diff options
Diffstat (limited to 'blockdev.c')
| -rw-r--r-- | blockdev.c | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/blockdev.c b/blockdev.c index 91a21eb0b8..d8e3e31975 100644 --- a/blockdev.c +++ b/blockdev.c @@ -1773,6 +1773,12 @@ static void external_snapshot_prepare(BlkActionState *common, flags |= BDRV_O_NO_BACKING; } + /* There is no BB attached during bdrv_open(), so we can't set a + * writethrough mode. bdrv_append() will swap the WCE setting so that the + * backing file becomes unconditionally writeback (which is what backing + * files should always be) and the new overlay gets the original setting. */ + flags |= BDRV_O_CACHE_WB; + assert(state->new_bs == NULL); ret = bdrv_open(&state->new_bs, new_image_file, snapshot_ref, options, flags, errp); @@ -2517,6 +2523,7 @@ void qmp_blockdev_change_medium(const char *device, const char *filename, BlockBackend *blk; BlockDriverState *medium_bs = NULL; int bdrv_flags, ret; + bool writethrough; QDict *options = NULL; Error *err = NULL; @@ -2535,6 +2542,12 @@ void qmp_blockdev_change_medium(const char *device, const char *filename, bdrv_flags &= ~(BDRV_O_TEMPORARY | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_PROTOCOL); + /* Must open the image in writeback mode as long as no BlockBackend is + * attached. The right mode can be set as the final step after changing the + * medium. */ + writethrough = !(bdrv_flags & BDRV_O_CACHE_WB); + bdrv_flags |= BDRV_O_CACHE_WB; + if (!has_read_only) { read_only = BLOCKDEV_CHANGE_READ_ONLY_MODE_RETAIN; } @@ -2592,6 +2605,8 @@ void qmp_blockdev_change_medium(const char *device, const char *filename, goto fail; } + bdrv_set_enable_write_cache(medium_bs, !writethrough); + qmp_blockdev_close_tray(device, errp); fail: @@ -3217,7 +3232,7 @@ static void do_drive_backup(const char *device, const char *target, goto out; } - flags = bs->open_flags | BDRV_O_RDWR; + flags = bs->open_flags | BDRV_O_CACHE_WB | BDRV_O_RDWR; /* See if we have a backing HD we can use to create our new image * on top of. */ @@ -3512,7 +3527,7 @@ void qmp_drive_mirror(const char *device, const char *target, format = mode == NEW_IMAGE_MODE_EXISTING ? NULL : bs->drv->format_name; } - flags = bs->open_flags | BDRV_O_RDWR; + flags = bs->open_flags | BDRV_O_CACHE_WB | BDRV_O_RDWR; source = backing_bs(bs); if (!source && sync == MIRROR_SYNC_MODE_TOP) { sync = MIRROR_SYNC_MODE_FULL; |