Re: [PATCH v7 1/5] block: introduce bio_in_atomic()

[Jan Kara]

On Thu 30-07-26 02:57:51, Tal Zussman wrote:
> Move the atomic context detection logic from erofs's z_erofs_in_atomic()
> into the block layer as bio_in_atomic(). This helper returns true when
> the current context is unsafe for sleeping bio completion handlers (e.g.,
> hard/soft IRQ, preempt-disabled).
> 
> The logic was originally added to erofs in commit c99fab6e80b7 ("erofs:
> fix atomic context detection when !CONFIG_DEBUG_LOCK_ALLOC"). A
> subsequent patch will use it in the block layer's bio completion
> infrastructure, so move it to include/linux/bio.h where both subsystems
> can share it.
> 
> Convert erofs to call the new bio_in_atomic() directly.
> 
> Suggested-by: Christoph Hellwig <hch@xxxxxxxxxxxxx>
> Signed-off-by: Tal Zussman <tz2294@xxxxxxxxxxxx>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

								Honza


> ---
>  fs/erofs/zdata.c    | 11 +----------
>  include/linux/bio.h | 15 +++++++++++++++
>  2 files changed, 16 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
> index 74520e910259..f796bb3ef53b 100644
> --- a/fs/erofs/zdata.c
> +++ b/fs/erofs/zdata.c
> @@ -1427,15 +1427,6 @@ static void z_erofs_decompressqueue_kthread_work(struct kthread_work *work)
>  }
>  #endif
>  
> -/* Use (kthread_)work in atomic contexts to minimize scheduling overhead */
> -static inline bool z_erofs_in_atomic(void)
> -{
> -	if (IS_ENABLED(CONFIG_PREEMPTION) && rcu_preempt_depth())
> -		return true;
> -	if (!IS_ENABLED(CONFIG_PREEMPT_COUNT))
> -		return true;
> -	return !preemptible();
> -}
>  
>  static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
>  				       int bios)
> @@ -1452,7 +1443,7 @@ static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
>  
>  	if (atomic_add_return(bios, &io->pending_bios))
>  		return;
> -	if (z_erofs_in_atomic()) {
> +	if (bio_in_atomic()) {
>  		/* See `sync_decompress` in sysfs-fs-erofs for more details */
>  		if (sbi->sync_decompress == EROFS_SYNC_DECOMPRESS_AUTO)
>  			sbi->sync_decompress = EROFS_SYNC_DECOMPRESS_FORCE_ON;
> diff --git a/include/linux/bio.h b/include/linux/bio.h
> index 8f33f717b14f..62a983758e09 100644
> --- a/include/linux/bio.h
> +++ b/include/linux/bio.h
> @@ -368,6 +368,21 @@ static inline struct bio *bio_alloc(struct block_device *bdev,
>  
>  void submit_bio(struct bio *bio);
>  
> +/**
> + * bio_in_atomic - check if the current context is unsafe for bio completion
> + *
> + * Return: %true in atomic contexts (e.g. hard/soft IRQ, preempt-disabled);
> + * %false when a bio can be safely completed in the current context.
> + */
> +static inline bool bio_in_atomic(void)
> +{
> +	if (IS_ENABLED(CONFIG_PREEMPTION) && rcu_preempt_depth())
> +		return true;
> +	if (!IS_ENABLED(CONFIG_PREEMPT_COUNT))
> +		return true;
> +	return !preemptible();
> +}
> +
>  extern void bio_endio(struct bio *);
>  
>  /**
> 
> -- 
> 2.39.5
> 
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR