There is a bug when migrate from !feature-persistent host to feature-persistent host, because domU still thinks new host/backend doesn'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
The fix is to recheck feature-persistent of new backend in blkif_recover(). See: https://lkml.org/lkml/2015/5/25/469 As Roger suggested, we can split the part of blkfront_connect that checks for optional features, like persistent grants, indirect descriptors and flush/barrier features to a separate function and call it from both blkfront_connect and blkif_recover Signed-off-by: Bob Liu <bob....@oracle.com> --- Changes in v2: * Also put blkfront_setup_indirect() inside --- drivers/block/xen-blkfront.c | 122 +++++++++++++++++++++++------------------- 1 file changed, 68 insertions(+), 54 deletions(-) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 5b45ee5..3b193cf 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -181,6 +181,7 @@ 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) { @@ -1514,7 +1515,7 @@ 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; @@ -1694,20 +1695,13 @@ 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) @@ -1771,6 +1765,68 @@ out_of_memory: } /* + * 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). */ @@ -1781,7 +1837,6 @@ 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: @@ -1838,48 +1893,7 @@ 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); -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
