110,7 +110,10 @@ static int coroutine_fn
> backup_cow_with_bounce_buffer(BackupBlockJob *job,
> BlockBackend *blk = job->common.blk;
> int nbytes;
> int read_flags = is_write_notifier ? BDRV_REQ_NO_SERIALISING : 0;
> - int write_flags = job->serialize_target_writes ? BDRV_REQ_SERIALISING :
> 0;
> + int write_flags =
> + (job->serialize_target_writes ? BDRV_REQ_SERIALISING : 0) |
> + (job->compress ? BDRV_REQ_WRITE_COMPRESSED : 0);
> +
>
> assert(QEMU_IS_ALIGNED(start, job->cluster_size));
> hbitmap_reset(job->copy_bitmap, start, job->cluster_size);
> @@ -128,14 +131,8 @@ static int coroutine_fn
> backup_cow_with_bounce_buffer(BackupBlockJob *job,
> goto fail;
> }
>
> - if (buffer_is_zero(*bounce_buffer, nbytes)) {
> - ret = blk_co_pwrite_zeroes(job->target, start,
> - nbytes, write_flags | BDRV_REQ_MAY_UNMAP);
> - } else {
> - ret = blk_co_pwrite(job->target, start,
> - nbytes, *bounce_buffer, write_flags |
> - (job->compress ? BDRV_REQ_WRITE_COMPRESSED : 0));
> - }
> + ret = blk_co_pwrite(job->target, start, nbytes, *bounce_buffer,
> + write_flags);
> if (ret < 0) {
> trace_backup_do_cow_write_fail(job, start, ret);
> if (error_is_read) {
> diff --git a/blockdev.c b/blockdev.c
> index 4d141e9a1f..a94d754504 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -3434,7 +3434,7 @@ static BlockJob *do_drive_backup(DriveBackup *backup,
> JobTxn *txn,
> BlockJob *job = NULL;
> BdrvDirtyBitmap *bmap = NULL;
> AioContext *aio_context;
> - QDict *options = NULL;
> + QDict *options;
> Error *local_err = NULL;
> int flags, job_flags = JOB_DEFAULT;
> int64_t size;
> @@ -3529,10 +3529,10 @@ static BlockJob *do_drive_backup(DriveBackup *backup,
> JobTxn *txn,
> goto out;
> }
>
> + options = qdict_new();
> + qdict_put_str(options, "discard", "unmap");
> + qdict_put_str(options, "detect-zeroes", "unmap");
> if (backup->format) {
> - if (!options) {
> - options = qdict_new();
> - }
> qdict_put_str(options, "driver", backup->format);
> }
>
>
I'm less sure of this one personally. Is it right to always try to set
unmap on the target?
I like the idea of removing special cases and handling things more
centrally though, but I'll want Max (or Kevin) to take a peek.
--js