return 0;
}
+/**
+ * The copy-on-read flag is actually a reference count so multiple users may
+ * use the feature without worrying about clobbering its previous state.
+ * Copy-on-read stays enabled until all users have called to disable it.
+ */
+void bdrv_enable_copy_on_read(BlockDriverState *bs)
+{
+ bs->copy_on_read++;
+}
+
+void bdrv_disable_copy_on_read(BlockDriverState *bs)
+{
+ assert(bs->copy_on_read > 0);
+ bs->copy_on_read--;
+}
+
/*
* Common part for opening disk images and files
*/
bs->growable = 0;
bs->buffer_alignment = 512;
+ assert(bs->copy_on_read == 0); /* bdrv_new() and bdrv_close() make it so */
+ if ((flags & BDRV_O_RDWR) && (flags & BDRV_O_COPY_ON_READ)) {
+ bdrv_enable_copy_on_read(bs);
+ }
+
pstrcpy(bs->filename, sizeof(bs->filename), filename);
bs->backing_file[0] = '\0';
#endif
bs->opaque = NULL;
bs->drv = NULL;
+ bs->copy_on_read = 0;
if (bs->file != NULL) {
bdrv_close(bs->file);
#define BDRV_O_NATIVE_AIO 0x0080 /* use native AIO instead of the thread pool */
#define BDRV_O_NO_BACKING 0x0100 /* don't open the backing file */
#define BDRV_O_NO_FLUSH 0x0200 /* disable flushing on this disk */
+#define BDRV_O_COPY_ON_READ 0x0400 /* copy read backing sectors into image */
#define BDRV_O_CACHE_MASK (BDRV_O_NOCACHE | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH)
int nr_sectors);
int64_t bdrv_get_dirty_count(BlockDriverState *bs);
+void bdrv_enable_copy_on_read(BlockDriverState *bs);
+void bdrv_disable_copy_on_read(BlockDriverState *bs);
+
void bdrv_set_in_use(BlockDriverState *bs, int in_use);
int bdrv_in_use(BlockDriverState *bs);
int encrypted; /* if true, the media is encrypted */
int valid_key; /* if true, a valid encryption key has been set */
int sg; /* if true, the device is a /dev/sg* */
+ int copy_on_read; /* if true, copy read backing sectors into image
+ note this is a reference count */
BlockDriver *drv; /* NULL means no media */
void *opaque;