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Commit ae18be11 authored by Li Dongyang's avatar Li Dongyang Committed by Konrad Rzeszutek Wilk
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xen-blkback: convert hole punching to discard request on loop devices 



As of dfaa2ef6, loop devices support
discard request now. We could just issue a discard request, and
the loop driver will punch the hole for us, so we don't need to touch
the internals of loop device and punch the hole ourselves, Thanks.

V0->V1: rebased on devel/for-jens-3.3

Signed-off-by: default avatarLi Dongyang <lidongyang@novell.com>
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent 42146352

drivers/block/xen-blkback/blkback.c

+2 −17
Original line number Diff line number Diff line
@@ -39,9 +39,6 @@ 
#include <linux/list.h>

#include <linux/delay.h>

#include <linux/freezer.h>

#include <linux/loop.h>

#include <linux/falloc.h>

#include <linux/fs.h>



#include <xen/events.h>

#include <xen/page.h>
@@ -426,27 +423,15 @@ static int dispatch_discard_io(struct xen_blkif *blkif, 
	blkif->st_ds_req++;



	xen_blkif_get(blkif);

	if (blkif->blk_backend_type == BLKIF_BACKEND_PHY) {

	if (blkif->blk_backend_type == BLKIF_BACKEND_PHY ||

	    blkif->blk_backend_type == BLKIF_BACKEND_FILE) {

		unsigned long secure = (blkif->vbd.discard_secure &&

			(req->u.discard.flag & BLKIF_DISCARD_SECURE)) ?

			BLKDEV_DISCARD_SECURE : 0;

		/* just forward the discard request */

		err = blkdev_issue_discard(bdev,

				req->u.discard.sector_number,

				req->u.discard.nr_sectors,

				GFP_KERNEL, secure);

	} else if (blkif->blk_backend_type == BLKIF_BACKEND_FILE) {

		/* punch a hole in the backing file */

		struct loop_device *lo = bdev->bd_disk->private_data;

		struct file *file = lo->lo_backing_file;



		if (file->f_op->fallocate)

			err = file->f_op->fallocate(file,

				FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,

				req->u.discard.sector_number << 9,

				req->u.discard.nr_sectors << 9);

		else

			err = -EOPNOTSUPP;

	} else

		err = -EOPNOTSUPP;