On Sun, Jun 27, 2010 at 05:49:29PM +0900, FUJITA Tomonori wrote: > On Sat, 26 Jun 2010 15:56:50 -0400 > Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > > > Fix leaks introduced via "block: don't allocate a payload for discard > > request" commit a1d949f5f44. > > > > sd_done() is not called for REQ_TYPE_BLOCK_PC commands so cleanup > > discard request's payload directly in scsi_finish_command(). > > Instead of adding another discard hack to scsi_finish_command(), how > about converting discard to REQ_TYPE_FS request? discard is FS request > from the perspective of the block layer. It also fixes a problem that > discard isn't retried in the case of UNIT ATTENTION. > > I think that we can get more cleaner code if we handle discard as > normal (fs) request in the block layer (and scsi-ml). We need more > changes but this patch is the first step. Making discard a REQ_TYPE_FS inside scsi (it already is before entering sd_prep_fn) means we'll need to special case it all over the I/O submission and completion path. Having the payload length not matching the transfer length is something we don't expect for FS requests. > index e16185b..9e15c46 100644 > --- a/block/blk-lib.c > +++ b/block/blk-lib.c > @@ -20,6 +20,10 @@ static void blkdev_discard_end_io(struct bio *bio, int err) > if (bio->bi_private) > complete(bio->bi_private); > > + /* free the page that the lower layer allocated */ > + if (bio_page(bio)) > + __free_page(bio_page(bio)); > + This is exactly what this patchkit gets rid off. Having a payload page that the caller tracks (previously fully, with this patch only for freeing) makes DM's life a lot harder. Remember we don't actually store any payload in there before entering sd_prep_fn - it's just that the scsi commands implementing discards need some payload - either a sector sizes zero filled buffer for WRITE SAME, or an LBA/len encoding inside the payload for UNMAP. > - rq->cmd_type = REQ_TYPE_BLOCK_PC; > + rq->cmd_type = REQ_TYPE_FS; No need to set REQ_TYPE_FS here, it's already set up that way. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
