Merge branch 'stable/for-jens-4.2' of git://git.kernel.org/pub/scm/linux/kernel/git...

Konrad writes:

"There are three bugs that have been found in the xen-blkfront (and
backend). Two of them have the stable tree CC-ed. They have been found
where an guest is migrating to a host that is missing
'feature-persistent' support (from one that has it enabled). We end up
hitting an BUG() in the driver code."

diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index ced96777b677b9bcddd65bae004a7a51b5cf0dc3..954c0029fb3babc49d1a1f490f9d420934701e30 100644 (file)
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -369,8 +369,8 @@ static void purge_persistent_gnt(struct xen_blkif *blkif)
                return;
        }
 
-       if (work_pending(&blkif->persistent_purge_work)) {
-               pr_alert_ratelimited("Scheduled work from previous purge is still pending, cannot purge list\n");
+       if (work_busy(&blkif->persistent_purge_work)) {
+               pr_alert_ratelimited("Scheduled work from previous purge is still busy, cannot purge list\n");
                return;
        }
 

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 6d89ed35d80c0caaf8bf57ba82c7e9f3a9194bb9..7a8a73f1fc0462feab5bad706573ff6eb4536ef7 100644 (file)
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -179,6 +179,7 @@ static DEFINE_SPINLOCK(minor_lock);
        ((_segs + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME)
 
 static int blkfront_setup_indirect(struct blkfront_info *info);
+static int blkfront_gather_backend_features(struct blkfront_info *info);
 
 static int get_id_from_freelist(struct blkfront_info *info)
 {
@@ -1128,8 +1129,10 @@ 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);
                        }
@@ -1519,7 +1522,7 @@ 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;
 
-       rc = blkfront_setup_indirect(info);
+       rc = blkfront_gather_backend_features(info);
        if (rc) {
                kfree(copy);
                return rc;
@@ -1720,20 +1723,13 @@ static void blkfront_setup_discard(struct blkfront_info *info)
 
 static int blkfront_setup_indirect(struct blkfront_info *info)
 {
-       unsigned int indirect_segments, segs;
+       unsigned int segs;
        int err, i;
 
-       err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
-                           "feature-max-indirect-segments", "%u", &indirect_segments,
-                           NULL);
-       if (err) {
-               info->max_indirect_segments = 0;
+       if (info->max_indirect_segments == 0)
                segs = BLKIF_MAX_SEGMENTS_PER_REQUEST;
-       } else {
-               info->max_indirect_segments = min(indirect_segments,
-                                                 xen_blkif_max_segments);
+       else
                segs = info->max_indirect_segments;
-       }
 
        err = fill_grant_buffer(info, (segs + INDIRECT_GREFS(segs)) * BLK_RING_SIZE(info));
        if (err)
@@ -1796,6 +1792,68 @@ out_of_memory:
        return -ENOMEM;
 }
 
+/*
+ * Gather all backend feature-*
+ */
+static int blkfront_gather_backend_features(struct blkfront_info *info)
+{
+       int err;
+       int barrier, flush, discard, persistent;
+       unsigned int indirect_segments;
+
+       info->feature_flush = 0;
+
+       err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
+                       "feature-barrier", "%d", &barrier,
+                       NULL);
+
+       /*
+        * If there's no "feature-barrier" defined, then it means
+        * we're dealing with a very old backend which writes
+        * synchronously; nothing to do.
+        *
+        * If there are barriers, then we use flush.
+        */
+       if (!err && barrier)
+               info->feature_flush = REQ_FLUSH | REQ_FUA;
+       /*
+        * And if there is "feature-flush-cache" use that above
+        * barriers.
+        */
+       err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
+                       "feature-flush-cache", "%d", &flush,
+                       NULL);
+
+       if (!err && flush)
+               info->feature_flush = REQ_FLUSH;
+
+       err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
+                       "feature-discard", "%d", &discard,
+                       NULL);
+
+       if (!err && discard)
+               blkfront_setup_discard(info);
+
+       err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
+                       "feature-persistent", "%u", &persistent,
+                       NULL);
+       if (err)
+               info->feature_persistent = 0;
+       else
+               info->feature_persistent = persistent;
+
+       err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
+                           "feature-max-indirect-segments", "%u", &indirect_segments,
+                           NULL);
+       if (err)
+               info->max_indirect_segments = 0;
+       else
+               info->max_indirect_segments = min(indirect_segments,
+                                                 xen_blkif_max_segments);
+
+       return blkfront_setup_indirect(info);
+}
+
 /*
  * Invoked when the backend is finally 'ready' (and has told produced
  * the details about the physical device - #sectors, size, etc).
@@ -1807,7 +1865,6 @@ static void blkfront_connect(struct blkfront_info *info)
        unsigned int physical_sector_size;
        unsigned int binfo;
        int err;
-       int barrier, flush, discard, persistent;
 
        switch (info->connected) {
        case BLKIF_STATE_CONNECTED:
@@ -1864,48 +1921,7 @@ static void blkfront_connect(struct blkfront_info *info)
        if (err != 1)
                physical_sector_size = sector_size;
 
-       info->feature_flush = 0;
-
-       err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
-                           "feature-barrier", "%d", &barrier,
-                           NULL);
-
-       /*
-        * If there's no "feature-barrier" defined, then it means
-        * we're dealing with a very old backend which writes
-        * synchronously; nothing to do.
-        *
-        * If there are barriers, then we use flush.
-        */
-       if (!err && barrier)
-               info->feature_flush = REQ_FLUSH | REQ_FUA;
-       /*
-        * And if there is "feature-flush-cache" use that above
-        * barriers.
-        */
-       err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
-                           "feature-flush-cache", "%d", &flush,
-                           NULL);
-
-       if (!err && flush)
-               info->feature_flush = REQ_FLUSH;
-
-       err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
-                           "feature-discard", "%d", &discard,
-                           NULL);
-
-       if (!err && discard)
-               blkfront_setup_discard(info);
-
-       err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
-                           "feature-persistent", "%u", &persistent,
-                           NULL);
-       if (err)
-               info->feature_persistent = 0;
-       else
-               info->feature_persistent = persistent;
-
-       err = blkfront_setup_indirect(info);
+       err = blkfront_gather_backend_features(info);
        if (err) {
                xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
                                 info->xbdev->otherend);