From ecd30d2d978493f2280798f4c48f674d6290efa4 Mon Sep 17 00:00:00 2001 From: Alberto Garcia Date: Thu, 10 Jun 2021 15:05:36 +0300 Subject: [PATCH] block: Allow changing bs->file on reopen When the x-blockdev-reopen was added it allowed reconfiguring the graph by replacing backing files, but changing the 'file' option was forbidden. Because of this restriction some operations are not possible, notably inserting and removing block filters. This patch adds support for replacing the 'file' option. This is similar to replacing the backing file and the user is likewise responsible for the correctness of the resulting graph, otherwise this can lead to data corruption. Signed-off-by: Alberto Garcia [vsementsov: bdrv_reopen_parse_file_or_backing() is modified a lot] Signed-off-by: Vladimir Sementsov-Ogievskiy Message-Id: <20210610120537.196183-9-vsementsov@virtuozzo.com> Signed-off-by: Kevin Wolf --- block.c | 78 +++++++++++++++++++++++++++++------------- include/block/block.h | 1 + tests/qemu-iotests/245 | 23 +++++++------ 3 files changed, 67 insertions(+), 35 deletions(-) diff --git a/block.c b/block.c index ca11078cd2..acd35cb0cb 100644 --- a/block.c +++ b/block.c @@ -92,7 +92,7 @@ static void bdrv_remove_filter_or_cow_child(BlockDriverState *bs, static int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, - Transaction *set_backings_tran, Error **errp); + Transaction *change_child_tran, Error **errp); static void bdrv_reopen_commit(BDRVReopenState *reopen_state); static void bdrv_reopen_abort(BDRVReopenState *reopen_state); @@ -4148,6 +4148,10 @@ int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp) refresh_list = bdrv_topological_dfs(refresh_list, found, state->old_backing_bs); } + if (state->old_file_bs) { + refresh_list = bdrv_topological_dfs(refresh_list, found, + state->old_file_bs); + } } /* @@ -4240,64 +4244,81 @@ int bdrv_reopen_set_read_only(BlockDriverState *bs, bool read_only, * * Return 0 on success, otherwise return < 0 and set @errp. */ -static int bdrv_reopen_parse_backing(BDRVReopenState *reopen_state, - Transaction *set_backings_tran, - Error **errp) +static int bdrv_reopen_parse_file_or_backing(BDRVReopenState *reopen_state, + bool is_backing, Transaction *tran, + Error **errp) { BlockDriverState *bs = reopen_state->bs; - BlockDriverState *new_backing_bs; + BlockDriverState *new_child_bs; + BlockDriverState *old_child_bs = is_backing ? child_bs(bs->backing) : + child_bs(bs->file); + const char *child_name = is_backing ? "backing" : "file"; QObject *value; const char *str; - value = qdict_get(reopen_state->options, "backing"); + value = qdict_get(reopen_state->options, child_name); if (value == NULL) { return 0; } switch (qobject_type(value)) { case QTYPE_QNULL: - new_backing_bs = NULL; + assert(is_backing); /* The 'file' option does not allow a null value */ + new_child_bs = NULL; break; case QTYPE_QSTRING: str = qstring_get_str(qobject_to(QString, value)); - new_backing_bs = bdrv_lookup_bs(NULL, str, errp); - if (new_backing_bs == NULL) { + new_child_bs = bdrv_lookup_bs(NULL, str, errp); + if (new_child_bs == NULL) { return -EINVAL; - } else if (bdrv_recurse_has_child(new_backing_bs, bs)) { - error_setg(errp, "Making '%s' a backing file of '%s' " - "would create a cycle", str, bs->node_name); + } else if (bdrv_recurse_has_child(new_child_bs, bs)) { + error_setg(errp, "Making '%s' a %s child of '%s' would create a " + "cycle", str, child_name, bs->node_name); return -EINVAL; } break; default: - /* 'backing' does not allow any other data type */ + /* + * The options QDict has been flattened, so 'backing' and 'file' + * do not allow any other data type here. + */ g_assert_not_reached(); } - if (bs->backing) { - if (bdrv_skip_implicit_filters(bs->backing->bs) == new_backing_bs) { + if (old_child_bs == new_child_bs) { + return 0; + } + + if (old_child_bs) { + if (bdrv_skip_implicit_filters(old_child_bs) == new_child_bs) { return 0; } - if (bs->backing->bs->implicit) { - error_setg(errp, "Cannot change backing link if '%s' has " - "an implicit backing file", bs->node_name); + if (old_child_bs->implicit) { + error_setg(errp, "Cannot replace implicit %s child of %s", + child_name, bs->node_name); return -EPERM; } } - if (bs->drv->is_filter && !bs->backing) { + if (bs->drv->is_filter && !old_child_bs) { /* * Filters always have a file or a backing child, so we are trying to * change wrong child */ error_setg(errp, "'%s' is a %s filter node that does not support a " - "backing child", bs->node_name, bs->drv->format_name); + "%s child", bs->node_name, bs->drv->format_name, child_name); return -EINVAL; } - reopen_state->old_backing_bs = bs->backing ? bs->backing->bs : NULL; - return bdrv_set_backing_noperm(bs, new_backing_bs, set_backings_tran, errp); + if (is_backing) { + reopen_state->old_backing_bs = old_child_bs; + } else { + reopen_state->old_file_bs = old_child_bs; + } + + return bdrv_set_file_or_backing_noperm(bs, new_child_bs, is_backing, + tran, errp); } /* @@ -4319,7 +4340,7 @@ static int bdrv_reopen_parse_backing(BDRVReopenState *reopen_state, */ static int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, - Transaction *set_backings_tran, Error **errp) + Transaction *change_child_tran, Error **errp) { int ret = -1; int old_flags; @@ -4439,12 +4460,21 @@ static int bdrv_reopen_prepare(BDRVReopenState *reopen_state, * either a reference to an existing node (using its node name) * or NULL to simply detach the current backing file. */ - ret = bdrv_reopen_parse_backing(reopen_state, set_backings_tran, errp); + ret = bdrv_reopen_parse_file_or_backing(reopen_state, true, + change_child_tran, errp); if (ret < 0) { goto error; } qdict_del(reopen_state->options, "backing"); + /* Allow changing the 'file' option. In this case NULL is not allowed */ + ret = bdrv_reopen_parse_file_or_backing(reopen_state, false, + change_child_tran, errp); + if (ret < 0) { + goto error; + } + qdict_del(reopen_state->options, "file"); + /* Options that are not handled are only okay if they are unchanged * compared to the old state. It is expected that some options are only * used for the initial open, but not reopen (e.g. filename) */ diff --git a/include/block/block.h b/include/block/block.h index d28022e761..7ec77ecb1a 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -209,6 +209,7 @@ typedef struct BDRVReopenState { BlockdevDetectZeroesOptions detect_zeroes; bool backing_missing; BlockDriverState *old_backing_bs; /* keep pointer for permissions update */ + BlockDriverState *old_file_bs; /* keep pointer for permissions update */ QDict *options; QDict *explicit_options; void *opaque; diff --git a/tests/qemu-iotests/245 b/tests/qemu-iotests/245 index c7d671366a..d955e0dfd3 100755 --- a/tests/qemu-iotests/245 +++ b/tests/qemu-iotests/245 @@ -146,8 +146,8 @@ class TestBlockdevReopen(iotests.QMPTestCase): self.reopen(opts, {'driver': 'raw'}, "Cannot change the option 'driver'") self.reopen(opts, {'driver': ''}, "Invalid parameter ''") self.reopen(opts, {'driver': None}, "Invalid parameter type for 'driver', expected: string") - self.reopen(opts, {'file': 'not-found'}, "Cannot change the option 'file'") - self.reopen(opts, {'file': ''}, "Cannot change the option 'file'") + self.reopen(opts, {'file': 'not-found'}, "Cannot find device='' nor node-name='not-found'") + self.reopen(opts, {'file': ''}, "Cannot find device='' nor node-name=''") self.reopen(opts, {'file': None}, "Invalid parameter type for 'file', expected: BlockdevRef") self.reopen(opts, {'file.node-name': 'newname'}, "Cannot change the option 'node-name'") self.reopen(opts, {'file.driver': 'host_device'}, "Cannot change the option 'driver'") @@ -443,7 +443,7 @@ class TestBlockdevReopen(iotests.QMPTestCase): # Illegal operation: hd2 is a child of hd1 self.reopen(opts[2], {'backing': 'hd1'}, - "Making 'hd1' a backing file of 'hd2' would create a cycle") + "Making 'hd1' a backing child of 'hd2' would create a cycle") # hd2 <- hd0, hd2 <- hd1 self.reopen(opts[0], {'backing': 'hd2'}) @@ -454,8 +454,9 @@ class TestBlockdevReopen(iotests.QMPTestCase): # More illegal operations self.reopen(opts[2], {'backing': 'hd1'}, - "Making 'hd1' a backing file of 'hd2' would create a cycle") - self.reopen(opts[2], {'file': 'hd0-file'}, "Cannot change the option 'file'") + "Making 'hd1' a backing child of 'hd2' would create a cycle") + self.reopen(opts[2], {'file': 'hd0-file'}, + "Permission conflict on node 'hd0-file': permissions 'write, resize' are both required by node 'hd0' (uses node 'hd0-file' as 'file' child) and unshared by node 'hd2' (uses node 'hd0-file' as 'file' child).") result = self.vm.qmp('blockdev-del', conv_keys = True, node_name = 'hd2') self.assert_qmp(result, 'error/class', 'GenericError') @@ -497,18 +498,18 @@ class TestBlockdevReopen(iotests.QMPTestCase): # Illegal: hd2 is backed by hd1 self.reopen(opts[1], {'backing': 'hd2'}, - "Making 'hd2' a backing file of 'hd1' would create a cycle") + "Making 'hd2' a backing child of 'hd1' would create a cycle") # hd1 <- hd0 <- hd2 self.reopen(opts[2], {'backing': 'hd0'}) # Illegal: hd2 is backed by hd0, which is backed by hd1 self.reopen(opts[1], {'backing': 'hd2'}, - "Making 'hd2' a backing file of 'hd1' would create a cycle") + "Making 'hd2' a backing child of 'hd1' would create a cycle") # Illegal: hd1 cannot point to itself self.reopen(opts[1], {'backing': 'hd1'}, - "Making 'hd1' a backing file of 'hd1' would create a cycle") + "Making 'hd1' a backing child of 'hd1' would create a cycle") # Remove all backing files self.reopen(opts[0]) @@ -530,7 +531,7 @@ class TestBlockdevReopen(iotests.QMPTestCase): # Illegal: hd0 is a child of the blkverify node self.reopen(opts[0], {'backing': 'bv'}, - "Making 'bv' a backing file of 'hd0' would create a cycle") + "Making 'bv' a backing child of 'hd0' would create a cycle") # Delete the blkverify node result = self.vm.qmp('blockdev-del', conv_keys = True, node_name = 'bv') @@ -563,7 +564,7 @@ class TestBlockdevReopen(iotests.QMPTestCase): # You can't make quorum0 a backing file of hd0: # hd0 is already a child of quorum0. self.reopen(hd_opts(0), {'backing': 'quorum0'}, - "Making 'quorum0' a backing file of 'hd0' would create a cycle") + "Making 'quorum0' a backing child of 'hd0' would create a cycle") # Delete quorum0 result = self.vm.qmp('blockdev-del', conv_keys = True, node_name = 'quorum0') @@ -969,7 +970,7 @@ class TestBlockdevReopen(iotests.QMPTestCase): # We can't remove hd1 while the commit job is ongoing opts['backing'] = None - self.reopen(opts, {}, "Cannot change backing link if 'hd0' has an implicit backing file") + self.reopen(opts, {}, "Cannot replace implicit backing child of hd0") # hd2 <- hd0 self.vm.run_job('commit0', auto_finalize = False, auto_dismiss = True)