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| author | David Woodhouse <David.Woodhouse@intel.com> | 2008-08-05 18:01:53 +0100 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2008-10-09 08:56:01 +0200 |
| commit | fb2dce862d9f9a68e6b9374579056ec9eca02a63 (patch) | |
| tree | 888e0fd7248c9329fa1aa3981043a2dc2457d488 /include/linux/bio.h | |
| parent | d628eaef310533767ce68664873869c2d7f78f09 (diff) | |
| download | lwn-fb2dce862d9f9a68e6b9374579056ec9eca02a63.tar.gz lwn-fb2dce862d9f9a68e6b9374579056ec9eca02a63.zip | |
Add 'discard' request handling
Some block devices benefit from a hint that they can forget the contents
of certain sectors. Add basic support for this to the block core, along
with a 'blkdev_issue_discard()' helper function which issues such
requests.
The caller doesn't get to provide an end_io functio, since
blkdev_issue_discard() will automatically split the request up into
multiple bios if appropriate. Neither does the function wait for
completion -- it's expected that callers won't care about when, or even
_if_, the request completes. It's only a hint to the device anyway. By
definition, the file system doesn't _care_ about these sectors any more.
[With feedback from OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> and
Jens Axboe <jens.axboe@oracle.com]
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'include/linux/bio.h')
| -rw-r--r-- | include/linux/bio.h | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/include/linux/bio.h b/include/linux/bio.h index 17f1fbdb31bf..1fdfc5621c83 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -149,6 +149,8 @@ struct bio { * bit 2 -- barrier * bit 3 -- fail fast, don't want low level driver retries * bit 4 -- synchronous I/O hint: the block layer will unplug immediately + * bit 5 -- metadata request + * bit 6 -- discard sectors */ #define BIO_RW 0 /* Must match RW in req flags (blkdev.h) */ #define BIO_RW_AHEAD 1 /* Must match FAILFAST in req flags */ @@ -156,6 +158,7 @@ struct bio { #define BIO_RW_FAILFAST 3 #define BIO_RW_SYNC 4 #define BIO_RW_META 5 +#define BIO_RW_DISCARD 6 /* * upper 16 bits of bi_rw define the io priority of this bio @@ -186,13 +189,14 @@ struct bio { #define bio_rw_ahead(bio) ((bio)->bi_rw & (1 << BIO_RW_AHEAD)) #define bio_rw_meta(bio) ((bio)->bi_rw & (1 << BIO_RW_META)) #define bio_empty_barrier(bio) (bio_barrier(bio) && !bio_has_data(bio)) +#define bio_discard(bio) ((bio)->bi_rw & (1 << BIO_RW_DISCARD)) static inline unsigned int bio_cur_sectors(struct bio *bio) { if (bio->bi_vcnt) return bio_iovec(bio)->bv_len >> 9; - - return 0; + else /* dataless requests such as discard */ + return bio->bi_size >> 9; } static inline void *bio_data(struct bio *bio) |