On 6/8/25 8:55 PM, Christoph Hellwig wrote:
The problem here is that blk_crypto_fallback_split_bio_if_needed does
sneaky splits behind the back of the main splitting code.
The fix is to include the limit imposed by it in __bio_split_to_limits
as well if the crypto fallback is used.
(+Eric)
Hmm ... my understanding is that when the inline encryption fallback
code is used that the bio must be split before
blk_crypto_fallback_encrypt_bio() encrypts the bio. Making
__bio_split_to_limits() take the inline encryption limit into account
would require to encrypt the data much later. How to perform encryption
later for bio-based drivers? Would moving the blk_crypto_bio_prep() call
from submit_bio() to just before __bio_split_to_limits() perhaps require
modifying all bio-based drivers that do not call
__bio_split_to_limits()?
If you have time to fix this that would be great. Otherwise I can
give it a spin, but it's public holiday and travel season here, so
my availability is a bit limited.
This is not the solution that you are looking for but this seems to
work:
diff --git a/block/blk-crypto-fallback.c b/block/blk-crypto-fallback.c
index 7c33e9573e5e..f4fefecdcc5e 100644
--- a/block/blk-crypto-fallback.c
+++ b/block/blk-crypto-fallback.c
@@ -213,6 +213,7 @@ blk_crypto_fallback_alloc_cipher_req(struct
blk_crypto_keyslot *slot,
static bool blk_crypto_fallback_split_bio_if_needed(struct bio **bio_ptr)
{
struct bio *bio = *bio_ptr;
+ const struct queue_limits *lim = bdev_limits(bio->bi_bdev);
unsigned int i = 0;
unsigned int num_sectors = 0;
struct bio_vec bv;
@@ -223,6 +224,7 @@ static bool
blk_crypto_fallback_split_bio_if_needed(struct bio **bio_ptr)
if (++i == BIO_MAX_VECS)
break;
}
+ num_sectors = min(num_sectors, get_max_io_size(bio, lim));
if (num_sectors < bio_sectors(bio)) {
struct bio *split_bio;
diff --git a/block/blk-merge.c b/block/blk-merge.c
index fb6253c07387..e308325a333c 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -192,8 +192,7 @@ static inline unsigned int
blk_boundary_sectors(const struct queue_limits *lim,
* requests that are submitted to a block device if the start of a bio
is not
* aligned to a physical block boundary.
*/
-static inline unsigned get_max_io_size(struct bio *bio,
- const struct queue_limits *lim)
+unsigned get_max_io_size(struct bio *bio, const struct queue_limits *lim)
{
unsigned pbs = lim->physical_block_size >> SECTOR_SHIFT;
unsigned lbs = lim->logical_block_size >> SECTOR_SHIFT;
diff --git a/block/blk.h b/block/blk.h
index 37ec459fe656..5f97db919cdf 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -425,6 +425,8 @@ static inline unsigned get_max_segment_size(const
struct queue_limits *lim,
(unsigned long)lim->max_segment_size - 1) + 1);
}
+unsigned get_max_io_size(struct bio *bio, const struct queue_limits *lim);
+
int ll_back_merge_fn(struct request *req, struct bio *bio,
unsigned int nr_segs);
bool blk_attempt_req_merge(struct request_queue *q, struct request *rq,
Thanks,
Bart.
