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Re: [Qemu-block] [PATCH v2] block: mirror - fix full sync mode when targ
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-block] [PATCH v2] block: mirror - fix full sync mode when target does not support zero init |
Date: |
Thu, 1 Oct 2015 12:13:29 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 |
On 01/10/2015 06:31, Jeff Cody wrote:
> During mirror, if the target device does not support zero init, a
> mirror may result in a corrupted image for sync="full" mode.
>
> This is due to how the initial dirty bitmap is set up prior to copying
> data - we did not mark sectors as dirty that are unallocated. This
> means those unallocated sectors are skipped over on the target, and for
> a device without zero init, invalid data may reside in those holes.
>
> If both of the following conditions are true, then we will explicitly
> mark all sectors as dirty:
>
> 1.) sync = "full"
> 2.) bdrv_has_zero_init(target) == false
>
> If the target does support zero init, but a target image is passed in
> with data already present (i.e. an "existing" image), it is assumed the
> data present in the existing image is valid data for those sectors.
>
> Signed-off-by: Jeff Cody <address@hidden>
> ---
> block/mirror.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/block/mirror.c b/block/mirror.c
> index a258926..5d7828b 100644
> --- a/block/mirror.c
> +++ b/block/mirror.c
> @@ -61,6 +61,7 @@ typedef struct MirrorBlockJob {
> int ret;
> bool unmap;
> bool waiting_for_io;
> + bool mark_all_dirty;
> } MirrorBlockJob;
>
> typedef struct MirrorOp {
> @@ -477,7 +478,7 @@ static void coroutine_fn mirror_run(void *opaque)
> }
>
> assert(n > 0);
> - if (ret == 1) {
> + if (ret == 1 || s->mark_all_dirty) {
We can get the information directly in mirror_run, since we have target
and we have the sync mode (it is 'full' if s->base == NULL). This
avoids adding a zillionth argument to mirror_start_job. :)
Paolo
> bdrv_set_dirty_bitmap(s->dirty_bitmap, sector_num, n);
> }
> sector_num += n;
> @@ -688,7 +689,7 @@ static void mirror_start_job(BlockDriverState *bs,
> BlockDriverState *target,
> int64_t buf_size,
> BlockdevOnError on_source_error,
> BlockdevOnError on_target_error,
> - bool unmap,
> + bool unmap, bool mark_all_dirty,
> BlockCompletionFunc *cb,
> void *opaque, Error **errp,
> const BlockJobDriver *driver,
> @@ -732,6 +733,7 @@ static void mirror_start_job(BlockDriverState *bs,
> BlockDriverState *target,
> s->granularity = granularity;
> s->buf_size = ROUND_UP(buf_size, granularity);
> s->unmap = unmap;
> + s->mark_all_dirty = mark_all_dirty;
>
> s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp);
> if (!s->dirty_bitmap) {
> @@ -757,6 +759,7 @@ void mirror_start(BlockDriverState *bs, BlockDriverState
> *target,
> void *opaque, Error **errp)
> {
> bool is_none_mode;
> + bool mark_all_dirty;
> BlockDriverState *base;
>
> if (mode == MIRROR_SYNC_MODE_INCREMENTAL) {
> @@ -764,11 +767,13 @@ void mirror_start(BlockDriverState *bs,
> BlockDriverState *target,
> return;
> }
> is_none_mode = mode == MIRROR_SYNC_MODE_NONE;
> + mark_all_dirty = mode == MIRROR_SYNC_MODE_FULL &&
> + !bdrv_has_zero_init(target);
> base = mode == MIRROR_SYNC_MODE_TOP ? bs->backing_hd : NULL;
> mirror_start_job(bs, target, replaces,
> speed, granularity, buf_size,
> - on_source_error, on_target_error, unmap, cb, opaque,
> errp,
> - &mirror_job_driver, is_none_mode, base);
> + on_source_error, on_target_error, unmap, mark_all_dirty,
> + cb, opaque, errp, &mirror_job_driver, is_none_mode,
> base);
> }
>
> void commit_active_start(BlockDriverState *bs, BlockDriverState *base,
> @@ -815,7 +820,7 @@ void commit_active_start(BlockDriverState *bs,
> BlockDriverState *base,
>
> bdrv_ref(base);
> mirror_start_job(bs, base, NULL, speed, 0, 0,
> - on_error, on_error, false, cb, opaque, &local_err,
> + on_error, on_error, false, false, cb, opaque,
> &local_err,
> &commit_active_job_driver, false, base);
> if (local_err) {
> error_propagate(errp, local_err);
>