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Commit 14cb0dc6 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

block: don't let passthrough IO go into .make_request_fn() 



Commit a8821f3f("block: Improvements to bounce-buffer handling") tries
to make sure that the bio to .make_request_fn won't exceed BIO_MAX_PAGES,
but ignores that passthrough I/O can use blk_queue_bounce() too.
Especially, passthrough IO may not be sector-aligned, and the check
of 'sectors < bio_sectors(*bio_orig)' inside __blk_queue_bounce() may
become true even though the max bvec number doesn't exceed BIO_MAX_PAGES,
then cause the bio splitted, and the original passthrough bio is submited
to generic_make_request().

This patch fixes this issue by checking if the bio is passthrough IO,
and use bio_kmalloc() to allocate the cloned passthrough bio.

Cc: NeilBrown <neilb@suse.com>
Fixes: a8821f3f("block: Improvements to bounce-buffer handling")
Tested-by: default avatarMichele Ballabio <barra_cuda@katamail.com>
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent a9fa9914

block/bounce.c

+4 −2
Original line number Diff line number Diff line
@@ -200,6 +200,7 @@ static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, 
	unsigned i = 0;

	bool bounce = false;

	int sectors = 0;

	bool passthrough = bio_is_passthrough(*bio_orig);



	bio_for_each_segment(from, *bio_orig, iter) {

		if (i++ < BIO_MAX_PAGES)
@@ -210,13 +211,14 @@ static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, 
	if (!bounce)

		return;



	if (sectors < bio_sectors(*bio_orig)) {

	if (!passthrough && sectors < bio_sectors(*bio_orig)) {

		bio = bio_split(*bio_orig, sectors, GFP_NOIO, bounce_bio_split);

		bio_chain(bio, *bio_orig);

		generic_make_request(*bio_orig);

		*bio_orig = bio;

	}

	bio = bio_clone_bioset(*bio_orig, GFP_NOIO, bounce_bio_set);

	bio = bio_clone_bioset(*bio_orig, GFP_NOIO, passthrough ? NULL :

			bounce_bio_set);



	bio_for_each_segment_all(to, bio, i) {

		struct page *page = to->bv_page;

include/linux/blkdev.h

+19 −2
Original line number Diff line number Diff line
@@ -241,14 +241,24 @@ struct request { 
	struct request *next_rq;

};



static inline bool blk_op_is_scsi(unsigned int op)

{

	return op == REQ_OP_SCSI_IN || op == REQ_OP_SCSI_OUT;

}



static inline bool blk_op_is_private(unsigned int op)

{

	return op == REQ_OP_DRV_IN || op == REQ_OP_DRV_OUT;

}



static inline bool blk_rq_is_scsi(struct request *rq)

{

	return req_op(rq) == REQ_OP_SCSI_IN || req_op(rq) == REQ_OP_SCSI_OUT;

	return blk_op_is_scsi(req_op(rq));

}



static inline bool blk_rq_is_private(struct request *rq)

{

	return req_op(rq) == REQ_OP_DRV_IN || req_op(rq) == REQ_OP_DRV_OUT;

	return blk_op_is_private(req_op(rq));

}



static inline bool blk_rq_is_passthrough(struct request *rq)
@@ -256,6 +266,13 @@ static inline bool blk_rq_is_passthrough(struct request *rq) 
	return blk_rq_is_scsi(rq) || blk_rq_is_private(rq);

}



static inline bool bio_is_passthrough(struct bio *bio)

{

	unsigned op = bio_op(bio);



	return blk_op_is_scsi(op) || blk_op_is_private(op);

}



static inline unsigned short req_get_ioprio(struct request *req)

{

	return req->ioprio;