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block-backend: implement .change_aio_ctx in child_root

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blk_root_change_aio_ctx() is very similar to blk_root_can_set_aio_ctx(),
but implements a new transaction so that if all check pass, the new
transaction's .commit will take care of changing the BlockBackend
AioContext. blk_root_set_aio_ctx_commit() is the same as
blk_root_set_aio_ctx().

Note: bdrv_child_try_change_aio_context() is not called by
anyone at this point.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20221025084952.2139888-7-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Emanuele Giuseppe Esposito 2022-10-25 04:49:48 -04:00 committed by Kevin Wolf
parent 27633e740e
commit 3394939621
1 changed files with 52 additions and 0 deletions
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52
block/block-backend.c
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@ -138,6 +138,9 @@ static bool blk_root_can_set_aio_ctx(BdrvChild *child, AioContext *ctx,
GSList **ignore, Error **errp);
static void blk_root_set_aio_ctx(BdrvChild *child, AioContext *ctx,
GSList **ignore);
static bool blk_root_change_aio_ctx(BdrvChild *child, AioContext *ctx,
GHashTable *visited, Transaction *tran,
Error **errp);
static char *blk_root_get_parent_desc(BdrvChild *child)
{
@ -336,6 +339,7 @@ static const BdrvChildClass child_root = {
.can_set_aio_ctx = blk_root_can_set_aio_ctx,
.set_aio_ctx = blk_root_set_aio_ctx,
.change_aio_ctx = blk_root_change_aio_ctx,
.get_parent_aio_context = blk_root_get_parent_aio_context,
};
@ -2177,6 +2181,54 @@ int blk_set_aio_context(BlockBackend *blk, AioContext *new_context,
return blk_do_set_aio_context(blk, new_context, true, errp);
}
typedef struct BdrvStateBlkRootContext {
AioContext *new_ctx;
BlockBackend *blk;
} BdrvStateBlkRootContext;
static void blk_root_set_aio_ctx_commit(void *opaque)
{
BdrvStateBlkRootContext *s = opaque;
BlockBackend *blk = s->blk;
blk_do_set_aio_context(blk, s->new_ctx, false, &error_abort);
}
static TransactionActionDrv set_blk_root_context = {
.commit = blk_root_set_aio_ctx_commit,
.clean = g_free,
};
static bool blk_root_change_aio_ctx(BdrvChild *child, AioContext *ctx,
GHashTable *visited, Transaction *tran,
Error **errp)
{
BlockBackend *blk = child->opaque;
BdrvStateBlkRootContext *s;
if (!blk->allow_aio_context_change) {
/*
* Manually created BlockBackends (those with a name) that are not
* attached to anything can change their AioContext without updating
* their user; return an error for others.
*/
if (!blk->name || blk->dev) {
/* TODO Add BB name/QOM path */
error_setg(errp, "Cannot change iothread of active block backend");
return false;
}
}
s = g_new(BdrvStateBlkRootContext, 1);
*s = (BdrvStateBlkRootContext) {
.new_ctx = ctx,
.blk = blk,
};
tran_add(tran, &set_blk_root_context, s);
return true;
}
static bool blk_root_can_set_aio_ctx(BdrvChild *child, AioContext *ctx,
GSList **ignore, Error **errp)
{