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xen-blkback: convert hole punching to discard request on loop devices 

As of dfaa2ef68e, 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: Li Dongyang <lidongyang@novell.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Li Dongyang 2011-11-10 15:52:06 +08:00 committed by Konrad Rzeszutek Wilk
parent 421463526f
commit ae18be11b5
1 changed files with 2 additions and 17 deletions
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19
drivers/block/xen-blkback/blkback.c
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@ -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;