[qemu.git] / block / snapshot.c

/*
 * Block layer snapshot related functions
 *
 * Copyright (c) 2003-2008 Fabrice Bellard
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "block/snapshot.h"
#include "block/block_int.h"

QemuOptsList internal_snapshot_opts = {
    .name = "snapshot",
    .head = QTAILQ_HEAD_INITIALIZER(internal_snapshot_opts.head),
    .desc = {
        {
            .name = SNAPSHOT_OPT_ID,
            .type = QEMU_OPT_STRING,
            .help = "snapshot id"
        },{
            .name = SNAPSHOT_OPT_NAME,
            .type = QEMU_OPT_STRING,
            .help = "snapshot name"
        },{
            /* end of list */
        }
    },
};

int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info,
                       const char *name)
{
    QEMUSnapshotInfo *sn_tab, *sn;
    int nb_sns, i, ret;

    ret = -ENOENT;
    nb_sns = bdrv_snapshot_list(bs, &sn_tab);
    if (nb_sns < 0) {
        return ret;
    }
    for (i = 0; i < nb_sns; i++) {
        sn = &sn_tab[i];
        if (!strcmp(sn->id_str, name) || !strcmp(sn->name, name)) {
            *sn_info = *sn;
            ret = 0;
            break;
        }
    }
    g_free(sn_tab);
    return ret;
}

/**
 * Look up an internal snapshot by @id and @name.
 * @bs: block device to search
 * @id: unique snapshot ID, or NULL
 * @name: snapshot name, or NULL
 * @sn_info: location to store information on the snapshot found
 * @errp: location to store error, will be set only for exception
 *
 * This function will traverse snapshot list in @bs to search the matching
 * one, @id and @name are the matching condition:
 * If both @id and @name are specified, find the first one with id @id and
 * name @name.
 * If only @id is specified, find the first one with id @id.
 * If only @name is specified, find the first one with name @name.
 * if none is specified, abort().
 *
 * Returns: true when a snapshot is found and @sn_info will be filled, false
 * when error or not found. If all operation succeed but no matching one is
 * found, @errp will NOT be set.
 */
bool bdrv_snapshot_find_by_id_and_name(BlockDriverState *bs,
                                       const char *id,
                                       const char *name,
                                       QEMUSnapshotInfo *sn_info,
                                       Error **errp)
{
    QEMUSnapshotInfo *sn_tab, *sn;
    int nb_sns, i;
    bool ret = false;

    assert(id || name);

    nb_sns = bdrv_snapshot_list(bs, &sn_tab);
    if (nb_sns < 0) {
        error_setg_errno(errp, -nb_sns, "Failed to get a snapshot list");
        return false;
    } else if (nb_sns == 0) {
        return false;
    }

    if (id && name) {
        for (i = 0; i < nb_sns; i++) {
            sn = &sn_tab[i];
            if (!strcmp(sn->id_str, id) && !strcmp(sn->name, name)) {
                *sn_info = *sn;
                ret = true;
                break;
            }
        }
    } else if (id) {
        for (i = 0; i < nb_sns; i++) {
            sn = &sn_tab[i];
            if (!strcmp(sn->id_str, id)) {
                *sn_info = *sn;
                ret = true;
                break;
            }
        }
    } else if (name) {
        for (i = 0; i < nb_sns; i++) {
            sn = &sn_tab[i];
            if (!strcmp(sn->name, name)) {
                *sn_info = *sn;
                ret = true;
                break;
            }
        }
    }

    g_free(sn_tab);
    return ret;
}

int bdrv_can_snapshot(BlockDriverState *bs)
{
    BlockDriver *drv = bs->drv;
    if (!drv || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) {
        return 0;
    }

    if (!drv->bdrv_snapshot_create) {
        if (bs->file != NULL) {
            return bdrv_can_snapshot(bs->file);
        }
        return 0;
    }

    return 1;
}

int bdrv_snapshot_create(BlockDriverState *bs,
                         QEMUSnapshotInfo *sn_info)
{
    BlockDriver *drv = bs->drv;
    if (!drv) {
        return -ENOMEDIUM;
    }
    if (drv->bdrv_snapshot_create) {
        return drv->bdrv_snapshot_create(bs, sn_info);
    }
    if (bs->file) {
        return bdrv_snapshot_create(bs->file, sn_info);
    }
    return -ENOTSUP;
}

int bdrv_snapshot_goto(BlockDriverState *bs,
                       const char *snapshot_id)
{
    BlockDriver *drv = bs->drv;
    int ret, open_ret;

    if (!drv) {
        return -ENOMEDIUM;
    }
    if (drv->bdrv_snapshot_goto) {
        return drv->bdrv_snapshot_goto(bs, snapshot_id);
    }

    if (bs->file) {
        drv->bdrv_close(bs);
        ret = bdrv_snapshot_goto(bs->file, snapshot_id);
        open_ret = drv->bdrv_open(bs, NULL, bs->open_flags, NULL);
        if (open_ret < 0) {
            bdrv_unref(bs->file);
            bs->drv = NULL;
            return open_ret;
        }
        return ret;
    }

    return -ENOTSUP;
}

/**
 * Delete an internal snapshot by @snapshot_id and @name.
 * @bs: block device used in the operation
 * @snapshot_id: unique snapshot ID, or NULL
 * @name: snapshot name, or NULL
 * @errp: location to store error
 *
 * If both @snapshot_id and @name are specified, delete the first one with
 * id @snapshot_id and name @name.
 * If only @snapshot_id is specified, delete the first one with id
 * @snapshot_id.
 * If only @name is specified, delete the first one with name @name.
 * if none is specified, return -EINVAL.
 *
 * Returns: 0 on success, -errno on failure. If @bs is not inserted, return
 * -ENOMEDIUM. If @snapshot_id and @name are both NULL, return -EINVAL. If @bs
 * does not support internal snapshot deletion, return -ENOTSUP. If @bs does
 * not support parameter @snapshot_id or @name, or one of them is not correctly
 * specified, return -EINVAL. If @bs can't find one matching @id and @name,
 * return -ENOENT. If @errp != NULL, it will always be filled with error
 * message on failure.
 */
int bdrv_snapshot_delete(BlockDriverState *bs,
                         const char *snapshot_id,
                         const char *name,
                         Error **errp)
{
    BlockDriver *drv = bs->drv;
    if (!drv) {
        error_set(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs));
        return -ENOMEDIUM;
    }
    if (!snapshot_id && !name) {
        error_setg(errp, "snapshot_id and name are both NULL");
        return -EINVAL;
    }
    if (drv->bdrv_snapshot_delete) {
        return drv->bdrv_snapshot_delete(bs, snapshot_id, name, errp);
    }
    if (bs->file) {
        return bdrv_snapshot_delete(bs->file, snapshot_id, name, errp);
    }
    error_set(errp, QERR_BLOCK_FORMAT_FEATURE_NOT_SUPPORTED,
              drv->format_name, bdrv_get_device_name(bs),
              "internal snapshot deletion");
    return -ENOTSUP;
}

void bdrv_snapshot_delete_by_id_or_name(BlockDriverState *bs,
                                        const char *id_or_name,
                                        Error **errp)
{
    int ret;
    Error *local_err = NULL;

    ret = bdrv_snapshot_delete(bs, id_or_name, NULL, &local_err);
    if (ret == -ENOENT || ret == -EINVAL) {
        error_free(local_err);
        local_err = NULL;
        ret = bdrv_snapshot_delete(bs, NULL, id_or_name, &local_err);
    }

    if (ret < 0) {
        error_propagate(errp, local_err);
    }
}

int bdrv_snapshot_list(BlockDriverState *bs,
                       QEMUSnapshotInfo **psn_info)
{
    BlockDriver *drv = bs->drv;
    if (!drv) {
        return -ENOMEDIUM;
    }
    if (drv->bdrv_snapshot_list) {
        return drv->bdrv_snapshot_list(bs, psn_info);
    }
    if (bs->file) {
        return bdrv_snapshot_list(bs->file, psn_info);
    }
    return -ENOTSUP;
}

/**
 * Temporarily load an internal snapshot by @snapshot_id and @name.
 * @bs: block device used in the operation
 * @snapshot_id: unique snapshot ID, or NULL
 * @name: snapshot name, or NULL
 * @errp: location to store error
 *
 * If both @snapshot_id and @name are specified, load the first one with
 * id @snapshot_id and name @name.
 * If only @snapshot_id is specified, load the first one with id
 * @snapshot_id.
 * If only @name is specified, load the first one with name @name.
 * if none is specified, return -EINVAL.
 *
 * Returns: 0 on success, -errno on fail. If @bs is not inserted, return
 * -ENOMEDIUM. If @bs is not readonly, return -EINVAL. If @bs did not support
 * internal snapshot, return -ENOTSUP. If qemu can't find a matching @id and
 * @name, return -ENOENT. If @errp != NULL, it will always be filled on
 * failure.
 */
int bdrv_snapshot_load_tmp(BlockDriverState *bs,
                           const char *snapshot_id,
                           const char *name,
                           Error **errp)
{
    BlockDriver *drv = bs->drv;

    if (!drv) {
        error_set(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs));
        return -ENOMEDIUM;
    }
    if (!snapshot_id && !name) {
        error_setg(errp, "snapshot_id and name are both NULL");
        return -EINVAL;
    }
    if (!bs->read_only) {
        error_setg(errp, "Device is not readonly");
        return -EINVAL;
    }
    if (drv->bdrv_snapshot_load_tmp) {
        return drv->bdrv_snapshot_load_tmp(bs, snapshot_id, name, errp);
    }
    error_set(errp, QERR_BLOCK_FORMAT_FEATURE_NOT_SUPPORTED,
              drv->format_name, bdrv_get_device_name(bs),
              "temporarily load internal snapshot");
    return -ENOTSUP;
}

int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs,
                                         const char *id_or_name,
                                         Error **errp)
{
    int ret;
    Error *local_err = NULL;

    ret = bdrv_snapshot_load_tmp(bs, id_or_name, NULL, &local_err);
    if (ret == -ENOENT || ret == -EINVAL) {
        error_free(local_err);
        local_err = NULL;
        ret = bdrv_snapshot_load_tmp(bs, NULL, id_or_name, &local_err);
    }

    if (local_err) {
        error_propagate(errp, local_err);
    }

    return ret;
}
Commit	Line	Data
de08c606 WX	1	/*
	2	* Block layer snapshot related functions
	3	*
	4	* Copyright (c) 2003-2008 Fabrice Bellard
	5	*
	6	* Permission is hereby granted, free of charge, to any person obtaining a copy
	7	* of this software and associated documentation files (the "Software"), to deal
	8	* in the Software without restriction, including without limitation the rights
	9	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	10	* copies of the Software, and to permit persons to whom the Software is
	11	* furnished to do so, subject to the following conditions:
	12	*
	13	* The above copyright notice and this permission notice shall be included in
	14	* all copies or substantial portions of the Software.
	15	*
	16	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	17	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	18	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	19	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	20	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	21	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	22	* THE SOFTWARE.
	23	*/
	24
	25	#include "block/snapshot.h"
	26	#include "block/block_int.h"
	27
8c116b0e WX	28	QemuOptsList internal_snapshot_opts = {
	29	.name = "snapshot",
	30	.head = QTAILQ_HEAD_INITIALIZER(internal_snapshot_opts.head),
	31	.desc = {
	32	{
	33	.name = SNAPSHOT_OPT_ID,
	34	.type = QEMU_OPT_STRING,
	35	.help = "snapshot id"
	36	},{
	37	.name = SNAPSHOT_OPT_NAME,
	38	.type = QEMU_OPT_STRING,
	39	.help = "snapshot name"
	40	},{
	41	/* end of list */
	42	}
	43	},
	44	};
	45
de08c606 WX	46	int bdrv_snapshot_find(BlockDriverState bs, QEMUSnapshotInfo sn_info,
	47	const char *name)
	48	{
	49	QEMUSnapshotInfo sn_tab, sn;
	50	int nb_sns, i, ret;
	51
	52	ret = -ENOENT;
	53	nb_sns = bdrv_snapshot_list(bs, &sn_tab);
	54	if (nb_sns < 0) {
	55	return ret;
	56	}
	57	for (i = 0; i < nb_sns; i++) {
	58	sn = &sn_tab[i];
	59	if (!strcmp(sn->id_str, name) \|\| !strcmp(sn->name, name)) {
	60	sn_info = sn;
	61	ret = 0;
	62	break;
	63	}
	64	}
	65	g_free(sn_tab);
	66	return ret;
	67	}
	68
2ea1dd75 WX	69	/**
	70	* Look up an internal snapshot by @id and @name.
	71	* @bs: block device to search
	72	* @id: unique snapshot ID, or NULL
	73	* @name: snapshot name, or NULL
	74	* @sn_info: location to store information on the snapshot found
	75	* @errp: location to store error, will be set only for exception
	76	*
	77	* This function will traverse snapshot list in @bs to search the matching
	78	* one, @id and @name are the matching condition:
	79	* If both @id and @name are specified, find the first one with id @id and
	80	* name @name.
	81	* If only @id is specified, find the first one with id @id.
	82	* If only @name is specified, find the first one with name @name.
	83	* if none is specified, abort().
	84	*
	85	* Returns: true when a snapshot is found and @sn_info will be filled, false
	86	* when error or not found. If all operation succeed but no matching one is
	87	* found, @errp will NOT be set.
	88	*/
	89	bool bdrv_snapshot_find_by_id_and_name(BlockDriverState *bs,
	90	const char *id,
	91	const char *name,
	92	QEMUSnapshotInfo *sn_info,
	93	Error **errp)
	94	{
	95	QEMUSnapshotInfo sn_tab, sn;
	96	int nb_sns, i;
	97	bool ret = false;
	98
	99	assert(id \|\| name);
	100
	101	nb_sns = bdrv_snapshot_list(bs, &sn_tab);
	102	if (nb_sns < 0) {
	103	error_setg_errno(errp, -nb_sns, "Failed to get a snapshot list");
	104	return false;
	105	} else if (nb_sns == 0) {
	106	return false;
	107	}
	108
	109	if (id && name) {
	110	for (i = 0; i < nb_sns; i++) {
	111	sn = &sn_tab[i];
	112	if (!strcmp(sn->id_str, id) && !strcmp(sn->name, name)) {
	113	sn_info = sn;
	114	ret = true;
	115	break;
	116	}
	117	}
	118	} else if (id) {
	119	for (i = 0; i < nb_sns; i++) {
	120	sn = &sn_tab[i];
	121	if (!strcmp(sn->id_str, id)) {
	122	sn_info = sn;
	123	ret = true;
	124	break;
	125	}
	126	}
	127	} else if (name) {
	128	for (i = 0; i < nb_sns; i++) {
	129	sn = &sn_tab[i];
	130	if (!strcmp(sn->name, name)) {
	131	sn_info = sn;
	132	ret = true;
133	break;
134	}
135	}
136	}
137
138	g_free(sn_tab);
139	return ret;
140	}
141
de08c606 WX	142	int bdrv_can_snapshot(BlockDriverState *bs)
	143	{
	144	BlockDriver *drv = bs->drv;
	145	if (!drv \|\| !bdrv_is_inserted(bs) \|\| bdrv_is_read_only(bs)) {
	146	return 0;
	147	}
	148
	149	if (!drv->bdrv_snapshot_create) {
	150	if (bs->file != NULL) {
	151	return bdrv_can_snapshot(bs->file);
	152	}
	153	return 0;
	154	}
	155
	156	return 1;
	157	}
	158
	159	int bdrv_snapshot_create(BlockDriverState *bs,
	160	QEMUSnapshotInfo *sn_info)
	161	{
	162	BlockDriver *drv = bs->drv;
	163	if (!drv) {
	164	return -ENOMEDIUM;
	165	}
	166	if (drv->bdrv_snapshot_create) {
	167	return drv->bdrv_snapshot_create(bs, sn_info);
	168	}
	169	if (bs->file) {
	170	return bdrv_snapshot_create(bs->file, sn_info);
	171	}
	172	return -ENOTSUP;
	173	}
	174
	175	int bdrv_snapshot_goto(BlockDriverState *bs,
	176	const char *snapshot_id)
	177	{
	178	BlockDriver *drv = bs->drv;
	179	int ret, open_ret;
	180
	181	if (!drv) {
	182	return -ENOMEDIUM;
	183	}
	184	if (drv->bdrv_snapshot_goto) {
	185	return drv->bdrv_snapshot_goto(bs, snapshot_id);
	186	}
	187
	188	if (bs->file) {
	189	drv->bdrv_close(bs);
	190	ret = bdrv_snapshot_goto(bs->file, snapshot_id);
015a1036	191	open_ret = drv->bdrv_open(bs, NULL, bs->open_flags, NULL);
de08c606	192	if (open_ret < 0) {
4f6fd349	193	bdrv_unref(bs->file);
de08c606 WX	194	bs->drv = NULL;
	195	return open_ret;
	196	}
	197	return ret;
	198	}
	199
	200	return -ENOTSUP;
	201	}
	202
a89d89d3 WX	203	/**
	204	* Delete an internal snapshot by @snapshot_id and @name.
	205	* @bs: block device used in the operation
	206	* @snapshot_id: unique snapshot ID, or NULL
	207	* @name: snapshot name, or NULL
	208	* @errp: location to store error
	209	*
	210	* If both @snapshot_id and @name are specified, delete the first one with
	211	* id @snapshot_id and name @name.
	212	* If only @snapshot_id is specified, delete the first one with id
	213	* @snapshot_id.
	214	* If only @name is specified, delete the first one with name @name.
7b4c4781	215	* if none is specified, return -EINVAL.
a89d89d3 WX	216	*
	217	* Returns: 0 on success, -errno on failure. If @bs is not inserted, return
	218	* -ENOMEDIUM. If @snapshot_id and @name are both NULL, return -EINVAL. If @bs
	219	* does not support internal snapshot deletion, return -ENOTSUP. If @bs does
	220	* not support parameter @snapshot_id or @name, or one of them is not correctly
	221	* specified, return -EINVAL. If @bs can't find one matching @id and @name,
	222	* return -ENOENT. If @errp != NULL, it will always be filled with error
	223	* message on failure.
	224	*/
	225	int bdrv_snapshot_delete(BlockDriverState *bs,
	226	const char *snapshot_id,
	227	const char *name,
	228	Error **errp)
de08c606 WX	229	{
	230	BlockDriver *drv = bs->drv;
	231	if (!drv) {
a89d89d3	232	error_set(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs));
de08c606 WX	233	return -ENOMEDIUM;
de08c606 WX	234	}
a89d89d3 WX	235	if (!snapshot_id && !name) {
	236	error_setg(errp, "snapshot_id and name are both NULL");
	237	return -EINVAL;
	238	}
de08c606	239	if (drv->bdrv_snapshot_delete) {
a89d89d3	240	return drv->bdrv_snapshot_delete(bs, snapshot_id, name, errp);
de08c606 WX	241	}
de08c606 WX	242	if (bs->file) {
a89d89d3	243	return bdrv_snapshot_delete(bs->file, snapshot_id, name, errp);
de08c606	244	}
a89d89d3 WX	245	error_set(errp, QERR_BLOCK_FORMAT_FEATURE_NOT_SUPPORTED,
	246	drv->format_name, bdrv_get_device_name(bs),
	247	"internal snapshot deletion");
de08c606 WX	248	return -ENOTSUP;
	249	}
	250
a89d89d3 WX	251	void bdrv_snapshot_delete_by_id_or_name(BlockDriverState *bs,
	252	const char *id_or_name,
	253	Error **errp)
	254	{
	255	int ret;
	256	Error *local_err = NULL;
	257
	258	ret = bdrv_snapshot_delete(bs, id_or_name, NULL, &local_err);
	259	if (ret == -ENOENT \|\| ret == -EINVAL) {
	260	error_free(local_err);
	261	local_err = NULL;
	262	ret = bdrv_snapshot_delete(bs, NULL, id_or_name, &local_err);
	263	}
	264
	265	if (ret < 0) {
	266	error_propagate(errp, local_err);
	267	}
	268	}
	269
de08c606 WX	270	int bdrv_snapshot_list(BlockDriverState *bs,
	271	QEMUSnapshotInfo **psn_info)
	272	{
	273	BlockDriver *drv = bs->drv;
	274	if (!drv) {
	275	return -ENOMEDIUM;
	276	}
	277	if (drv->bdrv_snapshot_list) {
	278	return drv->bdrv_snapshot_list(bs, psn_info);
	279	}
	280	if (bs->file) {
	281	return bdrv_snapshot_list(bs->file, psn_info);
	282	}
	283	return -ENOTSUP;
	284	}
	285
7b4c4781 WX	286	/**
	287	* Temporarily load an internal snapshot by @snapshot_id and @name.
	288	* @bs: block device used in the operation
	289	* @snapshot_id: unique snapshot ID, or NULL
	290	* @name: snapshot name, or NULL
	291	* @errp: location to store error
	292	*
	293	* If both @snapshot_id and @name are specified, load the first one with
	294	* id @snapshot_id and name @name.
	295	* If only @snapshot_id is specified, load the first one with id
	296	* @snapshot_id.
	297	* If only @name is specified, load the first one with name @name.
	298	* if none is specified, return -EINVAL.
	299	*
	300	* Returns: 0 on success, -errno on fail. If @bs is not inserted, return
	301	* -ENOMEDIUM. If @bs is not readonly, return -EINVAL. If @bs did not support
	302	* internal snapshot, return -ENOTSUP. If qemu can't find a matching @id and
	303	* @name, return -ENOENT. If @errp != NULL, it will always be filled on
	304	* failure.
	305	*/
de08c606	306	int bdrv_snapshot_load_tmp(BlockDriverState *bs,
7b4c4781 WX	307	const char *snapshot_id,
	308	const char *name,
	309	Error **errp)
de08c606 WX	310	{
de08c606 WX	311	BlockDriver *drv = bs->drv;
7b4c4781	312
de08c606	313	if (!drv) {
7b4c4781	314	error_set(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs));
de08c606 WX	315	return -ENOMEDIUM;
de08c606 WX	316	}
7b4c4781 WX	317	if (!snapshot_id && !name) {
	318	error_setg(errp, "snapshot_id and name are both NULL");
	319	return -EINVAL;
	320	}
de08c606	321	if (!bs->read_only) {
7b4c4781	322	error_setg(errp, "Device is not readonly");
de08c606 WX	323	return -EINVAL;
	324	}
	325	if (drv->bdrv_snapshot_load_tmp) {
7b4c4781	326	return drv->bdrv_snapshot_load_tmp(bs, snapshot_id, name, errp);
de08c606	327	}
7b4c4781 WX	328	error_set(errp, QERR_BLOCK_FORMAT_FEATURE_NOT_SUPPORTED,
	329	drv->format_name, bdrv_get_device_name(bs),
	330	"temporarily load internal snapshot");
de08c606 WX	331	return -ENOTSUP;
de08c606 WX	332	}
7b4c4781 WX	333
	334	int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs,
	335	const char *id_or_name,
	336	Error **errp)
	337	{
	338	int ret;
	339	Error *local_err = NULL;
	340
	341	ret = bdrv_snapshot_load_tmp(bs, id_or_name, NULL, &local_err);
	342	if (ret == -ENOENT \|\| ret == -EINVAL) {
	343	error_free(local_err);
	344	local_err = NULL;
	345	ret = bdrv_snapshot_load_tmp(bs, NULL, id_or_name, &local_err);
	346	}
	347
84d18f06	348	if (local_err) {
7b4c4781 WX	349	error_propagate(errp, local_err);
	350	}
	351
	352	return ret;
	353	}