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qcow2: Define and use QCOW2_COMPRESSED_SECTOR_SIZE

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When an L2 table entry points to a compressed cluster the space used
by the data is specified in 512-byte sectors. This size is independent
from BDRV_SECTOR_SIZE and is specific to the qcow2 file format.

The QCOW2_COMPRESSED_SECTOR_SIZE constant defined in this patch makes
this explicit.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Alberto Garcia 2019-05-10 19:22:54 +03:00 • committed by Kevin Wolf
parent 50ba5b2d99
commit b6c246942b
4 changed files with 23 additions and 14 deletions
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4
block/qcow2.h
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@ -74,6 +74,10 @@
#define MIN_CLUSTER_BITS 9
#define MAX_CLUSTER_BITS 21
/* Defined in the qcow2 spec (compressed cluster descriptor) */
#define QCOW2_COMPRESSED_SECTOR_SIZE 512U
#define QCOW2_COMPRESSED_SECTOR_MASK (~(QCOW2_COMPRESSED_SECTOR_SIZE - 1))
/* Must be at least 2 to cover COW */
#define MIN_L2_CACHE_SIZE 2 /* cache entries */