On Thu 11-11-21 17:52:38, Shin'ichiro Kawasaki wrote:
> When BLKRESETZONE ioctl and data read race, the data read leaves stale
> page cache. The commit e5113505904e ("block: Discard page cache of zone
> reset target range") added page cache truncation to avoid stale page
> cache after the ioctl. However, the stale page cache still can be read
> during the reset zone operation for the ioctl. To avoid the stale page
> cache completely, hold invalidate_lock of the block device file mapping.
>
> Fixes: e5113505904e ("block: Discard page cache of zone reset target range")
> 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/blk-zoned.c | 15 +++++----------
> 1 file changed, 5 insertions(+), 10 deletions(-)
>
> diff --git a/block/blk-zoned.c b/block/blk-zoned.c
> index 1d0c76c18fc5..774ecc598bee 100644
> --- a/block/blk-zoned.c
> +++ b/block/blk-zoned.c
> @@ -429,9 +429,10 @@ int blkdev_zone_mgmt_ioctl(struct block_device *bdev, fmode_t mode,
> op = REQ_OP_ZONE_RESET;
>
> /* Invalidate the page cache, including dirty pages. */
> + filemap_invalidate_lock(bdev->bd_inode->i_mapping);
> ret = blkdev_truncate_zone_range(bdev, mode, &zrange);
> if (ret)
> - return ret;
> + goto fail;
> break;
> case BLKOPENZONE:
> op = REQ_OP_ZONE_OPEN;
> @@ -449,15 +450,9 @@ int blkdev_zone_mgmt_ioctl(struct block_device *bdev, fmode_t mode,
> ret = blkdev_zone_mgmt(bdev, op, zrange.sector, zrange.nr_sectors,
> GFP_KERNEL);
>
> - /*
> - * Invalidate the page cache again for zone reset: writes can only be
> - * direct for zoned devices so concurrent writes would not add any page
> - * to the page cache after/during reset. The page cache may be filled
> - * again due to concurrent reads though and dropping the pages for
> - * these is fine.
> - */
> - if (!ret && cmd == BLKRESETZONE)
> - ret = blkdev_truncate_zone_range(bdev, mode, &zrange);
> +fail:
> + if (cmd == BLKRESETZONE)
> + filemap_invalidate_unlock(bdev->bd_inode->i_mapping);
>
> return ret;
> }
> --
> 2.33.1
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
