Re: [PATCH v2] null_blk: use sector_div instead of do_div

From: Jens Axboe
Date: Wed Jan 13 2016 - 17:11:16 EST


On 01/13/2016 03:04 PM, Arnd Bergmann wrote:
Dividing a sector_t number should be done using sector_div rather than do_div
to optimize the 32-bit sector_t case, and with the latest do_div optimizations,
we now get a compile-time warning for this:

arch/arm/include/asm/div64.h:32:95: note: expected 'uint64_t * {aka long long unsigned int *}' but argument is of type 'sector_t * {aka long unsigned int *}'
drivers/block/null_blk.c:521:81: warning: comparison of distinct pointer types lacks a cast

This changes the newly added code to use sector_div. It is a simplified version
of the original patch, as Linus Torvalds pointed out that we should not be using
an expensive division function in the first place.

This version was suggested by Matias Bjorling.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Matias Bjorling <m@xxxxxxxxxxx>
Fixes: b2b7e00148a2 ("null_blk: register as a LightNVM device")
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[resent to Jens' correct address, sorry about the duplicates]

Thanks Arnd, added.

--
Jens Axboe