From 826b6ca0b0c00bf27562a85bc073f800dad1259b Mon Sep 17 00:00:00 2001 From: Fam Zheng Date: Fri, 23 May 2014 21:29:47 +0800 Subject: [PATCH] block: Add backing_blocker in BlockDriverState This makes use of op_blocker and blocks all the operations except for commit target, on each BlockDriverState->backing_hd. The asserts for op_blocker in bdrv_swap are removed because with this change, the target of block commit has at least the backing blocker of its child, so the assertion is not true. Callers should do their check. Signed-off-by: Fam Zheng Signed-off-by: Stefan Hajnoczi --- block.c | 23 +++++++++++++++++++---- block/mirror.c | 2 +- include/block/block_int.h | 3 +++ 3 files changed, 23 insertions(+), 5 deletions(-) diff --git a/block.c b/block.c index 1271dd2acd..aa9b5abf5d 100644 --- a/block.c +++ b/block.c @@ -1097,14 +1097,30 @@ fail: void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd) { + if (bs->backing_hd) { + assert(bs->backing_blocker); + bdrv_op_unblock_all(bs->backing_hd, bs->backing_blocker); + } else if (backing_hd) { + error_setg(&bs->backing_blocker, + "device is used as backing hd of '%s'", + bs->device_name); + } + bs->backing_hd = backing_hd; if (!backing_hd) { + error_free(bs->backing_blocker); + bs->backing_blocker = NULL; goto out; } bs->open_flags &= ~BDRV_O_NO_BACKING; pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_hd->filename); pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_hd->drv ? backing_hd->drv->format_name : ""); + + bdrv_op_block_all(bs->backing_hd, bs->backing_blocker); + /* Otherwise we won't be able to commit due to check in bdrv_commit */ + bdrv_op_unblock(bs->backing_hd, BLOCK_OP_TYPE_COMMIT, + bs->backing_blocker); out: bdrv_refresh_limits(bs); } @@ -1803,8 +1819,9 @@ void bdrv_close(BlockDriverState *bs) if (bs->drv) { if (bs->backing_hd) { - bdrv_unref(bs->backing_hd); - bs->backing_hd = NULL; + BlockDriverState *backing_hd = bs->backing_hd; + bdrv_set_backing_hd(bs, NULL); + bdrv_unref(backing_hd); } bs->drv->bdrv_close(bs); g_free(bs->opaque); @@ -2006,7 +2023,6 @@ void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old) assert(QLIST_EMPTY(&bs_new->dirty_bitmaps)); assert(bs_new->job == NULL); assert(bs_new->dev == NULL); - assert(bdrv_op_blocker_is_empty(bs_new)); assert(bs_new->io_limits_enabled == false); assert(!throttle_have_timer(&bs_new->throttle_state)); @@ -2025,7 +2041,6 @@ void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old) /* Check a few fields that should remain attached to the device */ assert(bs_new->dev == NULL); assert(bs_new->job == NULL); - assert(bdrv_op_blocker_is_empty(bs_new)); assert(bs_new->io_limits_enabled == false); assert(!throttle_have_timer(&bs_new->throttle_state)); diff --git a/block/mirror.c b/block/mirror.c index 1c38aa8f77..94c8661777 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -498,7 +498,7 @@ immediate_exit: /* drop the bs loop chain formed by the swap: break the loop then * trigger the unref from the top one */ BlockDriverState *p = s->base->backing_hd; - s->base->backing_hd = NULL; + bdrv_set_backing_hd(s->base, NULL); bdrv_unref(p); } } diff --git a/include/block/block_int.h b/include/block/block_int.h index 7b1c013c30..f2e753f632 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -369,6 +369,9 @@ struct BlockDriverState { QDict *options; BlockdevDetectZeroesOptions detect_zeroes; + + /* The error object in use for blocking operations on backing_hd */ + Error *backing_blocker; }; int get_tmp_filename(char *filename, int size); -- 2.39.5