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Commit cb5bd4d1 authored by Roger Pau Monne's avatar Roger Pau Monne Committed by Konrad Rzeszutek Wilk
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xen/blkback: persistent-grants fixes 



This patch contains fixes for persistent grants implementation v2:

 * handle == 0 is a valid handle, so initialize grants in blkback
   setting the handle to BLKBACK_INVALID_HANDLE instead of 0. Reported
   by Konrad Rzeszutek Wilk.

 * new_map is a boolean, use "true" or "false" instead of 1 and 0.
   Reported by Konrad Rzeszutek Wilk.

 * blkfront announces the persistent-grants feature as
   feature-persistent-grants, use feature-persistent instead which is
   consistent with blkback and the public Xen headers.

 * Add a consistency check in blkfront to make sure we don't try to
   access segments that have not been set.

Reported-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: default avatarRoger Pau Monne <roger.pau@citrix.com>
[v1: The new_map int->bool had already been changed]
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent 0a8704a5

drivers/block/xen-blkback/blkback.c

+6 −3
Original line number Diff line number Diff line
@@ -512,7 +512,7 @@ static int xen_blkbk_map(struct blkif_request *req, 
			 * not mapped but we have room for it

			 */

			new_map = true;

			persistent_gnt = kzalloc(

			persistent_gnt = kmalloc(

				sizeof(struct persistent_gnt),

				GFP_KERNEL);

			if (!persistent_gnt)
@@ -523,6 +523,7 @@ static int xen_blkbk_map(struct blkif_request *req, 
				return -ENOMEM;

			}

			persistent_gnt->gnt = req->u.rw.seg[i].gref;

			persistent_gnt->handle = BLKBACK_INVALID_HANDLE;



			pages_to_gnt[segs_to_map] =

				persistent_gnt->page;
@@ -584,7 +585,8 @@ static int xen_blkbk_map(struct blkif_request *req, 
	 */

	bitmap_zero(pending_req->unmap_seg, BLKIF_MAX_SEGMENTS_PER_REQUEST);

	for (i = 0, j = 0; i < nseg; i++) {

		if (!persistent_gnts[i] || !persistent_gnts[i]->handle) {

		if (!persistent_gnts[i] ||

		    persistent_gnts[i]->handle == BLKBACK_INVALID_HANDLE) {

			/* This is a newly mapped grant */

			BUG_ON(j >= segs_to_map);

			if (unlikely(map[j].status != 0)) {
@@ -601,7 +603,8 @@ static int xen_blkbk_map(struct blkif_request *req, 
			}

		}

		if (persistent_gnts[i]) {

			if (!persistent_gnts[i]->handle) {

			if (persistent_gnts[i]->handle ==

			    BLKBACK_INVALID_HANDLE) {

				/*

				 * If this is a new persistent grant

				 * save the handler

drivers/block/xen-blkback/xenbus.c

+1 −1
Original line number Diff line number Diff line
@@ -760,7 +760,7 @@ static int connect_ring(struct backend_info *be) 
		return -1;

	}

	err = xenbus_gather(XBT_NIL, dev->otherend,

			    "feature-persistent-grants", "%u",

			    "feature-persistent", "%u",

			    &pers_grants, NULL);

	if (err)

		pers_grants = 0;

drivers/block/xen-blkfront.c

+2 −1
Original line number Diff line number Diff line
@@ -852,6 +852,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info, 
		rq_for_each_segment(bvec, s->request, iter) {

			BUG_ON((bvec->bv_offset + bvec->bv_len) > PAGE_SIZE);

			i = offset >> PAGE_SHIFT;

			BUG_ON(i >= s->req.u.rw.nr_segments);

			shared_data = kmap_atomic(

				pfn_to_page(s->grants_used[i]->pfn));

			bvec_data = bvec_kmap_irq(bvec, &flags);
@@ -1069,7 +1070,7 @@ again: 
		goto abort_transaction;

	}

	err = xenbus_printf(xbt, dev->nodename,

			    "feature-persistent-grants", "%u", 1);

			    "feature-persistent", "%u", 1);

	if (err)

		dev_warn(&dev->dev,

			 "writing persistent grants feature to xenbus");