diff options
Diffstat (limited to 'block.c')
| -rw-r--r-- | block.c | 148 |
1 files changed, 78 insertions, 70 deletions
@@ -767,6 +767,11 @@ static int bdrv_open_flags(BlockDriverState *bs, int flags) { int open_flags = flags | BDRV_O_CACHE_WB; + /* The backing file of a temporary snapshot is read-only */ + if (flags & BDRV_O_SNAPSHOT) { + open_flags &= ~BDRV_O_RDWR; + } + /* * Clear flags that are internal to the block layer before opening the * image. @@ -1162,6 +1167,68 @@ done: return ret; } +void bdrv_append_temp_snapshot(BlockDriverState *bs, Error **errp) +{ + /* TODO: extra byte is a hack to ensure MAX_PATH space on Windows. */ + char tmp_filename[PATH_MAX + 1]; + + int64_t total_size; + BlockDriver *bdrv_qcow2; + QEMUOptionParameter *create_options; + QDict *snapshot_options; + BlockDriverState *bs_snapshot; + Error *local_err; + int ret; + + /* if snapshot, we create a temporary backing file and open it + instead of opening 'filename' directly */ + + /* Get the required size from the image */ + total_size = bdrv_getlength(bs) & BDRV_SECTOR_MASK; + + /* Create the temporary image */ + ret = get_tmp_filename(tmp_filename, sizeof(tmp_filename)); + if (ret < 0) { + error_setg_errno(errp, -ret, "Could not get temporary filename"); + return; + } + + bdrv_qcow2 = bdrv_find_format("qcow2"); + create_options = parse_option_parameters("", bdrv_qcow2->create_options, + NULL); + + set_option_parameter_int(create_options, BLOCK_OPT_SIZE, total_size); + + ret = bdrv_create(bdrv_qcow2, tmp_filename, create_options, &local_err); + free_option_parameters(create_options); + if (ret < 0) { + error_setg_errno(errp, -ret, "Could not create temporary overlay " + "'%s': %s", tmp_filename, + error_get_pretty(local_err)); + error_free(local_err); + return; + } + + /* Prepare a new options QDict for the temporary file */ + snapshot_options = qdict_new(); + qdict_put(snapshot_options, "file.driver", + qstring_from_str("file")); + qdict_put(snapshot_options, "file.filename", + qstring_from_str(tmp_filename)); + + bs_snapshot = bdrv_new(""); + bs_snapshot->is_temporary = 1; + + ret = bdrv_open(&bs_snapshot, NULL, NULL, snapshot_options, + bs->open_flags & ~BDRV_O_SNAPSHOT, bdrv_qcow2, &local_err); + if (ret < 0) { + error_propagate(errp, local_err); + return; + } + + bdrv_append(bs_snapshot, bs); +} + /* * Opens a disk image (raw, qcow2, vmdk, ...) * @@ -1182,8 +1249,6 @@ int bdrv_open(BlockDriverState **pbs, const char *filename, BlockDriver *drv, Error **errp) { int ret; - /* TODO: extra byte is a hack to ensure MAX_PATH space on Windows. */ - char tmp_filename[PATH_MAX + 1]; BlockDriverState *file = NULL, *bs; const char *drvname; Error *local_err = NULL; @@ -1243,74 +1308,6 @@ int bdrv_open(BlockDriverState **pbs, const char *filename, } } - /* For snapshot=on, create a temporary qcow2 overlay */ - if (flags & BDRV_O_SNAPSHOT) { - BlockDriverState *bs1; - int64_t total_size; - BlockDriver *bdrv_qcow2; - QEMUOptionParameter *create_options; - QDict *snapshot_options; - - /* if snapshot, we create a temporary backing file and open it - instead of opening 'filename' directly */ - - /* Get the required size from the image */ - QINCREF(options); - bs1 = NULL; - ret = bdrv_open(&bs1, filename, NULL, options, BDRV_O_NO_BACKING, - drv, &local_err); - if (ret < 0) { - goto fail; - } - total_size = bdrv_getlength(bs1) & BDRV_SECTOR_MASK; - - bdrv_unref(bs1); - - /* Create the temporary image */ - ret = get_tmp_filename(tmp_filename, sizeof(tmp_filename)); - if (ret < 0) { - error_setg_errno(errp, -ret, "Could not get temporary filename"); - goto fail; - } - - bdrv_qcow2 = bdrv_find_format("qcow2"); - create_options = parse_option_parameters("", bdrv_qcow2->create_options, - NULL); - - set_option_parameter_int(create_options, BLOCK_OPT_SIZE, total_size); - - ret = bdrv_create(bdrv_qcow2, tmp_filename, create_options, &local_err); - free_option_parameters(create_options); - if (ret < 0) { - error_setg_errno(errp, -ret, "Could not create temporary overlay " - "'%s': %s", tmp_filename, - error_get_pretty(local_err)); - error_free(local_err); - local_err = NULL; - goto fail; - } - - /* Prepare a new options QDict for the temporary file, where user - * options refer to the backing file */ - if (filename) { - qdict_put(options, "file.filename", qstring_from_str(filename)); - } - if (drv) { - qdict_put(options, "driver", qstring_from_str(drv->format_name)); - } - - snapshot_options = qdict_new(); - qdict_put(snapshot_options, "backing", options); - qdict_flatten(snapshot_options); - - bs->options = snapshot_options; - options = qdict_clone_shallow(bs->options); - - filename = tmp_filename; - drv = bdrv_qcow2; - bs->is_temporary = 1; - } - /* Open image file without format layer */ if (flags & BDRV_O_RDWR) { flags |= BDRV_O_ALLOW_RDWR; @@ -1372,6 +1369,17 @@ int bdrv_open(BlockDriverState **pbs, const char *filename, } } + /* For snapshot=on, create a temporary qcow2 overlay. bs points to the + * temporary snapshot afterwards. */ + if (flags & BDRV_O_SNAPSHOT) { + bdrv_append_temp_snapshot(bs, &local_err); + if (local_err) { + error_propagate(errp, local_err); + goto close_and_fail; + } + } + + done: /* Check if any unknown options were used */ if (options && (qdict_size(options) != 0)) { |