On Tue, May 20, 2014 at 02:04:27PM +0800, Fam Zheng wrote: > 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 <f...@redhat.com> > Reviewed-by: Benoit Canet <ben...@irqsave.net> > Reviewed-by: Jeff Cody <jc...@redhat.com> > --- > block.c | 76 > +++++++++++++++++++++++++++++++++++++++++++++++ > include/block/block.h | 7 +++++ > include/block/block_int.h | 5 ++++ > 3 files changed, 88 insertions(+)
Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com>
