diff mbox series

[v4,12/30] qcow2: Update get/set_l2_entry() and add get/set_l2_bitmap()

Message ID c3d6c8e03c353a694b6415d9f6ae253f22a620ea.1584468723.git.berto@igalia.com (mailing list archive)
State New, archived
Headers show
Series Add subcluster allocation to qcow2 | expand

Commit Message

Alberto Garcia March 17, 2020, 6:16 p.m. UTC 
Extended L2 entries are 128-bit wide: 64 bits for the entry itself and
64 bits for the subcluster allocation bitmap.

In order to support them correctly get/set_l2_entry() need to be
updated so they take the entry width into account in order to
calculate the correct offset.

This patch also adds the get/set_l2_bitmap() functions that are
used to access the bitmaps. For convenience we allow calling
get_l2_bitmap() on images without subclusters, although the caller
does not need and should ignore the returned value.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
---
 block/qcow2.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

Comments

Vladimir Sementsov-Ogievskiy April 14, 2020, 9:49 a.m. UTC | #1 
17.03.2020 21:16, Alberto Garcia wrote:
> Extended L2 entries are 128-bit wide: 64 bits for the entry itself and
> 64 bits for the subcluster allocation bitmap.
> 
> In order to support them correctly get/set_l2_entry() need to be
> updated so they take the entry width into account in order to
> calculate the correct offset.
> 
> This patch also adds the get/set_l2_bitmap() functions that are
> used to access the bitmaps. For convenience we allow calling
> get_l2_bitmap() on images without subclusters, although the caller
> does not need and should ignore the returned value.
> 
> Signed-off-by: Alberto Garcia <berto@igalia.com>
> Reviewed-by: Max Reitz <mreitz@redhat.com>

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
diff mbox series

Patch

diff --git a/block/qcow2.h b/block/qcow2.h
index 1eb4b46807..9611efbc52 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -518,15 +518,37 @@  static inline size_t l2_entry_size(BDRVQcow2State *s)
 static inline uint64_t get_l2_entry(BDRVQcow2State *s, uint64_t *l2_slice,
                                     int idx)
 {
+    idx *= l2_entry_size(s) / sizeof(uint64_t);
     return be64_to_cpu(l2_slice[idx]);
 }
 
+static inline uint64_t get_l2_bitmap(BDRVQcow2State *s, uint64_t *l2_slice,
+                                     int idx)
+{
+    if (has_subclusters(s)) {
+        idx *= l2_entry_size(s) / sizeof(uint64_t);
+        return be64_to_cpu(l2_slice[idx + 1]);
+    } else {
+        /* For convenience only; the caller should ignore this value. */
+        return 0;
+    }
+}
+
 static inline void set_l2_entry(BDRVQcow2State *s, uint64_t *l2_slice,
                                 int idx, uint64_t entry)
 {
+    idx *= l2_entry_size(s) / sizeof(uint64_t);
     l2_slice[idx] = cpu_to_be64(entry);
 }
 
+static inline void set_l2_bitmap(BDRVQcow2State *s, uint64_t *l2_slice,
+                                 int idx, uint64_t bitmap)
+{
+    assert(has_subclusters(s));
+    idx *= l2_entry_size(s) / sizeof(uint64_t);
+    l2_slice[idx + 1] = cpu_to_be64(bitmap);
+}
+
 static inline bool has_data_file(BlockDriverState *bs)
 {
     BDRVQcow2State *s = bs->opaque;