From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ren Mingxin Subject: [PATCH 1/4] block: add function disk_name_format() into block core Date: Fri, 30 Mar 2012 17:52:27 +0800 Message-ID: <4F75825B.80108__25191.5780282163$1333381106$gmane$org@cn.fujitsu.com> References: <4F7581D4.4040301@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4F7581D4.4040301@cn.fujitsu.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Jens Axboe , "Michael S. Tsirkin" , Rusty Russell , Tejun Heo Cc: VIRTUAL , LKML , SCSI , KVM List-Id: virtualization@lists.linuxfoundation.org According to 3e1a7ff8a0a7b948f2684930166954f9e8e776fe, I copied function "sd_format_disk_name()" into block core with the name of "disk_name_format()". Signed-off-by: Ren Mingxin --- block/genhd.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/genhd.h | 2 ++ 2 files changed, 51 insertions(+) diff --git a/block/genhd.c b/block/genhd.c index df9816e..10c04b6 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -357,6 +357,55 @@ void unregister_blkdev(unsigned int major, const char *name) EXPORT_SYMBOL(unregister_blkdev); +/* + * disk_name_format - format disk name + * @prefix: name prefix - ie. "sd" for SCSI disks + * @index: index of the disk to format name for + * @buf: output buffer + * @buflen: length of the output buffer + * + * Take SCSI disks for example. Disk names starts at sda. The + * 26th device is sdz and the 27th is sdaa. The last one for + * two lettered suffix is sdzz which is followed by sdaaa. + * + * This is basically 26 base counting with one extra 'nil' entry + * at the beginning from the second digit on and can be + * determined using similar method as 26 base conversion with the + * index shifted -1 after each digit is computed. + * + * CONTEXT: + * Don't care. + * + * RETURNS: + * 0 on success, -errno on failure. + */ + +int disk_name_format(char *prefix, int index, char *buf, int buflen) +{ + const int base = 'z' - 'a' + 1; + char *begin = buf + strlen(prefix); + char *end = buf + buflen; + char *p; + int unit; + + p = end - 1; + *p = '\0'; + unit = base; + do { + if (p == begin) + return -EINVAL; + *--p = 'a' + (index % unit); + index = (index / unit) - 1; + } while (index >= 0); + + memmove(begin, p, end - p); + memcpy(buf, prefix, strlen(prefix)); + + return 0; +} + +EXPORT_SYMBOL(disk_name_format); + static struct kobj_map *bdev_map; /** diff --git a/include/linux/genhd.h b/include/linux/genhd.h index e61d319..cd3d5e5 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -407,6 +407,8 @@ static inline void free_part_info(struct hd_struct *part) extern void part_round_stats(int cpu, struct hd_struct *part); /* block/genhd.c */ +extern int disk_name_format(char *prefix, int index, char *buf, int buflen); + extern void add_disk(struct gendisk *disk); extern void del_gendisk(struct gendisk *gp); extern struct gendisk *get_gendisk(dev_t dev, int *partno);