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mirror: Deal with filters

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This includes some permission limiting (for example, we only need to
take the RESIZE permission for active commits where the base is smaller
than the top).

base_overlay is introduced so we can query bdrv_is_allocated_above() on
it - we cannot do that with base itself, because a filter's block_status
is the same as its child node, so if there are filters on base,
bdrv_is_allocated_above() on base would return information including
base.

Use this opportunity to rename qmp_drive_mirror()'s "source" BDS to
"target_backing_bs", because that is what it really refers to.

Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Max Reitz 2019-06-12 16:27:32 +02:00 committed by Kevin Wolf
parent c6f6d8462c
commit 3f072a7fb7
3 changed files with 118 additions and 38 deletions
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114
block/mirror.c
View File

@ -42,6 +42,7 @@ typedef struct MirrorBlockJob {
BlockBackend *target;
BlockDriverState *mirror_top_bs;
BlockDriverState *base;
BlockDriverState *base_overlay;
/* The name of the graph node to replace */
char *replaces;
@ -677,8 +678,10 @@ static int mirror_exit_common(Job *job)
&error_abort);
if (!abort && s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) {
BlockDriverState *backing = s->is_none_mode ? src : s->base;
if (backing_bs(target_bs) != backing) {
bdrv_set_backing_hd(target_bs, backing, &local_err);
BlockDriverState *unfiltered_target = bdrv_skip_filters(target_bs);
if (bdrv_cow_bs(unfiltered_target) != backing) {
bdrv_set_backing_hd(unfiltered_target, backing, &local_err);
if (local_err) {
error_report_err(local_err);
local_err = NULL;
@ -740,7 +743,7 @@ static int mirror_exit_common(Job *job)
* valid.
*/
block_job_remove_all_bdrv(bjob);
bdrv_replace_node(mirror_top_bs, backing_bs(mirror_top_bs), &error_abort);
bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort);
/* We just changed the BDS the job BB refers to (with either or both of the
* bdrv_replace_node() calls), so switch the BB back so the cleanup does
@ -786,7 +789,6 @@ static void coroutine_fn mirror_throttle(MirrorBlockJob *s)
static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s)
{
int64_t offset;
BlockDriverState *base = s->base;
BlockDriverState *bs = s->mirror_top_bs->backing->bs;
BlockDriverState *target_bs = blk_bs(s->target);
int ret;
@ -837,7 +839,8 @@ static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s)
return 0;
}
ret = bdrv_is_allocated_above(bs, base, false, offset, bytes, &count);
ret = bdrv_is_allocated_above(bs, s->base_overlay, true, offset, bytes,
&count);
if (ret < 0) {
return ret;
}
@ -936,7 +939,7 @@ static int coroutine_fn mirror_run(Job *job, Error **errp)
} else {
s->target_cluster_size = BDRV_SECTOR_SIZE;
}
if (backing_filename[0] && !target_bs->backing &&
if (backing_filename[0] && !bdrv_backing_chain_next(target_bs) &&
s->granularity < s->target_cluster_size) {
s->buf_size = MAX(s->buf_size, s->target_cluster_size);
s->cow_bitmap = bitmap_new(length);
@ -1116,8 +1119,9 @@ static void mirror_complete(Job *job, Error **errp)
if (s->backing_mode == MIRROR_OPEN_BACKING_CHAIN) {
int ret;
assert(!target->backing);
ret = bdrv_open_backing_file(target, NULL, "backing", errp);
assert(!bdrv_backing_chain_next(target));
ret = bdrv_open_backing_file(bdrv_skip_filters(target), NULL,
"backing", errp);
if (ret < 0) {
return;
}
@ -1555,8 +1559,8 @@ static BlockJob *mirror_start_job(
MirrorBlockJob *s;
MirrorBDSOpaque *bs_opaque;
BlockDriverState *mirror_top_bs;
bool target_graph_mod;
bool target_is_backing;
uint64_t target_perms, target_shared_perms;
Error *local_err = NULL;
int ret;
@ -1575,7 +1579,7 @@ static BlockJob *mirror_start_job(
buf_size = DEFAULT_MIRROR_BUF_SIZE;
}
if (bs == target) {
if (bdrv_skip_filters(bs) == bdrv_skip_filters(target)) {
error_setg(errp, "Can't mirror node into itself");
return NULL;
}
@ -1639,15 +1643,50 @@ static BlockJob *mirror_start_job(
* In the case of active commit, things look a bit different, though,
* because the target is an already populated backing file in active use.
* We can allow anything except resize there.*/
target_perms = BLK_PERM_WRITE;
target_shared_perms = BLK_PERM_WRITE_UNCHANGED;
target_is_backing = bdrv_chain_contains(bs, target);
target_graph_mod = (backing_mode != MIRROR_LEAVE_BACKING_CHAIN);
if (target_is_backing) {
int64_t bs_size, target_size;
bs_size = bdrv_getlength(bs);
if (bs_size < 0) {
error_setg_errno(errp, -bs_size,
"Could not inquire top image size");
goto fail;
}
target_size = bdrv_getlength(target);
if (target_size < 0) {
error_setg_errno(errp, -target_size,
"Could not inquire base image size");
goto fail;
}
if (target_size < bs_size) {
target_perms |= BLK_PERM_RESIZE;
}
target_shared_perms |= BLK_PERM_CONSISTENT_READ
| BLK_PERM_WRITE
| BLK_PERM_GRAPH_MOD;
} else if (bdrv_chain_contains(bs, bdrv_skip_filters(target))) {
/*
* We may want to allow this in the future, but it would
* require taking some extra care.
*/
error_setg(errp, "Cannot mirror to a filter on top of a node in the "
"source's backing chain");
goto fail;
}
if (backing_mode != MIRROR_LEAVE_BACKING_CHAIN) {
target_perms |= BLK_PERM_GRAPH_MOD;
}
s->target = blk_new(s->common.job.aio_context,
BLK_PERM_WRITE | BLK_PERM_RESIZE |
(target_graph_mod ? BLK_PERM_GRAPH_MOD : 0),
BLK_PERM_WRITE_UNCHANGED |
(target_is_backing ? BLK_PERM_CONSISTENT_READ |
BLK_PERM_WRITE |
BLK_PERM_GRAPH_MOD : 0));
target_perms, target_shared_perms);
ret = blk_insert_bs(s->target, target, errp);
if (ret < 0) {
goto fail;
@ -1672,6 +1711,7 @@ static BlockJob *mirror_start_job(
s->zero_target = zero_target;
s->copy_mode = copy_mode;
s->base = base;
s->base_overlay = bdrv_find_overlay(bs, base);
s->granularity = granularity;
s->buf_size = ROUND_UP(buf_size, granularity);
s->unmap = unmap;
@ -1702,15 +1742,39 @@ static BlockJob *mirror_start_job(
/* In commit_active_start() all intermediate nodes disappear, so
* any jobs in them must be blocked */
if (target_is_backing) {
BlockDriverState *iter;
for (iter = backing_bs(bs); iter != target; iter = backing_bs(iter)) {
/* XXX BLK_PERM_WRITE needs to be allowed so we don't block
BlockDriverState *iter, *filtered_target;
uint64_t iter_shared_perms;
/*
* The topmost node with
* bdrv_skip_filters(filtered_target) == bdrv_skip_filters(target)
*/
filtered_target = bdrv_cow_bs(bdrv_find_overlay(bs, target));
assert(bdrv_skip_filters(filtered_target) ==
bdrv_skip_filters(target));
/*
* XXX BLK_PERM_WRITE needs to be allowed so we don't block
* ourselves at s->base (if writes are blocked for a node, they are
* also blocked for its backing file). The other options would be a
* second filter driver above s->base (== target). */
* second filter driver above s->base (== target).
*/
iter_shared_perms = BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE;
for (iter = bdrv_filter_or_cow_bs(bs); iter != target;
iter = bdrv_filter_or_cow_bs(iter))
{
if (iter == filtered_target) {
/*
* From here on, all nodes are filters on the base.
* This allows us to share BLK_PERM_CONSISTENT_READ.
*/
iter_shared_perms |= BLK_PERM_CONSISTENT_READ;
}
ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0,
BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE,
errp);
iter_shared_perms, errp);
if (ret < 0) {
goto fail;
}
@ -1746,7 +1810,7 @@ fail:
bs_opaque->stop = true;
bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing,
&error_abort);
bdrv_replace_node(mirror_top_bs, backing_bs(mirror_top_bs), &error_abort);
bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort);
bdrv_unref(mirror_top_bs);
@ -1774,7 +1838,7 @@ void mirror_start(const char *job_id, BlockDriverState *bs,
return;
}
is_none_mode = mode == MIRROR_SYNC_MODE_NONE;
base = mode == MIRROR_SYNC_MODE_TOP ? backing_bs(bs) : NULL;
base = mode == MIRROR_SYNC_MODE_TOP ? bdrv_backing_chain_next(bs) : NULL;
mirror_start_job(job_id, bs, creation_flags, target, replaces,
speed, granularity, buf_size, backing_mode, zero_target,
on_source_error, on_target_error, unmap, NULL, NULL,

32
blockdev.c
View File

@ -2899,6 +2899,7 @@ static void blockdev_mirror_common(const char *job_id, BlockDriverState *bs,
bool has_auto_dismiss, bool auto_dismiss,
Error **errp)
{
BlockDriverState *unfiltered_bs;
int job_flags = JOB_DEFAULT;
if (!has_speed) {
@ -2950,10 +2951,19 @@ static void blockdev_mirror_common(const char *job_id, BlockDriverState *bs,
return;
}
if (!bs->backing && sync == MIRROR_SYNC_MODE_TOP) {
if (!bdrv_backing_chain_next(bs) && sync == MIRROR_SYNC_MODE_TOP) {
sync = MIRROR_SYNC_MODE_FULL;
}
if (!has_replaces) {
/* We want to mirror from @bs, but keep implicit filters on top */
unfiltered_bs = bdrv_skip_implicit_filters(bs);
if (unfiltered_bs != bs) {
replaces = unfiltered_bs->node_name;
has_replaces = true;
}
}
if (has_replaces) {
BlockDriverState *to_replace_bs;
AioContext *replace_aio_context;
@ -3000,7 +3010,7 @@ static void blockdev_mirror_common(const char *job_id, BlockDriverState *bs,
void qmp_drive_mirror(DriveMirror *arg, Error **errp)
{
BlockDriverState *bs;
BlockDriverState *source, *target_bs;
BlockDriverState *target_backing_bs, *target_bs;
AioContext *aio_context;
AioContext *old_context;
BlockMirrorBackingMode backing_mode;
@ -3035,12 +3045,12 @@ void qmp_drive_mirror(DriveMirror *arg, Error **errp)
}
flags = bs->open_flags | BDRV_O_RDWR;
source = backing_bs(bs);
if (!source && arg->sync == MIRROR_SYNC_MODE_TOP) {
target_backing_bs = bdrv_cow_bs(bdrv_skip_filters(bs));
if (!target_backing_bs && arg->sync == MIRROR_SYNC_MODE_TOP) {
arg->sync = MIRROR_SYNC_MODE_FULL;
}
if (arg->sync == MIRROR_SYNC_MODE_NONE) {
source = bs;
target_backing_bs = bs;
}
size = bdrv_getlength(bs);
@ -3066,7 +3076,7 @@ void qmp_drive_mirror(DriveMirror *arg, Error **errp)
/* Don't open backing image in create() */
flags |= BDRV_O_NO_BACKING;
if ((arg->sync == MIRROR_SYNC_MODE_FULL || !source)
if ((arg->sync == MIRROR_SYNC_MODE_FULL || !target_backing_bs)
&& arg->mode != NEW_IMAGE_MODE_EXISTING)
{
/* create new image w/o backing file */
@ -3074,15 +3084,19 @@ void qmp_drive_mirror(DriveMirror *arg, Error **errp)
bdrv_img_create(arg->target, format,
NULL, NULL, NULL, size, flags, false, &local_err);
} else {
/* Implicit filters should not appear in the filename */
BlockDriverState *explicit_backing =
bdrv_skip_implicit_filters(target_backing_bs);
switch (arg->mode) {
case NEW_IMAGE_MODE_EXISTING:
break;
case NEW_IMAGE_MODE_ABSOLUTE_PATHS:
/* create new image with backing file */
bdrv_refresh_filename(source);
bdrv_refresh_filename(explicit_backing);
bdrv_img_create(arg->target, format,
source->filename,
source->drv->format_name,
explicit_backing->filename,
explicit_backing->drv->format_name,
NULL, size, flags, false, &local_err);
break;
default:

6
qapi/block-core.json
View File

@ -1948,7 +1948,8 @@
#
# @replaces: with sync=full graph node name to be replaced by the new
# image when a whole image copy is done. This can be used to repair
# broken Quorum files. (Since 2.1)
# broken Quorum files. By default, @device is replaced, although
# implicitly created filters on it are kept. (Since 2.1)
#
# @mode: whether and how QEMU should create a new image, default is
# 'absolute-paths'.
@ -2259,7 +2260,8 @@
#
# @replaces: with sync=full graph node name to be replaced by the new
# image when a whole image copy is done. This can be used to repair
# broken Quorum files.
# broken Quorum files. By default, @device is replaced, although
# implicitly created filters on it are kept.
#
# @speed: the maximum speed, in bytes per second
#