[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] xen-blkback: convert hole punching to discard request on loop devices
On Wed, Nov 9, 2011 at 12:01 AM, Jan Beulich <JBeulich@xxxxxxxx> wrote: >>>> On 07.11.11 at 09:34, Li Dongyang <lidongyang@xxxxxxxxxx> wrote: >> As of dfaa2ef68e80c378e610e3c8c536f1c239e8d3ef, 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. > > Looking at what the loop driver now does - doesn't the original code > here lack support for lo_offset being non-zero then? If so, should we > fix this in pre-3.2 kernels? yes, you are right, but will we ever setup the loop device with lo_offset non-zero? I don't think so but I'm not sure. > > Jan > >> Signed-off-by: Li Dongyang <lidongyang@xxxxxxxxxx> >> --- >> drivers/block/xen-blkback/blkback.c | 21 +++------------------ >> 1 files changed, 3 insertions(+), 18 deletions(-) >> >> diff --git a/drivers/block/xen-blkback/blkback.c >> b/drivers/block/xen-blkback/blkback.c >> index 15ec4db..ad365a7 100644 >> --- a/drivers/block/xen-blkback/blkback.c >> +++ b/drivers/block/xen-blkback/blkback.c >> @@ -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> >> @@ -422,25 +419,13 @@ static void xen_blk_discard(struct xen_blkif *blkif, >> struct blkif_request *req) >> int status = BLKIF_RSP_OKAY; >> struct block_device *bdev = blkif->vbd.bdev; >> >> - if (blkif->blk_backend_type == BLKIF_BACKEND_PHY) >> - /* just forward the discard request */ >> + if (blkif->blk_backend_type == BLKIF_BACKEND_PHY || >> + blkif->blk_backend_type == BLKIF_BACKEND_FILE) >> err = blkdev_issue_discard(bdev, >> req->u.discard.sector_number, >> req->u.discard.nr_sectors, >> GFP_KERNEL, 0); >> - 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 >> + else >> err = -EOPNOTSUPP; >> >> if (err == -EOPNOTSUPP) { > > > > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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