block: introduce partition 0
genhd and partition code handled disk and partitions separately. All
information about the whole disk was in struct genhd and partitions in
struct hd_struct. However, the whole disk (part0) and other
partitions have a lot in common and the data structures end up having
good number of common fields and thus separate code paths doing the
same thing. Also, the partition array was indexed by partno - 1 which
gets pretty confusing at times.
This patch introduces partition 0 and makes the partition array
indexed by partno. Following patches will unify the handling of disk
and parts piece-by-piece.
This patch also implements disk_partitionable() which tests whether a
disk is partitionable. With coming dynamic partition array change,
the most common usage of disk_max_parts() will be testing whether a
disk is partitionable and the number of max partitions will become
much less important.
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 0a2f16b..65b7386 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -54,10 +54,10 @@
{
struct hd_struct *part;
- if (unlikely(partno < 1 || partno > disk_max_parts(disk)))
+ if (unlikely(partno < 0 || partno >= disk_max_parts(disk)))
return NULL;
rcu_read_lock();
- part = rcu_dereference(disk->__part[partno - 1]);
+ part = rcu_dereference(disk->__part[partno]);
if (part)
get_device(part_to_dev(part));
rcu_read_unlock();
@@ -85,8 +85,10 @@
if (flags & DISK_PITER_REVERSE)
piter->idx = disk_max_parts(piter->disk) - 1;
- else
+ else if (flags & DISK_PITER_INCL_PART0)
piter->idx = 0;
+ else
+ piter->idx = 1;
piter->flags = flags;
}
@@ -114,7 +116,10 @@
/* determine iteration parameters */
if (piter->flags & DISK_PITER_REVERSE) {
inc = -1;
- end = -1;
+ if (piter->flags & DISK_PITER_INCL_PART0)
+ end = -1;
+ else
+ end = 0;
} else {
inc = 1;
end = disk_max_parts(piter->disk);
@@ -177,7 +182,7 @@
{
int i;
- for (i = 0; i < disk_max_parts(disk); i++) {
+ for (i = 1; i < disk_max_parts(disk); i++) {
struct hd_struct *part = rcu_dereference(disk->__part[i]);
if (part && part->start_sect <= sector &&
@@ -669,7 +674,7 @@
char buf[BDEVNAME_SIZE];
/* Don't show non-partitionable removeable devices or empty devices */
- if (!get_capacity(sgp) || (!disk_max_parts(sgp) &&
+ if (!get_capacity(sgp) || (!disk_partitionable(sgp) &&
(sgp->flags & GENHD_FL_REMOVABLE)))
return 0;
if (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO)
@@ -742,7 +747,7 @@
{
struct gendisk *disk = dev_to_disk(dev);
- return sprintf(buf, "%d\n", disk_max_parts(disk) + 1);
+ return sprintf(buf, "%d\n", disk_max_parts(disk));
}
static ssize_t disk_removable_show(struct device *dev,
@@ -998,7 +1003,7 @@
if (strcmp(dev->bus_id, name))
continue;
- if (partno < 0 || partno > disk_max_parts(disk))
+ if (partno < 0 || partno >= disk_max_parts(disk))
continue;
if (partno == 0)
@@ -1045,21 +1050,22 @@
GFP_KERNEL | __GFP_ZERO, node_id);
if (disk) {
int tot_minors = minors + ext_minors;
+ int size = tot_minors * sizeof(struct hd_struct *);
if (!init_disk_stats(disk)) {
kfree(disk);
return NULL;
}
- if (tot_minors > 1) {
- int size = (tot_minors - 1) * sizeof(struct hd_struct *);
- disk->__part = kmalloc_node(size,
- GFP_KERNEL | __GFP_ZERO, node_id);
- if (!disk->__part) {
- free_disk_stats(disk);
- kfree(disk);
- return NULL;
- }
+
+ disk->__part = kmalloc_node(size, GFP_KERNEL | __GFP_ZERO,
+ node_id);
+ if (!disk->__part) {
+ free_disk_stats(disk);
+ kfree(disk);
+ return NULL;
}
+ disk->__part[0] = &disk->part0;
+
disk->minors = minors;
disk->ext_minors = ext_minors;
rand_initialize_disk(disk);
diff --git a/block/ioctl.c b/block/ioctl.c
index a5f672a..64e7c67 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -30,7 +30,7 @@
if (bdev != bdev->bd_contains)
return -EINVAL;
partno = p.pno;
- if (partno <= 0 || partno > disk_max_parts(disk))
+ if (partno <= 0 || partno >= disk_max_parts(disk))
return -EINVAL;
switch (a.op) {
case BLKPG_ADD_PARTITION:
@@ -102,7 +102,7 @@
struct gendisk *disk = bdev->bd_disk;
int res;
- if (!disk_max_parts(disk) || bdev != bdev->bd_contains)
+ if (!disk_partitionable(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 a02df22..c982a91 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -892,7 +892,7 @@
if (bdops->revalidate_disk)
bdops->revalidate_disk(bdev->bd_disk);
- if (disk_max_parts(bdev->bd_disk))
+ if (disk_partitionable(bdev->bd_disk))
bdev->bd_invalidated = 1;
return 1;
}
diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index ac0df3a..b60699c 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -173,7 +173,7 @@
if (isdigit(state->name[strlen(state->name)-1]))
sprintf(state->name, "p");
- state->limit = disk_max_parts(hd) + 1;
+ state->limit = disk_max_parts(hd);
i = res = err = 0;
while (!res && check_part[i]) {
memset(&state->parts, 0, sizeof(state->parts));
@@ -329,12 +329,12 @@
{
struct hd_struct *part;
- part = disk->__part[partno-1];
+ part = disk->__part[partno];
if (!part)
return;
blk_free_devt(part_devt(part));
- rcu_assign_pointer(disk->__part[partno-1], NULL);
+ rcu_assign_pointer(disk->__part[partno], NULL);
kobject_put(part->holder_dir);
device_del(part_to_dev(part));
@@ -359,7 +359,7 @@
const char *dname;
int err;
- if (disk->__part[partno - 1])
+ if (disk->__part[partno])
return -EBUSY;
p = kzalloc(sizeof(*p), GFP_KERNEL);
@@ -413,7 +413,7 @@
/* everything is up and running, commence */
INIT_RCU_HEAD(&p->rcu_head);
- rcu_assign_pointer(disk->__part[partno - 1], p);
+ rcu_assign_pointer(disk->__part[partno], p);
/* suppress uevent if the disk supresses it */
if (!ddev->uevent_suppress)
@@ -467,7 +467,7 @@
disk_sysfs_add_subdirs(disk);
/* No minors to use for partitions */
- if (!disk_max_parts(disk))
+ if (!disk_partitionable(disk))
goto exit;
/* No such device (e.g., media were just removed) */
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index e4e18c5..9e866a2 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -127,12 +127,13 @@
char disk_name[32]; /* name of major driver */
- /* Array of pointers to partitions indexed by partno - 1.
+ /* Array of pointers to partitions indexed by partno.
* Protected with matching bdev lock but stat and other
* non-critical accesses use RCU. Always access through
* helpers.
*/
struct hd_struct **__part;
+ struct hd_struct part0;
struct block_device_operations *fops;
struct request_queue *queue;
@@ -171,7 +172,12 @@
static inline int disk_max_parts(struct gendisk *disk)
{
- return disk->minors + disk->ext_minors - 1;
+ return disk->minors + disk->ext_minors;
+}
+
+static inline bool disk_partitionable(struct gendisk *disk)
+{
+ return disk_max_parts(disk) > 1;
}
static inline dev_t disk_devt(struct gendisk *disk)
@@ -197,6 +203,7 @@
*/
#define DISK_PITER_REVERSE (1 << 0) /* iterate in the reverse direction */
#define DISK_PITER_INCL_EMPTY (1 << 1) /* include 0-sized parts */
+#define DISK_PITER_INCL_PART0 (1 << 2) /* include partition 0 */
struct disk_part_iter {
struct gendisk *disk;
