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block: force an unlimited segment size on queues with a virt boundary 

We currently fail to update the front/back segment size in the bio when
deciding to allow an otherwise gappy segement to a device with a
virt boundary.  The reason why this did not cause problems is that
devices with a virt boundary fundamentally don't use segments as we
know it and thus don't care.  Make that assumption formal by forcing
an unlimited segement size in this case.

Fixes: f6970f83ef ("block: don't check if adjacent bvecs in one bio can be mergeable")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2019-05-21 09:01:41 +02:00 committed by Jens Axboe
parent eded341c08
commit 09324d32d2
1 changed files with 11 additions and 0 deletions
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11
block/blk-settings.c
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@ -310,6 +310,9 @@ void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size)
__func__, max_size);
}
/* see blk_queue_virt_boundary() for the explanation */
WARN_ON_ONCE(q->limits.virt_boundary_mask);
q->limits.max_segment_size = max_size;
}
EXPORT_SYMBOL(blk_queue_max_segment_size);
@ -742,6 +745,14 @@ EXPORT_SYMBOL(blk_queue_segment_boundary);
void blk_queue_virt_boundary(struct request_queue *q, unsigned long mask)
{
q->limits.virt_boundary_mask = mask;
/*
* Devices that require a virtual boundary do not support scatter/gather
* I/O natively, but instead require a descriptor list entry for each
* page (which might not be idential to the Linux PAGE_SIZE). Because
* of that they are not limited by our notion of "segment size".
*/
q->limits.max_segment_size = UINT_MAX;
}
EXPORT_SYMBOL(blk_queue_virt_boundary);