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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/fs.h | |
| parent | Fix up comments about matching flags between bio and rq (diff) | |
| download | linux-dev-fb2dce862d9f9a68e6b9374579056ec9eca02a63.tar.xz linux-dev-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/fs.h')
| -rw-r--r-- | include/linux/fs.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h index 580b513668fe..eb0131319134 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -86,7 +86,8 @@ extern int dir_notify_enable; #define READ_META (READ | (1 << BIO_RW_META)) #define WRITE_SYNC (WRITE | (1 << BIO_RW_SYNC)) #define SWRITE_SYNC (SWRITE | (1 << BIO_RW_SYNC)) -#define WRITE_BARRIER ((1 << BIO_RW) | (1 << BIO_RW_BARRIER)) +#define WRITE_BARRIER (WRITE | (1 << BIO_RW_BARRIER)) +#define WRITE_DISCARD (WRITE | (1 << BIO_RW_DISCARD)) #define SEL_IN 1 #define SEL_OUT 2 |