On 8/21/2020 12:11 PM, Coly Li wrote:

On 2020/8/21 10:03, Zhen Lei wrote:

quoted

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 <redacted>

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

Thanks.

Coly Li

quoted

---
 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]

quoted

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]