diff options
Diffstat (limited to 'blockdev.c')
-rw-r--r-- | blockdev.c | 79 |
1 files changed, 79 insertions, 0 deletions
@@ -2367,6 +2367,85 @@ void qmp_block_job_complete(const char *device, Error **errp) block_job_complete(job, errp); } +void qmp_change_backing_file(const char *device, + const char *image_node_name, + const char *backing_file, + Error **errp) +{ + BlockDriverState *bs = NULL; + BlockDriverState *image_bs = NULL; + Error *local_err = NULL; + bool ro; + int open_flags; + int ret; + + /* find the top layer BDS of the chain */ + bs = bdrv_find(device); + if (!bs) { + error_set(errp, QERR_DEVICE_NOT_FOUND, device); + return; + } + + image_bs = bdrv_lookup_bs(NULL, image_node_name, &local_err); + if (local_err) { + error_propagate(errp, local_err); + return; + } + + if (!image_bs) { + error_setg(errp, "image file not found"); + return; + } + + if (bdrv_find_base(image_bs) == image_bs) { + error_setg(errp, "not allowing backing file change on an image " + "without a backing file"); + return; + } + + /* even though we are not necessarily operating on bs, we need it to + * determine if block ops are currently prohibited on the chain */ + if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_CHANGE, errp)) { + return; + } + + /* final sanity check */ + if (!bdrv_chain_contains(bs, image_bs)) { + error_setg(errp, "'%s' and image file are not in the same chain", + device); + return; + } + + /* if not r/w, reopen to make r/w */ + open_flags = image_bs->open_flags; + ro = bdrv_is_read_only(image_bs); + + if (ro) { + bdrv_reopen(image_bs, open_flags | BDRV_O_RDWR, &local_err); + if (local_err) { + error_propagate(errp, local_err); + return; + } + } + + ret = bdrv_change_backing_file(image_bs, backing_file, + image_bs->drv ? image_bs->drv->format_name : ""); + + if (ret < 0) { + error_setg_errno(errp, -ret, "Could not change backing file to '%s'", + backing_file); + /* don't exit here, so we can try to restore open flags if + * appropriate */ + } + + if (ro) { + bdrv_reopen(image_bs, open_flags, &local_err); + if (local_err) { + error_propagate(errp, local_err); /* will preserve prior errp */ + } + } +} + void qmp_blockdev_add(BlockdevOptions *options, Error **errp) { QmpOutputVisitor *ov = qmp_output_visitor_new(); |