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| author | Jens Axboe <axboe@fb.com> | 2015-04-17 16:23:59 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2015-05-05 13:32:49 -0600 |
| commit | dac56212e8127dbc0bff7be35c508bc280213309 (patch) | |
| tree | a1a066d7f6deb7d66403137b8edafb394ce0ca6a /include/linux/blk_types.h | |
| parent | c4cf5261f8bffd9de132b50660a69148e7575bd6 (diff) | |
| download | op-kernel-dev-dac56212e8127dbc0bff7be35c508bc280213309.zip op-kernel-dev-dac56212e8127dbc0bff7be35c508bc280213309.tar.gz | |
bio: skip atomic inc/dec of ->bi_cnt for most use cases
Struct bio has a reference count that controls when it can be freed.
Most uses cases is allocating the bio, which then returns with a
single reference to it, doing IO, and then dropping that single
reference. We can remove this atomic_dec_and_test() in the completion
path, if nobody else is holding a reference to the bio.
If someone does call bio_get() on the bio, then we flag the bio as
now having valid count and that we must properly honor the reference
count when it's being put.
Tested-by: Robert Elliott <elliott@hp.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'include/linux/blk_types.h')
| -rw-r--r-- | include/linux/blk_types.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index 8b07e06..93d2e71 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -92,7 +92,7 @@ struct bio { unsigned short bi_max_vecs; /* max bvl_vecs we can hold */ - atomic_t bi_cnt; /* pin count */ + atomic_t __bi_cnt; /* pin count */ struct bio_vec *bi_io_vec; /* the actual vec list */ @@ -123,6 +123,7 @@ struct bio { #define BIO_QUIET 9 /* Make BIO Quiet */ #define BIO_SNAP_STABLE 10 /* bio data must be snapshotted during write */ #define BIO_CHAIN 11 /* chained bio, ->bi_remaining in effect */ +#define BIO_REFFED 12 /* bio has elevated ->bi_cnt */ /* * Flags starting here get preserved by bio_reset() - this includes |
