On 05/11/2024 07:21, Hannes Reinecke wrote:
On 10/31/24 10:59, John Garry wrote:
Instead of returning an inconclusive value of NULL for an error in
calling
bio_split(), return a ERR_PTR() always.
Also remove the BUG_ON() calls, and WARN_ON_ONCE() instead. Indeed, since
almost all callers don't check the return code from bio_split(), we'll
crash anyway (for those failures).
Fix up the only user which checks bio_split() return code today (directly
or indirectly), blk_crypto_fallback_split_bio_if_needed(). The md/bcache
code does check the return code in cached_dev_cache_miss() ->
bio_next_split() -> bio_split(), but only to see if there was a split, so
there would be no change in behaviour here (when returning a ERR_PTR()).
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>
Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx>
---
block/bio.c | 10 ++++++----
block/blk-crypto-fallback.c | 2 +-
2 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/block/bio.c b/block/bio.c
index 95e2ee14cea2..7a93724e4a49 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1740,16 +1740,18 @@ struct bio *bio_split(struct bio *bio, int
sectors,
{
struct bio *split;
- BUG_ON(sectors <= 0);
- BUG_ON(sectors >= bio_sectors(bio));
+ if (WARN_ON_ONCE(sectors <= 0))
+ return ERR_PTR(-EINVAL);
+ if (WARN_ON_ONCE(sectors >= bio_sectors(bio)))
+ return ERR_PTR(-EINVAL);
/* Zone append commands cannot be split */
if (WARN_ON_ONCE(bio_op(bio) == REQ_OP_ZONE_APPEND))
- return NULL;
+ return ERR_PTR(-EINVAL);
split = bio_alloc_clone(bio->bi_bdev, bio, gfp, bs);
if (!split)
- return NULL;
+ return ERR_PTR(-ENOMEM);
split->bi_iter.bi_size = sectors << 9;
diff --git a/block/blk-crypto-fallback.c b/block/blk-crypto-fallback.c
index b1e7415f8439..29a205482617 100644
--- a/block/blk-crypto-fallback.c
+++ b/block/blk-crypto-fallback.c
@@ -226,7 +226,7 @@ static bool
blk_crypto_fallback_split_bio_if_needed(struct bio **bio_ptr)
split_bio = bio_split(bio, num_sectors, GFP_NOIO,
&crypto_bio_split);
- if (!split_bio) {
+ if (IS_ERR(split_bio)) {
bio->bi_status = BLK_STS_RESOURCE;
return false;
}
Don't you need to modify block/bounce.c, too?
Today we have __blk_queue_bounce() -> bio_split(), but the return value
from bio_split() is not checked for errors (NULL) there, so it is
already in a poor state.
I will look to remedy that and other callsites which don't check
bio_split() return value for errors in next phase.
Thanks,
John
