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[Qemu-block] [PULL 06/17] qcow2: Respect new_block in alloc_refcount_blo
From: |
Kevin Wolf |
Subject: |
[Qemu-block] [PULL 06/17] qcow2: Respect new_block in alloc_refcount_block() |
Date: |
Mon, 16 Mar 2015 17:57:10 +0100 |
From: Max Reitz <address@hidden>
When choosing a new place for the refcount table, alloc_refcount_block()
tries to infer the number of clusters used so far from its argument
cluster_index (which comes from the idea that if any cluster with an
index greater than cluster_index was in use, the refcount table would
have to be big enough already to describe cluster_index).
However, there is a cluster that may be at or after cluster_index, and
which is not covered by the refcount structures, and that is the new
refcount block new_block. Therefore, it should be taken into account for
the blocks_used calculation.
Also, because new_block already describes (or is intended to describe)
cluster_index, we may not put the new refcount structures there.
Signed-off-by: Max Reitz <address@hidden>
Message-id: address@hidden
Reviewed-by: Eric Blake <address@hidden>
Reviewed-by: Kevin Wolf <address@hidden>
Signed-off-by: Max Reitz <address@hidden>
---
block/qcow2-refcount.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index dc8d186..6cbae1d 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -466,8 +466,20 @@ static int alloc_refcount_block(BlockDriverState *bs,
*/
BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_GROW);
- /* Calculate the number of refcount blocks needed so far */
- uint64_t blocks_used = DIV_ROUND_UP(cluster_index, s->refcount_block_size);
+ /* Calculate the number of refcount blocks needed so far; this will be the
+ * basis for calculating the index of the first cluster used for the
+ * self-describing refcount structures which we are about to create.
+ *
+ * Because we reached this point, there cannot be any refcount entries for
+ * cluster_index or higher indices yet. However, because new_block has been
+ * allocated to describe that cluster (and it will assume this role later
+ * on), we cannot use that index; also, new_block may actually have a
higher
+ * cluster index than cluster_index, so it needs to be taken into account
+ * here (and 1 needs to be added to its value because that cluster is
used).
+ */
+ uint64_t blocks_used = DIV_ROUND_UP(MAX(cluster_index + 1,
+ (new_block >> s->cluster_bits) +
1),
+ s->refcount_block_size);
if (blocks_used > QCOW_MAX_REFTABLE_SIZE / sizeof(uint64_t)) {
return -EFBIG;
--
1.8.3.1
- [Qemu-block] [PULL 00/17] Block patches for 2.3.0-rc0, Kevin Wolf, 2015/03/16
- [Qemu-block] [PULL 02/17] qemu-img: Fix convert, amend error messages for unknown options, Kevin Wolf, 2015/03/16
- [Qemu-block] [PULL 03/17] block: Deprecate QCOW/QCOW2 encryption, Kevin Wolf, 2015/03/16
- [Qemu-block] [PULL 01/17] iotests: Update 051's reference output, Kevin Wolf, 2015/03/16
- [Qemu-block] [PULL 04/17] block: Fix block-set-write-threshold not to use funky error class, Kevin Wolf, 2015/03/16
- [Qemu-block] [PULL 06/17] qcow2: Respect new_block in alloc_refcount_block(),
Kevin Wolf <=
- [Qemu-block] [PULL 05/17] qemu-img: Avoid qerror_report_err() outside QMP handlers, again, Kevin Wolf, 2015/03/16
- [Qemu-block] [PULL 09/17] monitor: Convert bdrv_find to blk_by_name, Kevin Wolf, 2015/03/16
- [Qemu-block] [PULL 10/17] migration: Convert bdrv_find to blk_by_name, Kevin Wolf, 2015/03/16
- [Qemu-block] [PULL 07/17] iotests: Add tests for refcount table growth, Kevin Wolf, 2015/03/16
- [Qemu-block] [PULL 08/17] iotests: Test non-self-referential qcow2 refblocks, Kevin Wolf, 2015/03/16
- [Qemu-block] [PULL 11/17] blockdev: Convert bdrv_find to blk_by_name, Kevin Wolf, 2015/03/16
- [Qemu-block] [PULL 13/17] block/vpc: optimize vpc_co_get_block_status, Kevin Wolf, 2015/03/16
- [Qemu-block] [PULL 16/17] block/vpc: rename footer->size -> footer->current_size, Kevin Wolf, 2015/03/16
- [Qemu-block] [PULL 12/17] block: Drop bdrv_find, Kevin Wolf, 2015/03/16
- [Qemu-block] [PULL 14/17] vpc: Ignore geometry for large images, Kevin Wolf, 2015/03/16