diff options
| author | NeilBrown <neilb@suse.com> | 2017-04-07 11:10:44 +1000 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2017-04-07 09:39:29 -0600 |
| commit | dbde775cdbf5e401b8739f30c87d1af12c0028db (patch) | |
| tree | cdc69a1d6bf1ab83ce3cb1e1fa9a348a5b83d92e | |
| parent | 1dd5198b2df913aec9b77c14529f9ff1b6d33e30 (diff) | |
block: simple improvements for bio->flags
The comment for the 'flags' field of 'bio' mentions
"command" which is no longer stored there, and doesn't
mention the bvec pool number, which is.
BIO_RESET_BITS is set in such a way that it would need to be
updated if new bits were added, which is easy to miss.
BVEC_POOL_BITS is larger than needed. The BVEC_POOL_IDX()
ranges from 0 to 6, so 3 bits are sufficient.
This patch make improvements in each of these areas.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
| -rw-r--r-- | include/linux/blk_types.h | 22 |
1 files changed, 13 insertions, 9 deletions
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index 67bcf8a5326e..1ebbc289b642 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -33,7 +33,7 @@ struct bio { * top bits REQ_OP. Use * accessors. */ - unsigned short bi_flags; /* status, command, etc */ + unsigned short bi_flags; /* status, etc and bvec pool number */ unsigned short bi_ioprio; struct bvec_iter bi_iter; @@ -110,12 +110,7 @@ struct bio { #define BIO_REFFED 8 /* bio has elevated ->bi_cnt */ #define BIO_THROTTLED 9 /* This bio has already been subjected to * throttling rules. Don't do it again. */ - -/* - * Flags starting here get preserved by bio_reset() - this includes - * BVEC_POOL_IDX() - */ -#define BIO_RESET_BITS 10 +/* See BVEC_POOL_OFFSET below before adding new flags */ /* * We support 6 different bvec pools, the last one is magic in that it @@ -125,13 +120,22 @@ struct bio { #define BVEC_POOL_MAX (BVEC_POOL_NR - 1) /* - * Top 4 bits of bio flags indicate the pool the bvecs came from. We add + * Top 3 bits of bio flags indicate the pool the bvecs came from. We add * 1 to the actual index so that 0 indicates that there are no bvecs to be * freed. */ -#define BVEC_POOL_BITS (4) +#define BVEC_POOL_BITS (3) #define BVEC_POOL_OFFSET (16 - BVEC_POOL_BITS) #define BVEC_POOL_IDX(bio) ((bio)->bi_flags >> BVEC_POOL_OFFSET) +#if (1<< BVEC_POOL_BITS) < (BVEC_POOL_NR+1) +# error "BVEC_POOL_BITS is too small" +#endif + +/* + * Flags starting here get preserved by bio_reset() - this includes + * only BVEC_POOL_IDX() + */ +#define BIO_RESET_BITS BVEC_POOL_OFFSET /* * Operations and flags common to the bio and request structures. |