From 3e1a7ff8a0a7b948f2684930166954f9e8e776fe Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 25 Aug 2008 19:56:17 +0900 Subject: [PATCH] block: allow disk to have extended device number Now that disk and partition handlings are mostly unified, it's easy to allow disk to have extended device number. This patch makes add_disk() use extended device number if disk->minors is zero. Both sd and ide-disk are updated to use this. * sd_format_disk_name() is implemented which can generically determine the drive name. This removes disk number restriction stemming from limited device names. * If sd index goes over SD_MAX_DISKS (which can be increased now BTW), sd simply doesn't initialize minors letting block layer choose extended device number. * If CONFIG_DEBUG_EXT_DEVT is set, both sd and ide-disk always set minors to 0 and use extended device numbers. Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe --- block/genhd.c | 25 +++++++++++++- drivers/ide/ide-disk.c | 2 +- drivers/scsi/sd.c | 74 ++++++++++++++++++++++++++++++------------ fs/partitions/check.c | 1 + include/linux/genhd.h | 3 +- 5 files changed, 82 insertions(+), 23 deletions(-) diff --git a/block/genhd.c b/block/genhd.c index eedab5b4685..d9de3e482d1 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -478,14 +478,37 @@ static int exact_lock(dev_t devt, void *data) * * This function registers the partitioning information in @disk * with the kernel. + * + * FIXME: error handling */ void add_disk(struct gendisk *disk) { struct backing_dev_info *bdi; + dev_t devt; int retval; + /* minors == 0 indicates to use ext devt from part0 and should + * be accompanied with EXT_DEVT flag. Make sure all + * parameters make sense. + */ + WARN_ON(disk->minors && !(disk->major || disk->first_minor)); + WARN_ON(!disk->minors && !(disk->flags & GENHD_FL_EXT_DEVT)); + disk->flags |= GENHD_FL_UP; - disk_to_dev(disk)->devt = MKDEV(disk->major, disk->first_minor); + + retval = blk_alloc_devt(&disk->part0, &devt); + if (retval) { + WARN_ON(1); + return; + } + disk_to_dev(disk)->devt = devt; + + /* ->major and ->first_minor aren't supposed to be + * dereferenced from here on, but set them just in case. + */ + disk->major = MAJOR(devt); + disk->first_minor = MINOR(devt); + blk_register_region(disk_devt(disk), disk->minors, NULL, exact_match, exact_lock, disk); register_disk(disk); diff --git a/drivers/ide/ide-disk.c b/drivers/ide/ide-disk.c index 29c8ae75268..33ea8c04871 100644 --- a/drivers/ide/ide-disk.c +++ b/drivers/ide/ide-disk.c @@ -44,7 +44,7 @@ #if !defined(CONFIG_DEBUG_BLOCK_EXT_DEVT) #define IDE_DISK_MINORS (1 << PARTN_BITS) #else -#define IDE_DISK_MINORS 1 +#define IDE_DISK_MINORS 0 #endif struct ide_disk_obj { diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 6598024531d..bcb04b2a767 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -89,7 +89,7 @@ MODULE_ALIAS_SCSI_DEVICE(TYPE_RBC); #if !defined(CONFIG_DEBUG_BLOCK_EXT_DEVT) #define SD_MINORS 16 #else -#define SD_MINORS 1 +#define SD_MINORS 0 #endif static int sd_revalidate_disk(struct gendisk *); @@ -1769,6 +1769,52 @@ static int sd_revalidate_disk(struct gendisk *disk) return 0; } +/** + * sd_format_disk_name - 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 + * + * SCSI 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 beggining 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. + */ +static int sd_format_disk_name(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; +} + /** * sd_probe - called during driver initialization and whenever a * new scsi device is attached to the system. It is called once @@ -1821,8 +1867,8 @@ static int sd_probe(struct device *dev) if (error) goto out_put; - error = -EBUSY; - if (index >= SD_MAX_DISKS) + error = sd_format_disk_name("sd", index, gd->disk_name, DISK_NAME_LEN); + if (error) goto out_free_index; sdkp->device = sdp; @@ -1849,24 +1895,12 @@ static int sd_probe(struct device *dev) get_device(&sdp->sdev_gendev); - gd->major = sd_major((index & 0xf0) >> 4); - gd->first_minor = ((index & 0xf) << 4) | (index & 0xfff00); - gd->minors = SD_MINORS; - gd->fops = &sd_fops; - - if (index < 26) { - sprintf(gd->disk_name, "sd%c", 'a' + index % 26); - } else if (index < (26 + 1) * 26) { - sprintf(gd->disk_name, "sd%c%c", - 'a' + index / 26 - 1,'a' + index % 26); - } else { - const unsigned int m1 = (index / 26 - 1) / 26 - 1; - const unsigned int m2 = (index / 26 - 1) % 26; - const unsigned int m3 = index % 26; - sprintf(gd->disk_name, "sd%c%c%c", - 'a' + m1, 'a' + m2, 'a' + m3); + if (index < SD_MAX_DISKS) { + gd->major = sd_major((index & 0xf0) >> 4); + gd->first_minor = ((index & 0xf) << 4) | (index & 0xfff00); + gd->minors = SD_MINORS; } - + gd->fops = &sd_fops; gd->private_data = &sdkp->driver; gd->queue = sdkp->device->request_queue; diff --git a/fs/partitions/check.c b/fs/partitions/check.c index 772b2ed8d23..0e411603fdf 100644 --- a/fs/partitions/check.c +++ b/fs/partitions/check.c @@ -593,6 +593,7 @@ void del_gendisk(struct gendisk *disk) disk_part_iter_exit(&piter); invalidate_partition(disk, 0); + blk_free_devt(disk_to_dev(disk)->devt); set_capacity(disk, 0); disk->flags &= ~GENHD_FL_UP; unlink_gendisk(disk); diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 04524c213de..206cdf96c3a 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -59,6 +59,7 @@ enum { }; #define DISK_MAX_PARTS 256 +#define DISK_NAME_LEN 32 #include #include @@ -140,7 +141,7 @@ struct gendisk { int minors; /* maximum number of minors, =1 for * disks that can't be partitioned. */ - char disk_name[32]; /* name of major driver */ + char disk_name[DISK_NAME_LEN]; /* name of major driver */ /* Array of pointers to partitions indexed by partno. * Protected with matching bdev lock but stat and other -- 2.41.1