Commit 565ac01f authored by Stefan Hajnoczi's avatar Stefan Hajnoczi
Browse files

mirror: follow AioContext change gracefully 



Add block_job_pause_point() calls to mark quiescent points and make sure
to complete in-flight requests when switching AioContexts.

This patch solves undefined behavior in the mirror block job when the
BDS AioContext is changed by dataplane.

Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: default avatarFam Zheng <famz@redhat.com>
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: default avatarFam Zheng <famz@redhat.com>
Message-id: 1466096189-6477-8-git-send-email-stefanha@redhat.com
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent 463e0be1

block/mirror.c

+35 −8
Original line number Diff line number Diff line
@@ -331,6 +331,8 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) 
        mirror_wait_for_io(s);

    }



    block_job_pause_point(&s->common);



    /* Find the number of consective dirty chunks following the first dirty

     * one, and wait for in flight requests in them. */

    while (nb_chunks * sectors_per_chunk < (s->buf_size >> BDRV_SECTOR_BITS)) {
@@ -582,6 +584,8 @@ static void coroutine_fn mirror_run(void *opaque) 
            if (now - last_pause_ns > SLICE_TIME) {

                last_pause_ns = now;

                block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, 0);

            } else {

                block_job_pause_point(&s->common);

            }



            if (block_job_is_cancelled(&s->common)) {
@@ -613,6 +617,8 @@ static void coroutine_fn mirror_run(void *opaque) 
            goto immediate_exit;

        }



        block_job_pause_point(&s->common);



        cnt = bdrv_get_dirty_count(s->dirty_bitmap);

        /* s->common.offset contains the number of bytes already processed so

         * far, cnt is the number of dirty sectors remaining and
@@ -795,11 +801,30 @@ static void mirror_complete(BlockJob *job, Error **errp) 
    block_job_enter(&s->common);

}



/* There is no matching mirror_resume() because mirror_run() will begin

 * iterating again when the job is resumed.

 */

static void coroutine_fn mirror_pause(BlockJob *job)

{

    MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);



    mirror_drain(s);

}



static void mirror_attached_aio_context(BlockJob *job, AioContext *new_context)

{

    MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);



    blk_set_aio_context(s->target, new_context);

}



static const BlockJobDriver mirror_job_driver = {

    .instance_size          = sizeof(MirrorBlockJob),

    .job_type               = BLOCK_JOB_TYPE_MIRROR,

    .set_speed              = mirror_set_speed,

    .complete               = mirror_complete,

    .pause                  = mirror_pause,

    .attached_aio_context   = mirror_attached_aio_context,

};



static const BlockJobDriver commit_active_job_driver = {
@@ -807,6 +832,8 @@ static const BlockJobDriver commit_active_job_driver = { 
    .job_type               = BLOCK_JOB_TYPE_COMMIT,

    .set_speed              = mirror_set_speed,

    .complete               = mirror_complete,

    .pause                  = mirror_pause,

    .attached_aio_context   = mirror_attached_aio_context,

};



static void mirror_start_job(BlockDriverState *bs, BlockDriverState *target,