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@xxxxxxxxx>
---
block/compat_ioctl.c | 1 +
block/ioctl.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/fs.h | 1 +
3 files changed, 76 insertions(+), 0 deletions(-)
diff --git a/block/compat_ioctl.c b/block/compat_ioctl.c
index c23177e..1e559fb 100644
--- a/block/compat_ioctl.c
+++ b/block/compat_ioctl.c
@@ -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
diff --git a/block/ioctl.c b/block/ioctl.c
index 77185e5..8193fbb 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -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 +321,17 @@ int blkdev_ioctl(struct inode *inode, struct file *file, unsigned cmd,
set_device_ro(bdev, n);
unlock_kernel();
return 0;
+
+ case BLKDISCARD: {
+ uint64_t start, len;
+
+ if (get_user(start, (uint64_t __user *)(arg)) ||
+ get_user(len, (uint64_t __user *)(arg+8)))
+ return -EFAULT;
+
+ return blk_ioctl_discard(bdev, start, len);
+ }
+
case HDIO_GETGEO: {
struct hd_geometry geo;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index eb01313..88358ca 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -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 */
--
1.5.5.1
--
David Woodhouse Open Source Technology Centre
David.Woodhouse@xxxxxxxxx Intel Corporation
--
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