Messages in this thread Patch in this message | | | From | Kent Overstreet <> | Subject | [PATCH v9 6/9] block: Add bio_reset() | Date | Thu, 6 Sep 2012 14:32:53 -0700 |
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Reusing bios is something that's been highly frowned upon in the past, but driver code keeps doing it anyways. If it's going to happen anyways, we should provide a generic method.
This'll help with getting rid of bi_destructor - drivers/block/pktcdvd.c was open coding it, by doing a bio_init() and resetting bi_destructor.
This required reordering struct bio, but the block layer is not yet nearly fast enough for any cacheline effects to matter here.
v5: Add a define BIO_RESET_BITS, to be very explicit about what parts of bio->bi_flags are saved. v6: Further commenting verbosity, per Tejun v9: Add a function comment
Signed-off-by: Kent Overstreet <koverstreet@google.com> CC: Jens Axboe <axboe@kernel.dk> Acked-by: Tejun Heo <tj@kernel.org> --- fs/bio.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)
diff --git a/fs/bio.c b/fs/bio.c index 208141f..74ab3f0 100644 --- a/fs/bio.c +++ b/fs/bio.c @@ -277,6 +277,30 @@ void bio_reset(struct bio *bio) EXPORT_SYMBOL(bio_reset); /** + * bio_reset - reinitialize a bio + * @bio: bio to reset + * + * Description: + * After calling bio_reset(), @bio will be in the same state as a freshly + * allocated bio returned bio bio_alloc_bioset() - the only fields that are + * preserved are the ones that are initialized by bio_alloc_bioset(). See + * comment in struct bio. + */ +void bio_reset(struct bio *bio) +{ + unsigned long flags = bio->bi_flags & (~0UL << BIO_RESET_BITS); + + if (bio_integrity(bio)) + bio_integrity_free(bio, bio->bi_pool); + + bio_disassociate_task(bio); + + memset(bio, 0, BIO_RESET_BYTES); + bio->bi_flags = flags|(1 << BIO_UPTODATE); +} +EXPORT_SYMBOL(bio_reset); + +/** * bio_alloc_bioset - allocate a bio for I/O * @gfp_mask: the GFP_ mask given to the slab allocator * @nr_iovecs: number of iovecs to pre-allocate -- 1.7.12
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