On Tue 09-11-21 19:47:23, Shin'ichiro Kawasaki wrote:
> When BLKZEROOUT ioctl and data read race, the data read leaves stale
> page cache. To avoid the stale page cache, hold invalidate_lock of the
> block device file mapping. The stale page cache is observed when
> blktests test case block/009 is modified to call "blkdiscard -z" command
> and repeated hundreds of times.
>
> This patch can be applied back to the stable kernel version v5.15.y.
> Rework is required for older stable kernels.
>
> Fixes: 22dd6d356628 ("block: invalidate the page cache when issuing BLKZEROOUT")
> Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@xxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # v5.15
Looks good to me. Feel free to add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> block/ioctl.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/block/ioctl.c b/block/ioctl.c
> index 9fa87f64f703..0a1d10ac2e1a 100644
> --- a/block/ioctl.c
> +++ b/block/ioctl.c
> @@ -154,6 +154,7 @@ static int blk_ioctl_zeroout(struct block_device *bdev, fmode_t mode,
> {
> uint64_t range[2];
> uint64_t start, end, len;
> + struct inode *inode = bdev->bd_inode;
> int err;
>
> if (!(mode & FMODE_WRITE))
> @@ -176,12 +177,17 @@ static int blk_ioctl_zeroout(struct block_device *bdev, fmode_t mode,
> return -EINVAL;
>
> /* Invalidate the page cache, including dirty pages */
> + filemap_invalidate_lock(inode->i_mapping);
> err = truncate_bdev_range(bdev, mode, start, end);
> if (err)
> - return err;
> + goto fail;
> +
> + err = blkdev_issue_zeroout(bdev, start >> 9, len >> 9, GFP_KERNEL,
> + BLKDEV_ZERO_NOUNMAP);
>
> - return blkdev_issue_zeroout(bdev, start >> 9, len >> 9, GFP_KERNEL,
> - BLKDEV_ZERO_NOUNMAP);
> +fail:
> + filemap_invalidate_unlock(inode->i_mapping);
> + return err;
> }
>
> static int put_ushort(unsigned short __user *argp, unsigned short val)
> --
> 2.33.1
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
