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Message-Id: <20190421035328.19322-2-marcos.souza.org@gmail.com> Date: Sun, 21 Apr 2019 00:53:27 -0300 From: Marcos Paulo de Souza <marcos.souza.org@...il.com> To: linux-kernel@...r.kernel.org Cc: Ming Lei <ming.lei@...hat.com>, Greg Edwards <gedwards@....com>, Hannes Reinecke <hare@...e.com>, linux-block@...r.kernel.org, "Martin K. Petersen" <martin.petersen@...cle.com>, Jens Axboe <axboe@...nel.dk>, Bart Van Assche <bvanassche@....org>, Marcos Paulo de Souza <marcos.souza.org@...il.com>, Omar Sandoval <osandov@...com>, Damien Le Moal <damien.lemoal@....com> Subject: [RFC PATCH 1/2] blkdev.h: Introduce size_to_sectors hlper function This function takes an argument to specify the size of a block device, in bytes, and return the number of sectors of 512 bytes. Signed-off-by: Marcos Paulo de Souza <marcos.souza.org@...il.com> --- include/linux/blkdev.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 317ab30d2904..7bf7b99161b7 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -871,6 +871,24 @@ 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 operation 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. For example, for a capacity + * of 32M (33554432 bytes), the number of sectors will be 65536. + * + * 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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