From fbe40ff780564526e6f639b3b78366727d34955c Mon Sep 17 00:00:00 2001 From: Fam Zheng Date: Fri, 23 May 2014 21:29:42 +0800 Subject: block: Introduce op_blockers to BlockDriverState BlockDriverState.op_blockers is an array of lists with BLOCK_OP_TYPE_MAX elements. Each list is a list of blockers of an operation type (BlockOpType), that marks this BDS as currently blocked for a certain type of operation with reason errors stored in the list. The rule of usage is: * BDS user who wants to take an operation should check if there's any blocker of the type with bdrv_op_is_blocked(). * BDS user who wants to block certain types of operation, should call bdrv_op_block (or bdrv_op_block_all to block all types of operations, which is similar to the existing bdrv_set_in_use()). * A blocker is only referenced by op_blockers, so the lifecycle is managed by caller, and shouldn't be lost until unblock, so typically a caller does these: - Allocate a blocker with error_setg or similar, call bdrv_op_block() to block some operations. - Hold the blocker, do his job. - Unblock operations that it blocked, with the same reason pointer passed to bdrv_op_unblock(). - Release the blocker with error_free(). Signed-off-by: Fam Zheng Reviewed-by: Benoit Canet Reviewed-by: Jeff Cody Reviewed-by: Stefan Hajnoczi Signed-off-by: Stefan Hajnoczi --- block.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 76 insertions(+) (limited to 'block.c') diff --git a/block.c b/block.c index 40c5e1aa73..589c6e3376 100644 --- a/block.c +++ b/block.c @@ -335,6 +335,7 @@ void bdrv_register(BlockDriver *bdrv) BlockDriverState *bdrv_new(const char *device_name, Error **errp) { BlockDriverState *bs; + int i; if (bdrv_find(device_name)) { error_setg(errp, "Device with id '%s' already exists", @@ -353,6 +354,9 @@ BlockDriverState *bdrv_new(const char *device_name, Error **errp) if (device_name[0] != '\0') { QTAILQ_INSERT_TAIL(&bdrv_states, bs, device_list); } + for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { + QLIST_INIT(&bs->op_blockers[i]); + } bdrv_iostatus_disable(bs); notifier_list_init(&bs->close_notifiers); notifier_with_return_list_init(&bs->before_write_notifiers); @@ -1952,6 +1956,8 @@ static void bdrv_move_feature_fields(BlockDriverState *bs_dest, pstrcpy(bs_dest->device_name, sizeof(bs_dest->device_name), bs_src->device_name); bs_dest->device_list = bs_src->device_list; + memcpy(bs_dest->op_blockers, bs_src->op_blockers, + sizeof(bs_dest->op_blockers)); } /* @@ -5325,6 +5331,76 @@ void bdrv_unref(BlockDriverState *bs) } } +struct BdrvOpBlocker { + Error *reason; + QLIST_ENTRY(BdrvOpBlocker) list; +}; + +bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp) +{ + BdrvOpBlocker *blocker; + assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX); + if (!QLIST_EMPTY(&bs->op_blockers[op])) { + blocker = QLIST_FIRST(&bs->op_blockers[op]); + if (errp) { + error_setg(errp, "Device '%s' is busy: %s", + bs->device_name, error_get_pretty(blocker->reason)); + } + return true; + } + return false; +} + +void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason) +{ + BdrvOpBlocker *blocker; + assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX); + + blocker = g_malloc0(sizeof(BdrvOpBlocker)); + blocker->reason = reason; + QLIST_INSERT_HEAD(&bs->op_blockers[op], blocker, list); +} + +void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reason) +{ + BdrvOpBlocker *blocker, *next; + assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX); + QLIST_FOREACH_SAFE(blocker, &bs->op_blockers[op], list, next) { + if (blocker->reason == reason) { + QLIST_REMOVE(blocker, list); + g_free(blocker); + } + } +} + +void bdrv_op_block_all(BlockDriverState *bs, Error *reason) +{ + int i; + for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { + bdrv_op_block(bs, i, reason); + } +} + +void bdrv_op_unblock_all(BlockDriverState *bs, Error *reason) +{ + int i; + for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { + bdrv_op_unblock(bs, i, reason); + } +} + +bool bdrv_op_blocker_is_empty(BlockDriverState *bs) +{ + int i; + + for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { + if (!QLIST_EMPTY(&bs->op_blockers[i])) { + return false; + } + } + return true; +} + void bdrv_set_in_use(BlockDriverState *bs, int in_use) { assert(bs->in_use != in_use); -- cgit v1.2.3