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block: rename backup-top to copy-before-write

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We are going to convert backup_top to full featured public filter,
which can be used in separate of backup job. Start from renaming from
"how it used" to "what it does".

While updating comments in 283 iotest, drop and rephrase also things
about ".active", as this field is now dropped, and filter doesn't have
"inactive" mode.

Note that this change may be considered as incompatible interface
change, as backup-top filter format name was visible through
query-block and query-named-block-nodes.

Still, consider the following reasoning:

1. backup-top was never documented, so if someone depends on format
   name (for driver that can't be used other than it is automatically
   inserted on backup job start), it's a kind of "undocumented feature
   use". So I think we are free to change it.

2. There is a hope, that there is no such users: it's a lot more native
   to give a good node-name to backup-top filter if need to operate
   with it somehow, and don't touch format name.

3. Another "incompatible" change in further commit would be moving
   copy-before-write filter from using backing child to file child. And
   this is even more reasonable than renaming: for now all public
   filters are file-child based.

So, it's a risky change, but risk seems small and good interface worth
it.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210824083856.17408-6-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2021-08-24 11:38:27 +03:00 • committed by Hanna Reitz
parent d1a58c176a
commit d003e0aece
7 changed files with 95 additions and 100 deletions
Download patch file Download diff file Expand all files Collapse all files

22
block/backup.c
View file

@ -27,13 +27,13 @@
#include "qemu/bitmap.h"
#include "qemu/error-report.h"
#include "block/backup-top.h"
#include "block/copy-before-write.h"
#define BACKUP_CLUSTER_SIZE_DEFAULT (1 << 16)
typedef struct BackupBlockJob {
BlockJob common;
BlockDriverState *backup_top;
BlockDriverState *cbw;
BlockDriverState *source_bs;
BlockDriverState *target_bs;
@ -104,7 +104,7 @@ static void backup_clean(Job *job)
{
BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
block_job_remove_all_bdrv(&s->common);
bdrv_backup_top_drop(s->backup_top);
bdrv_cbw_drop(s->cbw);
}
void backup_do_checkpoint(BlockJob *job, Error **errp)
@ -408,7 +408,7 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
BackupBlockJob *job = NULL;
int64_t cluster_size;
BdrvRequestFlags write_flags;
BlockDriverState *backup_top = NULL;
BlockDriverState *cbw = NULL;
BlockCopyState *bcs = NULL;
assert(bs);
@ -521,22 +521,22 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
write_flags = (bdrv_chain_contains(target, bs) ? BDRV_REQ_SERIALISING : 0) |
(compress ? BDRV_REQ_WRITE_COMPRESSED : 0),
backup_top = bdrv_backup_top_append(bs, target, filter_node_name,
cbw = bdrv_cbw_append(bs, target, filter_node_name,
cluster_size, perf,
write_flags, &bcs, errp);
if (!backup_top) {
if (!cbw) {
goto error;
}
/* job->len is fixed, so we can't allow resize */
job = block_job_create(job_id, &backup_job_driver, txn, backup_top,
job = block_job_create(job_id, &backup_job_driver, txn, cbw,
0, BLK_PERM_ALL,
speed, creation_flags, cb, opaque, errp);
if (!job) {
goto error;
}
job->backup_top = backup_top;
job->cbw = cbw;
job->source_bs = bs;
job->target_bs = target;
job->on_source_error = on_source_error;
@ -552,7 +552,7 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
block_copy_set_progress_meter(bcs, &job->common.job.progress);
block_copy_set_speed(bcs, speed);
/* Required permissions are already taken by backup-top target */
/* Required permissions are taken by copy-before-write filter target */
block_job_add_bdrv(&job->common, "target", target, 0, BLK_PERM_ALL,
&error_abort);
@ -562,8 +562,8 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
if (sync_bitmap) {
bdrv_reclaim_dirty_bitmap(sync_bitmap, NULL);
}
if (backup_top) {
bdrv_backup_top_drop(backup_top);
if (cbw) {
bdrv_cbw_drop(cbw);
}
return NULL;