Messages in this thread Patch in this message | | | From | Marcos Paulo de Souza <> | Subject | [PATCH 1/2] blkdev.h: Introduce size_to_sectors hlper function | Date | Mon, 29 Apr 2019 22:32:04 -0300 |
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This function takes an argument to specify the size of a block device, in bytes, and return the number of sectors of 512 bytes.
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Marcos Paulo de Souza <marcos.souza.org@gmail.com> ---
Changes from v1: Reworked the documentation of size_to_sectors by removing a sentence that was explaining the size -> sectors math, which wasn't necessary given the description prior to the example. (suggested by Chaitanya)
include/linux/blkdev.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 317ab30d2904..f6cfe6970756 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -871,6 +871,23 @@ static inline struct request_queue *bdev_get_queue(struct block_device *bdev) #define SECTOR_SIZE (1 << SECTOR_SHIFT) #endif +/** + * size_to_sectors - Convert size in bytes to number of sectors of 512 bytes + * @size: size in bytes to be converted to sectors + * + * Description: + * Kernel I/O operations are always made in "sectors". In order to set the + * correct number of sectors for a given number of bytes, we need to group the + * number of bytes in "sectors of 512 bytes" by shifting the size value by 9, + * which is the same than dividing the size by 512. + * + * Returns the number of sectors by the given number of bytes. + */ +static inline sector_t size_to_sectors(long long size) +{ + return size >> SECTOR_SHIFT; +} + /* * blk_rq_pos() : the current sector * blk_rq_bytes() : bytes left in the entire request -- 2.16.4
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