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xen/blkback: persistent-grants fixes

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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: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
[v1: The new_map int->bool had already been changed]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Roger Pau Monne 2012-11-02 16:43:04 +01:00 committed by Konrad Rzeszutek Wilk
parent 0a8704a51f
commit cb5bd4d19b
3 changed files with 9 additions and 5 deletions
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9
drivers/block/xen-blkback/blkback.c
View File

@ -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

2
drivers/block/xen-blkback/xenbus.c
View File

@ -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;

3
drivers/block/xen-blkfront.c
View File

@ -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");