return 0;
}
+static char *bdrv_child_get_parent_desc(BdrvChild *c)
+{
+ BlockDriverState *parent = c->opaque;
+ return g_strdup(bdrv_get_device_or_node_name(parent));
+}
+
static void bdrv_child_cb_drained_begin(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
}
const BdrvChildRole child_file = {
+ .get_parent_desc = bdrv_child_get_parent_desc,
.inherit_options = bdrv_inherited_options,
.drained_begin = bdrv_child_cb_drained_begin,
.drained_end = bdrv_child_cb_drained_end,
}
const BdrvChildRole child_format = {
+ .get_parent_desc = bdrv_child_get_parent_desc,
.inherit_options = bdrv_inherited_fmt_options,
.drained_begin = bdrv_child_cb_drained_begin,
.drained_end = bdrv_child_cb_drained_end,
};
+static void bdrv_backing_attach(BdrvChild *c)
+{
+ BlockDriverState *parent = c->opaque;
+ BlockDriverState *backing_hd = c->bs;
+
+ assert(!parent->backing_blocker);
+ error_setg(&parent->backing_blocker,
+ "node is used as backing hd of '%s'",
+ bdrv_get_device_or_node_name(parent));
+
+ parent->open_flags &= ~BDRV_O_NO_BACKING;
+ pstrcpy(parent->backing_file, sizeof(parent->backing_file),
+ backing_hd->filename);
+ pstrcpy(parent->backing_format, sizeof(parent->backing_format),
+ backing_hd->drv ? backing_hd->drv->format_name : "");
+
+ bdrv_op_block_all(backing_hd, parent->backing_blocker);
+ /* Otherwise we won't be able to commit or stream */
+ bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_COMMIT_TARGET,
+ parent->backing_blocker);
+ bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_STREAM,
+ parent->backing_blocker);
+ /*
+ * We do backup in 3 ways:
+ * 1. drive backup
+ * The target bs is new opened, and the source is top BDS
+ * 2. blockdev backup
+ * Both the source and the target are top BDSes.
+ * 3. internal backup(used for block replication)
+ * Both the source and the target are backing file
+ *
+ * In case 1 and 2, neither the source nor the target is the backing file.
+ * In case 3, we will block the top BDS, so there is only one block job
+ * for the top BDS and its backing chain.
+ */
+ bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE,
+ parent->backing_blocker);
+ bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_TARGET,
+ parent->backing_blocker);
+}
+
+static void bdrv_backing_detach(BdrvChild *c)
+{
+ BlockDriverState *parent = c->opaque;
+
+ assert(parent->backing_blocker);
+ bdrv_op_unblock_all(c->bs, parent->backing_blocker);
+ error_free(parent->backing_blocker);
+ parent->backing_blocker = NULL;
+}
+
/*
* Returns the options and flags that bs->backing should get, based on the
* given options and flags for the parent BDS
*child_flags = flags;
}
-static const BdrvChildRole child_backing = {
+const BdrvChildRole child_backing = {
+ .get_parent_desc = bdrv_child_get_parent_desc,
+ .attach = bdrv_backing_attach,
+ .detach = bdrv_backing_detach,
.inherit_options = bdrv_backing_options,
.drained_begin = bdrv_child_cb_drained_begin,
.drained_end = bdrv_child_cb_drained_end,
if (file != NULL) {
filename = blk_bs(file)->filename;
} else {
+ /*
+ * Caution: while qdict_get_try_str() is fine, getting
+ * non-string types would require more care. When @options
+ * come from -blockdev or blockdev_add, its members are typed
+ * according to the QAPI schema, but when they come from
+ * -drive, they're all QString.
+ */
filename = qdict_get_try_str(options, "filename");
}
ret = strstart(filename, "json:", &filename);
assert(ret);
- options_obj = qobject_from_json(filename);
+ options_obj = qobject_from_json(filename, errp);
if (!options_obj) {
- error_setg(errp, "Could not parse the JSON options");
+ /* Work around qobject_from_json() lossage TODO fix that */
+ if (errp && !*errp) {
+ error_setg(errp, "Could not parse the JSON options");
+ return NULL;
+ }
+ error_prepend(errp, "Could not parse the JSON options: ");
return NULL;
}
BlockDriver *drv = NULL;
Error *local_err = NULL;
+ /*
+ * Caution: while qdict_get_try_str() is fine, getting non-string
+ * types would require more care. When @options come from
+ * -blockdev or blockdev_add, its members are typed according to
+ * the QAPI schema, but when they come from -drive, they're all
+ * QString.
+ */
drvname = qdict_get_try_str(*options, "driver");
if (drvname) {
drv = bdrv_find_format(drvname);
}
/* Find the right block driver */
+ /* See cautionary note on accessing @options above */
filename = qdict_get_try_str(*options, "filename");
if (!drvname && protocol) {
return 0;
}
-static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs)
+static int bdrv_child_check_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
+ GSList *ignore_children, Error **errp);
+static void bdrv_child_abort_perm_update(BdrvChild *c);
+static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared);
+
+/*
+ * Check whether permissions on this node can be changed in a way that
+ * @cumulative_perms and @cumulative_shared_perms are the new cumulative
+ * permissions of all its parents. This involves checking whether all necessary
+ * permission changes to child nodes can be performed.
+ *
+ * A call to this function must always be followed by a call to bdrv_set_perm()
+ * or bdrv_abort_perm_update().
+ */
+static int bdrv_check_perm(BlockDriverState *bs, uint64_t cumulative_perms,
+ uint64_t cumulative_shared_perms,
+ GSList *ignore_children, Error **errp)
+{
+ BlockDriver *drv = bs->drv;
+ BdrvChild *c;
+ int ret;
+
+ /* Write permissions never work with read-only images */
+ if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) &&
+ bdrv_is_read_only(bs))
+ {
+ error_setg(errp, "Block node is read-only");
+ return -EPERM;
+ }
+
+ /* Check this node */
+ if (!drv) {
+ return 0;
+ }
+
+ if (drv->bdrv_check_perm) {
+ return drv->bdrv_check_perm(bs, cumulative_perms,
+ cumulative_shared_perms, errp);
+ }
+
+ /* Drivers that never have children can omit .bdrv_child_perm() */
+ if (!drv->bdrv_child_perm) {
+ assert(QLIST_EMPTY(&bs->children));
+ return 0;
+ }
+
+ /* Check all children */
+ QLIST_FOREACH(c, &bs->children, next) {
+ uint64_t cur_perm, cur_shared;
+ drv->bdrv_child_perm(bs, c, c->role,
+ cumulative_perms, cumulative_shared_perms,
+ &cur_perm, &cur_shared);
+ ret = bdrv_child_check_perm(c, cur_perm, cur_shared, ignore_children,
+ errp);
+ if (ret < 0) {
+ return ret;
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * Notifies drivers that after a previous bdrv_check_perm() call, the
+ * permission update is not performed and any preparations made for it (e.g.
+ * taken file locks) need to be undone.
+ *
+ * This function recursively notifies all child nodes.
+ */
+static void bdrv_abort_perm_update(BlockDriverState *bs)
+{
+ BlockDriver *drv = bs->drv;
+ BdrvChild *c;
+
+ if (!drv) {
+ return;
+ }
+
+ if (drv->bdrv_abort_perm_update) {
+ drv->bdrv_abort_perm_update(bs);
+ }
+
+ QLIST_FOREACH(c, &bs->children, next) {
+ bdrv_child_abort_perm_update(c);
+ }
+}
+
+static void bdrv_set_perm(BlockDriverState *bs, uint64_t cumulative_perms,
+ uint64_t cumulative_shared_perms)
+{
+ BlockDriver *drv = bs->drv;
+ BdrvChild *c;
+
+ if (!drv) {
+ return;
+ }
+
+ /* Update this node */
+ if (drv->bdrv_set_perm) {
+ drv->bdrv_set_perm(bs, cumulative_perms, cumulative_shared_perms);
+ }
+
+ /* Drivers that never have children can omit .bdrv_child_perm() */
+ if (!drv->bdrv_child_perm) {
+ assert(QLIST_EMPTY(&bs->children));
+ return;
+ }
+
+ /* Update all children */
+ QLIST_FOREACH(c, &bs->children, next) {
+ uint64_t cur_perm, cur_shared;
+ drv->bdrv_child_perm(bs, c, c->role,
+ cumulative_perms, cumulative_shared_perms,
+ &cur_perm, &cur_shared);
+ bdrv_child_set_perm(c, cur_perm, cur_shared);
+ }
+}
+
+static void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm,
+ uint64_t *shared_perm)
+{
+ BdrvChild *c;
+ uint64_t cumulative_perms = 0;
+ uint64_t cumulative_shared_perms = BLK_PERM_ALL;
+
+ QLIST_FOREACH(c, &bs->parents, next_parent) {
+ cumulative_perms |= c->perm;
+ cumulative_shared_perms &= c->shared_perm;
+ }
+
+ *perm = cumulative_perms;
+ *shared_perm = cumulative_shared_perms;
+}
+
+static char *bdrv_child_user_desc(BdrvChild *c)
+{
+ if (c->role->get_parent_desc) {
+ return c->role->get_parent_desc(c);
+ }
+
+ return g_strdup("another user");
+}
+
+static char *bdrv_perm_names(uint64_t perm)
+{
+ struct perm_name {
+ uint64_t perm;
+ const char *name;
+ } permissions[] = {
+ { BLK_PERM_CONSISTENT_READ, "consistent read" },
+ { BLK_PERM_WRITE, "write" },
+ { BLK_PERM_WRITE_UNCHANGED, "write unchanged" },
+ { BLK_PERM_RESIZE, "resize" },
+ { BLK_PERM_GRAPH_MOD, "change children" },
+ { 0, NULL }
+ };
+
+ char *result = g_strdup("");
+ struct perm_name *p;
+
+ for (p = permissions; p->name; p++) {
+ if (perm & p->perm) {
+ char *old = result;
+ result = g_strdup_printf("%s%s%s", old, *old ? ", " : "", p->name);
+ g_free(old);
+ }
+ }
+
+ return result;
+}
+
+/*
+ * Checks whether a new reference to @bs can be added if the new user requires
+ * @new_used_perm/@new_shared_perm as its permissions. If @ignore_children is
+ * set, the BdrvChild objects in this list are ignored in the calculations;
+ * this allows checking permission updates for an existing reference.
+ *
+ * Needs to be followed by a call to either bdrv_set_perm() or
+ * bdrv_abort_perm_update(). */
+static int bdrv_check_update_perm(BlockDriverState *bs, uint64_t new_used_perm,
+ uint64_t new_shared_perm,
+ GSList *ignore_children, Error **errp)
+{
+ BdrvChild *c;
+ uint64_t cumulative_perms = new_used_perm;
+ uint64_t cumulative_shared_perms = new_shared_perm;
+
+ /* There is no reason why anyone couldn't tolerate write_unchanged */
+ assert(new_shared_perm & BLK_PERM_WRITE_UNCHANGED);
+
+ QLIST_FOREACH(c, &bs->parents, next_parent) {
+ if (g_slist_find(ignore_children, c)) {
+ continue;
+ }
+
+ if ((new_used_perm & c->shared_perm) != new_used_perm) {
+ char *user = bdrv_child_user_desc(c);
+ char *perm_names = bdrv_perm_names(new_used_perm & ~c->shared_perm);
+ error_setg(errp, "Conflicts with use by %s as '%s', which does not "
+ "allow '%s' on %s",
+ user, c->name, perm_names, bdrv_get_node_name(c->bs));
+ g_free(user);
+ g_free(perm_names);
+ return -EPERM;
+ }
+
+ if ((c->perm & new_shared_perm) != c->perm) {
+ char *user = bdrv_child_user_desc(c);
+ char *perm_names = bdrv_perm_names(c->perm & ~new_shared_perm);
+ error_setg(errp, "Conflicts with use by %s as '%s', which uses "
+ "'%s' on %s",
+ user, c->name, perm_names, bdrv_get_node_name(c->bs));
+ g_free(user);
+ g_free(perm_names);
+ return -EPERM;
+ }
+
+ cumulative_perms |= c->perm;
+ cumulative_shared_perms &= c->shared_perm;
+ }
+
+ return bdrv_check_perm(bs, cumulative_perms, cumulative_shared_perms,
+ ignore_children, errp);
+}
+
+/* Needs to be followed by a call to either bdrv_child_set_perm() or
+ * bdrv_child_abort_perm_update(). */
+static int bdrv_child_check_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
+ GSList *ignore_children, Error **errp)
+{
+ int ret;
+
+ ignore_children = g_slist_prepend(g_slist_copy(ignore_children), c);
+ ret = bdrv_check_update_perm(c->bs, perm, shared, ignore_children, errp);
+ g_slist_free(ignore_children);
+
+ return ret;
+}
+
+static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared)
+{
+ uint64_t cumulative_perms, cumulative_shared_perms;
+
+ c->perm = perm;
+ c->shared_perm = shared;
+
+ bdrv_get_cumulative_perm(c->bs, &cumulative_perms,
+ &cumulative_shared_perms);
+ bdrv_set_perm(c->bs, cumulative_perms, cumulative_shared_perms);
+}
+
+static void bdrv_child_abort_perm_update(BdrvChild *c)
+{
+ bdrv_abort_perm_update(c->bs);
+}
+
+int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
+ Error **errp)
+{
+ int ret;
+
+ ret = bdrv_child_check_perm(c, perm, shared, NULL, errp);
+ if (ret < 0) {
+ bdrv_child_abort_perm_update(c);
+ return ret;
+ }
+
+ bdrv_child_set_perm(c, perm, shared);
+
+ return 0;
+}
+
+#define DEFAULT_PERM_PASSTHROUGH (BLK_PERM_CONSISTENT_READ \
+ | BLK_PERM_WRITE \
+ | BLK_PERM_WRITE_UNCHANGED \
+ | BLK_PERM_RESIZE)
+#define DEFAULT_PERM_UNCHANGED (BLK_PERM_ALL & ~DEFAULT_PERM_PASSTHROUGH)
+
+void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c,
+ const BdrvChildRole *role,
+ uint64_t perm, uint64_t shared,
+ uint64_t *nperm, uint64_t *nshared)
+{
+ if (c == NULL) {
+ *nperm = perm & DEFAULT_PERM_PASSTHROUGH;
+ *nshared = (shared & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED;
+ return;
+ }
+
+ *nperm = (perm & DEFAULT_PERM_PASSTHROUGH) |
+ (c->perm & DEFAULT_PERM_UNCHANGED);
+ *nshared = (shared & DEFAULT_PERM_PASSTHROUGH) |
+ (c->shared_perm & DEFAULT_PERM_UNCHANGED);
+}
+
+void bdrv_format_default_perms(BlockDriverState *bs, BdrvChild *c,
+ const BdrvChildRole *role,
+ uint64_t perm, uint64_t shared,
+ uint64_t *nperm, uint64_t *nshared)
+{
+ bool backing = (role == &child_backing);
+ assert(role == &child_backing || role == &child_file);
+
+ if (!backing) {
+ /* Apart from the modifications below, the same permissions are
+ * forwarded and left alone as for filters */
+ bdrv_filter_default_perms(bs, c, role, perm, shared, &perm, &shared);
+
+ /* Format drivers may touch metadata even if the guest doesn't write */
+ if (!bdrv_is_read_only(bs)) {
+ perm |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
+ }
+
+ /* bs->file always needs to be consistent because of the metadata. We
+ * can never allow other users to resize or write to it. */
+ perm |= BLK_PERM_CONSISTENT_READ;
+ shared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE);
+ } else {
+ /* We want consistent read from backing files if the parent needs it.
+ * No other operations are performed on backing files. */
+ perm &= BLK_PERM_CONSISTENT_READ;
+
+ /* If the parent can deal with changing data, we're okay with a
+ * writable and resizable backing file. */
+ /* TODO Require !(perm & BLK_PERM_CONSISTENT_READ), too? */
+ if (shared & BLK_PERM_WRITE) {
+ shared = BLK_PERM_WRITE | BLK_PERM_RESIZE;
+ } else {
+ shared = 0;
+ }
+
+ shared |= BLK_PERM_CONSISTENT_READ | BLK_PERM_GRAPH_MOD |
+ BLK_PERM_WRITE_UNCHANGED;
+ }
+
+ *nperm = perm;
+ *nshared = shared;
+}
+
+static void bdrv_replace_child_noperm(BdrvChild *child,
+ BlockDriverState *new_bs)
{
BlockDriverState *old_bs = child->bs;
+ if (old_bs && new_bs) {
+ assert(bdrv_get_aio_context(old_bs) == bdrv_get_aio_context(new_bs));
+ }
if (old_bs) {
if (old_bs->quiesce_counter && child->role->drained_end) {
child->role->drained_end(child);
}
+ if (child->role->detach) {
+ child->role->detach(child);
+ }
QLIST_REMOVE(child, next_parent);
}
if (new_bs->quiesce_counter && child->role->drained_begin) {
child->role->drained_begin(child);
}
+
+ if (child->role->attach) {
+ child->role->attach(child);
+ }
+ }
+}
+
+/*
+ * Updates @child to change its reference to point to @new_bs, including
+ * checking and applying the necessary permisson updates both to the old node
+ * and to @new_bs.
+ *
+ * NULL is passed as @new_bs for removing the reference before freeing @child.
+ *
+ * If @new_bs is not NULL, bdrv_check_perm() must be called beforehand, as this
+ * function uses bdrv_set_perm() to update the permissions according to the new
+ * reference that @new_bs gets.
+ */
+static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs)
+{
+ BlockDriverState *old_bs = child->bs;
+ uint64_t perm, shared_perm;
+
+ if (old_bs) {
+ /* Update permissions for old node. This is guaranteed to succeed
+ * because we're just taking a parent away, so we're loosening
+ * restrictions. */
+ bdrv_get_cumulative_perm(old_bs, &perm, &shared_perm);
+ bdrv_check_perm(old_bs, perm, shared_perm, NULL, &error_abort);
+ bdrv_set_perm(old_bs, perm, shared_perm);
+ }
+
+ bdrv_replace_child_noperm(child, new_bs);
+
+ if (new_bs) {
+ bdrv_get_cumulative_perm(new_bs, &perm, &shared_perm);
+ bdrv_set_perm(new_bs, perm, shared_perm);
}
}
BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
const char *child_name,
const BdrvChildRole *child_role,
- void *opaque)
+ uint64_t perm, uint64_t shared_perm,
+ void *opaque, Error **errp)
{
- BdrvChild *child = g_new(BdrvChild, 1);
+ BdrvChild *child;
+ int ret;
+
+ ret = bdrv_check_update_perm(child_bs, perm, shared_perm, NULL, errp);
+ if (ret < 0) {
+ bdrv_abort_perm_update(child_bs);
+ return NULL;
+ }
+
+ child = g_new(BdrvChild, 1);
*child = (BdrvChild) {
- .bs = NULL,
- .name = g_strdup(child_name),
- .role = child_role,
- .opaque = opaque,
+ .bs = NULL,
+ .name = g_strdup(child_name),
+ .role = child_role,
+ .perm = perm,
+ .shared_perm = shared_perm,
+ .opaque = opaque,
};
+ /* This performs the matching bdrv_set_perm() for the above check. */
bdrv_replace_child(child, child_bs);
return child;
BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
BlockDriverState *child_bs,
const char *child_name,
- const BdrvChildRole *child_role)
+ const BdrvChildRole *child_role,
+ Error **errp)
{
- BdrvChild *child = bdrv_root_attach_child(child_bs, child_name, child_role,
- parent_bs);
+ BdrvChild *child;
+ uint64_t perm, shared_perm;
+
+ bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm);
+
+ assert(parent_bs->drv);
+ assert(bdrv_get_aio_context(parent_bs) == bdrv_get_aio_context(child_bs));
+ parent_bs->drv->bdrv_child_perm(parent_bs, NULL, child_role,
+ perm, shared_perm, &perm, &shared_perm);
+
+ child = bdrv_root_attach_child(child_bs, child_name, child_role,
+ perm, shared_perm, parent_bs, errp);
+ if (child == NULL) {
+ return NULL;
+ }
+
QLIST_INSERT_HEAD(&parent_bs->children, child, next);
return child;
}
* Sets the backing file link of a BDS. A new reference is created; callers
* which don't need their own reference any more must call bdrv_unref().
*/
-void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd)
+void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
+ Error **errp)
{
if (backing_hd) {
bdrv_ref(backing_hd);
}
if (bs->backing) {
- assert(bs->backing_blocker);
- bdrv_op_unblock_all(bs->backing->bs, bs->backing_blocker);
bdrv_unref_child(bs, bs->backing);
- } else if (backing_hd) {
- error_setg(&bs->backing_blocker,
- "node is used as backing hd of '%s'",
- bdrv_get_device_or_node_name(bs));
}
if (!backing_hd) {
- error_free(bs->backing_blocker);
- bs->backing_blocker = NULL;
bs->backing = NULL;
goto out;
}
- bs->backing = bdrv_attach_child(bs, backing_hd, "backing", &child_backing);
- bs->open_flags &= ~BDRV_O_NO_BACKING;
- pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_hd->filename);
- pstrcpy(bs->backing_format, sizeof(bs->backing_format),
- backing_hd->drv ? backing_hd->drv->format_name : "");
- bdrv_op_block_all(backing_hd, bs->backing_blocker);
- /* Otherwise we won't be able to commit or stream */
- bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_COMMIT_TARGET,
- bs->backing_blocker);
- bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_STREAM,
- bs->backing_blocker);
- /*
- * We do backup in 3 ways:
- * 1. drive backup
- * The target bs is new opened, and the source is top BDS
- * 2. blockdev backup
- * Both the source and the target are top BDSes.
- * 3. internal backup(used for block replication)
- * Both the source and the target are backing file
- *
- * In case 1 and 2, neither the source nor the target is the backing file.
- * In case 3, we will block the top BDS, so there is only one block job
- * for the top BDS and its backing chain.
- */
- bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE,
- bs->backing_blocker);
- bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_TARGET,
- bs->backing_blocker);
+ bs->backing = bdrv_attach_child(bs, backing_hd, "backing", &child_backing,
+ errp);
+ if (!bs->backing) {
+ bdrv_unref(backing_hd);
+ }
+
+ bdrv_refresh_filename(bs);
+
out:
bdrv_refresh_limits(bs, NULL);
}
qdict_extract_subqdict(parent_options, &options, bdref_key_dot);
g_free(bdref_key_dot);
+ /*
+ * Caution: while qdict_get_try_str() is fine, getting non-string
+ * types would require more care. When @parent_options come from
+ * -blockdev or blockdev_add, its members are typed according to
+ * the QAPI schema, but when they come from -drive, they're all
+ * QString.
+ */
reference = qdict_get_try_str(parent_options, bdref_key);
if (reference || qdict_haskey(options, "file.filename")) {
backing_filename[0] = '\0';
/* Hook up the backing file link; drop our reference, bs owns the
* backing_hd reference now */
- bdrv_set_backing_hd(bs, backing_hd);
+ bdrv_set_backing_hd(bs, backing_hd, &local_err);
bdrv_unref(backing_hd);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ ret = -EINVAL;
+ goto free_exit;
+ }
qdict_del(parent_options, bdref_key);
qdict_extract_subqdict(options, &image_options, bdref_key_dot);
g_free(bdref_key_dot);
+ /*
+ * Caution: while qdict_get_try_str() is fine, getting non-string
+ * types would require more care. When @options come from
+ * -blockdev or blockdev_add, its members are typed according to
+ * the QAPI schema, but when they come from -drive, they're all
+ * QString.
+ */
reference = qdict_get_try_str(options, bdref_key);
if (!filename && !reference && !qdict_size(image_options)) {
if (!allow_none) {
const BdrvChildRole *child_role,
bool allow_none, Error **errp)
{
+ BdrvChild *c;
BlockDriverState *bs;
bs = bdrv_open_child_bs(filename, options, bdref_key, parent, child_role,
return NULL;
}
- return bdrv_attach_child(parent, bs, bdref_key, child_role);
+ c = bdrv_attach_child(parent, bs, bdref_key, child_role, errp);
+ if (!c) {
+ bdrv_unref(bs);
+ return NULL;
+ }
+
+ return c;
}
static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs,
int64_t total_size;
QemuOpts *opts = NULL;
BlockDriverState *bs_snapshot;
+ Error *local_err = NULL;
int ret;
/* if snapshot, we create a temporary backing file and open it
* call bdrv_unref() on it), so in order to be able to return one, we have
* to increase bs_snapshot's refcount here */
bdrv_ref(bs_snapshot);
- bdrv_append(bs_snapshot, bs);
+ bdrv_append(bs_snapshot, bs, &local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ ret = -EINVAL;
+ goto out;
+ }
g_free(tmp_filename);
return bs_snapshot;
goto fail;
}
- /* Set the BDRV_O_RDWR and BDRV_O_ALLOW_RDWR flags.
- * FIXME: we're parsing the QDict to avoid having to create a
- * QemuOpts just for this, but neither option is optimal. */
+ /*
+ * Set the BDRV_O_RDWR and BDRV_O_ALLOW_RDWR flags.
+ * Caution: getting a boolean member of @options requires care.
+ * When @options come from -blockdev or blockdev_add, members are
+ * typed according to the QAPI schema, but when they come from
+ * -drive, they're all QString.
+ */
if (g_strcmp0(qdict_get_try_str(options, BDRV_OPT_READ_ONLY), "on") &&
!qdict_get_try_bool(options, BDRV_OPT_READ_ONLY, false)) {
flags |= (BDRV_O_RDWR | BDRV_O_ALLOW_RDWR);
options = qdict_clone_shallow(options);
/* Find the right image format driver */
+ /* See cautionary note on accessing @options above */
drvname = qdict_get_try_str(options, "driver");
if (drvname) {
drv = bdrv_find_format(drvname);
assert(drvname || !(flags & BDRV_O_PROTOCOL));
+ /* See cautionary note on accessing @options above */
backing = qdict_get_try_str(options, "backing");
if (backing && *backing == '\0') {
flags |= BDRV_O_NO_BACKING;
goto fail;
}
if (file_bs != NULL) {
- file = blk_new();
- blk_insert_bs(file, file_bs);
+ file = blk_new(BLK_PERM_CONSISTENT_READ, BLK_PERM_ALL);
+ blk_insert_bs(file, file_bs, &local_err);
bdrv_unref(file_bs);
+ if (local_err) {
+ goto fail;
+ }
qdict_put(options, "file",
qstring_from_str(bdrv_get_node_name(file_bs)));
do {
QString *new_obj = qobject_to_qstring(entry->value);
const char *new = qstring_get_str(new_obj);
+ /*
+ * Caution: while qdict_get_try_str() is fine, getting
+ * non-string types would require more care. When
+ * bs->options come from -blockdev or blockdev_add, its
+ * members are typed according to the QAPI schema, but
+ * when they come from -drive, they're all QString.
+ */
const char *old = qdict_get_try_str(reopen_state->bs->options,
entry->key);
bs->drv->bdrv_close(bs);
bs->drv = NULL;
- bdrv_set_backing_hd(bs, NULL);
+ bdrv_set_backing_hd(bs, NULL, &error_abort);
if (bs->file != NULL) {
bdrv_unref_child(bs, bs->file);
assert(QTAILQ_EMPTY(&all_bdrv_states));
}
-static void change_parent_backing_link(BlockDriverState *from,
- BlockDriverState *to)
+static bool should_update_child(BdrvChild *c, BlockDriverState *to)
{
- BdrvChild *c, *next, *to_c;
+ BdrvChild *to_c;
- QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) {
- if (c->role == &child_backing) {
- /* @from is generally not allowed to be a backing file, except for
- * when @to is the overlay. In that case, @from may not be replaced
- * by @to as @to's backing node. */
- QLIST_FOREACH(to_c, &to->children, next) {
- if (to_c == c) {
- break;
- }
- }
- if (to_c) {
- continue;
+ if (c->role->stay_at_node) {
+ return false;
+ }
+
+ if (c->role == &child_backing) {
+ /* If @from is a backing file of @to, ignore the child to avoid
+ * creating a loop. We only want to change the pointer of other
+ * parents. */
+ QLIST_FOREACH(to_c, &to->children, next) {
+ if (to_c == c) {
+ break;
}
}
+ if (to_c) {
+ return false;
+ }
+ }
+
+ return true;
+}
+
+void bdrv_replace_node(BlockDriverState *from, BlockDriverState *to,
+ Error **errp)
+{
+ BdrvChild *c, *next;
+ GSList *list = NULL, *p;
+ uint64_t old_perm, old_shared;
+ uint64_t perm = 0, shared = BLK_PERM_ALL;
+ int ret;
+
+ assert(!atomic_read(&from->in_flight));
+ assert(!atomic_read(&to->in_flight));
+
+ /* Make sure that @from doesn't go away until we have successfully attached
+ * all of its parents to @to. */
+ bdrv_ref(from);
+
+ /* Put all parents into @list and calculate their cumulative permissions */
+ QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) {
+ if (!should_update_child(c, to)) {
+ continue;
+ }
+ list = g_slist_prepend(list, c);
+ perm |= c->perm;
+ shared &= c->shared_perm;
+ }
+
+ /* Check whether the required permissions can be granted on @to, ignoring
+ * all BdrvChild in @list so that they can't block themselves. */
+ ret = bdrv_check_update_perm(to, perm, shared, list, errp);
+ if (ret < 0) {
+ bdrv_abort_perm_update(to);
+ goto out;
+ }
+
+ /* Now actually perform the change. We performed the permission check for
+ * all elements of @list at once, so set the permissions all at once at the
+ * very end. */
+ for (p = list; p != NULL; p = p->next) {
+ c = p->data;
- assert(c->role != &child_backing);
bdrv_ref(to);
- bdrv_replace_child(c, to);
+ bdrv_replace_child_noperm(c, to);
bdrv_unref(from);
}
+
+ bdrv_get_cumulative_perm(to, &old_perm, &old_shared);
+ bdrv_set_perm(to, old_perm | perm, old_shared | shared);
+
+out:
+ g_slist_free(list);
+ bdrv_unref(from);
}
/*
* parents of bs_top after bdrv_append() returns. If the caller needs to keep a
* reference of its own, it must call bdrv_ref().
*/
-void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top)
+void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
+ Error **errp)
{
- assert(!bdrv_requests_pending(bs_top));
- assert(!bdrv_requests_pending(bs_new));
+ Error *local_err = NULL;
- bdrv_ref(bs_top);
+ bdrv_set_backing_hd(bs_new, bs_top, &local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ goto out;
+ }
- change_parent_backing_link(bs_top, bs_new);
- bdrv_set_backing_hd(bs_new, bs_top);
- bdrv_unref(bs_top);
+ bdrv_replace_node(bs_top, bs_new, &local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ bdrv_set_backing_hd(bs_new, NULL, &error_abort);
+ goto out;
+ }
/* bs_new is now referenced by its new parents, we don't need the
* additional reference any more. */
+out:
bdrv_unref(bs_new);
}
-void bdrv_replace_in_backing_chain(BlockDriverState *old, BlockDriverState *new)
-{
- assert(!bdrv_requests_pending(old));
- assert(!bdrv_requests_pending(new));
-
- bdrv_ref(old);
-
- change_parent_backing_link(old, new);
-
- bdrv_unref(old);
-}
-
static void bdrv_delete(BlockDriverState *bs)
{
assert(!bs->job);
BlockDriverState *base, const char *backing_file_str)
{
BlockDriverState *new_top_bs = NULL;
+ Error *local_err = NULL;
int ret = -EIO;
if (!top->drv || !base->drv) {
if (ret) {
goto exit;
}
- bdrv_set_backing_hd(new_top_bs, base);
+
+ bdrv_set_backing_hd(new_top_bs, base, &local_err);
+ if (local_err) {
+ ret = -EPERM;
+ error_report_err(local_err);
+ goto exit;
+ }
ret = 0;
exit:
BlockDriverState *bs = child->bs;
BlockDriver *drv = bs->drv;
int ret;
+
+ /* FIXME: Some format block drivers use this function instead of implicitly
+ * growing their file by writing beyond its end.
+ * See bdrv_aligned_pwritev() for an explanation why we currently
+ * cannot assert this permission in that case. */
+ // assert(child->perm & BLK_PERM_RESIZE);
+
if (!drv)
return -ENOMEDIUM;
if (!drv->bdrv_truncate)
return bs->aio_context;
}
+void bdrv_coroutine_enter(BlockDriverState *bs, Coroutine *co)
+{
+ aio_co_enter(bdrv_get_aio_context(bs), co);
+}
+
static void bdrv_do_remove_aio_context_notifier(BdrvAioNotifier *ban)
{
QLIST_REMOVE(ban, list);
void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context)
{
+ AioContext *ctx = bdrv_get_aio_context(bs);
+
+ aio_disable_external(ctx);
+ bdrv_parent_drained_begin(bs);
bdrv_drain(bs); /* ensure there are no in-flight requests */
+ while (aio_poll(ctx, false)) {
+ /* wait for all bottom halves to execute */
+ }
+
bdrv_detach_aio_context(bs);
/* This function executes in the old AioContext so acquire the new one in
*/
aio_context_acquire(new_context);
bdrv_attach_aio_context(bs, new_context);
+ bdrv_parent_drained_end(bs);
+ aio_enable_external(ctx);
aio_context_release(new_context);
}
projects / qemu.git / blobdiff