[Xen-devel] [PATCH] drivers: xen-blkfront: blkif_recover: recheck feature-persistent

[Bob Liu <bob.liu@xxxxxxxxxx>]

When migrate from !feature-persistent host to feature-persistent host, domU
still think new host/backend don't support persistent.
Dmesg like:
backed has not unmapped grant: 839
backed has not unmapped grant: 773
backed has not unmapped grant: 773
backed has not unmapped grant: 773
backed has not unmapped grant: 839

We should recheck whether the new backend support feature-persistent during
blkif_recover().

Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx>
---
 drivers/block/xen-blkfront.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index d3c1a95..cad4d8c 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -1504,7 +1504,7 @@ static int blkif_recover(struct blkfront_info *info)
        int i;
        struct request *req, *n;
        struct blk_shadow *copy;
-       int rc;
+       int rc, persistent;
        struct bio *bio, *cloned_bio;
        struct bio_list bio_list, merge_bio;
        unsigned int segs, offset;
@@ -1525,6 +1525,14 @@ static int blkif_recover(struct blkfront_info *info)
        info->shadow_free = info->ring.req_prod_pvt;
        info->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
 
+       /* Should check whether the new backend support feature-persistent */
+       rc = xenbus_gather(XBT_NIL, info->xbdev->otherend,
+                           "feature-persistent", "%u", &persistent,
+                           NULL);
+       if (rc)
+               info->feature_persistent = 0;
+       else
+               info->feature_persistent = persistent;
        rc = blkfront_setup_indirect(info);
        if (rc) {
                kfree(copy);
-- 
1.8.3.1


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