kevin/linux
1
Fork 0
Code

block: properly handle REQ_OP_ZONE_APPEND in __bio_split_to_limits

Browse Source 
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@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Reviewed-by: Hans Holmberg <hans.holmberg@wdc.com>
Link: https://lore.kernel.org/r/20240826173820.1690925-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2024-08-26 19:37:56 +02:00 committed by Jens Axboe
parent 379b122a3e
commit 1e8a7f6af9
2 changed files with 24 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
block/blk-merge.c
View File

@ -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

4
block/blk.h
View File

@ -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);