Currently REQ_OP_ZONE_APPEND is handled by the bio_split_rw case in
__bio_split_to_limits. This is harmful because REQ_OP_ZONE_APPEND
bios do not adhere to the soft max_limits value but instead use their
own capped version of max_hw_sectors, leading to incorrect splits that
later blow up in bio_split.
We still need the bio_split_rw logic to count nr_segs for blk-mq code,
so add a new wrapper that passes in the right limit, and turns any bio
that would need a split into an error as an additional debugging aid.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
block/blk-merge.c | 20 ++++++++++++++++++++
block/blk.h | 4 ++++
2 files changed, 24 insertions(+)
diff --git a/block/blk-merge.c b/block/blk-merge.c
index c7222c4685e060..56769c4bcd799b 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -378,6 +378,26 @@ struct bio *bio_split_rw(struct bio *bio, const struct queue_limits *lim,
get_max_io_size(bio, lim) << SECTOR_SHIFT));
}
+/*
+ * REQ_OP_ZONE_APPEND bios must never be split by the block layer.
+ *
+ * But we want the nr_segs calculation provided by bio_split_rw_at, and having
+ * a good sanity check that the submitter built the bio correctly is nice to
+ * have as well.
+ */
+struct bio *bio_split_zone_append(struct bio *bio,
+ const struct queue_limits *lim, unsigned *nr_segs)
+{
+ unsigned int max_sectors = queue_limits_max_zone_append_sectors(lim);
+ int split_sectors;
+
+ split_sectors = bio_split_rw_at(bio, lim, nr_segs,
+ max_sectors << SECTOR_SHIFT);
+ if (WARN_ON_ONCE(split_sectors > 0))
+ split_sectors = -EINVAL;
+ return bio_submit_split(bio, split_sectors);
+}
+
/**
* bio_split_to_limits - split a bio to fit the queue limits
* @bio: bio to be split
diff --git a/block/blk.h b/block/blk.h
index 0d8cd64c126064..61c2afa67daabb 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -337,6 +337,8 @@ struct bio *bio_split_write_zeroes(struct bio *bio,
const struct queue_limits *lim, unsigned *nsegs);
struct bio *bio_split_rw(struct bio *bio, const struct queue_limits *lim,
unsigned *nr_segs);
+struct bio *bio_split_zone_append(struct bio *bio,
+ const struct queue_limits *lim, unsigned *nr_segs);
/*
* All drivers must accept single-segments bios that are smaller than PAGE_SIZE.
@@ -375,6 +377,8 @@ static inline struct bio *__bio_split_to_limits(struct bio *bio,
return bio_split_rw(bio, lim, nr_segs);
*nr_segs = 1;
return bio;
+ case REQ_OP_ZONE_APPEND:
+ return bio_split_zone_append(bio, lim, nr_segs);
case REQ_OP_DISCARD:
case REQ_OP_SECURE_ERASE:
return bio_split_discard(bio, lim, nr_segs);
--
2.43.0
