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block: introduce bio_in_atomic()

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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 c99fab6e80 ("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@infradead.org>
Signed-off-by: Tal Zussman <tz2294@columbia.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260730-blk-dontcache-v7-1-3e8e6850068d@columbia.edu
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Tal Zussman
2026-07-30 02:57:51 -04:00
committed by Jens Axboe
parent 14b007e178
commit 8ed0831b52
2 changed files with 16 additions and 10 deletions
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11
fs/erofs/zdata.c
View File

@@ -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;

15
include/linux/bio.h
View File

@@ -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 *);
/**