From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
To: qemu-block@nongnu.org
Cc: qemu-devel@nongnu.org, vsementsov@virtuozzo.com,
jsnow@redhat.com, mreitz@redhat.com, kwolf@redhat.com
Subject: [PATCH v5 08/35] block-copy: always set BDRV_REQ_SERIALISING flag
Date: Thu, 10 Jun 2021 14:25:51 +0300 [thread overview]
Message-ID: <20210610112618.127378-9-vsementsov@virtuozzo.com> (raw)
In-Reply-To: <20210610112618.127378-1-vsementsov@virtuozzo.com>
It won't hurt in common case, so let's not bother with detecting image
fleecing.
Also, we want to simplify initialization interface of copy-before-write
filter as we are going to make it public.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
---
block/copy-before-write.h | 2 +-
include/block/block-copy.h | 3 +--
block/backup.c | 21 +--------------------
block/block-copy.c | 29 ++++++++++++++++++++++++++---
block/copy-before-write.c | 4 ++--
5 files changed, 31 insertions(+), 28 deletions(-)
diff --git a/block/copy-before-write.h b/block/copy-before-write.h
index 5977b7aa31..f37e2249ae 100644
--- a/block/copy-before-write.h
+++ b/block/copy-before-write.h
@@ -34,7 +34,7 @@ BlockDriverState *bdrv_cbw_append(BlockDriverState *source,
const char *filter_node_name,
uint64_t cluster_size,
BackupPerf *perf,
- BdrvRequestFlags write_flags,
+ bool compress,
BlockCopyState **bcs,
Error **errp);
void bdrv_cbw_drop(BlockDriverState *bs);
diff --git a/include/block/block-copy.h b/include/block/block-copy.h
index 338f2ea7fd..c013a20e1e 100644
--- a/include/block/block-copy.h
+++ b/include/block/block-copy.h
@@ -24,8 +24,7 @@ typedef struct BlockCopyCallState BlockCopyCallState;
BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
int64_t cluster_size, bool use_copy_range,
- BdrvRequestFlags write_flags,
- Error **errp);
+ bool compress, Error **errp);
void block_copy_set_progress_meter(BlockCopyState *s, ProgressMeter *pm);
diff --git a/block/backup.c b/block/backup.c
index ac91821b08..84f9a5f02c 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -407,7 +407,6 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
int64_t len, target_len;
BackupBlockJob *job = NULL;
int64_t cluster_size;
- BdrvRequestFlags write_flags;
BlockDriverState *cbw = NULL;
BlockCopyState *bcs = NULL;
@@ -504,26 +503,8 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
goto error;
}
- /*
- * If source is in backing chain of target assume that target is going to be
- * used for "image fleecing", i.e. it should represent a kind of snapshot of
- * source at backup-start point in time. And target is going to be read by
- * somebody (for example, used as NBD export) during backup job.
- *
- * In this case, we need to add BDRV_REQ_SERIALISING write flag to avoid
- * intersection of backup writes and third party reads from target,
- * otherwise reading from target we may occasionally read already updated by
- * guest data.
- *
- * For more information see commit f8d59dfb40bb and test
- * tests/qemu-iotests/222
- */
- write_flags = (bdrv_chain_contains(target, bs) ? BDRV_REQ_SERIALISING : 0) |
- (compress ? BDRV_REQ_WRITE_COMPRESSED : 0),
-
cbw = bdrv_cbw_append(bs, target, filter_node_name,
- cluster_size, perf,
- write_flags, &bcs, errp);
+ cluster_size, perf, compress, &bcs, errp);
if (!cbw) {
goto error;
}
diff --git a/block/block-copy.c b/block/block-copy.c
index 5808cfe657..22a7c64c10 100644
--- a/block/block-copy.c
+++ b/block/block-copy.c
@@ -247,7 +247,7 @@ static uint32_t block_copy_max_transfer(BdrvChild *source, BdrvChild *target)
BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
int64_t cluster_size, bool use_copy_range,
- BdrvRequestFlags write_flags, Error **errp)
+ bool compress, Error **errp)
{
BlockCopyState *s;
BdrvDirtyBitmap *copy_bitmap;
@@ -259,6 +259,28 @@ BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
}
bdrv_disable_dirty_bitmap(copy_bitmap);
+ /*
+ * Why we always set BDRV_REQ_SERIALISING write flag:
+ *
+ * Assume source is in backing chain of target assume that target is going
+ * to be used for "image fleecing", i.e. it should represent a kind of
+ * snapshot of source at backup-start point in time. And target is going to
+ * be read by somebody (for example, used as NBD export) during backup job.
+ *
+ * In this case, we need to add BDRV_REQ_SERIALISING write flag to avoid
+ * intersection of backup writes and third party reads from target,
+ * otherwise reading from target we may occasionally read already updated by
+ * guest data.
+ *
+ * For more information see commit f8d59dfb40bb and test
+ * tests/qemu-iotests/222
+ *
+ * Other cases? The only known reasonable case is "just copy to target, and
+ * target is not used for something else". In this case BDRV_REQ_SERIALISING
+ * change nothing, so let's not bother with detecting the "image fleecing"
+ * case and enabling BDRV_REQ_SERIALISING only for it.
+ */
+
s = g_new(BlockCopyState, 1);
*s = (BlockCopyState) {
.source = source,
@@ -266,7 +288,8 @@ BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
.copy_bitmap = copy_bitmap,
.cluster_size = cluster_size,
.len = bdrv_dirty_bitmap_size(copy_bitmap),
- .write_flags = write_flags,
+ .write_flags = BDRV_REQ_SERIALISING |
+ (compress ? BDRV_REQ_WRITE_COMPRESSED : 0),
.mem = shres_create(BLOCK_COPY_MAX_MEM),
};
@@ -279,7 +302,7 @@ BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
*/
s->use_copy_range = false;
s->copy_size = cluster_size;
- } else if (write_flags & BDRV_REQ_WRITE_COMPRESSED) {
+ } else if (compress) {
/* Compression supports only cluster-size writes and no copy-range. */
s->use_copy_range = false;
s->copy_size = cluster_size;
diff --git a/block/copy-before-write.c b/block/copy-before-write.c
index 0dc5a107cf..4337076c1c 100644
--- a/block/copy-before-write.c
+++ b/block/copy-before-write.c
@@ -171,7 +171,7 @@ BlockDriverState *bdrv_cbw_append(BlockDriverState *source,
const char *filter_node_name,
uint64_t cluster_size,
BackupPerf *perf,
- BdrvRequestFlags write_flags,
+ bool compress,
BlockCopyState **bcs,
Error **errp)
{
@@ -218,7 +218,7 @@ BlockDriverState *bdrv_cbw_append(BlockDriverState *source,
state->cluster_size = cluster_size;
state->bcs = block_copy_state_new(top->backing, state->target,
cluster_size, perf->use_copy_range,
- write_flags, errp);
+ compress, errp);
if (!state->bcs) {
error_prepend(errp, "Cannot create block-copy-state: ");
goto fail;
--
2.29.2
next prev parent reply other threads:[~2021-06-10 11:33 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-10 11:25 [PATCH v5 00/35] block: publish backup-top filter Vladimir Sementsov-Ogievskiy
2021-06-10 11:25 ` [PATCH v5 01/35] block: rename bdrv_replace_child to bdrv_replace_child_tran Vladimir Sementsov-Ogievskiy
2021-06-10 11:25 ` [PATCH v5 02/35] block: comment graph-modifying function not updating permissions Vladimir Sementsov-Ogievskiy
2021-06-10 11:25 ` [PATCH v5 03/35] block: introduce bdrv_replace_child_bs() Vladimir Sementsov-Ogievskiy
2021-06-10 11:25 ` [PATCH v5 04/35] block: introduce blk_replace_bs Vladimir Sementsov-Ogievskiy
2021-06-10 11:25 ` [PATCH v5 05/35] qdev-properties: PropertyInfo: add realized_set_allowed field Vladimir Sementsov-Ogievskiy
2021-06-10 11:25 ` [PATCH v5 06/35] qdev: allow setting drive property for realized device Vladimir Sementsov-Ogievskiy
2021-06-10 11:25 ` [PATCH v5 07/35] block: rename backup-top to copy-before-write Vladimir Sementsov-Ogievskiy
2021-06-10 11:25 ` Vladimir Sementsov-Ogievskiy [this message]
2021-06-10 11:25 ` [PATCH v5 09/35] block/block-copy: introduce block_copy_set_copy_opts() Vladimir Sementsov-Ogievskiy
2021-06-10 11:25 ` [PATCH v5 10/35] block/backup: set copy_range and compress after filter insertion Vladimir Sementsov-Ogievskiy
2021-06-10 11:25 ` [PATCH v5 11/35] block/backup: move cluster size calculation to block-copy Vladimir Sementsov-Ogievskiy
2021-06-10 11:25 ` [PATCH v5 12/35] block/copy-before-write: relax permission requirements when no parents Vladimir Sementsov-Ogievskiy
2021-06-10 11:25 ` [PATCH v5 13/35] block/copy-before-write: drop extra bdrv_unref on failure path Vladimir Sementsov-Ogievskiy
2021-06-10 11:25 ` [PATCH v5 14/35] block/copy-before-write: use file child instead of backing Vladimir Sementsov-Ogievskiy
2021-06-10 11:25 ` [PATCH v5 15/35] block/copy-before-write: bdrv_cbw_append(): replace child at last Vladimir Sementsov-Ogievskiy
2021-06-10 11:25 ` [PATCH v5 16/35] block/copy-before-write: introduce cbw_init() Vladimir Sementsov-Ogievskiy
2021-06-10 11:26 ` [PATCH v5 17/35] block/copy-before-write: cbw_init(): rename variables Vladimir Sementsov-Ogievskiy
2021-06-10 11:26 ` [PATCH v5 18/35] block/copy-before-write: cbw_init(): use file child after attaching Vladimir Sementsov-Ogievskiy
2021-06-10 11:26 ` [PATCH v5 19/35] block/copy-before-write: bdrv_cbw_append(): drop unused compress arg Vladimir Sementsov-Ogievskiy
2021-06-10 11:26 ` [PATCH v5 20/35] block/copy-before-write: cbw_init(): use options Vladimir Sementsov-Ogievskiy
2021-06-10 11:26 ` [PATCH v5 21/35] block/copy-before-write: initialize block-copy bitmap Vladimir Sementsov-Ogievskiy
2021-06-10 11:26 ` [PATCH v5 22/35] block/block-copy: make setting progress optional Vladimir Sementsov-Ogievskiy
2021-06-10 11:26 ` [PATCH v5 23/35] block/copy-before-write: make public block driver Vladimir Sementsov-Ogievskiy
2021-06-10 11:26 ` [PATCH v5 24/35] qapi: publish copy-before-write filter Vladimir Sementsov-Ogievskiy
2021-06-10 11:26 ` [PATCH v5 25/35] python/qemu/machine.py: refactor _qemu_args() Vladimir Sementsov-Ogievskiy
2021-06-10 11:26 ` [PATCH v5 26/35] python/qemu/machine: QEMUMachine: improve qmp() method Vladimir Sementsov-Ogievskiy
2021-06-10 11:26 ` [PATCH v5 27/35] iotests.py: VM: add own __enter__ method Vladimir Sementsov-Ogievskiy
2021-06-10 11:26 ` [PATCH v5 28/35] iotests/222: fix pylint and mypy complains Vladimir Sementsov-Ogievskiy
2021-06-10 11:26 ` [PATCH v5 29/35] iotests/222: constantly use single quotes for strings Vladimir Sementsov-Ogievskiy
2021-06-10 11:26 ` [PATCH v5 30/35] iotests: move 222 to tests/image-fleecing Vladimir Sementsov-Ogievskiy
2021-06-10 11:26 ` [PATCH v5 31/35] iotests.py: hmp_qemu_io: support qdev Vladimir Sementsov-Ogievskiy
2021-06-10 11:26 ` [PATCH v5 32/35] iotests/image-fleecing: proper source device Vladimir Sementsov-Ogievskiy
2021-06-10 11:26 ` [PATCH v5 33/35] iotests/image-fleecing: rename tgt_node Vladimir Sementsov-Ogievskiy
2021-06-10 11:26 ` [PATCH v5 34/35] iotests/image-fleecing: prepare for adding new test-case Vladimir Sementsov-Ogievskiy
2021-06-10 11:26 ` [PATCH v5 35/35] iotests/image-fleecing: add test-case for copy-before-write filter Vladimir Sementsov-Ogievskiy
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210610112618.127378-9-vsementsov@virtuozzo.com \
--to=vsementsov@virtuozzo.com \
--cc=jsnow@redhat.com \
--cc=kwolf@redhat.com \
--cc=mreitz@redhat.com \
--cc=qemu-block@nongnu.org \
--cc=qemu-devel@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).