diff options
| -rw-r--r-- | block.c | 32 | ||||
| -rw-r--r-- | block/mirror.c | 23 | ||||
| -rw-r--r-- | include/block/block.h | 4 | ||||
| -rw-r--r-- | qemu-img.c | 16 |
4 files changed, 49 insertions, 26 deletions
@@ -1095,7 +1095,7 @@ static BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs, return child; } -void bdrv_detach_child(BdrvChild *child) +static void bdrv_detach_child(BdrvChild *child) { QLIST_REMOVE(child, next); QLIST_REMOVE(child, next_parent); @@ -2232,6 +2232,36 @@ void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top) bdrv_unref(bs_new); } +void bdrv_replace_in_backing_chain(BlockDriverState *old, BlockDriverState *new) +{ + assert(!bdrv_requests_pending(old)); + assert(!bdrv_requests_pending(new)); + + bdrv_ref(old); + + if (old->blk) { + /* As long as these fields aren't in BlockBackend, but in the top-level + * BlockDriverState, it's not possible for a BDS to have two BBs. + * + * We really want to copy the fields from old to new, but we go for a + * swap instead so that pointers aren't duplicated and cause trouble. + * (Also, bdrv_swap() used to do the same.) */ + assert(!new->blk); + swap_feature_fields(old, new); + } + change_parent_backing_link(old, new); + + /* Change backing files if a previously independent node is added to the + * chain. For active commit, we replace top by its own (indirect) backing + * file and don't do anything here so we don't build a loop. */ + if (new->backing == NULL && !bdrv_chain_contains(backing_bs(old), new)) { + bdrv_set_backing_hd(new, backing_bs(old)); + bdrv_set_backing_hd(old, NULL); + } + + bdrv_unref(old); +} + static void bdrv_delete(BlockDriverState *bs) { assert(!bs->job); diff --git a/block/mirror.c b/block/mirror.c index c277691e4d..7e43511832 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -353,6 +353,11 @@ static void mirror_exit(BlockJob *job, void *opaque) MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); MirrorExitData *data = opaque; AioContext *replace_aio_context = NULL; + BlockDriverState *src = s->common.bs; + + /* Make sure that the source BDS doesn't go away before we called + * block_job_completed(). */ + bdrv_ref(src); if (s->to_replace) { replace_aio_context = bdrv_get_aio_context(s->to_replace); @@ -367,22 +372,7 @@ static void mirror_exit(BlockJob *job, void *opaque) if (bdrv_get_flags(s->target) != bdrv_get_flags(to_replace)) { bdrv_reopen(s->target, bdrv_get_flags(to_replace), NULL); } - bdrv_swap(s->target, to_replace); - if (s->common.driver->job_type == BLOCK_JOB_TYPE_COMMIT) { - /* drop the bs loop chain formed by the swap: break the loop then - * trigger the unref */ - /* FIXME This duplicates bdrv_set_backing_hd(), except for the - * actual detach/unref so that the loop can be broken. When - * bdrv_swap() gets replaced, this will become sane again. */ - BlockDriverState *backing = s->base->backing->bs; - assert(s->base->backing_blocker); - bdrv_op_unblock_all(backing, s->base->backing_blocker); - error_free(s->base->backing_blocker); - s->base->backing_blocker = NULL; - bdrv_detach_child(s->base->backing); - s->base->backing = NULL; - bdrv_unref(backing); - } + bdrv_replace_in_backing_chain(to_replace, s->target); } if (s->to_replace) { bdrv_op_unblock_all(s->to_replace, s->replace_blocker); @@ -396,6 +386,7 @@ static void mirror_exit(BlockJob *job, void *opaque) bdrv_unref(s->target); block_job_completed(&s->common, data->ret); g_free(data); + bdrv_unref(src); } static void coroutine_fn mirror_run(void *opaque) diff --git a/include/block/block.h b/include/block/block.h index da94bdfa9d..6d70eb42fe 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -203,6 +203,9 @@ BlockDriverState *bdrv_new(void); void bdrv_make_anon(BlockDriverState *bs); void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old); void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top); +void bdrv_replace_in_backing_chain(BlockDriverState *old, + BlockDriverState *new); + int bdrv_parse_cache_flags(const char *mode, int *flags); int bdrv_parse_discard_flags(const char *mode, int *flags); BdrvChild *bdrv_open_child(const char *filename, @@ -513,7 +516,6 @@ void bdrv_disable_copy_on_read(BlockDriverState *bs); void bdrv_ref(BlockDriverState *bs); void bdrv_unref(BlockDriverState *bs); void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child); -void bdrv_detach_child(BdrvChild *child); bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp); void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason); diff --git a/qemu-img.c b/qemu-img.c index e678fdc403..3025776e14 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -766,12 +766,12 @@ static int img_commit(int argc, char **argv) goto done; } - /* The block job will swap base_bs and bs (which is not what we really want - * here, but okay) and unref base_bs (after the swap, i.e., the old top - * image). In order to still be able to empty that top image afterwards, - * increment the reference counter here preemptively. */ + /* When the block job completes, the BlockBackend reference will point to + * the old backing file. In order to avoid that the top image is already + * deleted, so we can still empty it afterwards, increment the reference + * counter here preemptively. */ if (!drop) { - bdrv_ref(base_bs); + bdrv_ref(bs); } run_block_job(bs->job, &local_err); @@ -779,8 +779,8 @@ static int img_commit(int argc, char **argv) goto unref_backing; } - if (!drop && base_bs->drv->bdrv_make_empty) { - ret = base_bs->drv->bdrv_make_empty(base_bs); + if (!drop && bs->drv->bdrv_make_empty) { + ret = bs->drv->bdrv_make_empty(bs); if (ret) { error_setg_errno(&local_err, -ret, "Could not empty %s", filename); @@ -790,7 +790,7 @@ static int img_commit(int argc, char **argv) unref_backing: if (!drop) { - bdrv_unref(base_bs); + bdrv_unref(bs); } done: |