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[PATCH v8 12/43] stream: Deal with filters
From: |
Max Reitz |
Subject: |
[PATCH v8 12/43] stream: Deal with filters |
Date: |
Tue, 1 Sep 2020 16:33:53 +0200 |
Because of the (not so recent anymore) changes that make the stream job
independent of the base node and instead track the node above it, we
have to split that "bottom" node into two cases: The bottom COW node,
and the node directly above the base node (which may be an R/W filter
or the bottom COW node).
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
qapi/block-core.json | 13 ++++++---
block/stream.c | 63 ++++++++++++++++++++++++++++++++------------
blockdev.c | 4 ++-
3 files changed, 59 insertions(+), 21 deletions(-)
diff --git a/qapi/block-core.json b/qapi/block-core.json
index db08c58d78..f8f42cc836 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -2484,13 +2484,20 @@
# of 'device'.
#
# If a base file is specified then sectors are not copied from that base file
and
-# its backing chain. When streaming completes the image file will have the
base
-# file as its backing file. This can be used to stream a subset of the backing
-# file chain instead of flattening the entire image.
+# its backing chain. This can be used to stream a subset of the backing file
+# chain instead of flattening the entire image.
+# When streaming completes the image file will have the base file as its
backing
+# file, unless that node was changed while the job was running. In that case,
+# base's parent's backing (or filtered, whichever exists) child (i.e., base at
+# the beginning of the job) will be the new backing file.
#
# On successful completion the image file is updated to drop the backing file
# and the BLOCK_JOB_COMPLETED event is emitted.
#
+# In case @device is a filter node, block-stream modifies the first non-filter
+# overlay node below it to point to the new backing node instead of modifying
+# @device itself.
+#
# @job-id: identifier for the newly-created block job. If
# omitted, the device name will be used. (Since 2.7)
#
diff --git a/block/stream.c b/block/stream.c
index 310ccbaa4c..8ce6729a33 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -31,7 +31,8 @@ enum {
typedef struct StreamBlockJob {
BlockJob common;
- BlockDriverState *bottom;
+ BlockDriverState *base_overlay; /* COW overlay (stream from this) */
+ BlockDriverState *above_base; /* Node directly above the base */
BlockdevOnError on_error;
char *backing_file_str;
bool bs_read_only;
@@ -53,7 +54,7 @@ static void stream_abort(Job *job)
if (s->chain_frozen) {
BlockJob *bjob = &s->common;
- bdrv_unfreeze_backing_chain(blk_bs(bjob->blk), s->bottom);
+ bdrv_unfreeze_backing_chain(blk_bs(bjob->blk), s->above_base);
}
}
@@ -62,14 +63,15 @@ static int stream_prepare(Job *job)
StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
BlockJob *bjob = &s->common;
BlockDriverState *bs = blk_bs(bjob->blk);
- BlockDriverState *base = backing_bs(s->bottom);
+ BlockDriverState *unfiltered_bs = bdrv_skip_filters(bs);
+ BlockDriverState *base = bdrv_filter_or_cow_bs(s->above_base);
Error *local_err = NULL;
int ret = 0;
- bdrv_unfreeze_backing_chain(bs, s->bottom);
+ bdrv_unfreeze_backing_chain(bs, s->above_base);
s->chain_frozen = false;
- if (bs->backing) {
+ if (bdrv_cow_child(unfiltered_bs)) {
const char *base_id = NULL, *base_fmt = NULL;
if (base) {
base_id = s->backing_file_str;
@@ -77,8 +79,8 @@ static int stream_prepare(Job *job)
base_fmt = base->drv->format_name;
}
}
- bdrv_set_backing_hd(bs, base, &local_err);
- ret = bdrv_change_backing_file(bs, base_id, base_fmt, false);
+ bdrv_set_backing_hd(unfiltered_bs, base, &local_err);
+ ret = bdrv_change_backing_file(unfiltered_bs, base_id, base_fmt,
false);
if (local_err) {
error_report_err(local_err);
return -EPERM;
@@ -109,14 +111,15 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
BlockBackend *blk = s->common.blk;
BlockDriverState *bs = blk_bs(blk);
- bool enable_cor = !backing_bs(s->bottom);
+ BlockDriverState *unfiltered_bs = bdrv_skip_filters(bs);
+ bool enable_cor = !bdrv_cow_child(s->base_overlay);
int64_t len;
int64_t offset = 0;
uint64_t delay_ns = 0;
int error = 0;
int64_t n = 0; /* bytes */
- if (bs == s->bottom) {
+ if (unfiltered_bs == s->base_overlay) {
/* Nothing to stream */
return 0;
}
@@ -150,13 +153,14 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
copy = false;
- ret = bdrv_is_allocated(bs, offset, STREAM_CHUNK, &n);
+ ret = bdrv_is_allocated(unfiltered_bs, offset, STREAM_CHUNK, &n);
if (ret == 1) {
/* Allocated in the top, no need to copy. */
} else if (ret >= 0) {
/* Copy if allocated in the intermediate images. Limit to the
* known-unallocated area [offset, offset+n*BDRV_SECTOR_SIZE). */
- ret = bdrv_is_allocated_above(backing_bs(bs), s->bottom, true,
+ ret = bdrv_is_allocated_above(bdrv_cow_bs(unfiltered_bs),
+ s->base_overlay, true,
offset, n, &n);
/* Finish early if end of backing file has been reached */
if (ret == 0 && n == 0) {
@@ -223,9 +227,29 @@ void stream_start(const char *job_id, BlockDriverState *bs,
BlockDriverState *iter;
bool bs_read_only;
int basic_flags = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED;
- BlockDriverState *bottom = bdrv_find_overlay(bs, base);
+ BlockDriverState *base_overlay = bdrv_find_overlay(bs, base);
+ BlockDriverState *above_base;
- if (bdrv_freeze_backing_chain(bs, bottom, errp) < 0) {
+ if (!base_overlay) {
+ error_setg(errp, "'%s' is not in the backing chain of '%s'",
+ base->node_name, bs->node_name);
+ return;
+ }
+
+ /*
+ * Find the node directly above @base. @base_overlay is a COW overlay, so
+ * it must have a bdrv_cow_child(), but it is the immediate overlay of
+ * @base, so between the two there can only be filters.
+ */
+ above_base = base_overlay;
+ if (bdrv_cow_bs(above_base) != base) {
+ above_base = bdrv_cow_bs(above_base);
+ while (bdrv_filter_bs(above_base) != base) {
+ above_base = bdrv_filter_bs(above_base);
+ }
+ }
+
+ if (bdrv_freeze_backing_chain(bs, above_base, errp) < 0) {
return;
}
@@ -255,14 +279,19 @@ void stream_start(const char *job_id, BlockDriverState
*bs,
* and resizes. Reassign the base node pointer because the backing BS of
the
* bottom node might change after the call to bdrv_reopen_set_read_only()
* due to parallel block jobs running.
+ * above_base node might change after the call to
+ * bdrv_reopen_set_read_only() due to parallel block jobs running.
*/
- base = backing_bs(bottom);
- for (iter = backing_bs(bs); iter && iter != base; iter = backing_bs(iter))
{
+ base = bdrv_filter_or_cow_bs(above_base);
+ for (iter = bdrv_filter_or_cow_bs(bs); iter != base;
+ iter = bdrv_filter_or_cow_bs(iter))
+ {
block_job_add_bdrv(&s->common, "intermediate node", iter, 0,
basic_flags, &error_abort);
}
- s->bottom = bottom;
+ s->base_overlay = base_overlay;
+ s->above_base = above_base;
s->backing_file_str = g_strdup(backing_file_str);
s->bs_read_only = bs_read_only;
s->chain_frozen = true;
@@ -276,5 +305,5 @@ fail:
if (bs_read_only) {
bdrv_reopen_set_read_only(bs, true, NULL);
}
- bdrv_unfreeze_backing_chain(bs, bottom);
+ bdrv_unfreeze_backing_chain(bs, above_base);
}
diff --git a/blockdev.c b/blockdev.c
index 3848a9c8ab..862aa1b9aa 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2528,7 +2528,9 @@ void qmp_block_stream(bool has_job_id, const char
*job_id, const char *device,
}
/* Check for op blockers in the whole chain between bs and base */
- for (iter = bs; iter && iter != base_bs; iter = backing_bs(iter)) {
+ for (iter = bs; iter && iter != base_bs;
+ iter = bdrv_filter_or_cow_bs(iter))
+ {
if (bdrv_op_is_blocked(iter, BLOCK_OP_TYPE_STREAM, errp)) {
goto out;
}
--
2.26.2
- [PATCH v8 03/43] block: bdrv_cow_child() for bdrv_has_zero_init(), (continued)
- [PATCH v8 03/43] block: bdrv_cow_child() for bdrv_has_zero_init(), Max Reitz, 2020/09/01
- [PATCH v8 02/43] block: Add chain helper functions, Max Reitz, 2020/09/01
- [PATCH v8 04/43] block: bdrv_set_backing_hd() is about bs->backing, Max Reitz, 2020/09/01
- [PATCH v8 06/43] block: Drop bdrv_is_encrypted(), Max Reitz, 2020/09/01
- [PATCH v8 05/43] block: Include filters when freezing backing chain, Max Reitz, 2020/09/01
- [PATCH v8 07/43] block: Add bdrv_supports_compressed_writes(), Max Reitz, 2020/09/01
- [PATCH v8 08/43] throttle: Support compressed writes, Max Reitz, 2020/09/01
- [PATCH v8 09/43] copy-on-read: Support compressed writes, Max Reitz, 2020/09/01
- [PATCH v8 10/43] block: Use bdrv_filter_(bs|child) where obvious, Max Reitz, 2020/09/01
- [PATCH v8 11/43] block: Use CAFs in block status functions, Max Reitz, 2020/09/01
- [PATCH v8 12/43] stream: Deal with filters,
Max Reitz <=
- [PATCH v8 13/43] block: Use CAFs when working with backing chains, Max Reitz, 2020/09/01
- [PATCH v8 14/43] block: Use bdrv_cow_child() in bdrv_co_truncate(), Max Reitz, 2020/09/01
- [PATCH v8 15/43] block: Re-evaluate backing file handling in reopen, Max Reitz, 2020/09/01
- [PATCH v8 17/43] vmdk: Drop vmdk_co_flush(), Max Reitz, 2020/09/01
- [PATCH v8 16/43] block: Flush all children in generic code, Max Reitz, 2020/09/01
- [PATCH v8 18/43] block: Iterate over children in refresh_limits, Max Reitz, 2020/09/01
- [PATCH v8 19/43] block: Use CAFs in bdrv_refresh_filename(), Max Reitz, 2020/09/01
- [PATCH v8 20/43] block: Use CAF in bdrv_co_rw_vmstate(), Max Reitz, 2020/09/01
- [PATCH v8 21/43] block/snapshot: Fix fallback, Max Reitz, 2020/09/01
- [PATCH v8 24/43] block/null: Implement bdrv_get_allocated_file_size, Max Reitz, 2020/09/01