Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 802 insertions, 0 deletions

diff --git a/block/partitions/core.c b/block/partitions/core.c
new file mode 100644
index 000000000..e3d61ec4a
--- /dev/null
+++ b/block/partitions/core.c
@@ -0,0 +1,802 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 1991-1998  Linus Torvalds
+ * Re-organised Feb 1998 Russell King
+ */
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/ctype.h>
+#include <linux/genhd.h>
+#include <linux/vmalloc.h>
+#include <linux/blktrace_api.h>
+#include <linux/raid/detect.h>
+#include "check.h"
+
+static int (*check_part[])(struct parsed_partitions *) = {
+	/*
+	 * Probe partition formats with tables at disk address 0
+	 * that also have an ADFS boot block at 0xdc0.
+	 */
+#ifdef CONFIG_ACORN_PARTITION_ICS
+	adfspart_check_ICS,
+#endif
+#ifdef CONFIG_ACORN_PARTITION_POWERTEC
+	adfspart_check_POWERTEC,
+#endif
+#ifdef CONFIG_ACORN_PARTITION_EESOX
+	adfspart_check_EESOX,
+#endif
+
+	/*
+	 * Now move on to formats that only have partition info at
+	 * disk address 0xdc0.  Since these may also have stale
+	 * PC/BIOS partition tables, they need to come before
+	 * the msdos entry.
+	 */
+#ifdef CONFIG_ACORN_PARTITION_CUMANA
+	adfspart_check_CUMANA,
+#endif
+#ifdef CONFIG_ACORN_PARTITION_ADFS
+	adfspart_check_ADFS,
+#endif
+
+#ifdef CONFIG_CMDLINE_PARTITION
+	cmdline_partition,
+#endif
+#ifdef CONFIG_EFI_PARTITION
+	efi_partition,		/* this must come before msdos */
+#endif
+#ifdef CONFIG_SGI_PARTITION
+	sgi_partition,
+#endif
+#ifdef CONFIG_LDM_PARTITION
+	ldm_partition,		/* this must come before msdos */
+#endif
+#ifdef CONFIG_MSDOS_PARTITION
+	msdos_partition,
+#endif
+#ifdef CONFIG_OSF_PARTITION
+	osf_partition,
+#endif
+#ifdef CONFIG_SUN_PARTITION
+	sun_partition,
+#endif
+#ifdef CONFIG_AMIGA_PARTITION
+	amiga_partition,
+#endif
+#ifdef CONFIG_ATARI_PARTITION
+	atari_partition,
+#endif
+#ifdef CONFIG_MAC_PARTITION
+	mac_partition,
+#endif
+#ifdef CONFIG_ULTRIX_PARTITION
+	ultrix_partition,
+#endif
+#ifdef CONFIG_IBM_PARTITION
+	ibm_partition,
+#endif
+#ifdef CONFIG_KARMA_PARTITION
+	karma_partition,
+#endif
+#ifdef CONFIG_SYSV68_PARTITION
+	sysv68_partition,
+#endif
+	NULL
+};
+
+static struct parsed_partitions *allocate_partitions(struct gendisk *hd)
+{
+	struct parsed_partitions *state;
+	int nr;
+
+	state = kzalloc(sizeof(*state), GFP_KERNEL);
+	if (!state)
+		return NULL;
+
+	nr = disk_max_parts(hd);
+	state->parts = vzalloc(array_size(nr, sizeof(state->parts[0])));
+	if (!state->parts) {
+		kfree(state);
+		return NULL;
+	}
+
+	state->limit = nr;
+
+	return state;
+}
+
+static void free_partitions(struct parsed_partitions *state)
+{
+	vfree(state->parts);
+	kfree(state);
+}
+
+static struct parsed_partitions *check_partition(struct gendisk *hd,
+		struct block_device *bdev)
+{
+	struct parsed_partitions *state;
+	int i, res, err;
+
+	state = allocate_partitions(hd);
+	if (!state)
+		return NULL;
+	state->pp_buf = (char *)__get_free_page(GFP_KERNEL);
+	if (!state->pp_buf) {
+		free_partitions(state);
+		return NULL;
+	}
+	state->pp_buf[0] = '\0';
+
+	state->bdev = bdev;
+	disk_name(hd, 0, state->name);
+	snprintf(state->pp_buf, PAGE_SIZE, " %s:", state->name);
+	if (isdigit(state->name[strlen(state->name)-1]))
+		sprintf(state->name, "p");
+
+	i = res = err = 0;
+	while (!res && check_part[i]) {
+		memset(state->parts, 0, state->limit * sizeof(state->parts[0]));
+		res = check_part[i++](state);
+		if (res < 0) {
+			/*
+			 * We have hit an I/O error which we don't report now.
+			 * But record it, and let the others do their job.
+			 */
+			err = res;
+			res = 0;
+		}
+
+	}
+	if (res > 0) {
+		printk(KERN_INFO "%s", state->pp_buf);
+
+		free_page((unsigned long)state->pp_buf);
+		return state;
+	}
+	if (state->access_beyond_eod)
+		err = -ENOSPC;
+	/*
+	 * The partition is unrecognized. So report I/O errors if there were any
+	 */
+	if (err)
+		res = err;
+	if (res) {
+		strlcat(state->pp_buf,
+			" unable to read partition table\n", PAGE_SIZE);
+		printk(KERN_INFO "%s", state->pp_buf);
+	}
+
+	free_page((unsigned long)state->pp_buf);
+	free_partitions(state);
+	return ERR_PTR(res);
+}
+
+static ssize_t part_partition_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct hd_struct *p = dev_to_part(dev);
+
+	return sprintf(buf, "%d\n", p->partno);
+}
+
+static ssize_t part_start_show(struct device *dev,
+			       struct device_attribute *attr, char *buf)
+{
+	struct hd_struct *p = dev_to_part(dev);
+
+	return sprintf(buf, "%llu\n",(unsigned long long)p->start_sect);
+}
+
+static ssize_t part_ro_show(struct device *dev,
+			    struct device_attribute *attr, char *buf)
+{
+	struct hd_struct *p = dev_to_part(dev);
+	return sprintf(buf, "%d\n", p->policy ? 1 : 0);
+}
+
+static ssize_t part_alignment_offset_show(struct device *dev,
+					  struct device_attribute *attr, char *buf)
+{
+	struct hd_struct *p = dev_to_part(dev);
+
+	return sprintf(buf, "%u\n",
+		queue_limit_alignment_offset(&part_to_disk(p)->queue->limits,
+				p->start_sect));
+}
+
+static ssize_t part_discard_alignment_show(struct device *dev,
+					   struct device_attribute *attr, char *buf)
+{
+	struct hd_struct *p = dev_to_part(dev);
+
+	return sprintf(buf, "%u\n",
+		queue_limit_discard_alignment(&part_to_disk(p)->queue->limits,
+				p->start_sect));
+}
+
+static DEVICE_ATTR(partition, 0444, part_partition_show, NULL);
+static DEVICE_ATTR(start, 0444, part_start_show, NULL);
+static DEVICE_ATTR(size, 0444, part_size_show, NULL);
+static DEVICE_ATTR(ro, 0444, part_ro_show, NULL);
+static DEVICE_ATTR(alignment_offset, 0444, part_alignment_offset_show, NULL);
+static DEVICE_ATTR(discard_alignment, 0444, part_discard_alignment_show, NULL);
+static DEVICE_ATTR(stat, 0444, part_stat_show, NULL);
+static DEVICE_ATTR(inflight, 0444, part_inflight_show, NULL);
+#ifdef CONFIG_FAIL_MAKE_REQUEST
+static struct device_attribute dev_attr_fail =
+	__ATTR(make-it-fail, 0644, part_fail_show, part_fail_store);
+#endif
+
+static struct attribute *part_attrs[] = {
+	&dev_attr_partition.attr,
+	&dev_attr_start.attr,
+	&dev_attr_size.attr,
+	&dev_attr_ro.attr,
+	&dev_attr_alignment_offset.attr,
+	&dev_attr_discard_alignment.attr,
+	&dev_attr_stat.attr,
+	&dev_attr_inflight.attr,
+#ifdef CONFIG_FAIL_MAKE_REQUEST
+	&dev_attr_fail.attr,
+#endif
+	NULL
+};
+
+static struct attribute_group part_attr_group = {
+	.attrs = part_attrs,
+};
+
+static const struct attribute_group *part_attr_groups[] = {
+	&part_attr_group,
+#ifdef CONFIG_BLK_DEV_IO_TRACE
+	&blk_trace_attr_group,
+#endif
+	NULL
+};
+
+static void part_release(struct device *dev)
+{
+	struct hd_struct *p = dev_to_part(dev);
+	blk_free_devt(dev->devt);
+	hd_free_part(p);
+	kfree(p);
+}
+
+static int part_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+	struct hd_struct *part = dev_to_part(dev);
+
+	add_uevent_var(env, "PARTN=%u", part->partno);
+	if (part->info && part->info->volname[0])
+		add_uevent_var(env, "PARTNAME=%s", part->info->volname);
+	return 0;
+}
+
+struct device_type part_type = {
+	.name		= "partition",
+	.groups		= part_attr_groups,
+	.release	= part_release,
+	.uevent		= part_uevent,
+};
+
+static void hd_struct_free_work(struct work_struct *work)
+{
+	struct hd_struct *part =
+		container_of(to_rcu_work(work), struct hd_struct, rcu_work);
+	struct gendisk *disk = part_to_disk(part);
+
+	/*
+	 * Release the disk reference acquired in delete_partition here.
+	 * We can't release it in hd_struct_free because the final put_device
+	 * needs process context and thus can't be run directly from a
+	 * percpu_ref ->release handler.
+	 */
+	put_device(disk_to_dev(disk));
+
+	part->start_sect = 0;
+	part->nr_sects = 0;
+	part_stat_set_all(part, 0);
+	put_device(part_to_dev(part));
+}
+
+static void hd_struct_free(struct percpu_ref *ref)
+{
+	struct hd_struct *part = container_of(ref, struct hd_struct, ref);
+	struct gendisk *disk = part_to_disk(part);
+	struct disk_part_tbl *ptbl =
+		rcu_dereference_protected(disk->part_tbl, 1);
+
+	rcu_assign_pointer(ptbl->last_lookup, NULL);
+
+	INIT_RCU_WORK(&part->rcu_work, hd_struct_free_work);
+	queue_rcu_work(system_wq, &part->rcu_work);
+}
+
+int hd_ref_init(struct hd_struct *part)
+{
+	if (percpu_ref_init(&part->ref, hd_struct_free, 0, GFP_KERNEL))
+		return -ENOMEM;
+	return 0;
+}
+
+/*
+ * Must be called either with bd_mutex held, before a disk can be opened or
+ * after all disk users are gone.
+ */
+void delete_partition(struct hd_struct *part)
+{
+	struct gendisk *disk = part_to_disk(part);
+	struct disk_part_tbl *ptbl =
+		rcu_dereference_protected(disk->part_tbl, 1);
+	struct block_device *bdev;
+
+	/*
+	 * ->part_tbl is referenced in this part's release handler, so
+	 *  we have to hold the disk device
+	 */
+	get_device(disk_to_dev(disk));
+	rcu_assign_pointer(ptbl->part[part->partno], NULL);
+	kobject_put(part->holder_dir);
+	device_del(part_to_dev(part));
+
+	/*
+	 * Remove gendisk pointer from idr so that it cannot be looked up
+	 * while RCU period before freeing gendisk is running to prevent
+	 * use-after-free issues. Note that the device number stays
+	 * "in-use" until we really free the gendisk.
+	 */
+	blk_invalidate_devt(part_devt(part));
+
+	bdev = bdget_part(part);
+	if (bdev) {
+		remove_inode_hash(bdev->bd_inode);
+		bdput(bdev);
+	}
+	percpu_ref_kill(&part->ref);
+}
+
+static ssize_t whole_disk_show(struct device *dev,
+			       struct device_attribute *attr, char *buf)
+{
+	return 0;
+}
+static DEVICE_ATTR(whole_disk, 0444, whole_disk_show, NULL);
+
+/*
+ * Must be called either with bd_mutex held, before a disk can be opened or
+ * after all disk users are gone.
+ */
+static struct hd_struct *add_partition(struct gendisk *disk, int partno,
+				sector_t start, sector_t len, int flags,
+				struct partition_meta_info *info)
+{
+	struct hd_struct *p;
+	dev_t devt = MKDEV(0, 0);
+	struct device *ddev = disk_to_dev(disk);
+	struct device *pdev;
+	struct disk_part_tbl *ptbl;
+	const char *dname;
+	int err;
+
+	/*
+	 * Partitions are not supported on zoned block devices that are used as
+	 * such.
+	 */
+	switch (disk->queue->limits.zoned) {
+	case BLK_ZONED_HM:
+		pr_warn("%s: partitions not supported on host managed zoned block device\n",
+			disk->disk_name);
+		return ERR_PTR(-ENXIO);
+	case BLK_ZONED_HA:
+		pr_info("%s: disabling host aware zoned block device support due to partitions\n",
+			disk->disk_name);
+		disk->queue->limits.zoned = BLK_ZONED_NONE;
+		break;
+	case BLK_ZONED_NONE:
+		break;
+	}
+
+	err = disk_expand_part_tbl(disk, partno);
+	if (err)
+		return ERR_PTR(err);
+	ptbl = rcu_dereference_protected(disk->part_tbl, 1);
+
+	if (ptbl->part[partno])
+		return ERR_PTR(-EBUSY);
+
+	p = kzalloc(sizeof(*p), GFP_KERNEL);
+	if (!p)
+		return ERR_PTR(-EBUSY);
+
+	p->dkstats = alloc_percpu(struct disk_stats);
+	if (!p->dkstats) {
+		err = -ENOMEM;
+		goto out_free;
+	}
+
+	hd_sects_seq_init(p);
+	pdev = part_to_dev(p);
+
+	p->start_sect = start;
+	p->nr_sects = len;
+	p->partno = partno;
+	p->policy = get_disk_ro(disk);
+
+	if (info) {
+		struct partition_meta_info *pinfo;
+
+		pinfo = kzalloc_node(sizeof(*pinfo), GFP_KERNEL, disk->node_id);
+		if (!pinfo) {
+			err = -ENOMEM;
+			goto out_free_stats;
+		}
+		memcpy(pinfo, info, sizeof(*info));
+		p->info = pinfo;
+	}
+
+	dname = dev_name(ddev);
+	if (isdigit(dname[strlen(dname) - 1]))
+		dev_set_name(pdev, "%sp%d", dname, partno);
+	else
+		dev_set_name(pdev, "%s%d", dname, partno);
+
+	device_initialize(pdev);
+	pdev->class = &block_class;
+	pdev->type = &part_type;
+	pdev->parent = ddev;
+
+	err = blk_alloc_devt(p, &devt);
+	if (err)
+		goto out_free_info;
+	pdev->devt = devt;
+
+	/* delay uevent until 'holders' subdir is created */
+	dev_set_uevent_suppress(pdev, 1);
+	err = device_add(pdev);
+	if (err)
+		goto out_put;
+
+	err = -ENOMEM;
+	p->holder_dir = kobject_create_and_add("holders", &pdev->kobj);
+	if (!p->holder_dir)
+		goto out_del;
+
+	dev_set_uevent_suppress(pdev, 0);
+	if (flags & ADDPART_FLAG_WHOLEDISK) {
+		err = device_create_file(pdev, &dev_attr_whole_disk);
+		if (err)
+			goto out_del;
+	}
+
+	err = hd_ref_init(p);
+	if (err) {
+		if (flags & ADDPART_FLAG_WHOLEDISK)
+			goto out_remove_file;
+		goto out_del;
+	}
+
+	/* everything is up and running, commence */
+	rcu_assign_pointer(ptbl->part[partno], p);
+
+	/* suppress uevent if the disk suppresses it */
+	if (!dev_get_uevent_suppress(ddev))
+		kobject_uevent(&pdev->kobj, KOBJ_ADD);
+	return p;
+
+out_free_info:
+	kfree(p->info);
+out_free_stats:
+	free_percpu(p->dkstats);
+out_free:
+	kfree(p);
+	return ERR_PTR(err);
+out_remove_file:
+	device_remove_file(pdev, &dev_attr_whole_disk);
+out_del:
+	kobject_put(p->holder_dir);
+	device_del(pdev);
+out_put:
+	put_device(pdev);
+	return ERR_PTR(err);
+}
+
+static bool partition_overlaps(struct gendisk *disk, sector_t start,
+		sector_t length, int skip_partno)
+{
+	struct disk_part_iter piter;
+	struct hd_struct *part;
+	bool overlap = false;
+
+	disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
+	while ((part = disk_part_iter_next(&piter))) {
+		if (part->partno == skip_partno ||
+		    start >= part->start_sect + part->nr_sects ||
+		    start + length <= part->start_sect)
+			continue;
+		overlap = true;
+		break;
+	}
+
+	disk_part_iter_exit(&piter);
+	return overlap;
+}
+
+int bdev_add_partition(struct block_device *bdev, int partno,
+		sector_t start, sector_t length)
+{
+	struct hd_struct *part;
+
+	mutex_lock(&bdev->bd_mutex);
+	if (partition_overlaps(bdev->bd_disk, start, length, -1)) {
+		mutex_unlock(&bdev->bd_mutex);
+		return -EBUSY;
+	}
+
+	part = add_partition(bdev->bd_disk, partno, start, length,
+			ADDPART_FLAG_NONE, NULL);
+	mutex_unlock(&bdev->bd_mutex);
+	return PTR_ERR_OR_ZERO(part);
+}
+
+int bdev_del_partition(struct block_device *bdev, int partno)
+{
+	struct block_device *bdevp;
+	struct hd_struct *part = NULL;
+	int ret;
+
+	bdevp = bdget_disk(bdev->bd_disk, partno);
+	if (!bdevp)
+		return -ENXIO;
+
+	mutex_lock(&bdevp->bd_mutex);
+	mutex_lock_nested(&bdev->bd_mutex, 1);
+
+	ret = -ENXIO;
+	part = disk_get_part(bdev->bd_disk, partno);
+	if (!part)
+		goto out_unlock;
+
+	ret = -EBUSY;
+	if (bdevp->bd_openers)
+		goto out_unlock;
+
+	sync_blockdev(bdevp);
+	invalidate_bdev(bdevp);
+
+	delete_partition(part);
+	ret = 0;
+out_unlock:
+	mutex_unlock(&bdev->bd_mutex);
+	mutex_unlock(&bdevp->bd_mutex);
+	bdput(bdevp);
+	if (part)
+		disk_put_part(part);
+	return ret;
+}
+
+int bdev_resize_partition(struct block_device *bdev, int partno,
+		sector_t start, sector_t length)
+{
+	struct block_device *bdevp;
+	struct hd_struct *part;
+	int ret = 0;
+
+	part = disk_get_part(bdev->bd_disk, partno);
+	if (!part)
+		return -ENXIO;
+
+	ret = -ENOMEM;
+	bdevp = bdget_part(part);
+	if (!bdevp)
+		goto out_put_part;
+
+	mutex_lock(&bdevp->bd_mutex);
+	mutex_lock_nested(&bdev->bd_mutex, 1);
+
+	ret = -EINVAL;
+	if (start != part->start_sect)
+		goto out_unlock;
+
+	ret = -EBUSY;
+	if (partition_overlaps(bdev->bd_disk, start, length, partno))
+		goto out_unlock;
+
+	part_nr_sects_write(part, length);
+	bd_set_nr_sectors(bdevp, length);
+
+	ret = 0;
+out_unlock:
+	mutex_unlock(&bdevp->bd_mutex);
+	mutex_unlock(&bdev->bd_mutex);
+	bdput(bdevp);
+out_put_part:
+	disk_put_part(part);
+	return ret;
+}
+
+static bool disk_unlock_native_capacity(struct gendisk *disk)
+{
+	const struct block_device_operations *bdops = disk->fops;
+
+	if (bdops->unlock_native_capacity &&
+	    !(disk->flags & GENHD_FL_NATIVE_CAPACITY)) {
+		printk(KERN_CONT "enabling native capacity\n");
+		bdops->unlock_native_capacity(disk);
+		disk->flags |= GENHD_FL_NATIVE_CAPACITY;
+		return true;
+	} else {
+		printk(KERN_CONT "truncated\n");
+		return false;
+	}
+}
+
+int blk_drop_partitions(struct block_device *bdev)
+{
+	struct disk_part_iter piter;
+	struct hd_struct *part;
+
+	if (bdev->bd_part_count)
+		return -EBUSY;
+
+	sync_blockdev(bdev);
+	invalidate_bdev(bdev);
+
+	disk_part_iter_init(&piter, bdev->bd_disk, DISK_PITER_INCL_EMPTY);
+	while ((part = disk_part_iter_next(&piter)))
+		delete_partition(part);
+	disk_part_iter_exit(&piter);
+
+	return 0;
+}
+#ifdef CONFIG_S390
+/* for historic reasons in the DASD driver */
+EXPORT_SYMBOL_GPL(blk_drop_partitions);
+#endif
+
+static bool blk_add_partition(struct gendisk *disk, struct block_device *bdev,
+		struct parsed_partitions *state, int p)
+{
+	sector_t size = state->parts[p].size;
+	sector_t from = state->parts[p].from;
+	struct hd_struct *part;
+
+	if (!size)
+		return true;
+
+	if (from >= get_capacity(disk)) {
+		printk(KERN_WARNING
+		       "%s: p%d start %llu is beyond EOD, ",
+		       disk->disk_name, p, (unsigned long long) from);
+		if (disk_unlock_native_capacity(disk))
+			return false;
+		return true;
+	}
+
+	if (from + size > get_capacity(disk)) {
+		printk(KERN_WARNING
+		       "%s: p%d size %llu extends beyond EOD, ",
+		       disk->disk_name, p, (unsigned long long) size);
+
+		if (disk_unlock_native_capacity(disk))
+			return false;
+
+		/*
+		 * We can not ignore partitions of broken tables created by for
+		 * example camera firmware, but we limit them to the end of the
+		 * disk to avoid creating invalid block devices.
+		 */
+		size = get_capacity(disk) - from;
+	}
+
+	part = add_partition(disk, p, from, size, state->parts[p].flags,
+			     &state->parts[p].info);
+	if (IS_ERR(part) && PTR_ERR(part) != -ENXIO) {
+		printk(KERN_ERR " %s: p%d could not be added: %ld\n",
+		       disk->disk_name, p, -PTR_ERR(part));
+		return true;
+	}
+
+	if (IS_BUILTIN(CONFIG_BLK_DEV_MD) &&
+	    (state->parts[p].flags & ADDPART_FLAG_RAID))
+		md_autodetect_dev(part_to_dev(part)->devt);
+
+	return true;
+}
+
+int blk_add_partitions(struct gendisk *disk, struct block_device *bdev)
+{
+	struct parsed_partitions *state;
+	int ret = -EAGAIN, p, highest;
+
+	if (!disk_part_scan_enabled(disk))
+		return 0;
+
+	state = check_partition(disk, bdev);
+	if (!state)
+		return 0;
+	if (IS_ERR(state)) {
+		/*
+		 * I/O error reading the partition table.  If we tried to read
+		 * beyond EOD, retry after unlocking the native capacity.
+		 */
+		if (PTR_ERR(state) == -ENOSPC) {
+			printk(KERN_WARNING "%s: partition table beyond EOD, ",
+			       disk->disk_name);
+			if (disk_unlock_native_capacity(disk))
+				return -EAGAIN;
+		}
+		return -EIO;
+	}
+
+	/*
+	 * Partitions are not supported on host managed zoned block devices.
+	 */
+	if (disk->queue->limits.zoned == BLK_ZONED_HM) {
+		pr_warn("%s: ignoring partition table on host managed zoned block device\n",
+			disk->disk_name);
+		ret = 0;
+		goto out_free_state;
+	}
+
+	/*
+	 * If we read beyond EOD, try unlocking native capacity even if the
+	 * partition table was successfully read as we could be missing some
+	 * partitions.
+	 */
+	if (state->access_beyond_eod) {
+		printk(KERN_WARNING
+		       "%s: partition table partially beyond EOD, ",
+		       disk->disk_name);
+		if (disk_unlock_native_capacity(disk))
+			goto out_free_state;
+	}
+
+	/* tell userspace that the media / partition table may have changed */
+	kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
+
+	/*
+	 * Detect the highest partition number and preallocate disk->part_tbl.
+	 * This is an optimization and not strictly necessary.
+	 */
+	for (p = 1, highest = 0; p < state->limit; p++)
+		if (state->parts[p].size)
+			highest = p;
+	disk_expand_part_tbl(disk, highest);
+
+	for (p = 1; p < state->limit; p++)
+		if (!blk_add_partition(disk, bdev, state, p))
+			goto out_free_state;
+
+	ret = 0;
+out_free_state:
+	free_partitions(state);
+	return ret;
+}
+
+void *read_part_sector(struct parsed_partitions *state, sector_t n, Sector *p)
+{
+	struct address_space *mapping = state->bdev->bd_inode->i_mapping;
+	struct page *page;
+
+	if (n >= get_capacity(state->bdev->bd_disk)) {
+		state->access_beyond_eod = true;
+		return NULL;
+	}
+
+	page = read_mapping_page(mapping,
+			(pgoff_t)(n >> (PAGE_SHIFT - 9)), NULL);
+	if (IS_ERR(page))
+		goto out;
+	if (PageError(page))
+		goto out_put_page;
+
+	p->v = page;
+	return (unsigned char *)page_address(page) +
+			((n & ((1 << (PAGE_SHIFT - 9)) - 1)) << SECTOR_SHIFT);
+out_put_page:
+	put_page(page);
+out:
+	p->v = NULL;
+	return NULL;
+}