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authorChristoph Hellwig <hch@lst.de>2011-05-17 18:04:06 +0200
committerKevin Wolf <kwolf@redhat.com>2011-06-08 10:39:32 +0200
commita659979328fb6d4d6100d398f5bd9a2310c3e169 (patch)
tree8d465d20ea1efc82134941d9a589c4b224ce4b3b /block.c
parent69c38b8fcec823da05f98f6ea98ec2b0013d64e2 (diff)
downloadfocaccia-qemu-a659979328fb6d4d6100d398f5bd9a2310c3e169.tar.gz
focaccia-qemu-a659979328fb6d4d6100d398f5bd9a2310c3e169.zip
block: clarify the meaning of BDRV_O_NOCACHE
Change BDRV_O_NOCACHE to only imply bypassing the host OS file cache,
but no writeback semantics.  All existing callers are changed to also
specify BDRV_O_CACHE_WB to give them writeback semantics.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'block.c')
-rw-r--r--block.c8
1 files changed, 1 insertions, 7 deletions
diff --git a/block.c b/block.c
index effa86fd53..3036a2deed 100644
--- a/block.c
+++ b/block.c
@@ -439,13 +439,7 @@ static int bdrv_open_common(BlockDriverState *bs, const char *filename,
     bs->drv = drv;
     bs->opaque = qemu_mallocz(drv->instance_size);
 
-    /*
-     * Yes, BDRV_O_NOCACHE aka O_DIRECT means we have to present a
-     * write cache to the guest.  We do need the fdatasync to flush
-     * out transactions for block allocations, and we maybe have a
-     * volatile write cache in our backing device to deal with.
-     */
-    if (flags & (BDRV_O_CACHE_WB|BDRV_O_NOCACHE))
+    if (flags & BDRV_O_CACHE_WB)
         bs->enable_write_cache = 1;
 
     /*