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loop: set physical block size to PAGE_SIZE 

The physical block size is "the lowest possible sector size that the
hardware can operate on without reverting to read-modify-write
operations" (from the comment on blk_queue_physical_block_size()). Since
loop does buffered I/O on the backing file by default, the RMW unit is a
page. This isn't the case for direct I/O mode, but let's keep it simple.

Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
hifive-unleashed-5.1
Omar Sandoval 2017-08-24 00:03:42 -07:00 committed by Jens Axboe
parent 8a0740c410
commit 6c6b6f28b3
1 changed files with 2 additions and 0 deletions
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2
drivers/block/loop.c
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@ -1764,6 +1764,8 @@ static int loop_add(struct loop_device **l, int i)
}
lo->lo_queue->queuedata = lo;
blk_queue_physical_block_size(lo->lo_queue, PAGE_SIZE);
/*
* It doesn't make sense to enable merge because the I/O
* submitted to backing file is handled page by page.