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    Add 'discard' request handling · fb2dce86
    David Woodhouse 提交于
    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: NDavid Woodhouse <David.Woodhouse@intel.com>
    Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
    fb2dce86
blk-core.c 54.2 KB