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authorPeter Xu <peterx@redhat.com>2018-07-10 17:18:55 +0800
committerDr. David Alan Gilbert <dgilbert@redhat.com>2018-07-10 12:56:18 +0100
commita725ef9fe36424351faf51696c3fc441ded13f35 (patch)
tree22cdbe7f27ad4377cfa3f646bda6c594cd922b1f
parentfd037a656aca23dc3c47aa8c9de261bec6b8aad0 (diff)
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migration: fix incorrect bitmap size calculation
The calculation on size of received bitmap is incorrect for postcopy recovery. Here we wanted to let the size to cover all the valid bits in the bitmap, we should use DIV_ROUND_UP() instead of a division. For example, a RAMBlock with size=4K (which contains only one single 4K page) will have nbits=1, then nbits/8=0, then the real bitmap won't be sent to source at all. Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20180710091902.28780-4-peterx@redhat.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
-rw-r--r--migration/ram.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/migration/ram.c b/migration/ram.c
index 49068e8..52dd678 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -235,7 +235,7 @@ int64_t ramblock_recv_bitmap_send(QEMUFile *file,
bitmap_to_le(le_bitmap, block->receivedmap, nbits);
/* Size of the bitmap, in bytes */
- size = nbits / 8;
+ size = DIV_ROUND_UP(nbits, 8);
/*
* size is always aligned to 8 bytes for 64bit machines, but it
@@ -3944,7 +3944,7 @@ int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *block)
int ret = -EINVAL;
QEMUFile *file = s->rp_state.from_dst_file;
unsigned long *le_bitmap, nbits = block->used_length >> TARGET_PAGE_BITS;
- uint64_t local_size = nbits / 8;
+ uint64_t local_size = DIV_ROUND_UP(nbits, 8);
uint64_t size, end_mark;
trace_ram_dirty_bitmap_reload_begin(block->idstr);