On 2020-08-06 17:28, Bart Van Assche wrote:
On 2020-08-06 14:58, Keith Busch wrote:
A previous commit aligning splits to physical block sizes inadvertently modified one return case such that that it now returns 0 length splits when the number of sectors doesn't exceed the physical offset. This later hits a BUG in bio_split(). Restore the previous working behavior.
Reported-by: Eric Deal eric.deal@wdc.com Cc: Bart Van Assche bvanassche@acm.org Cc: stable@vger.kernel.org Fixes: 9cc5169cd478b ("block: Improve physical block alignment of split bios") Signed-off-by: Keith Busch kbusch@kernel.org
block/blk-merge.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/blk-merge.c b/block/blk-merge.c index 5196dc145270..d7fef954d42f 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -154,7 +154,7 @@ static inline unsigned get_max_io_size(struct request_queue *q, if (max_sectors > start_offset) return max_sectors - start_offset;
- return sectors & (lbs - 1);
- return sectors & ~(lbs - 1);
}
I think we agree that get_max_io_size() should never return zero. However, the above change seems wrong to me because it will cause get_max_io_size() to return zero if the logical block size is larger than 512 bytes and if sectors < lbs. How about changing the return statement as follows (untested):
This should work better than what was mentioned in my previous email:
- return sectors & (lbs - 1); + return sectors;
Thanks,
Bart.