linux-ext4 - Re: [PATCH v7 1/9] block: Keyslot Manager for Inline Encryption

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Date:   Fri, 21 Feb 2020 09:04:34 -0800
From:   Christoph Hellwig <hch@...radead.org>
To:     Satya Tangirala <satyat@...gle.com>
Cc:     linux-block@...r.kernel.org, linux-scsi@...r.kernel.org,
        linux-fscrypt@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net, linux-ext4@...r.kernel.org,
        Barani Muthukumaran <bmuthuku@....qualcomm.com>,
        Kuohong Wang <kuohong.wang@...iatek.com>,
        Kim Boojin <boojin.kim@...sung.com>
Subject: Re: [PATCH v7 1/9] block: Keyslot Manager for Inline Encryption

> +#ifdef CONFIG_PM
> +static inline void blk_ksm_set_dev(struct keyslot_manager *ksm,
> +				   struct device *dev)
> +{
> +	ksm->dev = dev;
> +}
> +
> +/* If there's an underlying device and it's suspended, resume it. */
> +static inline void blk_ksm_pm_get(struct keyslot_manager *ksm)
> +{
> +	if (ksm->dev)
> +		pm_runtime_get_sync(ksm->dev);
> +}
> +
> +static inline void blk_ksm_pm_put(struct keyslot_manager *ksm)
> +{
> +	if (ksm->dev)
> +		pm_runtime_put_sync(ksm->dev);
> +}
> +#else /* CONFIG_PM */
> +static inline void blk_ksm_set_dev(struct keyslot_manager *ksm,
> +				   struct device *dev)
> +{
> +}
> +
> +static inline void blk_ksm_pm_get(struct keyslot_manager *ksm)
> +{
> +}
> +
> +static inline void blk_ksm_pm_put(struct keyslot_manager *ksm)
> +{
> +}
> +#endif /* !CONFIG_PM */

I think no one is hurt by an unused dev field for the non-pm case.
I'd suggest to define the field unconditionally, and replace all
the above with direct calls below.

> +/**
> + * blk_ksm_get_slot() - Increment the refcount on the specified slot.
> + * @ksm: The keyslot manager that we want to modify.
> + * @slot: The slot to increment the refcount of.
> + *
> + * This function assumes that there is already an active reference to that slot
> + * and simply increments the refcount. This is useful when cloning a bio that
> + * already has a reference to a keyslot, and we want the cloned bio to also have
> + * its own reference.
> + *
> + * Context: Any context.
> + */
> +void blk_ksm_get_slot(struct keyslot_manager *ksm, unsigned int slot)

This function doesn't appear to be used at all in the whole series.

> +/**
> + * blk_ksm_put_slot() - Release a reference to a slot
> + * @ksm: The keyslot manager to release the reference from.
> + * @slot: The slot to release the reference from.
> + *
> + * Context: Any context.
> + */
> +void blk_ksm_put_slot(struct keyslot_manager *ksm, unsigned int slot)
> +{
> +	unsigned long flags;
> +
> +	if (WARN_ON(slot >= ksm->num_slots))
> +		return;
> +
> +	if (atomic_dec_and_lock_irqsave(&ksm->slots[slot].slot_refs,
> +					&ksm->idle_slots_lock, flags)) {
> +		list_add_tail(&ksm->slots[slot].idle_slot_node,
> +			      &ksm->idle_slots);
> +		spin_unlock_irqrestore(&ksm->idle_slots_lock, flags);
> +		wake_up(&ksm->idle_slots_wait_queue);
> +	}

Given that blk_ksm_get_slot_for_key returns a signed keyslot that
can return errors, and the only callers stores it in a signed variable
I think this function should take a signed slot as well, and the check
for a non-negative slot should be moved here from the only caller.

> diff --git a/include/linux/bio.h b/include/linux/bio.h
> index 853d92ceee64..b2103e207ed5 100644
> --- a/include/linux/bio.h
> +++ b/include/linux/bio.h
> @@ -8,6 +8,7 @@
>  #include <linux/highmem.h>
>  #include <linux/mempool.h>
>  #include <linux/ioprio.h>
> +#include <linux/blk-crypto.h>
>  
>  #ifdef CONFIG_BLOCK
>  /* struct bio, bio_vec and BIO_* flags are defined in blk_types.h */

This doesn't belong here, but into the patch that actually requires
crypto definitions in bio.h.