diff options
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/device-mapper.h | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index d1f6cd8486f2..6f0e73b4a80d 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -210,6 +210,12 @@ struct dm_target { */ unsigned num_write_same_requests; + /* + * The minimum number of extra bytes allocated in each bio for the + * target to use. dm_per_bio_data returns the data location. + */ + unsigned per_bio_data_size; + /* target specific data */ void *private; @@ -246,6 +252,30 @@ struct dm_target_callbacks { int (*congested_fn) (struct dm_target_callbacks *, int); }; +/* + * For bio-based dm. + * One of these is allocated for each bio. + * This structure shouldn't be touched directly by target drivers. + * It is here so that we can inline dm_per_bio_data and + * dm_bio_from_per_bio_data + */ +struct dm_target_io { + struct dm_io *io; + struct dm_target *ti; + union map_info info; + struct bio clone; +}; + +static inline void *dm_per_bio_data(struct bio *bio, size_t data_size) +{ + return (char *)bio - offsetof(struct dm_target_io, clone) - data_size; +} + +static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size) +{ + return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone)); +} + int dm_register_target(struct target_type *t); void dm_unregister_target(struct target_type *t); |