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,
cumulative_shared_perms, errp);
}
- /* Drivers may not have .bdrv_child_perm() */
+ /* Drivers that never have children can omit .bdrv_child_perm() */
if (!drv->bdrv_child_perm) {
+ assert(QLIST_EMPTY(&bs->children));
return 0;
}
drv->bdrv_set_perm(bs, cumulative_perms, cumulative_shared_perms);
}
- /* Drivers may not have .bdrv_child_perm() */
+ /* Drivers that never have children can omit .bdrv_child_perm() */
if (!drv->bdrv_child_perm) {
+ assert(QLIST_EMPTY(&bs->children));
return;
}
*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_child is set,
continue;
}
- if ((new_used_perm & c->shared_perm) != new_used_perm ||
- (c->perm & new_shared_perm) != c->perm)
- {
- const char *user = NULL;
- if (c->role->get_name) {
- user = c->role->get_name(c);
- if (user && !*user) {
- user = NULL;
- }
- }
- error_setg(errp, "Conflicts with %s", user ?: "another operation");
+ 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;
}
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(BdrvChild *child, BlockDriverState *new_bs,
bool check_new_perm)
{
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);
/* Update permissions for old node. This is guaranteed to succeed
bdrv_check_perm(new_bs, perm, shared_perm, &error_abort);
}
bdrv_set_perm(new_bs, perm, shared_perm);
+
+ if (child->role->attach) {
+ child->role->attach(child);
+ }
}
}
Error **errp)
{
BdrvChild *child;
+ uint64_t perm, shared_perm;
+
+ bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm);
+
+ assert(parent_bs->drv);
+ parent_bs->drv->bdrv_child_perm(parent_bs, NULL, child_role,
+ perm, shared_perm, &perm, &shared_perm);
- /* FIXME Use real permissions */
child = bdrv_root_attach_child(child_bs, child_name, child_role,
- 0, BLK_PERM_ALL, parent_bs, errp);
+ perm, shared_perm, parent_bs, errp);
if (child == NULL) {
return NULL;
}
* 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;
}
- /* FIXME Error handling */
+
bs->backing = bdrv_attach_child(bs, backing_hd, "backing", &child_backing,
- &error_abort);
- 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 : "");
+ errp);
+ if (!bs->backing) {
+ bdrv_unref(backing_hd);
+ }
- 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);
out:
bdrv_refresh_limits(bs, NULL);
}
/* 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) {
+ ret = -EINVAL;
+ goto free_exit;
+ }
qdict_del(parent_options, bdref_key);
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;
}
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)));
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);
BdrvChild *c, *next, *to_c;
QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) {
+ if (c->role->stay_at_node) {
+ continue;
+ }
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. */
+ /* 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;
}
}
- assert(c->role != &child_backing);
bdrv_ref(to);
/* FIXME Are we sure that bdrv_replace_child() can't run into
* &error_abort because of permissions? */
* 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;
+
+ assert(!atomic_read(&bs_top->in_flight));
+ assert(!atomic_read(&bs_new->in_flight));
- 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);
/* bs_new is now referenced by its new parents, we don't need the
* additional reference any more. */
+out:
bdrv_unref(bs_new);
}
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;
+
+ assert(child->perm & BLK_PERM_RESIZE);
+
if (!drv)
return -ENOMEDIUM;
if (!drv->bdrv_truncate)
projects / mirror_qemu.git / blobdiff