From d50babbe300eedf33ea5b00a12c5df3a05bd96c7 Mon Sep 17 00:00:00 2001 From: Bob Liu Date: Wed, 22 Jul 2015 14:40:08 +0800 Subject: [PATCH 1/3] xen-blkfront: introduce blkfront_gather_backend_features() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Acked-by: Roger Pau Monné Signed-off-by: Bob Liu Signed-off-by: Konrad Rzeszutek Wilk --- 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 fc770b7d3beb..f45f4e67c5d4 100644 --- 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) { @@ -1525,7 +1526,7 @@ 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; @@ -1726,20 +1727,13 @@ 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) @@ -1802,6 +1796,68 @@ static int blkfront_setup_indirect(struct blkfront_info *info) 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). @@ -1813,7 +1869,6 @@ 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: @@ -1870,48 +1925,7 @@ 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); From 7b0767502b5db11cb1f0daef2d01f6d71b1192dc Mon Sep 17 00:00:00 2001 From: Bob Liu Date: Wed, 22 Jul 2015 14:40:09 +0800 Subject: [PATCH 2/3] xen-blkfront: don't add indirect pages to list when !feature_persistent MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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. CC: stable@vger.kernel.org Acked-by: Roger Pau Monné Signed-off-by: Bob Liu Signed-off-by: Konrad Rzeszutek Wilk --- 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 f45f4e67c5d4..44b33d39441b 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -1135,8 +1135,10 @@ 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); } From 53bc7dc004fecf39e0ba70f2f8d120a1444315d3 Mon Sep 17 00:00:00 2001 From: Bob Liu Date: Wed, 22 Jul 2015 14:40:10 +0800 Subject: [PATCH 3/3] xen-blkback: replace work_pending with work_busy in purge_persistent_gnt() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The BUG_ON() in purge_persistent_gnt() will be triggered when previous purge work haven't finished. There is a work_pending() before this BUG_ON, but it doesn't account if the work is still currently running. CC: stable@vger.kernel.org Acked-by: Roger Pau Monné Signed-off-by: Bob Liu Signed-off-by: Konrad Rzeszutek Wilk --- drivers/block/xen-blkback/blkback.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c index 9121a2c3e26f..73c04040c8c8 100644 --- a/drivers/block/xen-blkback/blkback.c +++ b/drivers/block/xen-blkback/blkback.c @@ -382,8 +382,8 @@ 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; }