block: make bdrv_refresh_limits() to be a transaction action

To be used in further commit.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210428151804.439460-28-vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 29 insertions, 2 deletions

diff --git a/block/io.c b/block/io.c
index ca2dca3..35b6c56 100644
--- a/block/io.c
+++ b/block/io.c
@@ -133,13 +133,40 @@ static void bdrv_merge_limits(BlockLimits *dst, const BlockLimits *src)
     dst->max_iov = MIN_NON_ZERO(dst->max_iov, src->max_iov);
 }
 
-void bdrv_refresh_limits(BlockDriverState *bs, Error **errp)
+typedef struct BdrvRefreshLimitsState {
+    BlockDriverState *bs;
+    BlockLimits old_bl;
+} BdrvRefreshLimitsState;
+
+static void bdrv_refresh_limits_abort(void *opaque)
+{
+    BdrvRefreshLimitsState *s = opaque;
+
+    s->bs->bl = s->old_bl;
+}
+
+static TransactionActionDrv bdrv_refresh_limits_drv = {
+    .abort = bdrv_refresh_limits_abort,
+    .clean = g_free,
+};
+
+/* @tran is allowed to be NULL, in this case no rollback is possible. */
+void bdrv_refresh_limits(BlockDriverState *bs, Transaction *tran, Error **errp)
 {
     ERRP_GUARD();
     BlockDriver *drv = bs->drv;
     BdrvChild *c;
     bool have_limits;
 
+    if (tran) {
+        BdrvRefreshLimitsState *s = g_new(BdrvRefreshLimitsState, 1);
+        *s = (BdrvRefreshLimitsState) {
+            .bs = bs,
+            .old_bl = bs->bl,
+        };
+        tran_add(tran, &bdrv_refresh_limits_drv, s);
+    }
+
     memset(&bs->bl, 0, sizeof(bs->bl));
 
     if (!drv) {
@@ -156,7 +183,7 @@ void bdrv_refresh_limits(BlockDriverState *bs, Error **errp)
     QLIST_FOREACH(c, &bs->children, next) {
         if (c->role & (BDRV_CHILD_DATA | BDRV_CHILD_FILTERED | BDRV_CHILD_COW))
         {
-            bdrv_refresh_limits(c->bs, errp);
+            bdrv_refresh_limits(c->bs, tran, errp);
             if (*errp) {
                 return;
             }