Commit 2b24e6f6 authored by Johannes Thumshirn's avatar Johannes Thumshirn Committed by Jens Axboe
Browse files

block: bio: ensure newly added bio flags don't override BVEC_POOL_IDX 



With the introduction of BIO_NO_PAGE_REF we've used up all available bits
in bio::bi_flags.

Convert the defines of the flags to an enum and add a BUILD_BUG_ON() call
to make sure no-one adds a new one and thus overrides the BVEC_POOL_IDX
causing crashes.

Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.com>
Reviewed-by: default avatarBart Van Assche <bvanassche@acm.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 2bc13b83

block/bio.c

+3 −0
Original line number Diff line number Diff line
@@ -2218,6 +2218,9 @@ static int __init init_bio(void) 
	bio_slab_nr = 0;

	bio_slabs = kcalloc(bio_slab_max, sizeof(struct bio_slab),

			    GFP_KERNEL);



	BUILD_BUG_ON(BIO_FLAG_LAST > BVEC_POOL_OFFSET);



	if (!bio_slabs)

		panic("bio: can't allocate bios\n");

include/linux/blk_types.h

+16 −13
Original line number Diff line number Diff line
@@ -215,21 +215,24 @@ struct bio { 
/*

 * bio flags

 */

#define BIO_NO_PAGE_REF	0	/* don't put release vec pages */

#define BIO_SEG_VALID	1	/* bi_phys_segments valid */

#define BIO_CLONED	2	/* doesn't own data */

#define BIO_BOUNCED	3	/* bio is a bounce bio */

#define BIO_USER_MAPPED 4	/* contains user pages */

#define BIO_NULL_MAPPED 5	/* contains invalid user pages */

#define BIO_QUIET	6	/* Make BIO Quiet */

#define BIO_CHAIN	7	/* chained bio, ->bi_remaining in effect */

#define BIO_REFFED	8	/* bio has elevated ->bi_cnt */

#define BIO_THROTTLED	9	/* This bio has already been subjected to

enum {

	BIO_NO_PAGE_REF,	/* don't put release vec pages */

	BIO_SEG_VALID,		/* bi_phys_segments valid */

	BIO_CLONED,		/* doesn't own data */

	BIO_BOUNCED,		/* bio is a bounce bio */

	BIO_USER_MAPPED,	/* contains user pages */

	BIO_NULL_MAPPED,	/* contains invalid user pages */

	BIO_QUIET,		/* Make BIO Quiet */

	BIO_CHAIN,		/* chained bio, ->bi_remaining in effect */

	BIO_REFFED,		/* bio has elevated ->bi_cnt */

	BIO_THROTTLED,		/* This bio has already been subjected to

				 * throttling rules. Don't do it again. */

#define BIO_TRACE_COMPLETION 10	/* bio_endio() should trace the final completion

	BIO_TRACE_COMPLETION,	/* bio_endio() should trace the final completion

				 * of this bio. */

#define BIO_QUEUE_ENTERED 11	/* can use blk_queue_enter_live() */

#define BIO_TRACKED 12		/* set if bio goes through the rq_qos path */

	BIO_QUEUE_ENTERED,	/* can use blk_queue_enter_live() */

	BIO_TRACKED,		/* set if bio goes through the rq_qos path */

	BIO_FLAG_LAST

};



/* See BVEC_POOL_OFFSET below before adding new flags */

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