[Devel] [PATCH RH9 2/7] dm: add find_hole infrastructure

[Alexander Atanasov]

On 24.07.23 11:02, Konstantin Khorenko wrote:
> Implement intermediate find_hole() on device-mapper layer. Do some simple
> checks, add new function to target_type, so any dm devices may realize it
> 
> https://jira.vzint.dev/browse/PSBM-145746
> Signed-off-by: Andrey Zhadchenko <andrey.zhadchenko at virtuozzo.com>
> ---
>   drivers/md/dm.c               | 39 +++++++++++++++++++++++++++++++++++
>   include/linux/device-mapper.h |  4 ++++
>   2 files changed, 43 insertions(+)
> 
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index c6e16ee81281..38f810ca8829 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -480,6 +480,43 @@ static int dm_blk_ioctl(struct block_device *bdev, 
> fmode_t mode,
>       return r;
>   }
>   +static loff_t dm_find_hole(struct block_device *bdev, loff_t offset, 
> int whence)
> +{
> +    struct mapped_device *md = bdev->bd_disk->private_data;
> +    struct dm_table *table;
> +    struct dm_target *ti;
> +    loff_t ret = -ENOTTY;
> +    int srcu_idx;
> +
> +    table = dm_get_live_table(md, &srcu_idx);
> +    if (!table || !dm_table_get_size(table))
> +        goto out;
> +
> +    /*
> +     * For now we only support devices that have a single target.
> +     * But probably it is not hard to break it to a few requests to a 
> different
> +     * targets
> +     */
> +    if (table->num_targets != 1)
> +        goto out;

Do we need an error message here ?

> +
> +    ti = dm_table_get_target(table, 0);
> +
> +    if (dm_suspended_md(md)) {
> +        ret = -EAGAIN;
> +        goto out;
> +    }
> +
> +    if (!ti->type->find_hole)
> +        return -EINVAL;


mixing goto and return - on error dm_put_live_table call will be missed

> +
> +    ret = ti->type->find_hole(ti, offset, whence);
> +
> +out:
> +    dm_put_live_table(md, srcu_idx);
> +    return ret;
> +}
> +

-- 
Regards,
Alexander Atanasov