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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-25 10:19:47 +00:00
![Ming Lei](/assets/img/avatar_default.png)
The only possible problem of using mutex_lock() instead of trylock is about deadlock. If there aren't any locks held before calling blkdev_reread_part(), deadlock can't be caused by this conversion. If there are locks held before calling blkdev_reread_part(), and if these locks arn't required in open, close handler and I/O path, deadlock shouldn't be caused too. Both user space's ioctl(BLKRRPART) and md_setup_drive() from init/do_mounts_md.c belongs to the 1st case, so the conversion is safe for the two cases. For loop, the previous patches in this pathset has fixed the ABBA lock dependency, so the conversion is OK. For nbd, tx_lock is held when calling the function: - both open and release won't hold the lock - when blkdev_reread_part() is run, I/O thread has been stopped already, so tx_lock won't be acquired in I/O path at that time. - so the conversion won't cause deadlock for nbd For dasd, both dasd_open(), dasd_release() and request function don't acquire any mutex/semphone, so the conversion should be safe. Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: Jarod Wilson <jarod@redhat.com> Acked-by: Jarod Wilson <jarod@redhat.com> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
457 lines
12 KiB
C
457 lines
12 KiB
C
#include <linux/capability.h>
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#include <linux/blkdev.h>
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#include <linux/export.h>
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#include <linux/gfp.h>
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#include <linux/blkpg.h>
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#include <linux/hdreg.h>
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#include <linux/backing-dev.h>
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#include <linux/fs.h>
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#include <linux/blktrace_api.h>
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#include <asm/uaccess.h>
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static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user *arg)
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{
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struct block_device *bdevp;
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struct gendisk *disk;
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struct hd_struct *part, *lpart;
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struct blkpg_ioctl_arg a;
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struct blkpg_partition p;
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struct disk_part_iter piter;
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long long start, length;
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int partno;
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if (!capable(CAP_SYS_ADMIN))
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return -EACCES;
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if (copy_from_user(&a, arg, sizeof(struct blkpg_ioctl_arg)))
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return -EFAULT;
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if (copy_from_user(&p, a.data, sizeof(struct blkpg_partition)))
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return -EFAULT;
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disk = bdev->bd_disk;
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if (bdev != bdev->bd_contains)
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return -EINVAL;
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partno = p.pno;
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if (partno <= 0)
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return -EINVAL;
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switch (a.op) {
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case BLKPG_ADD_PARTITION:
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start = p.start >> 9;
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length = p.length >> 9;
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/* check for fit in a hd_struct */
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if (sizeof(sector_t) == sizeof(long) &&
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sizeof(long long) > sizeof(long)) {
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long pstart = start, plength = length;
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if (pstart != start || plength != length
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|| pstart < 0 || plength < 0 || partno > 65535)
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return -EINVAL;
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}
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mutex_lock(&bdev->bd_mutex);
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/* overlap? */
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disk_part_iter_init(&piter, disk,
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DISK_PITER_INCL_EMPTY);
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while ((part = disk_part_iter_next(&piter))) {
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if (!(start + length <= part->start_sect ||
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start >= part->start_sect + part->nr_sects)) {
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disk_part_iter_exit(&piter);
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mutex_unlock(&bdev->bd_mutex);
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return -EBUSY;
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}
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}
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disk_part_iter_exit(&piter);
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/* all seems OK */
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part = add_partition(disk, partno, start, length,
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ADDPART_FLAG_NONE, NULL);
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mutex_unlock(&bdev->bd_mutex);
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return PTR_ERR_OR_ZERO(part);
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case BLKPG_DEL_PARTITION:
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part = disk_get_part(disk, partno);
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if (!part)
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return -ENXIO;
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bdevp = bdget(part_devt(part));
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disk_put_part(part);
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if (!bdevp)
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return -ENOMEM;
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mutex_lock(&bdevp->bd_mutex);
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if (bdevp->bd_openers) {
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mutex_unlock(&bdevp->bd_mutex);
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bdput(bdevp);
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return -EBUSY;
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}
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/* all seems OK */
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fsync_bdev(bdevp);
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invalidate_bdev(bdevp);
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mutex_lock_nested(&bdev->bd_mutex, 1);
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delete_partition(disk, partno);
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mutex_unlock(&bdev->bd_mutex);
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mutex_unlock(&bdevp->bd_mutex);
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bdput(bdevp);
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return 0;
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case BLKPG_RESIZE_PARTITION:
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start = p.start >> 9;
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/* new length of partition in bytes */
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length = p.length >> 9;
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/* check for fit in a hd_struct */
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if (sizeof(sector_t) == sizeof(long) &&
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sizeof(long long) > sizeof(long)) {
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long pstart = start, plength = length;
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if (pstart != start || plength != length
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|| pstart < 0 || plength < 0)
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return -EINVAL;
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}
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part = disk_get_part(disk, partno);
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if (!part)
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return -ENXIO;
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bdevp = bdget(part_devt(part));
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if (!bdevp) {
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disk_put_part(part);
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return -ENOMEM;
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}
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mutex_lock(&bdevp->bd_mutex);
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mutex_lock_nested(&bdev->bd_mutex, 1);
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if (start != part->start_sect) {
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mutex_unlock(&bdevp->bd_mutex);
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mutex_unlock(&bdev->bd_mutex);
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bdput(bdevp);
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disk_put_part(part);
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return -EINVAL;
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}
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/* overlap? */
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disk_part_iter_init(&piter, disk,
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DISK_PITER_INCL_EMPTY);
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while ((lpart = disk_part_iter_next(&piter))) {
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if (lpart->partno != partno &&
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!(start + length <= lpart->start_sect ||
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start >= lpart->start_sect + lpart->nr_sects)
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) {
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disk_part_iter_exit(&piter);
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mutex_unlock(&bdevp->bd_mutex);
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mutex_unlock(&bdev->bd_mutex);
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bdput(bdevp);
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disk_put_part(part);
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return -EBUSY;
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}
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}
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disk_part_iter_exit(&piter);
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part_nr_sects_write(part, (sector_t)length);
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i_size_write(bdevp->bd_inode, p.length);
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mutex_unlock(&bdevp->bd_mutex);
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mutex_unlock(&bdev->bd_mutex);
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bdput(bdevp);
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disk_put_part(part);
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return 0;
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default:
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return -EINVAL;
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}
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}
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/*
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* This is an exported API for the block driver, and will not
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* acquire bd_mutex. This API should be used in case that
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* caller has held bd_mutex already.
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*/
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int __blkdev_reread_part(struct block_device *bdev)
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{
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struct gendisk *disk = bdev->bd_disk;
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if (!disk_part_scan_enabled(disk) || bdev != bdev->bd_contains)
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return -EINVAL;
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if (!capable(CAP_SYS_ADMIN))
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return -EACCES;
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lockdep_assert_held(&bdev->bd_mutex);
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return rescan_partitions(disk, bdev);
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}
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EXPORT_SYMBOL(__blkdev_reread_part);
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/*
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* This is an exported API for the block driver, and will
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* try to acquire bd_mutex. If bd_mutex has been held already
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* in current context, please call __blkdev_reread_part().
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*
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* Make sure the held locks in current context aren't required
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* in open()/close() handler and I/O path for avoiding ABBA deadlock:
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* - bd_mutex is held before calling block driver's open/close
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* handler
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* - reading partition table may submit I/O to the block device
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*/
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int blkdev_reread_part(struct block_device *bdev)
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{
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int res;
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mutex_lock(&bdev->bd_mutex);
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res = __blkdev_reread_part(bdev);
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mutex_unlock(&bdev->bd_mutex);
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return res;
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}
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EXPORT_SYMBOL(blkdev_reread_part);
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static int blk_ioctl_discard(struct block_device *bdev, uint64_t start,
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uint64_t len, int secure)
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{
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unsigned long flags = 0;
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if (start & 511)
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return -EINVAL;
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if (len & 511)
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return -EINVAL;
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start >>= 9;
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len >>= 9;
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if (start + len > (i_size_read(bdev->bd_inode) >> 9))
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return -EINVAL;
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if (secure)
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flags |= BLKDEV_DISCARD_SECURE;
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return blkdev_issue_discard(bdev, start, len, GFP_KERNEL, flags);
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}
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static int blk_ioctl_zeroout(struct block_device *bdev, uint64_t start,
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uint64_t len)
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{
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if (start & 511)
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return -EINVAL;
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if (len & 511)
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return -EINVAL;
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start >>= 9;
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len >>= 9;
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if (start + len > (i_size_read(bdev->bd_inode) >> 9))
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return -EINVAL;
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return blkdev_issue_zeroout(bdev, start, len, GFP_KERNEL, false);
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}
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static int put_ushort(unsigned long arg, unsigned short val)
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{
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return put_user(val, (unsigned short __user *)arg);
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}
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static int put_int(unsigned long arg, int val)
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{
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return put_user(val, (int __user *)arg);
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}
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static int put_uint(unsigned long arg, unsigned int val)
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{
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return put_user(val, (unsigned int __user *)arg);
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}
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static int put_long(unsigned long arg, long val)
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{
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return put_user(val, (long __user *)arg);
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}
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static int put_ulong(unsigned long arg, unsigned long val)
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{
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return put_user(val, (unsigned long __user *)arg);
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}
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static int put_u64(unsigned long arg, u64 val)
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{
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return put_user(val, (u64 __user *)arg);
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}
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int __blkdev_driver_ioctl(struct block_device *bdev, fmode_t mode,
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unsigned cmd, unsigned long arg)
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{
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struct gendisk *disk = bdev->bd_disk;
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if (disk->fops->ioctl)
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return disk->fops->ioctl(bdev, mode, cmd, arg);
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return -ENOTTY;
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}
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/*
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* For the record: _GPL here is only because somebody decided to slap it
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* on the previous export. Sheer idiocy, since it wasn't copyrightable
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* at all and could be open-coded without any exports by anybody who cares.
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*/
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EXPORT_SYMBOL_GPL(__blkdev_driver_ioctl);
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/*
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* Is it an unrecognized ioctl? The correct returns are either
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* ENOTTY (final) or ENOIOCTLCMD ("I don't know this one, try a
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* fallback"). ENOIOCTLCMD gets turned into ENOTTY by the ioctl
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* code before returning.
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*
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* Confused drivers sometimes return EINVAL, which is wrong. It
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* means "I understood the ioctl command, but the parameters to
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* it were wrong".
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*
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* We should aim to just fix the broken drivers, the EINVAL case
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* should go away.
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*/
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static inline int is_unrecognized_ioctl(int ret)
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{
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return ret == -EINVAL ||
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ret == -ENOTTY ||
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ret == -ENOIOCTLCMD;
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}
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/*
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* always keep this in sync with compat_blkdev_ioctl()
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*/
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int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
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unsigned long arg)
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{
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struct gendisk *disk = bdev->bd_disk;
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struct backing_dev_info *bdi;
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loff_t size;
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int ret, n;
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unsigned int max_sectors;
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switch(cmd) {
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case BLKFLSBUF:
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if (!capable(CAP_SYS_ADMIN))
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return -EACCES;
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ret = __blkdev_driver_ioctl(bdev, mode, cmd, arg);
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if (!is_unrecognized_ioctl(ret))
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return ret;
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fsync_bdev(bdev);
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invalidate_bdev(bdev);
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return 0;
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case BLKROSET:
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ret = __blkdev_driver_ioctl(bdev, mode, cmd, arg);
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if (!is_unrecognized_ioctl(ret))
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return ret;
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if (!capable(CAP_SYS_ADMIN))
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return -EACCES;
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if (get_user(n, (int __user *)(arg)))
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return -EFAULT;
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set_device_ro(bdev, n);
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return 0;
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case BLKDISCARD:
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case BLKSECDISCARD: {
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uint64_t range[2];
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if (!(mode & FMODE_WRITE))
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return -EBADF;
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if (copy_from_user(range, (void __user *)arg, sizeof(range)))
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return -EFAULT;
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return blk_ioctl_discard(bdev, range[0], range[1],
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cmd == BLKSECDISCARD);
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}
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case BLKZEROOUT: {
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uint64_t range[2];
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if (!(mode & FMODE_WRITE))
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return -EBADF;
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if (copy_from_user(range, (void __user *)arg, sizeof(range)))
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return -EFAULT;
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return blk_ioctl_zeroout(bdev, range[0], range[1]);
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}
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case HDIO_GETGEO: {
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struct hd_geometry geo;
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if (!arg)
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return -EINVAL;
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if (!disk->fops->getgeo)
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return -ENOTTY;
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/*
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* We need to set the startsect first, the driver may
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* want to override it.
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*/
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memset(&geo, 0, sizeof(geo));
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geo.start = get_start_sect(bdev);
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ret = disk->fops->getgeo(bdev, &geo);
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if (ret)
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return ret;
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if (copy_to_user((struct hd_geometry __user *)arg, &geo,
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sizeof(geo)))
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return -EFAULT;
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return 0;
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}
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case BLKRAGET:
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case BLKFRAGET:
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if (!arg)
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return -EINVAL;
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bdi = blk_get_backing_dev_info(bdev);
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return put_long(arg, (bdi->ra_pages * PAGE_CACHE_SIZE) / 512);
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case BLKROGET:
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return put_int(arg, bdev_read_only(bdev) != 0);
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case BLKBSZGET: /* get block device soft block size (cf. BLKSSZGET) */
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return put_int(arg, block_size(bdev));
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case BLKSSZGET: /* get block device logical block size */
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return put_int(arg, bdev_logical_block_size(bdev));
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case BLKPBSZGET: /* get block device physical block size */
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return put_uint(arg, bdev_physical_block_size(bdev));
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case BLKIOMIN:
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return put_uint(arg, bdev_io_min(bdev));
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case BLKIOOPT:
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return put_uint(arg, bdev_io_opt(bdev));
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case BLKALIGNOFF:
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return put_int(arg, bdev_alignment_offset(bdev));
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case BLKDISCARDZEROES:
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return put_uint(arg, bdev_discard_zeroes_data(bdev));
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case BLKSECTGET:
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max_sectors = min_t(unsigned int, USHRT_MAX,
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queue_max_sectors(bdev_get_queue(bdev)));
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return put_ushort(arg, max_sectors);
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case BLKROTATIONAL:
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return put_ushort(arg, !blk_queue_nonrot(bdev_get_queue(bdev)));
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case BLKRASET:
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case BLKFRASET:
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if(!capable(CAP_SYS_ADMIN))
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return -EACCES;
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bdi = blk_get_backing_dev_info(bdev);
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bdi->ra_pages = (arg * 512) / PAGE_CACHE_SIZE;
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return 0;
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case BLKBSZSET:
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/* set the logical block size */
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if (!capable(CAP_SYS_ADMIN))
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return -EACCES;
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if (!arg)
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return -EINVAL;
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if (get_user(n, (int __user *) arg))
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return -EFAULT;
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if (!(mode & FMODE_EXCL)) {
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bdgrab(bdev);
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if (blkdev_get(bdev, mode | FMODE_EXCL, &bdev) < 0)
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return -EBUSY;
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}
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ret = set_blocksize(bdev, n);
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if (!(mode & FMODE_EXCL))
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blkdev_put(bdev, mode | FMODE_EXCL);
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return ret;
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case BLKPG:
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ret = blkpg_ioctl(bdev, (struct blkpg_ioctl_arg __user *) arg);
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break;
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case BLKRRPART:
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ret = blkdev_reread_part(bdev);
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break;
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case BLKGETSIZE:
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size = i_size_read(bdev->bd_inode);
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if ((size >> 9) > ~0UL)
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return -EFBIG;
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return put_ulong(arg, size >> 9);
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case BLKGETSIZE64:
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return put_u64(arg, i_size_read(bdev->bd_inode));
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case BLKTRACESTART:
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case BLKTRACESTOP:
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case BLKTRACESETUP:
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case BLKTRACETEARDOWN:
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ret = blk_trace_ioctl(bdev, cmd, (char __user *) arg);
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break;
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default:
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ret = __blkdev_driver_ioctl(bdev, mode, cmd, arg);
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}
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return ret;
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}
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EXPORT_SYMBOL_GPL(blkdev_ioctl);
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