diff options
Diffstat (limited to 'block.c')
| -rw-r--r-- | block.c | 133 |
1 files changed, 85 insertions, 48 deletions
diff --git a/block.c b/block.c index 0973b91d98..f6e7cf4fb9 100644 --- a/block.c +++ b/block.c @@ -3004,13 +3004,14 @@ static TransactionActionDrv bdrv_attach_child_common_drv = { * @child_bs can move to a different AioContext in this function. Callers must * make sure that their AioContext locking is still correct after this. */ -static BdrvChild *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, - Transaction *tran, Error **errp) +static BdrvChild * GRAPH_WRLOCK +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, + Transaction *tran, Error **errp) { BdrvChild *new_child; AioContext *parent_ctx, *new_child_ctx; @@ -3088,10 +3089,8 @@ static BdrvChild *bdrv_attach_child_common(BlockDriverState *child_bs, * a problem, we already did this), but it will still poll until the parent * is fully quiesced, so it will not be negatively affected either. */ - bdrv_graph_wrlock(child_bs); bdrv_parent_drained_begin_single(new_child); bdrv_replace_child_noperm(new_child, child_bs); - bdrv_graph_wrunlock(); BdrvAttachChildCommonState *s = g_new(BdrvAttachChildCommonState, 1); *s = (BdrvAttachChildCommonState) { @@ -3116,13 +3115,14 @@ static BdrvChild *bdrv_attach_child_common(BlockDriverState *child_bs, * @child_bs can move to a different AioContext in this function. Callers must * make sure that their AioContext locking is still correct after this. */ -static BdrvChild *bdrv_attach_child_noperm(BlockDriverState *parent_bs, - BlockDriverState *child_bs, - const char *child_name, - const BdrvChildClass *child_class, - BdrvChildRole child_role, - Transaction *tran, - Error **errp) +static BdrvChild * GRAPH_WRLOCK +bdrv_attach_child_noperm(BlockDriverState *parent_bs, + BlockDriverState *child_bs, + const char *child_name, + const BdrvChildClass *child_class, + BdrvChildRole child_role, + Transaction *tran, + Error **errp) { uint64_t perm, shared_perm; @@ -3167,6 +3167,8 @@ BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs, GLOBAL_STATE_CODE(); + bdrv_graph_wrlock(child_bs); + child = bdrv_attach_child_common(child_bs, child_name, child_class, child_role, perm, shared_perm, opaque, tran, errp); @@ -3178,6 +3180,7 @@ BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs, ret = bdrv_refresh_perms(child_bs, tran, errp); out: + bdrv_graph_wrunlock(); tran_finalize(tran, ret); bdrv_unref(child_bs); @@ -3209,6 +3212,8 @@ BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs, GLOBAL_STATE_CODE(); + bdrv_graph_wrlock(child_bs); + child = bdrv_attach_child_noperm(parent_bs, child_bs, child_name, child_class, child_role, tran, errp); if (!child) { @@ -3222,6 +3227,7 @@ BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs, } out: + bdrv_graph_wrunlock(); tran_finalize(tran, ret); bdrv_unref(child_bs); @@ -3379,16 +3385,20 @@ static BdrvChildRole bdrv_backing_role(BlockDriverState *bs) * Sets the bs->backing or bs->file link of a BDS. A new reference is created; * callers which don't need their own reference any more must call bdrv_unref(). * + * If the respective child is already present (i.e. we're detaching a node), + * that child node must be drained. + * * Function doesn't update permissions, caller is responsible for this. * * The caller must hold the AioContext lock for @child_bs. Both @parent_bs and * @child_bs can move to a different AioContext in this function. Callers must * make sure that their AioContext locking is still correct after this. */ -static int bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs, - BlockDriverState *child_bs, - bool is_backing, - Transaction *tran, Error **errp) +static int GRAPH_WRLOCK +bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs, + BlockDriverState *child_bs, + bool is_backing, + Transaction *tran, Error **errp) { bool update_inherits_from = bdrv_inherits_from_recursive(child_bs, parent_bs); @@ -3439,14 +3449,9 @@ static int bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs, } if (child) { - bdrv_drained_begin(child->bs); - bdrv_graph_wrlock(NULL); - + assert(child->bs->quiesce_counter); bdrv_unset_inherits_from(parent_bs, child, tran); bdrv_remove_child(child, tran); - - bdrv_graph_wrunlock(); - bdrv_drained_end(child->bs); } if (!child_bs) { @@ -3471,9 +3476,7 @@ static int bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs, } out: - bdrv_graph_rdlock_main_loop(); bdrv_refresh_limits(parent_bs, tran, NULL); - bdrv_graph_rdunlock_main_loop(); return 0; } @@ -3482,10 +3485,14 @@ out: * The caller must hold the AioContext lock for @backing_hd. Both @bs and * @backing_hd can move to a different AioContext in this function. Callers must * make sure that their AioContext locking is still correct after this. + * + * If a backing child is already present (i.e. we're detaching a node), that + * child node must be drained. */ -static int bdrv_set_backing_noperm(BlockDriverState *bs, - BlockDriverState *backing_hd, - Transaction *tran, Error **errp) +static int GRAPH_WRLOCK +bdrv_set_backing_noperm(BlockDriverState *bs, + BlockDriverState *backing_hd, + Transaction *tran, Error **errp) { GLOBAL_STATE_CODE(); return bdrv_set_file_or_backing_noperm(bs, backing_hd, true, tran, errp); @@ -3500,6 +3507,10 @@ int bdrv_set_backing_hd_drained(BlockDriverState *bs, GLOBAL_STATE_CODE(); assert(bs->quiesce_counter > 0); + if (bs->backing) { + assert(bs->backing->bs->quiesce_counter > 0); + } + bdrv_graph_wrlock(backing_hd); ret = bdrv_set_backing_noperm(bs, backing_hd, tran, errp); if (ret < 0) { @@ -3508,6 +3519,7 @@ int bdrv_set_backing_hd_drained(BlockDriverState *bs, ret = bdrv_refresh_perms(bs, tran, errp); out: + bdrv_graph_wrunlock(); tran_finalize(tran, ret); return ret; } @@ -3515,12 +3527,15 @@ out: int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd, Error **errp) { + BlockDriverState *drain_bs = bs->backing ? bs->backing->bs : bs; int ret; GLOBAL_STATE_CODE(); - bdrv_drained_begin(bs); + bdrv_ref(drain_bs); + bdrv_drained_begin(drain_bs); ret = bdrv_set_backing_hd_drained(bs, backing_hd, errp); - bdrv_drained_end(bs); + bdrv_drained_end(drain_bs); + bdrv_unref(drain_bs); return ret; } @@ -4597,6 +4612,7 @@ int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp) abort: tran_abort(tran); + QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) { if (bs_entry->prepared) { ctx = bdrv_get_aio_context(bs_entry->state.bs); @@ -4746,6 +4762,11 @@ static int bdrv_reopen_parse_file_or_backing(BDRVReopenState *reopen_state, reopen_state->old_file_bs = old_child_bs; } + if (old_child_bs) { + bdrv_ref(old_child_bs); + bdrv_drained_begin(old_child_bs); + } + old_ctx = bdrv_get_aio_context(bs); ctx = bdrv_get_aio_context(new_child_bs); if (old_ctx != ctx) { @@ -4753,14 +4774,23 @@ static int bdrv_reopen_parse_file_or_backing(BDRVReopenState *reopen_state, aio_context_acquire(ctx); } + bdrv_graph_wrlock(new_child_bs); + ret = bdrv_set_file_or_backing_noperm(bs, new_child_bs, is_backing, tran, errp); + bdrv_graph_wrunlock(); + if (old_ctx != ctx) { aio_context_release(ctx); aio_context_acquire(old_ctx); } + if (old_child_bs) { + bdrv_drained_end(old_child_bs); + bdrv_unref(old_child_bs); + } + return ret; } @@ -5403,13 +5433,28 @@ int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top, BdrvChild *child; Transaction *tran = tran_new(); AioContext *old_context, *new_context = NULL; - bool drained = false; GLOBAL_STATE_CODE(); assert(!bs_new->backing); old_context = bdrv_get_aio_context(bs_top); + bdrv_drained_begin(bs_top); + + /* + * bdrv_drained_begin() requires that only the AioContext of the drained + * node is locked, and at this point it can still differ from the AioContext + * of bs_top. + */ + new_context = bdrv_get_aio_context(bs_new); + aio_context_release(old_context); + aio_context_acquire(new_context); + bdrv_drained_begin(bs_new); + aio_context_release(new_context); + aio_context_acquire(old_context); + new_context = NULL; + + bdrv_graph_wrlock(bs_top); child = bdrv_attach_child_noperm(bs_new, bs_top, "backing", &child_of_bds, bdrv_backing_role(bs_new), @@ -5420,10 +5465,9 @@ int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top, } /* - * 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. + * bdrv_attach_child_noperm could change the AioContext of bs_top and + * bs_new, but at least they are in the same AioContext now. This is the + * AioContext that we need to lock for the rest of the function. */ new_context = bdrv_get_aio_context(bs_top); @@ -5432,29 +5476,22 @@ int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top, aio_context_acquire(new_context); } - bdrv_drained_begin(bs_new); - bdrv_drained_begin(bs_top); - drained = true; - - bdrv_graph_wrlock(bs_new); ret = bdrv_replace_node_noperm(bs_top, bs_new, true, tran, errp); - bdrv_graph_wrunlock(); if (ret < 0) { goto out; } ret = bdrv_refresh_perms(bs_new, tran, errp); out: + bdrv_graph_wrunlock(); tran_finalize(tran, ret); bdrv_graph_rdlock_main_loop(); bdrv_refresh_limits(bs_top, NULL, NULL); bdrv_graph_rdunlock_main_loop(); - if (drained) { - bdrv_drained_end(bs_top); - bdrv_drained_end(bs_new); - } + bdrv_drained_end(bs_top); + bdrv_drained_end(bs_new); if (new_context && old_context != new_context) { aio_context_release(new_context); |