The QED_CF_STREAM flag can be set to automatically stream from the
backing file.
Signed-off-by: Stefan Hajnoczi <stefa...@linux.vnet.ibm.com>
---
block/qed.c | 5 +++++
block/qed.h | 6 +++++-
2 files changed, 10 insertions(+), 1 deletions(-)
diff --git a/block/qed.c b/block/qed.c
index 2c155d9..a61cee9 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -373,6 +373,11 @@ static int bdrv_qed_open(BlockDriverState *bs, int flags)
if (s->header.features & QED_F_BACKING_FORMAT_NO_PROBE) {
pstrcpy(bs->backing_format, sizeof(bs->backing_format), "raw");
}
+
+ if ((s->header.compat_features & QED_CF_STREAM) &&
+ !bdrv_is_read_only(bs->file)) {
+ bs->stream = 1;
+ }
}
/* Reset unknown autoclear feature bits. This is a backwards
diff --git a/block/qed.h b/block/qed.h
index 8e9e415..23a9bde 100644
--- a/block/qed.h
+++ b/block/qed.h
@@ -59,13 +59,17 @@ enum {
/* Reads to the backing file should populate the image file */
QED_CF_COPY_ON_READ = 0x01,
+ /* Stream until the backing image is no longer needed */
+ QED_CF_STREAM = 0x02,
+
/* Supported feature bits */
QED_FEATURE_MASK = QED_F_BACKING_FILE |
QED_F_NEED_CHECK |
QED_F_BACKING_FORMAT_NO_PROBE,
/* Supported compat feature bits */
- QED_COMPAT_FEATURE_MASK = QED_CF_COPY_ON_READ,
+ QED_COMPAT_FEATURE_MASK = QED_CF_COPY_ON_READ |
+ QED_CF_STREAM,
/* Supported autoclear feature bits */
QED_AUTOCLEAR_FEATURE_MASK = 0,
--
1.7.4.4
