diff options
| -rw-r--r-- | block.c | 23 |
1 files changed, 23 insertions, 0 deletions
@@ -5265,6 +5265,8 @@ int bdrv_drop_filter(BlockDriverState *bs, Error **errp) * child. * * This function does not create any image files. + * + * The caller must hold the AioContext lock for @bs_top. */ int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top, Error **errp) @@ -5272,11 +5274,14 @@ int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top, int ret; BdrvChild *child; Transaction *tran = tran_new(); + AioContext *old_context, *new_context = NULL; GLOBAL_STATE_CODE(); assert(!bs_new->backing); + old_context = bdrv_get_aio_context(bs_top); + child = bdrv_attach_child_noperm(bs_new, bs_top, "backing", &child_of_bds, bdrv_backing_role(bs_new), tran, errp); @@ -5285,6 +5290,19 @@ int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top, goto out; } + /* + * bdrv_attach_child_noperm could change the AioContext of bs_top. + * bdrv_replace_node_noperm calls bdrv_drained_begin, so let's temporarily + * hold the new AioContext, since bdrv_drained_begin calls BDRV_POLL_WHILE + * that assumes the new lock is taken. + */ + new_context = bdrv_get_aio_context(bs_top); + + if (old_context != new_context) { + aio_context_release(old_context); + aio_context_acquire(new_context); + } + ret = bdrv_replace_node_noperm(bs_top, bs_new, true, tran, errp); if (ret < 0) { goto out; @@ -5296,6 +5314,11 @@ out: bdrv_refresh_limits(bs_top, NULL, NULL); + if (new_context && old_context != new_context) { + aio_context_release(new_context); + aio_context_acquire(old_context); + } + return ret; } |