block/null_blk: Fix double blk_mq_start_request() warning
When CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION is enabled, null_queue_rq() would return BLK_STS_RESOURCE or BLK_STS_DEV_RESOURCE for the request, which has been marked as MQ_RQ_IN_FLIGHT by blk_mq_start_request(). Then null_queue_rqs() put these requests in the rqlist, return back to the block layer core, which would try to queue them individually again, so the warning in blk_mq_start_request() triggered. Fix it by splitting the null_queue_rq() into two parts: the first is the preparation of request, the second is the handling of request. We put the blk_mq_start_request() after the preparation part, which may fail and return back to the block layer core. The throttling also belongs to the preparation part, so move it before blk_mq_start_request(). And change the return type of null_handle_cmd() to void, since it always return BLK_STS_OK now. Reported-by:<syzbot+fcc47ba2476570cbbeb0@syzkaller.appspotmail.com> Closes: https://lore.kernel.org/all/0000000000000e6aac06098aee0c@google.com/ Fixes: d78bfa13 ("block/null_blk: add queue_rqs() support") Suggested-by:
Bart Van Assche <bvanassche@acm.org> Signed-off-by:
Chengming Zhou <zhouchengming@bytedance.com> Link: https://lore.kernel.org/r/20231120032521.1012037-1-chengming.zhou@linux.dev Signed-off-by:
Jens Axboe <axboe@kernel.dk>
parent
c96b8175
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