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Date: Tue, 21 Jul 2015 11:30:39 +0800
From: Bob Liu <bob.liu@...cle.com>
To: xen-devel@...ts.xenproject.org
Cc: david.vrabel@...rix.com, linux-kernel@...r.kernel.org,
roger.pau@...rix.com, konrad.wilk@...cle.com,
Bob Liu <bob.liu@...cle.com>
Subject: [PATCH 1/3] xen-blkfront: introduce blkfront_gather_backend_features()
There is a bug when migrate from !feature-persistent host to feature-persistent
host, because 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
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.liu@...cle.com>
---
drivers/block/xen-blkfront.c | 118 +++++++++++++++++++++++-------------------
1 file changed, 66 insertions(+), 52 deletions(-)
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 5b45ee5..e266d17 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 void blkfront_gather_backend_features(struct blkfront_info *info);
static int get_id_from_freelist(struct blkfront_info *info)
{
@@ -1514,6 +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;
+ blkfront_gather_backend_features(info);
rc = blkfront_setup_indirect(info);
if (rc) {
kfree(copy);
@@ -1694,20 +1696,13 @@ 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 +1766,66 @@ out_of_memory:
}
/*
+ * Gather all backend feature-*
+ */
+static void 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);
+}
+
+/*
* Invoked when the backend is finally 'ready' (and has told produced
* the details about the physical device - #sectors, size, etc).
*/
@@ -1781,7 +1836,6 @@ 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:
@@ -1838,47 +1892,7 @@ 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;
-
+ blkfront_gather_backend_features(info);
err = blkfront_setup_indirect(info);
if (err) {
xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
--
1.7.10.4
--
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