block: don't depend on consecutive minor space
* 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 <tj@kernel.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/genhd.c b/block/genhd.c
index dc9ad4c..fa32d09 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -186,13 +186,14 @@
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 @@
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 @@
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 @@
* 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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
{
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;
}