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 <h...@lst.de>
Index: qemu/block.c
===================================================================
--- qemu.orig/block.c 2011-03-08 20:11:08.188219978 +0100
+++ qemu/block.c 2011-03-08 20:12:44.971718742 +0100
@@ -439,13 +439,7 @@ static int bdrv_open_common(BlockDriverS
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;
/*
Index: qemu/block/raw-posix.c
===================================================================
--- qemu.orig/block/raw-posix.c 2011-03-08 20:11:08.200220692 +0100
+++ qemu/block/raw-posix.c 2011-03-08 20:11:22.229218596 +0100
@@ -154,7 +154,7 @@ static int raw_open_common(BlockDriverSt
* and O_DIRECT for no caching. */
if ((bdrv_flags & BDRV_O_NOCACHE))
s->open_flags |= O_DIRECT;
- else if (!(bdrv_flags & BDRV_O_CACHE_WB))
+ if (!(bdrv_flags & BDRV_O_CACHE_WB))
s->open_flags |= O_DSYNC;
s->fd = -1;
Index: qemu/block/raw-win32.c
===================================================================
--- qemu.orig/block/raw-win32.c 2011-03-08 20:11:08.212218227 +0100
+++ qemu/block/raw-win32.c 2011-03-08 20:11:22.237218180 +0100
@@ -88,9 +88,9 @@ static int raw_open(BlockDriverState *bs
}
overlapped = FILE_ATTRIBUTE_NORMAL;
- if ((flags & BDRV_O_NOCACHE))
- overlapped |= FILE_FLAG_NO_BUFFERING | FILE_FLAG_WRITE_THROUGH;
- else if (!(flags & BDRV_O_CACHE_WB))
+ if (flags & BDRV_O_NOCACHE)
+ overlapped |= FILE_FLAG_NO_BUFFERING;
+ if (!(flags & BDRV_O_CACHE_WB))
overlapped |= FILE_FLAG_WRITE_THROUGH;
s->hfile = CreateFile(filename, access_flags,
FILE_SHARE_READ, NULL,
@@ -349,9 +349,9 @@ static int hdev_open(BlockDriverState *b
create_flags = OPEN_EXISTING;
overlapped = FILE_ATTRIBUTE_NORMAL;
- if ((flags & BDRV_O_NOCACHE))
- overlapped |= FILE_FLAG_NO_BUFFERING | FILE_FLAG_WRITE_THROUGH;
- else if (!(flags & BDRV_O_CACHE_WB))
+ if (flags & BDRV_O_NOCACHE)
+ overlapped |= FILE_FLAG_NO_BUFFERING;
+ if (!(flags & BDRV_O_CACHE_WB))
overlapped |= FILE_FLAG_WRITE_THROUGH;
s->hfile = CreateFile(filename, access_flags,
FILE_SHARE_READ, NULL,
Index: qemu/blockdev.c
===================================================================
--- qemu.orig/blockdev.c 2011-03-08 20:11:08.220217606 +0100
+++ qemu/blockdev.c 2011-03-08 20:11:22.237218180 +0100
@@ -326,7 +326,7 @@ DriveInfo *drive_init(QemuOpts *opts, in
if ((buf = qemu_opt_get(opts, "cache")) != NULL) {
if (!strcmp(buf, "off") || !strcmp(buf, "none")) {
- bdrv_flags |= BDRV_O_NOCACHE;
+ bdrv_flags |= BDRV_O_NOCACHE | BDRV_O_CACHE_WB;
} else if (!strcmp(buf, "writeback")) {
bdrv_flags |= BDRV_O_CACHE_WB;
} else if (!strcmp(buf, "unsafe")) {
Index: qemu/qemu-io.c
===================================================================
--- qemu.orig/qemu-io.c 2011-03-08 20:11:08.232220650 +0100
+++ qemu/qemu-io.c 2011-03-08 20:11:22.245232398 +0100
@@ -1655,7 +1655,7 @@ open_f(int argc, char **argv)
flags |= BDRV_O_SNAPSHOT;
break;
case 'n':
- flags |= BDRV_O_NOCACHE;
+ flags |= BDRV_O_NOCACHE | BDRV_O_CACHE_WB;
break;
case 'r':
readonly = 1;
@@ -1751,7 +1751,7 @@ int main(int argc, char **argv)
flags |= BDRV_O_SNAPSHOT;
break;
case 'n':
- flags |= BDRV_O_NOCACHE;
+ flags |= BDRV_O_NOCACHE | BDRV_O_CACHE_WB;
break;
case 'c':
add_user_command(optarg);
Index: qemu/qemu-nbd.c
===================================================================
--- qemu.orig/qemu-nbd.c 2011-03-08 20:11:08.244217894 +0100
+++ qemu/qemu-nbd.c 2011-03-08 20:11:22.253267426 +0100
@@ -238,7 +238,7 @@ int main(int argc, char **argv)
flags |= BDRV_O_SNAPSHOT;
break;
case 'n':
- flags |= BDRV_O_NOCACHE;
+ flags |= BDRV_O_NOCACHE | BDRV_O_CACHE_WB;
break;
case 'b':
bindto = optarg;
