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Re: [PATCH v3 18/36] block: add bdrv_attach_child_common() transaction a
From: |
Kevin Wolf |
Subject: |
Re: [PATCH v3 18/36] block: add bdrv_attach_child_common() transaction action |
Date: |
Mon, 26 Apr 2021 18:14:00 +0200 |
Am 17.03.2021 um 15:35 hat Vladimir Sementsov-Ogievskiy geschrieben:
> Split out no-perm part of bdrv_root_attach_child() into separate
> transaction action. bdrv_root_attach_child() now moves to new
> permission update paradigm: first update graph relations then update
> permissions.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
> block.c | 189 ++++++++++++++++++++++++++++++++++++++++----------------
> 1 file changed, 135 insertions(+), 54 deletions(-)
>
> diff --git a/block.c b/block.c
> index 98ff44dbf7..b6bdc534d2 100644
> --- a/block.c
> +++ b/block.c
> @@ -2921,37 +2921,73 @@ static void bdrv_replace_child(BdrvChild *child,
> BlockDriverState *new_bs)
> }
> }
>
> -/*
> - * This function steals the reference to child_bs from the caller.
> - * That reference is later dropped by bdrv_root_unref_child().
> - *
> - * On failure NULL is returned, errp is set and the reference to
> - * child_bs is also dropped.
> - *
> - * The caller must hold the AioContext lock @child_bs, but not that of @ctx
> - * (unless @child_bs is already in @ctx).
> - */
> -BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
> - const char *child_name,
> - const BdrvChildClass *child_class,
> - BdrvChildRole child_role,
> - uint64_t perm, uint64_t shared_perm,
> - void *opaque, Error **errp)
> +static void bdrv_remove_empty_child(BdrvChild *child)
> {
> - BdrvChild *child;
> - Error *local_err = NULL;
> - int ret;
> - AioContext *ctx;
> + assert(!child->bs);
> + QLIST_SAFE_REMOVE(child, next);
> + g_free(child->name);
> + g_free(child);
> +}
>
> - ret = bdrv_check_update_perm(child_bs, NULL, perm, shared_perm, NULL,
> errp);
> - if (ret < 0) {
> - bdrv_abort_perm_update(child_bs);
> - bdrv_unref(child_bs);
> - return NULL;
> +typedef struct BdrvAttachChildCommonState {
> + BdrvChild **child;
> + AioContext *old_parent_ctx;
> + AioContext *old_child_ctx;
> +} BdrvAttachChildCommonState;
> +
> +static void bdrv_attach_child_common_abort(void *opaque)
> +{
> + BdrvAttachChildCommonState *s = opaque;
> + BdrvChild *child = *s->child;
> + BlockDriverState *bs = child->bs;
> +
> + bdrv_replace_child_noperm(child, NULL);
> +
> + if (bdrv_get_aio_context(bs) != s->old_child_ctx) {
> + bdrv_try_set_aio_context(bs, s->old_child_ctx, &error_abort);
> }
>
> - child = g_new(BdrvChild, 1);
> - *child = (BdrvChild) {
> + if (bdrv_child_get_parent_aio_context(child) != s->old_parent_ctx) {
> + GSList *ignore = g_slist_prepend(NULL, child);
> +
> + child->klass->can_set_aio_ctx(child, s->old_parent_ctx, &ignore,
> + &error_abort);
> + g_slist_free(ignore);
> + ignore = g_slist_prepend(NULL, child);
> + child->klass->set_aio_ctx(child, s->old_parent_ctx, &ignore);
> +
> + g_slist_free(ignore);
> + }
> +
> + bdrv_unref(bs);
> + bdrv_remove_empty_child(child);
> + *s->child = NULL;
> +}
> +
> +static TransactionActionDrv bdrv_attach_child_common_drv = {
> + .abort = bdrv_attach_child_common_abort,
> +};
> +
> +/*
> + * Common part of attoching bdrv child to bs or to blk or to job
> + */
> +static int bdrv_attach_child_common(BlockDriverState *child_bs,
> + const char *child_name,
> + const BdrvChildClass *child_class,
> + BdrvChildRole child_role,
> + uint64_t perm, uint64_t shared_perm,
> + void *opaque, BdrvChild **child,
> + Transaction *tran, Error **errp)
> +{
> + BdrvChild *new_child;
> + AioContext *parent_ctx;
> + AioContext *child_ctx = bdrv_get_aio_context(child_bs);
> +
> + assert(child);
> + assert(*child == NULL);
> +
> + new_child = g_new(BdrvChild, 1);
> + *new_child = (BdrvChild) {
> .bs = NULL,
> .name = g_strdup(child_name),
> .klass = child_class,
> @@ -2961,37 +2997,92 @@ BdrvChild *bdrv_root_attach_child(BlockDriverState
> *child_bs,
> .opaque = opaque,
> };
>
> - ctx = bdrv_child_get_parent_aio_context(child);
> -
> - /* If the AioContexts don't match, first try to move the subtree of
> + /*
> + * If the AioContexts don't match, first try to move the subtree of
> * child_bs into the AioContext of the new parent. If this doesn't work,
> - * try moving the parent into the AioContext of child_bs instead. */
> - if (bdrv_get_aio_context(child_bs) != ctx) {
> - ret = bdrv_try_set_aio_context(child_bs, ctx, &local_err);
> + * try moving the parent into the AioContext of child_bs instead.
> + */
> + parent_ctx = bdrv_child_get_parent_aio_context(new_child);
> + if (child_ctx != parent_ctx) {
> + Error *local_err = NULL;
> + int ret = bdrv_try_set_aio_context(child_bs, parent_ctx, &local_err);
> +
> if (ret < 0 && child_class->can_set_aio_ctx) {
> - GSList *ignore = g_slist_prepend(NULL, child);
> - ctx = bdrv_get_aio_context(child_bs);
> - if (child_class->can_set_aio_ctx(child, ctx, &ignore, NULL)) {
> + GSList *ignore = g_slist_prepend(NULL, new_child);
> + if (child_class->can_set_aio_ctx(new_child, child_ctx, &ignore,
> + NULL))
> + {
> error_free(local_err);
> ret = 0;
> g_slist_free(ignore);
> - ignore = g_slist_prepend(NULL, child);
> - child_class->set_aio_ctx(child, ctx, &ignore);
> + ignore = g_slist_prepend(NULL, new_child);
> + child_class->set_aio_ctx(new_child, child_ctx, &ignore);
> }
> g_slist_free(ignore);
> }
> +
> if (ret < 0) {
> error_propagate(errp, local_err);
> - g_free(child);
> - bdrv_abort_perm_update(child_bs);
> - bdrv_unref(child_bs);
> - return NULL;
> + bdrv_remove_empty_child(new_child);
> + return ret;
> }
> }
>
> - /* This performs the matching bdrv_set_perm() for the above check. */
> - bdrv_replace_child(child, child_bs);
> + bdrv_ref(child_bs);
> + bdrv_replace_child_noperm(new_child, child_bs);
> +
> + *child = new_child;
>
> + BdrvAttachChildCommonState *s = g_new(BdrvAttachChildCommonState, 1);
> + *s = (BdrvAttachChildCommonState) {
> + .child = child,
> + .old_parent_ctx = parent_ctx,
> + .old_child_ctx = child_ctx,
> + };
> + tran_add(tran, &bdrv_attach_child_common_drv, s);
Who frees s? Should bdrv_attach_child_common_drv have a .clean?
> +
> + return 0;
> +}
Kevin
- Re: [PATCH v3 18/36] block: add bdrv_attach_child_common() transaction action,
Kevin Wolf <=