[PATCH 3.16.y-ckt 088/130] xen-blkfront: don't add indirect pages to list when !feature_persistent

From: Luis Henriques
Date: Fri Sep 04 2015 - 09:31:37 EST

3.16.7-ckt17 -stable review patch. If anyone has any objections, please let me know.


From: Bob Liu <bob.liu@xxxxxxxxxx>

commit 7b0767502b5db11cb1f0daef2d01f6d71b1192dc upstream.

We should consider info->feature_persistent when adding indirect page to list
info->indirect_pages, else the BUG_ON() in blkif_free() would be triggered.

When we are using persistent grants the indirect_pages list
should always be empty because blkfront has pre-allocated enough
persistent pages to fill all requests on the ring.

Acked-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
drivers/block/xen-blkfront.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 5deb235bd18f..2a29cf69cd73 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -1093,8 +1093,10 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
* Add the used indirect page back to the list of
* available pages for indirect grefs.
- indirect_page = pfn_to_page(s->indirect_grants[i]->pfn);
- list_add(&indirect_page->lru, &info->indirect_pages);
+ if (!info->feature_persistent) {
+ indirect_page = pfn_to_page(s->indirect_grants[i]->pfn);
+ list_add(&indirect_page->lru, &info->indirect_pages);
+ }
s->indirect_grants[i]->gref = GRANT_INVALID_REF;
list_add_tail(&s->indirect_grants[i]->node, &info->grants);
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