6.6-stable review patch. If anyone has any objections, please let me know.
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From: Jens Axboe axboe@kernel.dk
[ Upstream commit 1f47ed294a2bd577d5ae43e6e28e1c9a3be4a833 ]
The conditions for whether or not a request is allowed adding to a completion batch are a bit hard to read, and they also have a few issues. One is that ioerror may indeed be a random value on passthrough, and it's being checked unconditionally of whether or not the given request is a passthrough request or not.
Rewrite the conditions to be separate for easier reading, and only check ioerror for non-passthrough requests. This fixes an issue with bio unmapping on passthrough, where it fails getting added to a batch. This both leads to suboptimal performance, and may trigger a potential schedule-under-atomic condition for polled passthrough IO.
Fixes: f794f3351f26 ("block: add support for blk_mq_end_request_batch()") Link: https://lore.kernel.org/r/20575f0a-656e-4bb3-9d82-dec6c7e3a35c@kernel.dk Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/blk-mq.h | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 958ed7e89b301..1d482c2aabbdf 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -849,12 +849,22 @@ static inline bool blk_mq_add_to_batch(struct request *req, void (*complete)(struct io_comp_batch *)) { /* - * blk_mq_end_request_batch() can't end request allocated from - * sched tags + * Check various conditions that exclude batch processing: + * 1) No batch container + * 2) Has scheduler data attached + * 3) Not a passthrough request and end_io set + * 4) Not a passthrough request and an ioerror */ - if (!iob || (req->rq_flags & RQF_SCHED_TAGS) || ioerror || - (req->end_io && !blk_rq_is_passthrough(req))) + if (!iob) return false; + if (req->rq_flags & RQF_SCHED_TAGS) + return false; + if (!blk_rq_is_passthrough(req)) { + if (req->end_io) + return false; + if (ioerror < 0) + return false; + }
if (!iob->complete) iob->complete = complete;