From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
To: qemu-block@nongnu.org
Cc: qemu-devel@nongnu.org, den@openvz.org, stefanha@redhat.com,
mreitz@redhat.com, kwolf@redhat.com, jsnow@redhat.com,
vsementsov@virtuozzo.com, eblake@redhat.com
Subject: [PATCH v2 2/6] parallels.txt: fix bitmap L1 table description
Date: Wed, 24 Feb 2021 13:47:03 +0300 [thread overview]
Message-ID: <20210224104707.88430-3-vsementsov@virtuozzo.com> (raw)
In-Reply-To: <20210224104707.88430-1-vsementsov@virtuozzo.com>
Actually L1 table entry offset is in 512 bytes sectors. Fix the spec.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
docs/interop/parallels.txt | 27 +++++++++++++++------------
1 file changed, 15 insertions(+), 12 deletions(-)
diff --git a/docs/interop/parallels.txt b/docs/interop/parallels.txt
index f15bf35bd1..73af9a2c4b 100644
--- a/docs/interop/parallels.txt
+++ b/docs/interop/parallels.txt
@@ -208,21 +208,24 @@ of its data area are:
28 - 31: l1_size
The number of entries in the L1 table of the bitmap.
- variable: l1_table (8 * l1_size bytes)
- L1 offset table (in bytes)
+ variable: L1 offset table (l1_table), size: 8 * l1_size bytes
-A dirty bitmap is stored using a one-level structure for the mapping to host
-clusters - an L1 table.
+Dirty bitmap is stored in the array of clusters inside Parallels Image file.
+Offsets of these clusters are saved in L1 offset table here. Each L1 table
+entry is a 64bit integer described below:
-Given an offset in bytes into the bitmap data, the offset in bytes into the
-image file can be obtained as follows:
+Given an offset in bytes into the bitmap data, corresponding L1 entry is
- offset = l1_table[offset / cluster_size] + (offset % cluster_size)
+ l1_table[offset / cluster_size]
-If an L1 table entry is 0, the corresponding cluster of the bitmap is assumed
-to be zero.
+If L1 table entry is 0, all bits in the corresponding cluster of the bitmap
+are assumed to be 0.
-If an L1 table entry is 1, the corresponding cluster of the bitmap is assumed
-to have all bits set.
+If L1 table entry is 1, all bits in the corresponding cluster of the bitmap
+are assumed to be 1.
-If an L1 table entry is not 0 or 1, it allocates a cluster from the data area.
+If an L1 table entry is not 0 or 1, it contains corresponding cluster offset
+(in 512b sectors). Given an offset in bytes into the bitmap data the offset in
+bytes into the image file can be obtained as follows:
+
+ offset = l1_table[offset / cluster_size] * 512 + (offset % cluster_size)
--
2.29.2
next prev parent reply other threads:[~2021-02-24 10:49 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-24 10:47 [PATCH v2 0/6] parallels: load bitmap extension Vladimir Sementsov-Ogievskiy
2021-02-24 10:47 ` [PATCH v2 1/6] qcow2-bitmap: make bytes_covered_by_bitmap_cluster() public Vladimir Sementsov-Ogievskiy
2021-02-24 10:47 ` Vladimir Sementsov-Ogievskiy [this message]
2021-02-24 10:50 ` [PATCH v2 2/6] parallels.txt: fix bitmap L1 table description Denis V. Lunev
2021-03-04 14:21 ` Kevin Wolf
2021-02-24 10:47 ` [PATCH v2 3/6] block/parallels: BDRVParallelsState: add cluster_size field Vladimir Sementsov-Ogievskiy
2021-02-24 10:51 ` Denis V. Lunev
2021-03-04 14:24 ` Kevin Wolf
2021-03-04 14:57 ` Denis V. Lunev
2021-03-04 15:11 ` Kevin Wolf
2021-02-24 10:47 ` [PATCH v2 4/6] parallels: support bitmap extension for read-only mode Vladimir Sementsov-Ogievskiy
2021-02-26 8:42 ` Denis V. Lunev
2021-02-24 10:47 ` [PATCH v2 5/6] iotests.py: add unarchive_sample_image() helper Vladimir Sementsov-Ogievskiy
2021-02-24 10:49 ` Denis V. Lunev
2021-02-24 10:47 ` [PATCH v2 6/6] iotests: add parallels-read-bitmap test Vladimir Sementsov-Ogievskiy
2021-02-26 8:39 ` Denis V. Lunev
2021-03-04 9:51 ` [PATCH v2 7/6] MAINTAINERS: update parallels block driver Vladimir Sementsov-Ogievskiy
2021-03-04 9:56 ` Denis V. Lunev
2021-03-04 9:58 ` Vladimir Sementsov-Ogievskiy
2021-03-04 10:20 ` Denis V. Lunev
2021-03-04 14:40 ` [PATCH v2 0/6] parallels: load bitmap extension Kevin Wolf
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