diff options
authorChristoph Hellwig <>2009-09-04 19:01:15 +0200
committerAnthony Liguori <>2009-09-11 10:19:46 -0500
commite900a7b748316b5b5a98e41dde36a0cb8e15be5f (patch)
treef41d52f388664258f5caa4a03645cb4409676065 /block_int.h
parentqemu: init all queues to NO_VECTOR value (diff)
block: add enable_write_cache flag
Add a enable_write_cache flag in the block driver state, and use it to decide if we claim to have a volatile write cache that needs controlled flushing from the guest. The flag is off if cache=writethrough is defined because O_DSYNC guarantees that every write goes to stable storage, and it is on for cache=none and cache=writeback. Both scsi-disk and ide now use the new flage, changing from their defaults of always off (ide) or always on (scsi-disk). Signed-off-by: Christoph Hellwig <> Signed-off-by: Anthony Liguori <>
Diffstat (limited to 'block_int.h')
1 files changed, 3 insertions, 0 deletions
diff --git a/block_int.h b/block_int.h
index 3e4b4a387..f95c80b90 100644
--- a/block_int.h
+++ b/block_int.h
@@ -158,6 +158,9 @@ struct BlockDriverState {
/* the memory alignment required for the buffers handled by this driver */
int buffer_alignment;
+ /* do we need to tell the quest if we have a volatile write cache? */
+ int enable_write_cache;
/* NOTE: the following infos are only hints for real hardware
drivers. They are not used by the block driver */
int cyls, heads, secs, translation;