Commit e93d12ae authored Jan 13, 2016 by Arnd Bergmann Committed by Jens Axboe Jan 13, 2016

null_blk: use sector_div instead of do_div

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@arndb.de>
Cc: Matias Bjorling <m@bjorling.me>
Fixes: b2b7e001 ("null_blk: register as a LightNVM device")
Signed-off-by: Jens Axboe <axboe@fb.com>

parent 038a75af

drivers/block/null_blk.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -510,17 +510,17 @@ static int null_lnvm_id(struct request_queue q, struct nvm_id id)
		id->ppaf.ch_offset = 56;
		id->ppaf.ch_len = 8;

		do_div(size, bs); /* convert size to pages */
		do_div(size, 256); /* concert size to pgs pr blk */
		sector_div(size, bs); /* convert size to pages */
		size >>= 8; /* concert size to pgs pr blk */
		grp = &id->groups[0];
		grp->mtype = 0;
		grp->fmtype = 0;
		grp->num_ch = 1;
		grp->num_pg = 256;
		blksize = size;
		do_div(size, (1 << 16));
		size >>= 16;
		grp->num_lun = size + 1;
		do_div(blksize, grp->num_lun);
		sector_div(blksize, grp->num_lun);
		grp->num_blk = blksize;
		grp->num_pln = 1;

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