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[189.26.185.89]) by smtp.gmail.com with ESMTPSA id d55sm9031059qtb.59.2019.05.01.18.57.43 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 01 May 2019 18:57:46 -0700 (PDT) From: Marcos Paulo de Souza To: linux-block@vger.kernel.org Cc: Marcos Paulo de Souza , Jens Axboe , Hannes Reinecke , Omar Sandoval , Ming Lei , Damien Le Moal , Bart Van Assche , Greg Edwards , linux-kernel@vger.kernel.org (open list) Subject: [PATCH v2 1/2] blkdev.h: Introduce bytes_to_sectors helper function Date: Wed, 1 May 2019 22:57:27 -0300 Message-Id: <20190502015728.71468-2-marcos.souza.org@gmail.com> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20190502015728.71468-1-marcos.souza.org@gmail.com> References: <20190502015728.71468-1-marcos.souza.org@gmail.com> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org 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 Signed-off-by: Marcos Paulo de Souza --- Changes from v1: Rename size_to_sectors to bytes_to_sectors. (Martin K. Petersen) Changes from RFC: 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..7ade2e24dbae 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 +/** + * bytes_to_sectors - Convert size in bytes to number of sectors of 512 bytes + * @bytes: number of 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 bytes_to_sectors(long long bytes) +{ + return bytes >> SECTOR_SHIFT; +} + /* * blk_rq_pos() : the current sector * blk_rq_bytes() : bytes left in the entire request -- 2.16.4