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Re: [Qemu-block] [PATCH v4 2/3] qcow2: handle reopening bitmaps on bdrv_


From: Vladimir Sementsov-Ogievskiy
Subject: Re: [Qemu-block] [PATCH v4 2/3] qcow2: handle reopening bitmaps on bdrv_invalidate_cache DROP IT
Date: Tue, 20 Mar 2018 20:07:56 +0300
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0

Oh, sorry, just drop it.
(the only difference is commit message subject)

20.03.2018 20:05, Vladimir Sementsov-Ogievskiy wrote:
On reopen with existing bitmaps, instead of loading bitmaps, lets
reopen them if needed. This also fixes bitmaps migration through
shared storage.
Consider the case. Persistent bitmaps are stored on bdrv_inactivate.
Then, on destination process_incoming_migration_bh() calls
bdrv_invalidate_cache_all() which leads to
qcow2_load_autoloading_dirty_bitmaps() which fails if bitmaps are
already loaded on destination start.

Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
  block/qcow2.c | 17 ++++++++++++++++-
  1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/block/qcow2.c b/block/qcow2.c
index 7472af6931..d2d129a2e6 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1480,7 +1480,22 @@ static int coroutine_fn qcow2_do_open(BlockDriverState 
*bs, QDict *options,
          s->autoclear_features &= QCOW2_AUTOCLEAR_MASK;
      }
- if (qcow2_load_dirty_bitmaps(bs, &local_err)) {
+    if (bdrv_dirty_bitmap_next(bs, NULL)) {
+        /* It's some kind of reopen with already existing dirty bitmaps. There
+         * are no known cases where we need loading bitmaps in such situation,
+         * so it's safer don't load them.
+         *
+         * Moreover, if we have some readonly bitmaps and we are reopening for
+         * rw we should reopen bitmaps correspondingly.
+         */
+        if (bdrv_has_readonly_bitmaps(bs) &&
+            !bdrv_is_read_only(bs) && !(bdrv_get_flags(bs) & BDRV_O_INACTIVE))
+        {
+            bool header_updated = false;
+            qcow2_reopen_bitmaps_rw_hint(bs, &header_updated, &local_err);
+            update_header = update_header && !header_updated;
+        }
+    } else if (qcow2_load_dirty_bitmaps(bs, &local_err)) {
          update_header = false;
      }
      if (local_err != NULL) {


--
Best regards,
Vladimir




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