tree d093ce493146779926df88b5831805c6f9ee14e1
parent 082439004b31adc146e96e5f1c574dd2b57dcd93
author Christoph Hellwig <hch@lst.de> 1276873182 +0200
committer Jens Axboe <jaxboe@fusionio.com> 1281198188 +0200

block: don't allocate a payload for discard request

Allocating a fixed payload for discard requests always was a horrible hack,
and it's not coming to byte us when adding support for discard in DM/MD.

So change the code to leave the allocation of a payload to the lowlevel
driver.  Unfortunately that means we'll need another hack, which allows
us to update the various block layer length fields indicating that we
have a payload.  Instead of hiding this in sd.c, which we already partially
do for UNMAP support add a documented helper in the core block layer for it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>