block: Add bio_reset()

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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>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

...

This commit is contained in:

Kent Overstreet 2012-09-06 15:34:58 -07:00 • committed by Jens Axboe

parent 9481874231

commit f44b48c769

3 changed files with 44 additions and 6 deletions

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24

fs/bio.c

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1

include/linux/bio.h

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25

include/linux/blk_types.h

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