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Add BLKDISCARD ioctl to allow userspace to discard sectors

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We may well want mkfs tools to use this to mark the whole device as
unwanted before they format it, for example.

The ioctl takes a pair of uint64_ts, which are start offset and length
in _bytes_. Although at the moment it might make sense for them both to
be in 512-byte sectors, I don't want to limit the ABI to that.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
David Woodhouse 2008-08-11 15:58:42 +01:00 committed by Jens Axboe
parent 2ebca85abc
commit d30a2605be
3 changed files with 78 additions and 0 deletions
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1
block/compat_ioctl.c
View file

@ -788,6 +788,7 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
return compat_hdio_getgeo(disk, bdev, compat_ptr(arg));
case BLKFLSBUF:
case BLKROSET:
case BLKDISCARD:
/*
* the ones below are implemented in blkdev_locked_ioctl,
* but we call blkdev_ioctl, which gets the lock for us

76
block/ioctl.c
View file

@ -111,6 +111,69 @@ static int blkdev_reread_part(struct block_device *bdev)
return res;
}
static void blk_ioc_discard_endio(struct bio *bio, int err)
{
if (err) {
if (err == -EOPNOTSUPP)
set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
clear_bit(BIO_UPTODATE, &bio->bi_flags);
}
complete(bio->bi_private);
}
static int blk_ioctl_discard(struct block_device *bdev, uint64_t start,
uint64_t len)
{
struct request_queue *q = bdev_get_queue(bdev);
int ret = 0;
if (start & 511)
return -EINVAL;
if (len & 511)
return -EINVAL;
start >>= 9;
len >>= 9;
if (start + len > (bdev->bd_inode->i_size >> 9))
return -EINVAL;
if (!q->prepare_discard_fn)
return -EOPNOTSUPP;
while (len && !ret) {
DECLARE_COMPLETION_ONSTACK(wait);
struct bio *bio;
bio = bio_alloc(GFP_KERNEL, 0);
if (!bio)
return -ENOMEM;
bio->bi_end_io = blk_ioc_discard_endio;
bio->bi_bdev = bdev;
bio->bi_private = &wait;
bio->bi_sector = start;
if (len > q->max_hw_sectors) {
bio->bi_size = q->max_hw_sectors << 9;
len -= q->max_hw_sectors;
start += q->max_hw_sectors;
} else {
bio->bi_size = len << 9;
len = 0;
}
submit_bio(WRITE_DISCARD, bio);
wait_for_completion(&wait);
if (bio_flagged(bio, BIO_EOPNOTSUPP))
ret = -EOPNOTSUPP;
else if (!bio_flagged(bio, BIO_UPTODATE))
ret = -EIO;
bio_put(bio);
}
return ret;
}
static int put_ushort(unsigned long arg, unsigned short val)
{
return put_user(val, (unsigned short __user *)arg);
@ -258,6 +321,19 @@ int blkdev_ioctl(struct inode *inode, struct file *file, unsigned cmd,
set_device_ro(bdev, n);
unlock_kernel();
return 0;
case BLKDISCARD: {
uint64_t range[2];
if (!(file->f_mode & FMODE_WRITE))
return -EBADF;
if (copy_from_user(range, (void __user *)arg, sizeof(range)))
return -EFAULT;
return blk_ioctl_discard(bdev, range[0], range[1]);
}
case HDIO_GETGEO: {
struct hd_geometry geo;

1
include/linux/fs.h
View file

@ -223,6 +223,7 @@ extern int dir_notify_enable;
#define BLKTRACESTART _IO(0x12,116)
#define BLKTRACESTOP _IO(0x12,117)
#define BLKTRACETEARDOWN _IO(0x12,118)
#define BLKDISCARD _IO(0x12,119)
#define BMAP_IOCTL 1 /* obsolete - kept for compatibility */
#define FIBMAP _IO(0x00,1) /* bmap access */