diff options
Diffstat (limited to 'hmp.c')
| -rw-r--r-- | hmp.c | 33 |
1 files changed, 31 insertions, 2 deletions
@@ -2045,13 +2045,17 @@ void hmp_qemu_io(Monitor *mon, const QDict *qdict) const char* device = qdict_get_str(qdict, "device"); const char* command = qdict_get_str(qdict, "command"); Error *err = NULL; + int ret; blk = blk_by_name(device); if (!blk) { BlockDriverState *bs = bdrv_lookup_bs(NULL, device, &err); if (bs) { - blk = local_blk = blk_new(); - blk_insert_bs(blk, bs); + blk = local_blk = blk_new(0, BLK_PERM_ALL); + ret = blk_insert_bs(blk, bs, &err); + if (ret < 0) { + goto fail; + } } else { goto fail; } @@ -2060,6 +2064,31 @@ void hmp_qemu_io(Monitor *mon, const QDict *qdict) aio_context = blk_get_aio_context(blk); aio_context_acquire(aio_context); + /* + * Notably absent: Proper permission management. This is sad, but it seems + * almost impossible to achieve without changing the semantics and thereby + * limiting the use cases of the qemu-io HMP command. + * + * In an ideal world we would unconditionally create a new BlockBackend for + * qemuio_command(), but we have commands like 'reopen' and want them to + * take effect on the exact BlockBackend whose name the user passed instead + * of just on a temporary copy of it. + * + * Another problem is that deleting the temporary BlockBackend involves + * draining all requests on it first, but some qemu-iotests cases want to + * issue multiple aio_read/write requests and expect them to complete in + * the background while the monitor has already returned. + * + * This is also what prevents us from saving the original permissions and + * restoring them later: We can't revoke permissions until all requests + * have completed, and we don't know when that is nor can we really let + * anything else run before we have revoken them to avoid race conditions. + * + * What happens now is that command() in qemu-io-cmds.c can extend the + * permissions if necessary for the qemu-io command. And they simply stay + * extended, possibly resulting in a read-only guest device keeping write + * permissions. Ugly, but it appears to be the lesser evil. + */ qemuio_command(blk, command); aio_context_release(aio_context); |