block/ioctl.c - kernel/common - Git at Google

 #include <linux/capability.h>
 #include <linux/blkdev.h>
 #include <linux/export.h>
 #include <linux/gfp.h>
 #include <linux/blkpg.h>
 #include <linux/hdreg.h>
 #include <linux/backing-dev.h>
 #include <linux/fs.h>
 #include <linux/blktrace_api.h>
 #include <linux/pr.h>
 #include <linux/uaccess.h>

 static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user *arg)
 {
 	struct block_device *bdevp;
 	struct gendisk *disk;
 	struct hd_struct *part, *lpart;
 	struct blkpg_ioctl_arg a;
 	struct blkpg_partition p;
 	struct disk_part_iter piter;
 	long long start, length;
 	int partno;

 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;
 	if (copy_from_user(&a, arg, sizeof(struct blkpg_ioctl_arg)))
 		return -EFAULT;
 	if (copy_from_user(&p, a.data, sizeof(struct blkpg_partition)))
 		return -EFAULT;
 	disk = bdev->bd_disk;
 	if (bdev != bdev->bd_contains)
 		return -EINVAL;
 	partno = p.pno;
 	if (partno <= 0)
 		return -EINVAL;
 	switch (a.op) {
 		case BLKPG_ADD_PARTITION:
 			start = p.start >> 9;
 			length = p.length >> 9;
 			/* check for fit in a hd_struct */
 			if (sizeof(sector_t) == sizeof(long) &&
 			    sizeof(long long) > sizeof(long)) {
 				long pstart = start, plength = length;
 				if (pstart != start || plength != length
 				    || pstart < 0 || plength < 0 || partno > 65535)
 					return -EINVAL;
 			}
 			/* check if partition is aligned to blocksize */
 			if (p.start & (bdev_logical_block_size(bdev) - 1))
 				return -EINVAL;

 			mutex_lock(&bdev->bd_mutex);

 			/* overlap? */
 			disk_part_iter_init(&piter, disk,
 					    DISK_PITER_INCL_EMPTY);
 			while ((part = disk_part_iter_next(&piter))) {
 				if (!(start + length <= part->start_sect ||
 				      start >= part->start_sect + part->nr_sects)) {
 					disk_part_iter_exit(&piter);
 					mutex_unlock(&bdev->bd_mutex);
 					return -EBUSY;
 				}
 			}
 			disk_part_iter_exit(&piter);

 			/* all seems OK */
 			part = add_partition(disk, partno, start, length,
 					     ADDPART_FLAG_NONE, NULL);
 			mutex_unlock(&bdev->bd_mutex);
 			return PTR_ERR_OR_ZERO(part);
 		case BLKPG_DEL_PARTITION:
 			part = disk_get_part(disk, partno);
 			if (!part)
 				return -ENXIO;

 			bdevp = bdget(part_devt(part));
 			disk_put_part(part);
 			if (!bdevp)
 				return -ENOMEM;

 			mutex_lock(&bdevp->bd_mutex);
 			if (bdevp->bd_openers) {
 				mutex_unlock(&bdevp->bd_mutex);
 				bdput(bdevp);
 				return -EBUSY;
 			}
 			/* all seems OK */
 			fsync_bdev(bdevp);
 			invalidate_bdev(bdevp);

 			mutex_lock_nested(&bdev->bd_mutex, 1);
 			delete_partition(disk, partno);
 			mutex_unlock(&bdev->bd_mutex);
 			mutex_unlock(&bdevp->bd_mutex);
 			bdput(bdevp);

 			return 0;
 		case BLKPG_RESIZE_PARTITION:
 			start = p.start >> 9;
 			/* new length of partition in bytes */
 			length = p.length >> 9;
 			/* check for fit in a hd_struct */
 			if (sizeof(sector_t) == sizeof(long) &&
 			    sizeof(long long) > sizeof(long)) {
 				long pstart = start, plength = length;
 				if (pstart != start || plength != length
 				    || pstart < 0 || plength < 0)
 					return -EINVAL;
 			}
 			part = disk_get_part(disk, partno);
 			if (!part)
 				return -ENXIO;
 			bdevp = bdget(part_devt(part));
 			if (!bdevp) {
 				disk_put_part(part);
 				return -ENOMEM;
 			}
 			mutex_lock(&bdevp->bd_mutex);
 			mutex_lock_nested(&bdev->bd_mutex, 1);
 			if (start != part->start_sect) {
 				mutex_unlock(&bdevp->bd_mutex);
 				mutex_unlock(&bdev->bd_mutex);
 				bdput(bdevp);
 				disk_put_part(part);
 				return -EINVAL;
 			}
 			/* overlap? */
 			disk_part_iter_init(&piter, disk,
 					    DISK_PITER_INCL_EMPTY);
 			while ((lpart = disk_part_iter_next(&piter))) {
 				if (lpart->partno != partno &&
 				   !(start + length <= lpart->start_sect ||
 				   start >= lpart->start_sect + lpart->nr_sects)
 				   ) {
 					disk_part_iter_exit(&piter);
 					mutex_unlock(&bdevp->bd_mutex);
 					mutex_unlock(&bdev->bd_mutex);
 					bdput(bdevp);
 					disk_put_part(part);
 					return -EBUSY;
 				}
 			}
 			disk_part_iter_exit(&piter);
 			part_nr_sects_write(part, (sector_t)length);
 			i_size_write(bdevp->bd_inode, p.length);
 			mutex_unlock(&bdevp->bd_mutex);
 			mutex_unlock(&bdev->bd_mutex);
 			bdput(bdevp);
 			disk_put_part(part);
 			return 0;
 		default:
 			return -EINVAL;
 	}
 }

 /*
  * This is an exported API for the block driver, and will not
  * acquire bd_mutex. This API should be used in case that
  * caller has held bd_mutex already.
  */
 int __blkdev_reread_part(struct block_device *bdev)
 {
 	struct gendisk *disk = bdev->bd_disk;

 	if (!disk_part_scan_enabled(disk) || bdev != bdev->bd_contains)
 		return -EINVAL;
 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;

 	lockdep_assert_held(&bdev->bd_mutex);

 	return rescan_partitions(disk, bdev);
 }
 EXPORT_SYMBOL(__blkdev_reread_part);

 /*
  * This is an exported API for the block driver, and will
  * try to acquire bd_mutex. If bd_mutex has been held already
  * in current context, please call __blkdev_reread_part().
  *
  * Make sure the held locks in current context aren't required
  * in open()/close() handler and I/O path for avoiding ABBA deadlock:
  * - bd_mutex is held before calling block driver's open/close
  *   handler
  * - reading partition table may submit I/O to the block device
  */
 int blkdev_reread_part(struct block_device *bdev)
 {
 	int res;

 	mutex_lock(&bdev->bd_mutex);
 	res = __blkdev_reread_part(bdev);
 	mutex_unlock(&bdev->bd_mutex);

 	return res;
 }
 EXPORT_SYMBOL(blkdev_reread_part);

 static int blk_ioctl_discard(struct block_device *bdev, fmode_t mode,
 		unsigned long arg, unsigned long flags)
 {
 	uint64_t range[2];
 	uint64_t start, len;

 	if (!(mode & FMODE_WRITE))
 		return -EBADF;

 	if (copy_from_user(range, (void __user *)arg, sizeof(range)))
 		return -EFAULT;

 	start = range[0];
 	len = range[1];

 	if (start & 511)
 		return -EINVAL;
 	if (len & 511)
 		return -EINVAL;
 	start >>= 9;
 	len >>= 9;

 	if (start + len > (i_size_read(bdev->bd_inode) >> 9))
 		return -EINVAL;
 	return blkdev_issue_discard(bdev, start, len, GFP_KERNEL, flags);
 }

 static int blk_ioctl_zeroout(struct block_device *bdev, fmode_t mode,
 		unsigned long arg)
 {
 	uint64_t range[2];
 	struct address_space *mapping;
 	uint64_t start, end, len;

 	if (!(mode & FMODE_WRITE))
 		return -EBADF;

 	if (copy_from_user(range, (void __user *)arg, sizeof(range)))
 		return -EFAULT;

 	start = range[0];
 	len = range[1];
 	end = start + len - 1;

 	if (start & 511)
 		return -EINVAL;
 	if (len & 511)
 		return -EINVAL;
 	if (end >= (uint64_t)i_size_read(bdev->bd_inode))
 		return -EINVAL;
 	if (end < start)
 		return -EINVAL;

 	/* Invalidate the page cache, including dirty pages */
 	mapping = bdev->bd_inode->i_mapping;
 	truncate_inode_pages_range(mapping, start, end);

 	return blkdev_issue_zeroout(bdev, start >> 9, len >> 9, GFP_KERNEL,
 			BLKDEV_ZERO_NOUNMAP);
 }

 static int put_ushort(unsigned long arg, unsigned short val)
 {
 	return put_user(val, (unsigned short __user *)arg);
 }

 static int put_int(unsigned long arg, int val)
 {
 	return put_user(val, (int __user *)arg);
 }

 static int put_uint(unsigned long arg, unsigned int val)
 {
 	return put_user(val, (unsigned int __user *)arg);
 }

 static int put_long(unsigned long arg, long val)
 {
 	return put_user(val, (long __user *)arg);
 }

 static int put_ulong(unsigned long arg, unsigned long val)
 {
 	return put_user(val, (unsigned long __user *)arg);
 }

 static int put_u64(unsigned long arg, u64 val)
 {
 	return put_user(val, (u64 __user *)arg);
 }

 int __blkdev_driver_ioctl(struct block_device *bdev, fmode_t mode,
 			unsigned cmd, unsigned long arg)
 {
 	struct gendisk *disk = bdev->bd_disk;

 	if (disk->fops->ioctl)
 		return disk->fops->ioctl(bdev, mode, cmd, arg);

 	return -ENOTTY;
 }
 /*
  * For the record: _GPL here is only because somebody decided to slap it
  * on the previous export.  Sheer idiocy, since it wasn't copyrightable
  * at all and could be open-coded without any exports by anybody who cares.
  */
 EXPORT_SYMBOL_GPL(__blkdev_driver_ioctl);

 static int blkdev_pr_register(struct block_device *bdev,
 		struct pr_registration __user *arg)
 {
 	const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;
 	struct pr_registration reg;

 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 	if (!ops || !ops->pr_register)
 		return -EOPNOTSUPP;
 	if (copy_from_user(&reg, arg, sizeof(reg)))
 		return -EFAULT;

 	if (reg.flags & ~PR_FL_IGNORE_KEY)
 		return -EOPNOTSUPP;
 	return ops->pr_register(bdev, reg.old_key, reg.new_key, reg.flags);
 }

 static int blkdev_pr_reserve(struct block_device *bdev,
 		struct pr_reservation __user *arg)
 {
 	const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;
 	struct pr_reservation rsv;

 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 	if (!ops || !ops->pr_reserve)
 		return -EOPNOTSUPP;
 	if (copy_from_user(&rsv, arg, sizeof(rsv)))
 		return -EFAULT;

 	if (rsv.flags & ~PR_FL_IGNORE_KEY)
 		return -EOPNOTSUPP;
 	return ops->pr_reserve(bdev, rsv.key, rsv.type, rsv.flags);
 }

 static int blkdev_pr_release(struct block_device *bdev,
 		struct pr_reservation __user *arg)
 {
 	const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;
 	struct pr_reservation rsv;

 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 	if (!ops || !ops->pr_release)
 		return -EOPNOTSUPP;
 	if (copy_from_user(&rsv, arg, sizeof(rsv)))
 		return -EFAULT;

 	if (rsv.flags)
 		return -EOPNOTSUPP;
 	return ops->pr_release(bdev, rsv.key, rsv.type);
 }

 static int blkdev_pr_preempt(struct block_device *bdev,
 		struct pr_preempt __user *arg, bool abort)
 {
 	const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;
 	struct pr_preempt p;

 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 	if (!ops || !ops->pr_preempt)
 		return -EOPNOTSUPP;
 	if (copy_from_user(&p, arg, sizeof(p)))
 		return -EFAULT;

 	if (p.flags)
 		return -EOPNOTSUPP;
 	return ops->pr_preempt(bdev, p.old_key, p.new_key, p.type, abort);
 }

 static int blkdev_pr_clear(struct block_device *bdev,
 		struct pr_clear __user *arg)
 {
 	const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;
 	struct pr_clear c;

 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 	if (!ops || !ops->pr_clear)
 		return -EOPNOTSUPP;
 	if (copy_from_user(&c, arg, sizeof(c)))
 		return -EFAULT;

 	if (c.flags)
 		return -EOPNOTSUPP;
 	return ops->pr_clear(bdev, c.key);
 }

 /*
  * Is it an unrecognized ioctl? The correct returns are either
  * ENOTTY (final) or ENOIOCTLCMD ("I don't know this one, try a
  * fallback"). ENOIOCTLCMD gets turned into ENOTTY by the ioctl
  * code before returning.
  *
  * Confused drivers sometimes return EINVAL, which is wrong. It
  * means "I understood the ioctl command, but the parameters to
  * it were wrong".
  *
  * We should aim to just fix the broken drivers, the EINVAL case
  * should go away.
  */
 static inline int is_unrecognized_ioctl(int ret)
 {
 	return	ret == -EINVAL ||
 		ret == -ENOTTY ||
 		ret == -ENOIOCTLCMD;
 }

 static int blkdev_flushbuf(struct block_device *bdev, fmode_t mode,
 		unsigned cmd, unsigned long arg)
 {
 	int ret;

 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;

 	ret = __blkdev_driver_ioctl(bdev, mode, cmd, arg);
 	if (!is_unrecognized_ioctl(ret))
 		return ret;

 	fsync_bdev(bdev);
 	invalidate_bdev(bdev);
 	return 0;
 }

 static int blkdev_roset(struct block_device *bdev, fmode_t mode,
 		unsigned cmd, unsigned long arg)
 {
 	int ret, n;

 	ret = __blkdev_driver_ioctl(bdev, mode, cmd, arg);
 	if (!is_unrecognized_ioctl(ret))
 		return ret;
 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;
 	if (get_user(n, (int __user *)arg))
 		return -EFAULT;
 	set_device_ro(bdev, n);
 	return 0;
 }

 static int blkdev_getgeo(struct block_device *bdev,
 		struct hd_geometry __user *argp)
 {
 	struct gendisk *disk = bdev->bd_disk;
 	struct hd_geometry geo;
 	int ret;

 	if (!argp)
 		return -EINVAL;
 	if (!disk->fops->getgeo)
 		return -ENOTTY;

 	/*
 	 * We need to set the startsect first, the driver may
 	 * want to override it.
 	 */
 	memset(&geo, 0, sizeof(geo));
 	geo.start = get_start_sect(bdev);
 	ret = disk->fops->getgeo(bdev, &geo);
 	if (ret)
 		return ret;
 	if (copy_to_user(argp, &geo, sizeof(geo)))
 		return -EFAULT;
 	return 0;
 }

 /* set the logical block size */
 static int blkdev_bszset(struct block_device *bdev, fmode_t mode,
 		int __user *argp)
 {
 	int ret, n;

 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;
 	if (!argp)
 		return -EINVAL;
 	if (get_user(n, argp))
 		return -EFAULT;

 	if (!(mode & FMODE_EXCL)) {
 		bdgrab(bdev);
 		if (blkdev_get(bdev, mode | FMODE_EXCL, &bdev) < 0)
 			return -EBUSY;
 	}

 	ret = set_blocksize(bdev, n);
 	if (!(mode & FMODE_EXCL))
 		blkdev_put(bdev, mode | FMODE_EXCL);
 	return ret;
 }

 /*
  * always keep this in sync with compat_blkdev_ioctl()
  */
 int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
 			unsigned long arg)
 {
 	void __user *argp = (void __user *)arg;
 	loff_t size;
 	unsigned int max_sectors;

 	switch (cmd) {
 	case BLKFLSBUF:
 		return blkdev_flushbuf(bdev, mode, cmd, arg);
 	case BLKROSET:
 		return blkdev_roset(bdev, mode, cmd, arg);
 	case BLKDISCARD:
 		return blk_ioctl_discard(bdev, mode, arg, 0);
 	case BLKSECDISCARD:
 		return blk_ioctl_discard(bdev, mode, arg,
 				BLKDEV_DISCARD_SECURE);
 	case BLKZEROOUT:
 		return blk_ioctl_zeroout(bdev, mode, arg);
 	case BLKREPORTZONE:
 		return blkdev_report_zones_ioctl(bdev, mode, cmd, arg);
 	case BLKRESETZONE:
 		return blkdev_reset_zones_ioctl(bdev, mode, cmd, arg);
 	case HDIO_GETGEO:
 		return blkdev_getgeo(bdev, argp);
 	case BLKRAGET:
 	case BLKFRAGET:
 		if (!arg)
 			return -EINVAL;
 		return put_long(arg, (bdev->bd_bdi->ra_pages*PAGE_SIZE) / 512);
 	case BLKROGET:
 		return put_int(arg, bdev_read_only(bdev) != 0);
 	case BLKBSZGET: /* get block device soft block size (cf. BLKSSZGET) */
 		return put_int(arg, block_size(bdev));
 	case BLKSSZGET: /* get block device logical block size */
 		return put_int(arg, bdev_logical_block_size(bdev));
 	case BLKPBSZGET: /* get block device physical block size */
 		return put_uint(arg, bdev_physical_block_size(bdev));
 	case BLKIOMIN:
 		return put_uint(arg, bdev_io_min(bdev));
 	case BLKIOOPT:
 		return put_uint(arg, bdev_io_opt(bdev));
 	case BLKALIGNOFF:
 		return put_int(arg, bdev_alignment_offset(bdev));
 	case BLKDISCARDZEROES:
 		return put_uint(arg, 0);
 	case BLKSECTGET:
 		max_sectors = min_t(unsigned int, USHRT_MAX,
 				    queue_max_sectors(bdev_get_queue(bdev)));
 		return put_ushort(arg, max_sectors);
 	case BLKROTATIONAL:
 		return put_ushort(arg, !blk_queue_nonrot(bdev_get_queue(bdev)));
 	case BLKRASET:
 	case BLKFRASET:
 		if(!capable(CAP_SYS_ADMIN))
 			return -EACCES;
 		bdev->bd_bdi->ra_pages = (arg * 512) / PAGE_SIZE;
 		return 0;
 	case BLKBSZSET:
 		return blkdev_bszset(bdev, mode, argp);
 	case BLKPG:
 		return blkpg_ioctl(bdev, argp);
 	case BLKRRPART:
 		return blkdev_reread_part(bdev);
 	case BLKGETSIZE:
 		size = i_size_read(bdev->bd_inode);
 		if ((size >> 9) > ~0UL)
 			return -EFBIG;
 		return put_ulong(arg, size >> 9);
 	case BLKGETSIZE64:
 		return put_u64(arg, i_size_read(bdev->bd_inode));
 	case BLKTRACESTART:
 	case BLKTRACESTOP:
 	case BLKTRACESETUP:
 	case BLKTRACETEARDOWN:
 		return blk_trace_ioctl(bdev, cmd, argp);
 	case IOC_PR_REGISTER:
 		return blkdev_pr_register(bdev, argp);
 	case IOC_PR_RESERVE:
 		return blkdev_pr_reserve(bdev, argp);
 	case IOC_PR_RELEASE:
 		return blkdev_pr_release(bdev, argp);
 	case IOC_PR_PREEMPT:
 		return blkdev_pr_preempt(bdev, argp, false);
 	case IOC_PR_PREEMPT_ABORT:
 		return blkdev_pr_preempt(bdev, argp, true);
 	case IOC_PR_CLEAR:
 		return blkdev_pr_clear(bdev, argp);
 	default:
 		return __blkdev_driver_ioctl(bdev, mode, cmd, arg);
 	}
 }
 EXPORT_SYMBOL_GPL(blkdev_ioctl);
	#include <linux/capability.h>
	#include <linux/blkdev.h>
	#include <linux/export.h>
	#include <linux/gfp.h>
	#include <linux/blkpg.h>
	#include <linux/hdreg.h>
	#include <linux/backing-dev.h>
	#include <linux/fs.h>
	#include <linux/blktrace_api.h>
	#include <linux/pr.h>
	#include <linux/uaccess.h>

	static int blkpg_ioctl(struct block_device bdev, struct blkpg_ioctl_arg __user arg)
	{
	struct block_device *bdevp;
	struct gendisk *disk;
	struct hd_struct part, lpart;
	struct blkpg_ioctl_arg a;
	struct blkpg_partition p;
	struct disk_part_iter piter;
	long long start, length;
	int partno;

	if (!capable(CAP_SYS_ADMIN))
	return -EACCES;
	if (copy_from_user(&a, arg, sizeof(struct blkpg_ioctl_arg)))
	return -EFAULT;
	if (copy_from_user(&p, a.data, sizeof(struct blkpg_partition)))
	return -EFAULT;
	disk = bdev->bd_disk;
	if (bdev != bdev->bd_contains)
	return -EINVAL;
	partno = p.pno;
	if (partno <= 0)
	return -EINVAL;
	switch (a.op) {
	case BLKPG_ADD_PARTITION:
	start = p.start >> 9;
	length = p.length >> 9;
	/* check for fit in a hd_struct */
	if (sizeof(sector_t) == sizeof(long) &&
	sizeof(long long) > sizeof(long)) {
	long pstart = start, plength = length;
	if (pstart != start \|\| plength != length
	\|\| pstart < 0 \|\| plength < 0 \|\| partno > 65535)
	return -EINVAL;
	}
	/* check if partition is aligned to blocksize */
	if (p.start & (bdev_logical_block_size(bdev) - 1))
	return -EINVAL;

	mutex_lock(&bdev->bd_mutex);

	/* overlap? */
	disk_part_iter_init(&piter, disk,
	DISK_PITER_INCL_EMPTY);
	while ((part = disk_part_iter_next(&piter))) {
	if (!(start + length <= part->start_sect \|\|
	start >= part->start_sect + part->nr_sects)) {
	disk_part_iter_exit(&piter);
	mutex_unlock(&bdev->bd_mutex);
	return -EBUSY;
	}
	}
	disk_part_iter_exit(&piter);

	/* all seems OK */
	part = add_partition(disk, partno, start, length,
	ADDPART_FLAG_NONE, NULL);
	mutex_unlock(&bdev->bd_mutex);
	return PTR_ERR_OR_ZERO(part);
	case BLKPG_DEL_PARTITION:
	part = disk_get_part(disk, partno);
	if (!part)
	return -ENXIO;

	bdevp = bdget(part_devt(part));
	disk_put_part(part);
	if (!bdevp)
	return -ENOMEM;

	mutex_lock(&bdevp->bd_mutex);
	if (bdevp->bd_openers) {
	mutex_unlock(&bdevp->bd_mutex);
	bdput(bdevp);
	return -EBUSY;
	}
	/* all seems OK */
	fsync_bdev(bdevp);
	invalidate_bdev(bdevp);

	mutex_lock_nested(&bdev->bd_mutex, 1);
	delete_partition(disk, partno);
	mutex_unlock(&bdev->bd_mutex);
	mutex_unlock(&bdevp->bd_mutex);
	bdput(bdevp);

	return 0;
	case BLKPG_RESIZE_PARTITION:
	start = p.start >> 9;
	/* new length of partition in bytes */
	length = p.length >> 9;
	/* check for fit in a hd_struct */
	if (sizeof(sector_t) == sizeof(long) &&
	sizeof(long long) > sizeof(long)) {
	long pstart = start, plength = length;
	if (pstart != start \|\| plength != length
	\|\| pstart < 0 \|\| plength < 0)
	return -EINVAL;
	}
	part = disk_get_part(disk, partno);
	if (!part)
	return -ENXIO;
	bdevp = bdget(part_devt(part));
	if (!bdevp) {
	disk_put_part(part);
	return -ENOMEM;
	}
	mutex_lock(&bdevp->bd_mutex);
	mutex_lock_nested(&bdev->bd_mutex, 1);
	if (start != part->start_sect) {
	mutex_unlock(&bdevp->bd_mutex);
	mutex_unlock(&bdev->bd_mutex);
	bdput(bdevp);
	disk_put_part(part);
	return -EINVAL;
	}
	/* overlap? */
	disk_part_iter_init(&piter, disk,
	DISK_PITER_INCL_EMPTY);
	while ((lpart = disk_part_iter_next(&piter))) {
	if (lpart->partno != partno &&
	!(start + length <= lpart->start_sect \|\|
	start >= lpart->start_sect + lpart->nr_sects)
	) {
	disk_part_iter_exit(&piter);
	mutex_unlock(&bdevp->bd_mutex);
	mutex_unlock(&bdev->bd_mutex);
	bdput(bdevp);
	disk_put_part(part);
	return -EBUSY;
	}
	}
	disk_part_iter_exit(&piter);
	part_nr_sects_write(part, (sector_t)length);
	i_size_write(bdevp->bd_inode, p.length);
	mutex_unlock(&bdevp->bd_mutex);
	mutex_unlock(&bdev->bd_mutex);
	bdput(bdevp);
	disk_put_part(part);
	return 0;
	default:
	return -EINVAL;
	}
	}

	/*
	* This is an exported API for the block driver, and will not
	* acquire bd_mutex. This API should be used in case that
	* caller has held bd_mutex already.
	*/
	int __blkdev_reread_part(struct block_device *bdev)
	{
	struct gendisk *disk = bdev->bd_disk;

	if (!disk_part_scan_enabled(disk) \|\| bdev != bdev->bd_contains)
	return -EINVAL;
	if (!capable(CAP_SYS_ADMIN))
	return -EACCES;

	lockdep_assert_held(&bdev->bd_mutex);

	return rescan_partitions(disk, bdev);
	}
	EXPORT_SYMBOL(__blkdev_reread_part);

	/*
	* This is an exported API for the block driver, and will
	* try to acquire bd_mutex. If bd_mutex has been held already
	* in current context, please call __blkdev_reread_part().
	*
	* Make sure the held locks in current context aren't required
	* in open()/close() handler and I/O path for avoiding ABBA deadlock:
	* - bd_mutex is held before calling block driver's open/close
	* handler
	* - reading partition table may submit I/O to the block device
	*/
	int blkdev_reread_part(struct block_device *bdev)
	{
	int res;

	mutex_lock(&bdev->bd_mutex);
	res = __blkdev_reread_part(bdev);
	mutex_unlock(&bdev->bd_mutex);

	return res;
	}
	EXPORT_SYMBOL(blkdev_reread_part);

	static int blk_ioctl_discard(struct block_device *bdev, fmode_t mode,
	unsigned long arg, unsigned long flags)
	{
	uint64_t range[2];
	uint64_t start, len;

	if (!(mode & FMODE_WRITE))
	return -EBADF;

	if (copy_from_user(range, (void __user *)arg, sizeof(range)))
	return -EFAULT;

	start = range[0];
	len = range[1];

	if (start & 511)
	return -EINVAL;
	if (len & 511)
	return -EINVAL;
	start >>= 9;
	len >>= 9;

	if (start + len > (i_size_read(bdev->bd_inode) >> 9))
	return -EINVAL;
	return blkdev_issue_discard(bdev, start, len, GFP_KERNEL, flags);
	}

	static int blk_ioctl_zeroout(struct block_device *bdev, fmode_t mode,
	unsigned long arg)
	{
	uint64_t range[2];
	struct address_space *mapping;
	uint64_t start, end, len;

	if (!(mode & FMODE_WRITE))
	return -EBADF;

	if (copy_from_user(range, (void __user *)arg, sizeof(range)))
	return -EFAULT;

	start = range[0];
	len = range[1];
	end = start + len - 1;

	if (start & 511)
	return -EINVAL;
	if (len & 511)
	return -EINVAL;
	if (end >= (uint64_t)i_size_read(bdev->bd_inode))
	return -EINVAL;
	if (end < start)
	return -EINVAL;

	/* Invalidate the page cache, including dirty pages */
	mapping = bdev->bd_inode->i_mapping;
	truncate_inode_pages_range(mapping, start, end);

	return blkdev_issue_zeroout(bdev, start >> 9, len >> 9, GFP_KERNEL,
	BLKDEV_ZERO_NOUNMAP);
	}

	static int put_ushort(unsigned long arg, unsigned short val)
	{
	return put_user(val, (unsigned short __user *)arg);
	}

	static int put_int(unsigned long arg, int val)
	{
	return put_user(val, (int __user *)arg);
	}

	static int put_uint(unsigned long arg, unsigned int val)
	{
	return put_user(val, (unsigned int __user *)arg);
	}

	static int put_long(unsigned long arg, long val)
	{
	return put_user(val, (long __user *)arg);
	}

	static int put_ulong(unsigned long arg, unsigned long val)
	{
	return put_user(val, (unsigned long __user *)arg);
	}

	static int put_u64(unsigned long arg, u64 val)
	{
	return put_user(val, (u64 __user *)arg);
	}

	int __blkdev_driver_ioctl(struct block_device *bdev, fmode_t mode,
	unsigned cmd, unsigned long arg)
	{
	struct gendisk *disk = bdev->bd_disk;

	if (disk->fops->ioctl)
	return disk->fops->ioctl(bdev, mode, cmd, arg);

	return -ENOTTY;
	}
	/*
	* For the record: _GPL here is only because somebody decided to slap it
	* on the previous export. Sheer idiocy, since it wasn't copyrightable
	* at all and could be open-coded without any exports by anybody who cares.
	*/
	EXPORT_SYMBOL_GPL(__blkdev_driver_ioctl);

	static int blkdev_pr_register(struct block_device *bdev,
	struct pr_registration __user *arg)
	{
	const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;
	struct pr_registration reg;

	if (!capable(CAP_SYS_ADMIN))
	return -EPERM;
	if (!ops \|\| !ops->pr_register)
	return -EOPNOTSUPP;
	if (copy_from_user(&reg, arg, sizeof(reg)))
	return -EFAULT;

	if (reg.flags & ~PR_FL_IGNORE_KEY)
	return -EOPNOTSUPP;
	return ops->pr_register(bdev, reg.old_key, reg.new_key, reg.flags);
	}

	static int blkdev_pr_reserve(struct block_device *bdev,
	struct pr_reservation __user *arg)
	{
	const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;
	struct pr_reservation rsv;

	if (!capable(CAP_SYS_ADMIN))
	return -EPERM;
	if (!ops \|\| !ops->pr_reserve)
	return -EOPNOTSUPP;
	if (copy_from_user(&rsv, arg, sizeof(rsv)))
	return -EFAULT;

	if (rsv.flags & ~PR_FL_IGNORE_KEY)
	return -EOPNOTSUPP;
	return ops->pr_reserve(bdev, rsv.key, rsv.type, rsv.flags);
	}

	static int blkdev_pr_release(struct block_device *bdev,
	struct pr_reservation __user *arg)
	{
	const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;
	struct pr_reservation rsv;

	if (!capable(CAP_SYS_ADMIN))
	return -EPERM;
	if (!ops \|\| !ops->pr_release)
	return -EOPNOTSUPP;
	if (copy_from_user(&rsv, arg, sizeof(rsv)))
	return -EFAULT;

	if (rsv.flags)
	return -EOPNOTSUPP;
	return ops->pr_release(bdev, rsv.key, rsv.type);
	}

	static int blkdev_pr_preempt(struct block_device *bdev,
	struct pr_preempt __user *arg, bool abort)
	{
	const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;
	struct pr_preempt p;

	if (!capable(CAP_SYS_ADMIN))
	return -EPERM;
	if (!ops \|\| !ops->pr_preempt)
	return -EOPNOTSUPP;
	if (copy_from_user(&p, arg, sizeof(p)))
	return -EFAULT;

	if (p.flags)
	return -EOPNOTSUPP;
	return ops->pr_preempt(bdev, p.old_key, p.new_key, p.type, abort);
	}

	static int blkdev_pr_clear(struct block_device *bdev,
	struct pr_clear __user *arg)
	{
	const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;
	struct pr_clear c;

	if (!capable(CAP_SYS_ADMIN))
	return -EPERM;
	if (!ops \|\| !ops->pr_clear)
	return -EOPNOTSUPP;
	if (copy_from_user(&c, arg, sizeof(c)))
	return -EFAULT;

	if (c.flags)
	return -EOPNOTSUPP;
	return ops->pr_clear(bdev, c.key);
	}

	/*
	* Is it an unrecognized ioctl? The correct returns are either
	* ENOTTY (final) or ENOIOCTLCMD ("I don't know this one, try a
	* fallback"). ENOIOCTLCMD gets turned into ENOTTY by the ioctl
	* code before returning.
	*
	* Confused drivers sometimes return EINVAL, which is wrong. It
	* means "I understood the ioctl command, but the parameters to
	* it were wrong".
	*
	* We should aim to just fix the broken drivers, the EINVAL case
	* should go away.
	*/
	static inline int is_unrecognized_ioctl(int ret)
	{
	return ret == -EINVAL \|\|
	ret == -ENOTTY \|\|
	ret == -ENOIOCTLCMD;
	}

	static int blkdev_flushbuf(struct block_device *bdev, fmode_t mode,
	unsigned cmd, unsigned long arg)
	{
	int ret;

	if (!capable(CAP_SYS_ADMIN))
	return -EACCES;

	ret = __blkdev_driver_ioctl(bdev, mode, cmd, arg);
	if (!is_unrecognized_ioctl(ret))
	return ret;

	fsync_bdev(bdev);
	invalidate_bdev(bdev);
	return 0;
	}

	static int blkdev_roset(struct block_device *bdev, fmode_t mode,
	unsigned cmd, unsigned long arg)
	{
	int ret, n;

	ret = __blkdev_driver_ioctl(bdev, mode, cmd, arg);
	if (!is_unrecognized_ioctl(ret))
	return ret;
	if (!capable(CAP_SYS_ADMIN))
	return -EACCES;
	if (get_user(n, (int __user *)arg))
	return -EFAULT;
	set_device_ro(bdev, n);
	return 0;
	}

	static int blkdev_getgeo(struct block_device *bdev,
	struct hd_geometry __user *argp)
	{
	struct gendisk *disk = bdev->bd_disk;
	struct hd_geometry geo;
	int ret;

	if (!argp)
	return -EINVAL;
	if (!disk->fops->getgeo)
	return -ENOTTY;

	/*
	* We need to set the startsect first, the driver may
	* want to override it.
	*/
	memset(&geo, 0, sizeof(geo));
	geo.start = get_start_sect(bdev);
	ret = disk->fops->getgeo(bdev, &geo);
	if (ret)
	return ret;
	if (copy_to_user(argp, &geo, sizeof(geo)))
	return -EFAULT;
	return 0;
	}

	/* set the logical block size */
	static int blkdev_bszset(struct block_device *bdev, fmode_t mode,
	int __user *argp)
	{
	int ret, n;

	if (!capable(CAP_SYS_ADMIN))
	return -EACCES;
	if (!argp)
	return -EINVAL;
	if (get_user(n, argp))
	return -EFAULT;

	if (!(mode & FMODE_EXCL)) {
	bdgrab(bdev);
	if (blkdev_get(bdev, mode \| FMODE_EXCL, &bdev) < 0)
	return -EBUSY;
	}

	ret = set_blocksize(bdev, n);
	if (!(mode & FMODE_EXCL))
	blkdev_put(bdev, mode \| FMODE_EXCL);
	return ret;
	}

	/*
	* always keep this in sync with compat_blkdev_ioctl()
	*/
	int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
	unsigned long arg)
	{
	void __user argp = (void __user )arg;
	loff_t size;
	unsigned int max_sectors;

	switch (cmd) {
	case BLKFLSBUF:
	return blkdev_flushbuf(bdev, mode, cmd, arg);
	case BLKROSET:
	return blkdev_roset(bdev, mode, cmd, arg);
	case BLKDISCARD:
	return blk_ioctl_discard(bdev, mode, arg, 0);
	case BLKSECDISCARD:
	return blk_ioctl_discard(bdev, mode, arg,
	BLKDEV_DISCARD_SECURE);
	case BLKZEROOUT:
	return blk_ioctl_zeroout(bdev, mode, arg);
	case BLKREPORTZONE:
	return blkdev_report_zones_ioctl(bdev, mode, cmd, arg);
	case BLKRESETZONE:
	return blkdev_reset_zones_ioctl(bdev, mode, cmd, arg);
	case HDIO_GETGEO:
	return blkdev_getgeo(bdev, argp);
	case BLKRAGET:
	case BLKFRAGET:
	if (!arg)
	return -EINVAL;
	return put_long(arg, (bdev->bd_bdi->ra_pages*PAGE_SIZE) / 512);
	case BLKROGET:
	return put_int(arg, bdev_read_only(bdev) != 0);
	case BLKBSZGET: /* get block device soft block size (cf. BLKSSZGET) */
	return put_int(arg, block_size(bdev));
	case BLKSSZGET: /* get block device logical block size */
	return put_int(arg, bdev_logical_block_size(bdev));
	case BLKPBSZGET: /* get block device physical block size */
	return put_uint(arg, bdev_physical_block_size(bdev));
	case BLKIOMIN:
	return put_uint(arg, bdev_io_min(bdev));
	case BLKIOOPT:
	return put_uint(arg, bdev_io_opt(bdev));
	case BLKALIGNOFF:
	return put_int(arg, bdev_alignment_offset(bdev));
	case BLKDISCARDZEROES:
	return put_uint(arg, 0);
	case BLKSECTGET:
	max_sectors = min_t(unsigned int, USHRT_MAX,
	queue_max_sectors(bdev_get_queue(bdev)));
	return put_ushort(arg, max_sectors);
	case BLKROTATIONAL:
	return put_ushort(arg, !blk_queue_nonrot(bdev_get_queue(bdev)));
	case BLKRASET:
	case BLKFRASET:
	if(!capable(CAP_SYS_ADMIN))
	return -EACCES;
	bdev->bd_bdi->ra_pages = (arg * 512) / PAGE_SIZE;
	return 0;
	case BLKBSZSET:
	return blkdev_bszset(bdev, mode, argp);
	case BLKPG:
	return blkpg_ioctl(bdev, argp);
	case BLKRRPART:
	return blkdev_reread_part(bdev);
	case BLKGETSIZE:
	size = i_size_read(bdev->bd_inode);
	if ((size >> 9) > ~0UL)
	return -EFBIG;
	return put_ulong(arg, size >> 9);
	case BLKGETSIZE64:
	return put_u64(arg, i_size_read(bdev->bd_inode));
	case BLKTRACESTART:
	case BLKTRACESTOP:
	case BLKTRACESETUP:
	case BLKTRACETEARDOWN:
	return blk_trace_ioctl(bdev, cmd, argp);
	case IOC_PR_REGISTER:
	return blkdev_pr_register(bdev, argp);
	case IOC_PR_RESERVE:
	return blkdev_pr_reserve(bdev, argp);
	case IOC_PR_RELEASE:
	return blkdev_pr_release(bdev, argp);
	case IOC_PR_PREEMPT:
	return blkdev_pr_preempt(bdev, argp, false);
	case IOC_PR_PREEMPT_ABORT:
	return blkdev_pr_preempt(bdev, argp, true);
	case IOC_PR_CLEAR:
	return blkdev_pr_clear(bdev, argp);
	default:
	return __blkdev_driver_ioctl(bdev, mode, cmd, arg);
	}
	}
	EXPORT_SYMBOL_GPL(blkdev_ioctl);