[PATCH 2/6] block: don't depend on consecutive minor space

From: Tejun Heo
Date: Thu Jul 03 2008 - 09:08:29 EST

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Implement disk_major(), disk_minor(), part_major() and part_minor()
and use them to directly access devt instead of computing it from
first_minor.

While at it, implement disk_max_parts() to avoid directly deferencing
genhd->minors.

These changes are to enable extended block minors.a

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
block/genhd.c | 80 ++++++++++++++++++++++++++++---------------------
block/ioctl.c | 6 ++--
fs/block_dev.c | 2 +-
fs/partitions/check.c | 22 +++++++------
include/linux/genhd.h | 27 ++++++++++++++++-
5 files changed, 88 insertions(+), 49 deletions(-)

diff --git a/block/genhd.c b/block/genhd.c
index b922d48..e7310ba 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -185,13 +185,14 @@ void add_disk(struct gendisk *disk)
struct backing_dev_info *bdi;

disk->flags |= GENHD_FL_UP;
- blk_register_region(MKDEV(disk->major, disk->first_minor),
- disk->minors, NULL, exact_match, exact_lock, disk);
+ disk->dev.devt = MKDEV(disk->major, disk->first_minor);
+ blk_register_region(disk->dev.devt, disk->minors, NULL,
+ exact_match, exact_lock, disk);
register_disk(disk);
blk_register_queue(disk);

bdi = &disk->queue->backing_dev_info;
- bdi_register_dev(bdi, MKDEV(disk->major, disk->first_minor));
+ bdi_register_dev(bdi, disk->dev.devt);
sysfs_create_link(&disk->dev.kobj, &bdi->dev->kobj, "bdi");
}

@@ -203,8 +204,7 @@ void unlink_gendisk(struct gendisk *disk)
sysfs_remove_link(&disk->dev.kobj, "bdi");
bdi_unregister(&disk->queue->backing_dev_info);
blk_unregister_queue(disk);
- blk_unregister_region(MKDEV(disk->major, disk->first_minor),
- disk->minors);
+ blk_unregister_region(disk->dev.devt, disk->minors);
}

/**
@@ -252,7 +252,7 @@ void __init printk_all_partitions(void)
* hex - the same format as the root= option takes.
*/
printk("%02x%02x %10llu %s",
- sgp->major, sgp->first_minor,
+ disk_major(sgp), disk_minor(sgp),
(unsigned long long)get_capacity(sgp) >> 1,
disk_name(sgp, 0, buf));
if (sgp->driverfs_dev != NULL &&
@@ -263,13 +263,14 @@ void __init printk_all_partitions(void)
printk(" (driver?)\n");

/* now show the partitions */
- for (n = 0; n < sgp->minors - 1; ++n) {
- if (sgp->part[n] == NULL)
- continue;
- if (sgp->part[n]->nr_sects == 0)
+ for (n = 0; n < disk_max_parts(sgp); ++n) {
+ struct hd_struct *part = sgp->part[n];
+
+ if (!part || !part->nr_sects)
continue;
+
printk(" %02x%02x %10llu %s\n",
- sgp->major, n + 1 + sgp->first_minor,
+ part_major(part), part_minor(part),
(unsigned long long)sgp->part[n]->nr_sects >> 1,
disk_name(sgp, n + 1, buf));
}
@@ -314,35 +315,36 @@ static void part_stop(struct seq_file *part, void *v)
mutex_unlock(&block_class_lock);
}

-static int show_partition(struct seq_file *part, void *v)
+static int show_partition(struct seq_file *seqf, void *v)
{
struct gendisk *sgp = v;
int n;
char buf[BDEVNAME_SIZE];

if (&sgp->dev.node == block_class.devices.next)
- seq_puts(part, "major minor #blocks name\n\n");
+ seq_puts(seqf, "major minor #blocks name\n\n");

/* Don't show non-partitionable removeable devices or empty devices */
- if (!get_capacity(sgp) ||
- (sgp->minors == 1 && (sgp->flags & GENHD_FL_REMOVABLE)))
+ if (!get_capacity(sgp) || (!disk_max_parts(sgp) &&
+ (sgp->flags & GENHD_FL_REMOVABLE)))
return 0;
if (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO)
return 0;

/* show the full disk and all non-0 size partitions of it */
- seq_printf(part, "%4d %4d %10llu %s\n",
- sgp->major, sgp->first_minor,
+ seq_printf(seqf, "%4d %4d %10llu %s\n",
+ disk_major(sgp), disk_minor(sgp),
(unsigned long long)get_capacity(sgp) >> 1,
disk_name(sgp, 0, buf));
- for (n = 0; n < sgp->minors - 1; n++) {
- if (!sgp->part[n])
+ for (n = 0; n < disk_max_parts(sgp); n++) {
+ struct hd_struct *part = sgp->part[n];
+ if (!part)
continue;
- if (sgp->part[n]->nr_sects == 0)
+ if (part->nr_sects == 0)
continue;
- seq_printf(part, "%4d %4d %10llu %s\n",
- sgp->major, n + 1 + sgp->first_minor,
- (unsigned long long)sgp->part[n]->nr_sects >> 1 ,
+ seq_printf(seqf, "%4d %4d %10llu %s\n",
+ part_major(part), part_minor(part),
+ (unsigned long long)part->nr_sects >> 1,
disk_name(sgp, n + 1, buf));
}

@@ -581,7 +583,7 @@ static int diskstats_show(struct seq_file *s, void *v)
disk_round_stats(gp);
preempt_enable();
seq_printf(s, "%4d %4d %s %lu %lu %llu %u %lu %lu %llu %u %u %u %u\n",
- gp->major, n + gp->first_minor, disk_name(gp, n, buf),
+ disk_major(gp), disk_minor(gp), disk_name(gp, n, buf),
disk_stat_read(gp, ios[0]), disk_stat_read(gp, merges[0]),
(unsigned long long)disk_stat_read(gp, sectors[0]),
jiffies_to_msecs(disk_stat_read(gp, ticks[0])),
@@ -593,7 +595,7 @@ static int diskstats_show(struct seq_file *s, void *v)
jiffies_to_msecs(disk_stat_read(gp, time_in_queue)));

/* now show all non-0 size partitions of it */
- for (n = 0; n < gp->minors - 1; n++) {
+ for (n = 0; n < disk_max_parts(gp); n++) {
struct hd_struct *hd = gp->part[n];

if (!hd || !hd->nr_sects)
@@ -604,7 +606,7 @@ static int diskstats_show(struct seq_file *s, void *v)
preempt_enable();
seq_printf(s, "%4d %4d %s %lu %lu %llu "
"%u %lu %lu %llu %u %u %u %u\n",
- gp->major, n + gp->first_minor + 1,
+ part_major(hd), part_minor(hd),
disk_name(gp, n + 1, buf),
part_stat_read(hd, ios[0]),
part_stat_read(hd, merges[0]),
@@ -653,23 +655,33 @@ void genhd_media_change_notify(struct gendisk *disk)
EXPORT_SYMBOL_GPL(genhd_media_change_notify);
#endif /* 0 */

-dev_t blk_lookup_devt(const char *name, int part)
+dev_t blk_lookup_devt(const char *name, int partno)
{
struct device *dev;
dev_t devt = MKDEV(0, 0);

mutex_lock(&block_class_lock);
list_for_each_entry(dev, &block_class.devices, node) {
+ struct gendisk *disk = dev_to_disk(dev);
+
if (dev->type != &disk_type)
continue;
- if (strcmp(dev->bus_id, name) == 0) {
- struct gendisk *disk = dev_to_disk(dev);
+ if (strcmp(dev->bus_id, name))
+ continue;
+ if (partno < 0 || partno > disk_max_parts(disk))
+ continue;

- if (part < disk->minors)
- devt = MKDEV(MAJOR(dev->devt),
- MINOR(dev->devt) + part);
- break;
+ if (partno == 0)
+ devt = disk->dev.devt;
+ else {
+ struct hd_struct *part = disk->part[partno - 1];
+
+ if (!part || !part->nr_sects)
+ continue;
+
+ devt = part->dev.devt;
}
+ break;
}
mutex_unlock(&block_class_lock);

@@ -760,7 +772,7 @@ void set_disk_ro(struct gendisk *disk, int flag)
{
int i;
disk->policy = flag;
- for (i = 0; i < disk->minors - 1; i++)
+ for (i = 0; i < disk_max_parts(disk); i++)
if (disk->part[i]) disk->part[i]->policy = flag;
}

diff --git a/block/ioctl.c b/block/ioctl.c
index 52d6385..9b008a2 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -28,7 +28,7 @@ static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user
if (bdev != bdev->bd_contains)
return -EINVAL;
part = p.pno;
- if (part <= 0 || part >= disk->minors)
+ if (part <= 0 || part > disk_max_parts(disk))
return -EINVAL;
switch (a.op) {
case BLKPG_ADD_PARTITION:
@@ -49,7 +49,7 @@ static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user
return -EBUSY;
}
/* overlap? */
- for (i = 0; i < disk->minors - 1; i++) {
+ for (i = 0; i < disk_max_parts(disk); i++) {
struct hd_struct *s = disk->part[i];

if (!s)
@@ -99,7 +99,7 @@ static int blkdev_reread_part(struct block_device *bdev)
struct gendisk *disk = bdev->bd_disk;
int res;

- if (disk->minors == 1 || bdev != bdev->bd_contains)
+ if (!disk_max_parts(disk) || bdev != bdev->bd_contains)
return -EINVAL;
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 10d8a0a..215e4be 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -892,7 +892,7 @@ int check_disk_change(struct block_device *bdev)

if (bdops->revalidate_disk)
bdops->revalidate_disk(bdev->bd_disk);
- if (bdev->bd_disk->minors > 1)
+ if (disk_max_parts(bdev->bd_disk))
bdev->bd_invalidated = 1;
return 1;
}
diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index b915ac2..994a621 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -134,8 +134,12 @@ char *disk_name(struct gendisk *hd, int part, char *buf)

const char *bdevname(struct block_device *bdev, char *buf)
{
- int part = MINOR(bdev->bd_dev) - bdev->bd_disk->first_minor;
- return disk_name(bdev->bd_disk, part, buf);
+ int partno = 0;
+
+ if (bdev->bd_part)
+ partno = bdev->bd_part->partno;
+
+ return disk_name(bdev->bd_disk, partno, buf);
}

EXPORT_SYMBOL(bdevname);
@@ -169,7 +173,7 @@ check_partition(struct gendisk *hd, struct block_device *bdev)
if (isdigit(state->name[strlen(state->name)-1]))
sprintf(state->name, "p");

- state->limit = hd->minors;
+ state->limit = disk_max_parts(hd) + 1;
i = res = err = 0;
while (!res && check_part[i]) {
memset(&state->parts, 0, sizeof(state->parts));
@@ -379,7 +383,6 @@ void add_partition(struct gendisk *disk, int part, sector_t start, sector_t len,
"%s%d", disk->dev.bus_id, part);

device_initialize(&p->dev);
- p->dev.devt = MKDEV(disk->major, disk->first_minor + part);
p->dev.class = &block_class;
p->dev.type = &part_type;
p->dev.parent = &disk->dev;
@@ -408,7 +411,6 @@ void register_disk(struct gendisk *disk)
int err;

disk->dev.parent = disk->driverfs_dev;
- disk->dev.devt = MKDEV(disk->major, disk->first_minor);

strlcpy(disk->dev.bus_id, disk->disk_name, KOBJ_NAME_LEN);
/* ewww... some of these buggers have / in the name... */
@@ -432,7 +434,7 @@ void register_disk(struct gendisk *disk)
disk_sysfs_add_subdirs(disk);

/* No minors to use for partitions */
- if (disk->minors == 1)
+ if (!disk_max_parts(disk))
goto exit;

/* No such device (e.g., media were just removed) */
@@ -455,8 +457,8 @@ exit:
kobject_uevent(&disk->dev.kobj, KOBJ_ADD);

/* announce possible partitions */
- for (i = 1; i < disk->minors; i++) {
- p = disk->part[i-1];
+ for (i = 0; i < disk_max_parts(disk); i++) {
+ p = disk->part[i];
if (!p || !p->nr_sects)
continue;
kobject_uevent(&p->dev.kobj, KOBJ_ADD);
@@ -474,7 +476,7 @@ int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
if (res)
return res;
bdev->bd_invalidated = 0;
- for (p = 1; p < disk->minors; p++)
+ for (p = 1; p <= disk_max_parts(disk); p++)
delete_partition(disk, p);
if (disk->fops->revalidate_disk)
disk->fops->revalidate_disk(disk);
@@ -531,7 +533,7 @@ void del_gendisk(struct gendisk *disk)
int p;

/* invalidate stuff */
- for (p = disk->minors - 1; p > 0; p--) {
+ for (p = disk_max_parts(disk); p > 0; p--) {
invalidate_partition(disk, p);
delete_partition(disk, p);
}
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 1f06681..1db5740 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -144,6 +144,31 @@ struct gendisk {
struct work_struct async_notify;
};

+static inline int disk_max_parts(struct gendisk *disk)
+{
+ return disk->minors - 1;
+}
+
+static inline int disk_major(struct gendisk *disk)
+{
+ return MAJOR(disk->dev.devt);
+}
+
+static inline int disk_minor(struct gendisk *disk)
+{
+ return MINOR(disk->dev.devt);
+}
+
+static inline int part_major(struct hd_struct *part)
+{
+ return MAJOR(part->dev.devt);
+}
+
+static inline int part_minor(struct hd_struct *part)
+{
+ return MINOR(part->dev.devt);
+}
+
/*
* Macros to operate on percpu disk statistics:
*
@@ -155,7 +180,7 @@ static inline struct hd_struct *get_part(struct gendisk *gendiskp,
{
struct hd_struct *part;
int i;
- for (i = 0; i < gendiskp->minors - 1; i++) {
+ for (i = 0; i < disk_max_parts(gendiskp); i++) {
part = gendiskp->part[i];
if (part && part->start_sect <= sector
&& sector < part->start_sect + part->nr_sects)
--
1.5.4.5

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Next message: Tejun Heo: "[PATCH 3/6] block: implement extended minors"
Previous message: Tejun Heo: "[PATCH 4/6] block: adjust formatting for large minors and add ext_range sysfs attr"
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Next in thread: Tejun Heo: "[PATCH 3/6] block: implement extended minors"
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