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block: don't depend on consecutive minor space

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* Implement disk_devt() and part_devt() and use them to directly
  access devt instead of computing it from ->major and ->first_minor.

  Note that all references to ->major and ->first_minor outside of
  block layer is used to determine devt of the disk (the part0) and as
  ->major and ->first_minor will continue to represent devt for the
  disk, converting these users aren't strictly necessary.  However,
  convert them for consistency.

* Implement disk_max_parts() to avoid directly deferencing
  genhd->minors.

* Update bdget_disk() such that it doesn't assume consecutive minor
  space.

* Move devt computation from register_disk() to add_disk() and make it
  the only one (all other usages use the initially determined value).

These changes clean up the code and will help disk->part dereference
fix and extended block device numbers.

Signed-off-by: Tejun Heo <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This commit is contained in:
Tejun Heo 2008-09-03 09:01:48 +02:00 • committed by Jens Axboe
commit f331c0296f
16 changed files with 132 additions and 67 deletions
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107
block/genhd.c
View file

@ -186,13 +186,14 @@ void add_disk(struct gendisk *disk)
int retval;
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_devt(disk), 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_devt(disk));
retval = sysfs_create_link(&disk->dev.kobj, &bdi->dev->kobj, "bdi");
WARN_ON(retval);
}
@ -205,8 +206,7 @@ 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_devt(disk), disk->minors);
}
/**
@ -225,6 +225,38 @@ struct gendisk *get_gendisk(dev_t devt, int *partno)
return kobj ? dev_to_disk(dev) : NULL;
}
/**
* bdget_disk - do bdget() by gendisk and partition number
* @disk: gendisk of interest
* @partno: partition number
*
* Find partition @partno from @disk, do bdget() on it.
*
* CONTEXT:
* Don't care.
*
* RETURNS:
* Resulting block_device on success, NULL on failure.
*/
extern struct block_device *bdget_disk(struct gendisk *disk, int partno)
{
dev_t devt = MKDEV(0, 0);
if (partno == 0)
devt = disk_devt(disk);
else {
struct hd_struct *part = disk->part[partno - 1];
if (part && part->nr_sects)
devt = part_devt(part);
}
if (likely(devt != MKDEV(0, 0)))
return bdget(devt);
return NULL;
}
EXPORT_SYMBOL(bdget_disk);
/*
* print a full list of all partitions - intended for places where the root
* filesystem can't be mounted and thus to give the victim some idea of what
@ -255,7 +287,7 @@ void __init printk_all_partitions(void)
* option takes.
*/
printk("%02x%02x %10llu %s",
disk->major, disk->first_minor,
MAJOR(disk_devt(disk)), MINOR(disk_devt(disk)),
(unsigned long long)get_capacity(disk) >> 1,
disk_name(disk, 0, buf));
if (disk->driverfs_dev != NULL &&
@ -266,15 +298,15 @@ void __init printk_all_partitions(void)
printk(" (driver?)\n");
/* now show the partitions */
for (n = 0; n < disk->minors - 1; ++n) {
if (disk->part[n] == NULL)
continue;
if (disk->part[n]->nr_sects == 0)
for (n = 0; n < disk_max_parts(disk); ++n) {
struct hd_struct *part = disk->part[n];
if (!part || !part->nr_sects)
continue;
printk(" %02x%02x %10llu %s\n",
disk->major, n + 1 + disk->first_minor,
(unsigned long long)disk->part[n]->nr_sects >> 1,
disk_name(disk, n + 1, buf));
MAJOR(part_devt(part)), MINOR(part_devt(part)),
(unsigned long long)part->nr_sects >> 1,
disk_name(disk, part->partno, buf));
}
}
class_dev_iter_exit(&iter);
@ -343,26 +375,27 @@ static int show_partition(struct seq_file *seqf, void *v)
char buf[BDEVNAME_SIZE];
/* 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(seqf, "%4d %4d %10llu %s\n",
sgp->major, sgp->first_minor,
MAJOR(disk_devt(sgp)), MINOR(disk_devt(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(seqf, "%4d %4d %10llu %s\n",
sgp->major, n + 1 + sgp->first_minor,
(unsigned long long)sgp->part[n]->nr_sects >> 1 ,
disk_name(sgp, n + 1, buf));
MAJOR(part_devt(part)), MINOR(part_devt(part)),
(unsigned long long)part->nr_sects >> 1,
disk_name(sgp, part->partno, buf));
}
return 0;
@ -578,7 +611,8 @@ static int diskstats_show(struct seq_file *seqf, void *v)
disk_round_stats(gp);
preempt_enable();
seq_printf(seqf, "%4d %4d %s %lu %lu %llu %u %lu %lu %llu %u %u %u %u\n",
gp->major, gp->first_minor, disk_name(gp, 0, buf),
MAJOR(disk_devt(gp)), MINOR(disk_devt(gp)),
disk_name(gp, 0, 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])),
@ -590,7 +624,7 @@ static int diskstats_show(struct seq_file *seqf, 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)
@ -601,8 +635,8 @@ static int diskstats_show(struct seq_file *seqf, void *v)
preempt_enable();
seq_printf(seqf, "%4d %4d %s %lu %lu %llu "
"%u %lu %lu %llu %u %u %u %u\n",
gp->major, n + gp->first_minor + 1,
disk_name(gp, n + 1, buf),
MAJOR(part_devt(hd)), MINOR(part_devt(hd)),
disk_name(gp, hd->partno, buf),
part_stat_read(hd, ios[0]),
part_stat_read(hd, merges[0]),
(unsigned long long)part_stat_read(hd, sectors[0]),
@ -661,11 +695,22 @@ dev_t blk_lookup_devt(const char *name, int partno)
while ((dev = class_dev_iter_next(&iter))) {
struct gendisk *disk = dev_to_disk(dev);
if (!strcmp(dev->bus_id, name) && partno < disk->minors) {
devt = MKDEV(MAJOR(dev->devt),
MINOR(dev->devt) + partno);
break;
if (strcmp(dev->bus_id, name))
continue;
if (partno < 0 || partno > disk_max_parts(disk))
continue;
if (partno == 0)
devt = disk_devt(disk);
else {
struct hd_struct *part = disk->part[partno - 1];
if (!part || !part->nr_sects)
continue;
devt = part_devt(part);
}
break;
}
class_dev_iter_exit(&iter);
return devt;
@ -755,7 +800,7 @@ 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;
}