On 09/19/2017 07:51 AM, Christoph Hellwig wrote:

On Sat, Sep 16, 2017 at 07:10:30AM +0800, Jianchao Wang wrote:

quoted

If the bio_integrity_merge_rq() return false or nr_phys_segments exceeds
the max_segments, the merging fails, but the bi_front/back_seg_size may
have been modified. To avoid it, move the sanity checking ahead.

Signed-off-by: Jianchao Wang <redacted>

This looks fine to me:

Reviewed-by: Christoph Hellwig <hch@lst.de>

But can you elaborate a little more on how this found and if there
is a way to easily reproduce it, say for a blktests test case?

It is found when I made the patch of 
'block: consider merge of segments when merge bio into rq' , not from an actual
issue or test case.

Thanks
Jianchao