crypt_alloc_buffer() conditionally acquires bio_alloc_lock around the allocation path and also contains the retry logic for the reclaim fallback.
Move one allocation attempt into crypt_alloc_buffer_try() so that bio_alloc_lock is always acquired and released in crypt_alloc_buffer(), and the retry decision is made only after the mutex has been dropped. This keeps the retry path outside the locked region and makes the locking context easier to analyze. Signed-off-by: Runyu Xiao <[email protected]> --- Changes in v2: - Move one allocation attempt into crypt_alloc_buffer_try(), as suggested by Bart Van Assche. - Keep bio_alloc_lock acquisition and release in crypt_alloc_buffer(), and make the retry decision only after releasing the lock. - Preserve the distinction between a page-pool retry and a final integrity allocation failure. v1: https://lore.kernel.org/r/[email protected] diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index 608b617fb817..7c68fad12960 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -1627,18 +1627,16 @@ static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone); * In order to reduce allocation overhead, we try to allocate compound pages in * the first pass. If they are not available, we fall back to the mempool. */ -static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned int size) +static struct bio *crypt_alloc_buffer_try(struct dm_crypt_io *io, + unsigned int size, gfp_t gfp_mask, + unsigned int order, bool *retry) { struct crypt_config *cc = io->cc; struct bio *clone; unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; - gfp_t gfp_mask = GFP_NOWAIT | __GFP_HIGHMEM; unsigned int remaining_size; - unsigned int order = MAX_PAGE_ORDER; -retry: - if (unlikely(gfp_mask & __GFP_DIRECT_RECLAIM)) - mutex_lock(&cc->bio_alloc_lock); + *retry = false; clone = bio_alloc_bioset(cc->dev->bdev, nr_iovecs, io->base_bio->bi_opf, GFP_NOIO, &cc->bs); @@ -1674,9 +1672,8 @@ static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned int size) if (!pages) { crypt_free_buffer_pages(cc, clone); bio_put(clone); - gfp_mask |= __GFP_DIRECT_RECLAIM; - order = 0; - goto retry; + *retry = true; + return NULL; } have_pages: @@ -1692,12 +1689,34 @@ static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned int size) clone = NULL; } - if (unlikely(gfp_mask & __GFP_DIRECT_RECLAIM)) - mutex_unlock(&cc->bio_alloc_lock); - return clone; } +static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned int size) +{ + struct crypt_config *cc = io->cc; + struct bio *clone; + gfp_t gfp_mask = GFP_NOWAIT | __GFP_HIGHMEM; + unsigned int order = MAX_PAGE_ORDER; + bool retry; + + for (;;) { + if (unlikely(gfp_mask & __GFP_DIRECT_RECLAIM)) + mutex_lock(&cc->bio_alloc_lock); + + clone = crypt_alloc_buffer_try(io, size, gfp_mask, order, &retry); + + if (unlikely(gfp_mask & __GFP_DIRECT_RECLAIM)) + mutex_unlock(&cc->bio_alloc_lock); + + if (!retry) + return clone; + + gfp_mask |= __GFP_DIRECT_RECLAIM; + order = 0; + } +} + static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone) { struct folio_iter fi; -- 2.34.1
