Commit 1e8a7f6a authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

block: properly handle REQ_OP_ZONE_APPEND in __bio_split_to_limits 



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: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDamien Le Moal <dlemoal@kernel.org>
Tested-by: default avatarHans Holmberg <hans.holmberg@wdc.com>
Reviewed-by: default avatarHans Holmberg <hans.holmberg@wdc.com>
Link: https://lore.kernel.org/r/20240826173820.1690925-4-hch@lst.de


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 379b122a

block/blk-merge.c

+20 −0
Original line number Diff line number Diff line
@@ -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

block/blk.h

+4 −0
Original line number Diff line number Diff line
@@ -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);