#include "block/nbd.h"
#include "block/qdict.h"
#include "qemu/error-report.h"
-#include "module_block.h"
+#include "block/module_block.h"
#include "qemu/main-loop.h"
#include "qemu/module.h"
#include "qapi/error.h"
{
static const char *whitelist_rw[] = {
CONFIG_BDRV_RW_WHITELIST
+ NULL
};
static const char *whitelist_ro[] = {
CONFIG_BDRV_RO_WHITELIST
+ NULL
};
const char **p;
int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz)
{
BlockDriver *drv = bs->drv;
+ BlockDriverState *filtered = bdrv_filter_bs(bs);
if (drv && drv->bdrv_probe_blocksizes) {
return drv->bdrv_probe_blocksizes(bs, bsz);
- } else if (drv && drv->is_filter && bs->file) {
- return bdrv_probe_blocksizes(bs->file->bs, bsz);
+ } else if (filtered) {
+ return bdrv_probe_blocksizes(filtered, bsz);
}
return -ENOTSUP;
int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo)
{
BlockDriver *drv = bs->drv;
+ BlockDriverState *filtered = bdrv_filter_bs(bs);
if (drv && drv->bdrv_probe_geometry) {
return drv->bdrv_probe_geometry(bs, geo);
- } else if (drv && drv->is_filter && bs->file) {
- return bdrv_probe_geometry(bs->file->bs, geo);
+ } else if (filtered) {
+ return bdrv_probe_geometry(filtered, geo);
}
return -ENOTSUP;
bdrv_refresh_filename(backing_hd);
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 */
return -EPERM;
}
+ /*
+ * Unaligned requests will automatically be aligned to bl.request_alignment
+ * and without RESIZE we can't extend requests to write to space beyond the
+ * end of the image, so it's required that the image size is aligned.
+ */
+ if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) &&
+ !(cumulative_perms & BLK_PERM_RESIZE))
+ {
+ if ((bs->total_sectors * BDRV_SECTOR_SIZE) % bs->bl.request_alignment) {
+ error_setg(errp, "Cannot get 'write' permission without 'resize': "
+ "Image size is not a multiple of request "
+ "alignment");
+ return -EPERM;
+ }
+ }
+
/* Check this node */
if (!drv) {
return 0;
* 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.
+ *
+ * Callers must ensure that child->frozen is false.
*/
static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs)
{
BlockDriverState *old_bs = child->bs;
uint64_t perm, shared_perm;
+ /* Asserts that child->frozen == false */
bdrv_replace_child_noperm(child, new_bs);
/*
g_free(child);
}
+/* Callers must ensure that child->frozen is false. */
void bdrv_root_unref_child(BdrvChild *child)
{
BlockDriverState *child_bs;
}
}
+/* Callers must ensure that child->frozen is false. */
void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child)
{
if (child == NULL) {
}
/*
- * Sets the backing file link of a BDS. A new reference is created; callers
+ * Sets the bs->backing 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,
bool update_inherits_from = bdrv_chain_contains(bs, backing_hd) &&
bdrv_inherits_from_recursive(backing_hd, bs);
- if (bdrv_is_backing_chain_frozen(bs, backing_bs(bs), errp)) {
+ if (bdrv_is_backing_chain_frozen(bs, child_bs(bs->backing), errp)) {
return;
}
}
if (bs->backing) {
+ /* Cannot be frozen, we checked that above */
bdrv_unref_child(bs, bs->backing);
bs->backing = NULL;
}
Error **errp)
{
BlockDriverState *bs = reopen_state->bs;
- BlockDriverState *overlay_bs, *new_backing_bs;
+ BlockDriverState *overlay_bs, *below_bs, *new_backing_bs;
QObject *value;
const char *str;
}
}
+ /*
+ * Ensure that @bs can really handle backing files, because we are
+ * about to give it one (or swap the existing one)
+ */
+ if (bs->drv->is_filter) {
+ /* Filters always have a file or a backing child */
+ if (!bs->backing) {
+ error_setg(errp, "'%s' is a %s filter node that does not support a "
+ "backing child", bs->node_name, bs->drv->format_name);
+ return -EINVAL;
+ }
+ } else if (!bs->drv->supports_backing) {
+ error_setg(errp, "Driver '%s' of node '%s' does not support backing "
+ "files", bs->drv->format_name, bs->node_name);
+ return -EINVAL;
+ }
+
/*
* Find the "actual" backing file by skipping all links that point
* to an implicit node, if any (e.g. a commit filter node).
+ * We cannot use any of the bdrv_skip_*() functions here because
+ * those return the first explicit node, while we are looking for
+ * its overlay here.
*/
overlay_bs = bs;
- while (backing_bs(overlay_bs) && backing_bs(overlay_bs)->implicit) {
- overlay_bs = backing_bs(overlay_bs);
+ for (below_bs = bdrv_filter_or_cow_bs(overlay_bs);
+ below_bs && below_bs->implicit;
+ below_bs = bdrv_filter_or_cow_bs(overlay_bs))
+ {
+ overlay_bs = below_bs;
}
/* If we want to replace the backing file we need some extra checks */
- if (new_backing_bs != backing_bs(overlay_bs)) {
+ if (new_backing_bs != bdrv_filter_or_cow_bs(overlay_bs)) {
/* Check for implicit nodes between bs and its backing file */
if (bs != overlay_bs) {
error_setg(errp, "Cannot change backing link if '%s' has "
"an implicit backing file", bs->node_name);
return -EPERM;
}
- /* Check if the backing link that we want to replace is frozen */
- if (bdrv_is_backing_chain_frozen(overlay_bs, backing_bs(overlay_bs),
- errp)) {
+ /*
+ * Check if the backing link that we want to replace is frozen.
+ * Note that
+ * bdrv_filter_or_cow_child(overlay_bs) == overlay_bs->backing,
+ * because we know that overlay_bs == bs, and that @bs
+ * either is a filter that uses ->backing or a COW format BDS
+ * with bs->drv->supports_backing == true.
+ */
+ if (bdrv_is_backing_chain_frozen(overlay_bs,
+ child_bs(overlay_bs->backing), errp))
+ {
return -EPERM;
}
reopen_state->replace_backing_bs = true;
* its metadata. Otherwise the 'backing' option can be omitted.
*/
if (drv->supports_backing && reopen_state->backing_missing &&
- (backing_bs(reopen_state->bs) || reopen_state->bs->backing_file[0])) {
+ (reopen_state->bs->backing || reopen_state->bs->backing_file[0])) {
error_setg(errp, "backing is missing for '%s'",
reopen_state->bs->node_name);
ret = -EINVAL;
* from bdrv_set_backing_hd()) has the new values.
*/
if (reopen_state->replace_backing_bs) {
- BlockDriverState *old_backing_bs = backing_bs(bs);
+ BlockDriverState *old_backing_bs = child_bs(bs->backing);
assert(!old_backing_bs || !old_backing_bs->implicit);
/* Abort the permission update on the backing bs we're detaching */
if (old_backing_bs) {
if (bs->drv) {
if (bs->drv->bdrv_close) {
+ /* Must unfreeze all children, so bdrv_unref_child() works */
bs->drv->bdrv_close(bs);
}
bs->drv = NULL;
}
/*
- * Finds the image layer in the chain that has 'bs' as its backing file.
- *
- * active is the current topmost image.
+ * Finds the first non-filter node above bs in the chain between
+ * active and bs. The returned node is either an immediate parent of
+ * bs, or there are only filter nodes between the two.
*
* Returns NULL if bs is not found in active's image chain,
* or if active == bs.
BlockDriverState *bdrv_find_overlay(BlockDriverState *active,
BlockDriverState *bs)
{
- while (active && bs != backing_bs(active)) {
- active = backing_bs(active);
+ bs = bdrv_skip_filters(bs);
+ active = bdrv_skip_filters(active);
+
+ while (active) {
+ BlockDriverState *next = bdrv_backing_chain_next(active);
+ if (bs == next) {
+ return active;
+ }
+ active = next;
}
- return active;
+ return NULL;
}
/* Given a BDS, searches for the base layer. */
}
/*
- * Return true if at least one of the backing links between @bs and
- * @base is frozen. @errp is set if that's the case.
+ * Return true if at least one of the COW (backing) and filter links
+ * between @bs and @base is frozen. @errp is set if that's the case.
* @base must be reachable from @bs, or NULL.
*/
bool bdrv_is_backing_chain_frozen(BlockDriverState *bs, BlockDriverState *base,
Error **errp)
{
BlockDriverState *i;
+ BdrvChild *child;
- for (i = bs; i != base; i = backing_bs(i)) {
- if (i->backing && i->backing->frozen) {
+ for (i = bs; i != base; i = child_bs(child)) {
+ child = bdrv_filter_or_cow_child(i);
+
+ if (child && child->frozen) {
error_setg(errp, "Cannot change '%s' link from '%s' to '%s'",
- i->backing->name, i->node_name,
- backing_bs(i)->node_name);
+ child->name, i->node_name, child->bs->node_name);
return true;
}
}
}
/*
- * Freeze all backing links between @bs and @base.
+ * Freeze all COW (backing) and filter links between @bs and @base.
* If any of the links is already frozen the operation is aborted and
* none of the links are modified.
* @base must be reachable from @bs, or NULL.
Error **errp)
{
BlockDriverState *i;
+ BdrvChild *child;
if (bdrv_is_backing_chain_frozen(bs, base, errp)) {
return -EPERM;
}
- for (i = bs; i != base; i = backing_bs(i)) {
- if (i->backing && backing_bs(i)->never_freeze) {
+ for (i = bs; i != base; i = child_bs(child)) {
+ child = bdrv_filter_or_cow_child(i);
+ if (child && child->bs->never_freeze) {
error_setg(errp, "Cannot freeze '%s' link to '%s'",
- i->backing->name, backing_bs(i)->node_name);
+ child->name, child->bs->node_name);
return -EPERM;
}
}
- for (i = bs; i != base; i = backing_bs(i)) {
- if (i->backing) {
- i->backing->frozen = true;
+ for (i = bs; i != base; i = child_bs(child)) {
+ child = bdrv_filter_or_cow_child(i);
+ if (child) {
+ child->frozen = true;
}
}
}
/*
- * Unfreeze all backing links between @bs and @base. The caller must
- * ensure that all links are frozen before using this function.
+ * Unfreeze all COW (backing) and filter links between @bs and @base.
+ * The caller must ensure that all links are frozen before using this
+ * function.
* @base must be reachable from @bs, or NULL.
*/
void bdrv_unfreeze_backing_chain(BlockDriverState *bs, BlockDriverState *base)
{
BlockDriverState *i;
+ BdrvChild *child;
- for (i = bs; i != base; i = backing_bs(i)) {
- if (i->backing) {
- assert(i->backing->frozen);
- i->backing->frozen = false;
+ for (i = bs; i != base; i = child_bs(child)) {
+ child = bdrv_filter_or_cow_child(i);
+ if (child) {
+ assert(child->frozen);
+ child->frozen = false;
}
}
}
* other intermediate nodes have been dropped.
* If 'top' is an implicit node (e.g. "commit_top") we should skip
* it because no one inherits from it. We use explicit_top for that. */
- while (explicit_top && explicit_top->implicit) {
- explicit_top = backing_bs(explicit_top);
- }
+ explicit_top = bdrv_skip_implicit_filters(explicit_top);
update_inherits_from = bdrv_inherits_from_recursive(base, explicit_top);
/* success - we can delete the intermediate states, and link top->base */
}
}
- /* Do the actual switch in the in-memory graph.
- * Completes bdrv_check_update_perm() transaction internally. */
+ /*
+ * Do the actual switch in the in-memory graph.
+ * Completes bdrv_check_update_perm() transaction internally.
+ * c->frozen is false, we have checked that above.
+ */
bdrv_ref(base);
bdrv_replace_child(c, base);
bdrv_unref(top);
return ret;
}
+/**
+ * Implementation of BlockDriver.bdrv_get_allocated_file_size() that
+ * sums the size of all data-bearing children. (This excludes backing
+ * children.)
+ */
+static int64_t bdrv_sum_allocated_file_size(BlockDriverState *bs)
+{
+ BdrvChild *child;
+ int64_t child_size, sum = 0;
+
+ QLIST_FOREACH(child, &bs->children, next) {
+ if (child->role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA |
+ BDRV_CHILD_FILTERED))
+ {
+ child_size = bdrv_get_allocated_file_size(child->bs);
+ if (child_size < 0) {
+ return child_size;
+ }
+ sum += child_size;
+ }
+ }
+
+ return sum;
+}
+
/**
* Length of a allocated file in bytes. Sparse files are counted by actual
* allocated space. Return < 0 if error or unknown.
if (drv->bdrv_get_allocated_file_size) {
return drv->bdrv_get_allocated_file_size(bs);
}
- if (bs->file) {
- return bdrv_get_allocated_file_size(bs->file->bs);
+
+ if (drv->bdrv_file_open) {
+ /*
+ * Protocol drivers default to -ENOTSUP (most of their data is
+ * not stored in any of their children (if they even have any),
+ * so there is no generic way to figure it out).
+ */
+ return -ENOTSUP;
+ } else if (drv->is_filter) {
+ /* Filter drivers default to the size of their filtered child */
+ return bdrv_get_allocated_file_size(bdrv_filter_bs(bs));
+ } else {
+ /* Other drivers default to summing their children's sizes */
+ return bdrv_sum_allocated_file_size(bs);
}
- return -ENOTSUP;
}
/*
return bs->sg;
}
-bool bdrv_is_encrypted(BlockDriverState *bs)
+/**
+ * Return whether the given node supports compressed writes.
+ */
+bool bdrv_supports_compressed_writes(BlockDriverState *bs)
{
- if (bs->backing && bs->backing->bs->encrypted) {
- return true;
+ BlockDriverState *filtered;
+
+ if (!bs->drv || !block_driver_can_compress(bs->drv)) {
+ return false;
}
- return bs->encrypted;
+
+ filtered = bdrv_filter_bs(bs);
+ if (filtered) {
+ /*
+ * Filters can only forward compressed writes, so we have to
+ * check the child.
+ */
+ return bdrv_supports_compressed_writes(filtered);
+ }
+
+ return true;
}
const char *bdrv_get_format_name(BlockDriverState *bs)
bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base)
{
while (top && top != base) {
- top = backing_bs(top);
+ top = bdrv_filter_or_cow_bs(top);
}
return top != NULL;
int bdrv_has_zero_init(BlockDriverState *bs)
{
+ BlockDriverState *filtered;
+
if (!bs->drv) {
return 0;
}
/* If BS is a copy on write image, it is initialized to
the contents of the base image, which may not be zeroes. */
- if (bs->backing) {
+ if (bdrv_cow_child(bs)) {
return 0;
}
if (bs->drv->bdrv_has_zero_init) {
return bs->drv->bdrv_has_zero_init(bs);
}
- if (bs->file && bs->drv->is_filter) {
- return bdrv_has_zero_init(bs->file->bs);
+
+ filtered = bdrv_filter_bs(bs);
+ if (filtered) {
+ return bdrv_has_zero_init(filtered);
}
/* safe default */
return -ENOMEDIUM;
}
if (!drv->bdrv_get_info) {
- if (bs->file && drv->is_filter) {
- return bdrv_get_info(bs->file->bs, bdi);
+ BlockDriverState *filtered = bdrv_filter_bs(bs);
+ if (filtered) {
+ return bdrv_get_info(filtered, bdi);
}
return -ENOTSUP;
}
static BlockDriverState *bdrv_find_debug_node(BlockDriverState *bs)
{
while (bs && bs->drv && !bs->drv->bdrv_debug_breakpoint) {
- if (bs->file) {
- bs = bs->file->bs;
- continue;
- }
-
- if (bs->drv->is_filter && bs->backing) {
- bs = bs->backing->bs;
- continue;
- }
-
- break;
+ bs = bdrv_primary_bs(bs);
}
if (bs && bs->drv && bs->drv->bdrv_debug_breakpoint) {
int bdrv_debug_resume(BlockDriverState *bs, const char *tag)
{
while (bs && (!bs->drv || !bs->drv->bdrv_debug_resume)) {
- bs = bs->file ? bs->file->bs : NULL;
+ bs = bdrv_primary_bs(bs);
}
if (bs && bs->drv && bs->drv->bdrv_debug_resume) {
bool bdrv_debug_is_suspended(BlockDriverState *bs, const char *tag)
{
while (bs && bs->drv && !bs->drv->bdrv_debug_is_suspended) {
- bs = bs->file ? bs->file->bs : NULL;
+ bs = bdrv_primary_bs(bs);
}
if (bs && bs->drv && bs->drv->bdrv_debug_is_suspended) {
char *backing_file_full = NULL;
char *filename_tmp = NULL;
int is_protocol = 0;
+ bool filenames_refreshed = false;
BlockDriverState *curr_bs = NULL;
BlockDriverState *retval = NULL;
+ BlockDriverState *bs_below;
if (!bs || !bs->drv || !backing_file) {
return NULL;
is_protocol = path_has_protocol(backing_file);
- for (curr_bs = bs; curr_bs->backing; curr_bs = curr_bs->backing->bs) {
+ /*
+ * Being largely a legacy function, skip any filters here
+ * (because filters do not have normal filenames, so they cannot
+ * match anyway; and allowing json:{} filenames is a bit out of
+ * scope).
+ */
+ for (curr_bs = bdrv_skip_filters(bs);
+ bdrv_cow_child(curr_bs) != NULL;
+ curr_bs = bs_below)
+ {
+ bs_below = bdrv_backing_chain_next(curr_bs);
+
+ if (bdrv_backing_overridden(curr_bs)) {
+ /*
+ * If the backing file was overridden, we can only compare
+ * directly against the backing node's filename.
+ */
+
+ if (!filenames_refreshed) {
+ /*
+ * This will automatically refresh all of the
+ * filenames in the rest of the backing chain, so we
+ * only need to do this once.
+ */
+ bdrv_refresh_filename(bs_below);
+ filenames_refreshed = true;
+ }
- /* If either of the filename paths is actually a protocol, then
- * compare unmodified paths; otherwise make paths relative */
- if (is_protocol || path_has_protocol(curr_bs->backing_file)) {
+ if (strcmp(backing_file, bs_below->filename) == 0) {
+ retval = bs_below;
+ break;
+ }
+ } else if (is_protocol || path_has_protocol(curr_bs->backing_file)) {
+ /*
+ * If either of the filename paths is actually a protocol, then
+ * compare unmodified paths; otherwise make paths relative.
+ */
char *backing_file_full_ret;
if (strcmp(backing_file, curr_bs->backing_file) == 0) {
- retval = curr_bs->backing->bs;
+ retval = bs_below;
break;
}
/* Also check against the full backing filename for the image */
bool equal = strcmp(backing_file, backing_file_full_ret) == 0;
g_free(backing_file_full_ret);
if (equal) {
- retval = curr_bs->backing->bs;
+ retval = bs_below;
break;
}
}
g_free(filename_tmp);
if (strcmp(backing_file_full, filename_full) == 0) {
- retval = curr_bs->backing->bs;
+ retval = bs_below;
break;
}
}
"same filename as the backing file");
goto out;
}
+ if (backing_file[0] == '\0') {
+ error_setg(errp, "Expected backing file name, got empty string");
+ goto out;
+ }
}
backing_fmt = qemu_opt_get(opts, BLOCK_OPT_BACKING_FMT);
bool bdrv_recurse_can_replace(BlockDriverState *bs,
BlockDriverState *to_replace)
{
+ BlockDriverState *filtered;
+
if (!bs || !bs->drv) {
return false;
}
}
/* For filters without an own implementation, we can recurse on our own */
- if (bs->drv->is_filter) {
- BdrvChild *child = bs->file ?: bs->backing;
- return bdrv_recurse_can_replace(child->bs, to_replace);
+ filtered = bdrv_filter_bs(bs);
+ if (filtered) {
+ return bdrv_recurse_can_replace(filtered, to_replace);
}
/* Safe default */
/* Note: This function may return false positives; it may return true
* even if opening the backing file specified by bs's image header
* would result in exactly bs->backing. */
-static bool bdrv_backing_overridden(BlockDriverState *bs)
+bool bdrv_backing_overridden(BlockDriverState *bs)
{
if (bs->backing) {
return strcmp(bs->auto_backing_file,
{
BlockDriver *drv = bs->drv;
BdrvChild *child;
+ BlockDriverState *primary_child_bs;
QDict *opts;
bool backing_overridden;
bool generate_json_filename; /* Whether our default implementation should
qobject_unref(bs->full_open_options);
bs->full_open_options = opts;
+ primary_child_bs = bdrv_primary_bs(bs);
+
if (drv->bdrv_refresh_filename) {
/* Obsolete information is of no use here, so drop the old file name
* information before refreshing it */
bs->exact_filename[0] = '\0';
drv->bdrv_refresh_filename(bs);
- } else if (bs->file) {
- /* Try to reconstruct valid information from the underlying file */
+ } else if (primary_child_bs) {
+ /*
+ * Try to reconstruct valid information from the underlying
+ * file -- this only works for format nodes (filter nodes
+ * cannot be probed and as such must be selected by the user
+ * either through an options dict, or through a special
+ * filename which the filter driver must construct in its
+ * .bdrv_refresh_filename() implementation).
+ */
bs->exact_filename[0] = '\0';
/*
* We can use the underlying file's filename if:
* - it has a filename,
+ * - the current BDS is not a filter,
* - the file is a protocol BDS, and
* - opening that file (as this BDS's format) will automatically create
* the BDS tree we have right now, that is:
* - no non-file child of this BDS has been overridden by the user
* Both of these conditions are represented by generate_json_filename.
*/
- if (bs->file->bs->exact_filename[0] &&
- bs->file->bs->drv->bdrv_file_open &&
- !generate_json_filename)
+ if (primary_child_bs->exact_filename[0] &&
+ primary_child_bs->drv->bdrv_file_open &&
+ !drv->is_filter && !generate_json_filename)
{
- strcpy(bs->exact_filename, bs->file->bs->exact_filename);
+ strcpy(bs->exact_filename, primary_child_bs->exact_filename);
}
}
char *bdrv_dirname(BlockDriverState *bs, Error **errp)
{
BlockDriver *drv = bs->drv;
+ BlockDriverState *child_bs;
if (!drv) {
error_setg(errp, "Node '%s' is ejected", bs->node_name);
return drv->bdrv_dirname(bs, errp);
}
- if (bs->file) {
- return bdrv_dirname(bs->file->bs, errp);
+ child_bs = bdrv_primary_bs(bs);
+ if (child_bs) {
+ return bdrv_dirname(child_bs, errp);
}
bdrv_refresh_filename(bs);
return 0;
}
+
+/*
+ * Return the child that @bs acts as an overlay for, and from which data may be
+ * copied in COW or COR operations. Usually this is the backing file.
+ */
+BdrvChild *bdrv_cow_child(BlockDriverState *bs)
+{
+ if (!bs || !bs->drv) {
+ return NULL;
+ }
+
+ if (bs->drv->is_filter) {
+ return NULL;
+ }
+
+ if (!bs->backing) {
+ return NULL;
+ }
+
+ assert(bs->backing->role & BDRV_CHILD_COW);
+ return bs->backing;
+}
+
+/*
+ * If @bs acts as a filter for exactly one of its children, return
+ * that child.
+ */
+BdrvChild *bdrv_filter_child(BlockDriverState *bs)
+{
+ BdrvChild *c;
+
+ if (!bs || !bs->drv) {
+ return NULL;
+ }
+
+ if (!bs->drv->is_filter) {
+ return NULL;
+ }
+
+ /* Only one of @backing or @file may be used */
+ assert(!(bs->backing && bs->file));
+
+ c = bs->backing ?: bs->file;
+ if (!c) {
+ return NULL;
+ }
+
+ assert(c->role & BDRV_CHILD_FILTERED);
+ return c;
+}
+
+/*
+ * Return either the result of bdrv_cow_child() or bdrv_filter_child(),
+ * whichever is non-NULL.
+ *
+ * Return NULL if both are NULL.
+ */
+BdrvChild *bdrv_filter_or_cow_child(BlockDriverState *bs)
+{
+ BdrvChild *cow_child = bdrv_cow_child(bs);
+ BdrvChild *filter_child = bdrv_filter_child(bs);
+
+ /* Filter nodes cannot have COW backing files */
+ assert(!(cow_child && filter_child));
+
+ return cow_child ?: filter_child;
+}
+
+/*
+ * Return the primary child of this node: For filters, that is the
+ * filtered child. For other nodes, that is usually the child storing
+ * metadata.
+ * (A generally more helpful description is that this is (usually) the
+ * child that has the same filename as @bs.)
+ *
+ * Drivers do not necessarily have a primary child; for example quorum
+ * does not.
+ */
+BdrvChild *bdrv_primary_child(BlockDriverState *bs)
+{
+ BdrvChild *c, *found = NULL;
+
+ QLIST_FOREACH(c, &bs->children, next) {
+ if (c->role & BDRV_CHILD_PRIMARY) {
+ assert(!found);
+ found = c;
+ }
+ }
+
+ return found;
+}
+
+static BlockDriverState *bdrv_do_skip_filters(BlockDriverState *bs,
+ bool stop_on_explicit_filter)
+{
+ BdrvChild *c;
+
+ if (!bs) {
+ return NULL;
+ }
+
+ while (!(stop_on_explicit_filter && !bs->implicit)) {
+ c = bdrv_filter_child(bs);
+ if (!c) {
+ /*
+ * A filter that is embedded in a working block graph must
+ * have a child. Assert this here so this function does
+ * not return a filter node that is not expected by the
+ * caller.
+ */
+ assert(!bs->drv || !bs->drv->is_filter);
+ break;
+ }
+ bs = c->bs;
+ }
+ /*
+ * Note that this treats nodes with bs->drv == NULL as not being
+ * filters (bs->drv == NULL should be replaced by something else
+ * anyway).
+ * The advantage of this behavior is that this function will thus
+ * always return a non-NULL value (given a non-NULL @bs).
+ */
+
+ return bs;
+}
+
+/*
+ * Return the first BDS that has not been added implicitly or that
+ * does not have a filtered child down the chain starting from @bs
+ * (including @bs itself).
+ */
+BlockDriverState *bdrv_skip_implicit_filters(BlockDriverState *bs)
+{
+ return bdrv_do_skip_filters(bs, true);
+}
+
+/*
+ * Return the first BDS that does not have a filtered child down the
+ * chain starting from @bs (including @bs itself).
+ */
+BlockDriverState *bdrv_skip_filters(BlockDriverState *bs)
+{
+ return bdrv_do_skip_filters(bs, false);
+}
+
+/*
+ * For a backing chain, return the first non-filter backing image of
+ * the first non-filter image.
+ */
+BlockDriverState *bdrv_backing_chain_next(BlockDriverState *bs)
+{
+ return bdrv_skip_filters(bdrv_cow_bs(bdrv_skip_filters(bs)));
+}
projects / qemu.git / blobdiff