writeback: implement wb_wait_for_single_work()
For cgroup writeback, multiple wb_writeback_work items may need to be issuedto accomplish a single task. The previous patch updated the waiting mechanism such that wb_wait_for_completion() can wait for multiple work items. Issuing mulitple work items involves memory allocation which may fail. As most writeback operations can't fail or blocked on memory allocation, in such cases, we'll fall back to sequential issuing of an on-stack work item, which would need to be waited upon sequentially. This patch implements wb_wait_for_single_work() which waits for a single work item independently from wb_completion waiting so that such fallback mechanism can be used without getting tangled with the usual issuing / completion operation. Signed-off-by:Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Signed-off-by:
Jens Axboe <axboe@fb.com>
parent
cc395d7f
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