Greetings; There are a lot of uses of PAGE_SIZE/SECTOR_SIZE scattered around, and it seems like a medium improvement to be able to refer to it as PAGE_SECTORS everywhere instead of just inside dm, bcache, and null_blk. Did this change progress forward somewhere? Thanks! John Dorminy On Mon, Sep 7, 2020 at 3:40 AM Leizhen (ThunderTown) <thunder.leizhen@xxxxxxxxxx> wrote: > > Hi, Jens Axboe, Alasdair Kergon, Mike Snitzer: > What's your opinion? > > > On 2020/8/21 15:05, Coly Li wrote: > > On 2020/8/21 14:48, Leizhen (ThunderTown) wrote: > >> > >> > >> On 8/21/2020 12:11 PM, Coly Li wrote: > >>> On 2020/8/21 10:03, Zhen Lei wrote: > >>>> There are too many PAGE_SECTORS definitions, and all of them are the > >>>> same. It looks a bit of a mess. So why not move it into <linux/blkdev.h>, > >>>> to achieve a basic and unique definition. > >>>> > >>>> Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx> > >>> > >>> > >>> A lazy question about page size > 4KB: currently in bcache code the > >>> sector size is assumed to be 512 sectors, if kernel page > 4KB, it is > >>> possible that PAGE_SECTORS in bcache will be a number > 8 ? > >> > >> Sorry, I don't fully understand your question. I known that the sector size > >> can be 512 or 4K, and the PAGE_SIZE can be 4K or 64K. So even if sector size > >> is 4K, isn't it greater than 8 for 64K pages? > >> > >> I'm not sure if the question you're asking is the one Matthew Wilcox has > >> answered before: > >> https://www.spinics.net/lists/raid/msg64345.html > > > > Thank you for the above information. Currently bcache code assumes > > sector size is always 512 bytes, you may see how many "<< 9" or ">> 9" > > are used. Therefore I doubt whether current code may stably work on e.g. > > 4Kn SSDs (this is only doubt because I don't have such SSD). > > > > Anyway your patch is fine to me. This change to bcache doesn't make > > thins worse or better, maybe it can be helpful to trigger my above > > suspicious early if people do have this kind of problem on 4Kn sector SSDs. > > > > For the bcache part of this patch, you may add, > > Acked-by: Coly Li <colyli@xxxxxxx> > > > > Thanks. > > > > Coly Li > > > >>>> --- > >>>> drivers/block/brd.c | 1 - > >>>> drivers/block/null_blk_main.c | 1 - > >>>> drivers/md/bcache/util.h | 2 -- > >>>> include/linux/blkdev.h | 5 +++-- > >>>> include/linux/device-mapper.h | 1 - > >>>> 5 files changed, 3 insertions(+), 7 deletions(-) > >>>> > >>> > >>> [snipped] > >>> > >>>> diff --git a/drivers/md/bcache/util.h b/drivers/md/bcache/util.h > >>>> index c029f7443190805..55196e0f37c32c6 100644 > >>>> --- a/drivers/md/bcache/util.h > >>>> +++ b/drivers/md/bcache/util.h > >>>> @@ -15,8 +15,6 @@ > >>>> > >>>> #include "closure.h" > >>>> > >>>> -#define PAGE_SECTORS (PAGE_SIZE / 512) > >>>> - > >>>> struct closure; > >>>> > >>>> #ifdef CONFIG_BCACHE_DEBUG > >>>> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h > >>>> index bb5636cc17b91a7..b068dfc5f2ef0ab 100644 > >>>> --- a/include/linux/blkdev.h > >>>> +++ b/include/linux/blkdev.h > >>>> @@ -949,11 +949,12 @@ static inline struct request_queue *bdev_get_queue(struct block_device *bdev) > >>>> * multiple of 512 bytes. Hence these two constants. > >>>> */ > >>>> #ifndef SECTOR_SHIFT > >>>> -#define SECTOR_SHIFT 9 > >>>> +#define SECTOR_SHIFT 9 > >>>> #endif > >>>> #ifndef SECTOR_SIZE > >>>> -#define SECTOR_SIZE (1 << SECTOR_SHIFT) > >>>> +#define SECTOR_SIZE (1 << SECTOR_SHIFT) > >>>> #endif > >>>> +#define PAGE_SECTORS (PAGE_SIZE / SECTOR_SIZE) > >>>> > >>>> /* > >>>> * blk_rq_pos() : the current sector > >>> [snipped] > >>> > >>> > >> > > > > > > . > > >
