diff options
| author | Christoph Hellwig <hch@lst.de> | 2024-08-26 19:37:57 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2024-08-29 04:32:32 -0600 |
| commit | 1251580983f267e2e6b6505609a835119b68c513 (patch) | |
| tree | 50aed8abde191727ac246b62bbb7fa7041eff93a /block | |
| parent | 1e8a7f6af926e266cc1d7ac49b56bd064057d625 (diff) | |
block: don't use bio_split_rw on misc operations
bio_split_rw is designed to split read and write bios with a payload.
Currently it is called by __bio_split_to_limits for all operations not
explicitly list, which works because bio_may_need_split explicitly checks
for bi_vcnt == 1 and thus skips the bypass if there is no payload and
bio_for_each_bvec loop will never execute it's body if bi_size is 0.
But all this is hard to understand, fragile and wasted pointless cycles.
Switch __bio_split_to_limits to only call bio_split_rw for READ and
WRITE command and don't attempt any kind split for operation that do not
require splitting.
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/20240826173820.1690925-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk.h | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/block/blk.h b/block/blk.h index 61c2afa67daa..32f4e9f630a3 100644 --- a/block/blk.h +++ b/block/blk.h @@ -372,7 +372,8 @@ static inline struct bio *__bio_split_to_limits(struct bio *bio, const struct queue_limits *lim, unsigned int *nr_segs) { switch (bio_op(bio)) { - default: + case REQ_OP_READ: + case REQ_OP_WRITE: if (bio_may_need_split(bio, lim)) return bio_split_rw(bio, lim, nr_segs); *nr_segs = 1; @@ -384,6 +385,10 @@ static inline struct bio *__bio_split_to_limits(struct bio *bio, return bio_split_discard(bio, lim, nr_segs); case REQ_OP_WRITE_ZEROES: return bio_split_write_zeroes(bio, lim, nr_segs); + default: + /* other operations can't be split */ + *nr_segs = 0; + return bio; } } |