Re: [PATCH 1/5] block: move discard checks into the ioctl handler

Keith Busch
2024-03-13T15:40:24Z

On Tue, Mar 12, 2024 at 08:45:27AM -0600, Christoph Hellwig wrote:
> @@ -95,6 +95,8 @@ static int compat_blkpg_ioctl(struct block_device *bdev,
> static int blk_ioctl_discard(struct block_device *bdev, blk_mode_t mode,
> unsigned long arg)
> {
> + sector_t bs_mask = (bdev_logical_block_size(bdev) >> SECTOR_SHIFT) - 1;
> + sector_t sector, nr_sects;
> uint64_t range[2];
> uint64_t start, len;
> struct inode *inode = bdev->bd_inode;
> @@ -105,18 +107,21 @@ static int blk_ioctl_discard(struct block_device *bdev, blk_mode_t mode,
>
> if (!bdev_max_discard_sectors(bdev))
> return -EOPNOTSUPP;
> + if (bdev_read_only(bdev))
> + return -EPERM;
>
> if (copy_from_user(range, (void __user *)arg, sizeof(range)))
> return -EFAULT;
>
> start = range[0];
> len = range[1];
> + sector = start >> SECTOR_SHIFT;
> + nr_sects = len >> SECTOR_SHIFT;
>
> - if (start & 511)
> + if (!nr_sects)
> return -EINVAL;
> - if (len & 511)
> + if ((sector | nr_sects) & bs_mask)
> return -EINVAL;
> -
> if (start + len > bdev_nr_bytes(bdev))
> return -EINVAL;
>
> @@ -124,7 +129,7 @@ static int blk_ioctl_discard(struct block_device *bdev, blk_mode_t mode,
> err = truncate_bdev_range(bdev, mode, start, start + len - 1);
> if (err)
> goto fail;
> - err = blkdev_issue_discard(bdev, start >> 9, len >> 9, GFP_KERNEL);
> + err = blkdev_issue_discard(bdev, sector, nr_sects, GFP_KERNEL);
> fail:
> filemap_invalidate_unlock(inode->i_mapping);
> return err;
> --

The incremental change I think you want atop this patch to keep the
previous behavior:

-- >8 --
diff --git b/block/ioctl.c a/block/ioctl.c
index 57c8171fda93c..e14388548ab97 100644
--- b/block/ioctl.c
+++ a/block/ioctl.c
@@ -95,7 +95,7 @@ static int compat_blkpg_ioctl(struct block_device *bdev,
static int blk_ioctl_discard(struct block_device *bdev, blk_mode_t mode,
unsigned long arg)
{
- sector_t bs_mask = (bdev_logical_block_size(bdev) >> SECTOR_SHIFT) - 1;
+ sector_t mask = bdev_logical_block_size(bdev) - 1;
sector_t sector, nr_sects;
uint64_t range[2];
uint64_t start, len;
@@ -120,7 +120,7 @@ static int blk_ioctl_discard(struct block_device *bdev, blk_mode_t mode,

if (!nr_sects)
return -EINVAL;
- if ((sector | nr_sects) & bs_mask)
+ if ((start | len) & mask)
return -EINVAL;
if (start + len > bdev_nr_bytes(bdev))
return -EINVAL;