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[Qemu-devel] [PATCH v17 18/23] block: Reuse bs as backing hd for drive-b
From: |
Fam Zheng |
Subject: |
[Qemu-devel] [PATCH v17 18/23] block: Reuse bs as backing hd for drive-backup sync=none |
Date: |
Wed, 3 May 2017 00:35:53 +0800 |
Opening the backing image for the second time is bad, especially here
when it is also in use as the active image as the source. The
drive-backup job itself doesn't read from target->backing for COW,
instead it gets data from the write notifier, so it's not a big problem.
However, exporting the target to NBD etc. won't work, because of the
likely stale metadata cache.
Use BDRV_O_NO_BACKING in this case and manually set up the backing
BdrvChild.
Cc: address@hidden
Signed-off-by: Fam Zheng <address@hidden>
---
blockdev.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/blockdev.c b/blockdev.c
index 4d8cded..654a880 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3155,6 +3155,7 @@ static BlockJob *do_drive_backup(DriveBackup *backup,
BlockJobTxn *txn,
Error *local_err = NULL;
int flags;
int64_t size;
+ bool set_backing_hd = false;
if (!backup->has_speed) {
backup->speed = 0;
@@ -3205,6 +3206,8 @@ static BlockJob *do_drive_backup(DriveBackup *backup,
BlockJobTxn *txn,
}
if (backup->sync == MIRROR_SYNC_MODE_NONE) {
source = bs;
+ flags |= BDRV_O_NO_BACKING;
+ set_backing_hd = true;
}
size = bdrv_getlength(bs);
@@ -3231,7 +3234,9 @@ static BlockJob *do_drive_backup(DriveBackup *backup,
BlockJobTxn *txn,
}
if (backup->format) {
- options = qdict_new();
+ if (!options) {
+ options = qdict_new();
+ }
qdict_put(options, "driver", qstring_from_str(backup->format));
}
@@ -3242,6 +3247,14 @@ static BlockJob *do_drive_backup(DriveBackup *backup,
BlockJobTxn *txn,
bdrv_set_aio_context(target_bs, aio_context);
+ if (set_backing_hd) {
+ bdrv_set_backing_hd(target_bs, source, &local_err);
+ if (local_err) {
+ bdrv_unref(target_bs);
+ goto out;
+ }
+ }
+
if (backup->has_bitmap) {
bmap = bdrv_find_dirty_bitmap(bs, backup->bitmap);
if (!bmap) {
--
2.9.3
- [Qemu-devel] [PATCH v17 07/23] iotests: 030: Prepare for image locking, (continued)
- [Qemu-devel] [PATCH v17 07/23] iotests: 030: Prepare for image locking, Fam Zheng, 2017/05/02
- [Qemu-devel] [PATCH v17 09/23] iotests: 055: Don't attach the target image already for drive-backup, Fam Zheng, 2017/05/02
- [Qemu-devel] [PATCH v17 11/23] iotests: 087: Don't attach test image twice, Fam Zheng, 2017/05/02
- [Qemu-devel] [PATCH v17 10/23] iotests: 085: Avoid image locking conflict, Fam Zheng, 2017/05/02
- [Qemu-devel] [PATCH v17 12/23] iotests: 091: Quit QEMU before checking image, Fam Zheng, 2017/05/02
- [Qemu-devel] [PATCH v17 13/23] iotests: 172: Use separate images for multiple devices, Fam Zheng, 2017/05/02
- [Qemu-devel] [PATCH v17 14/23] tests: Use null-co:// instead of /dev/null as the dummy image, Fam Zheng, 2017/05/02
- [Qemu-devel] [PATCH v17 15/23] file-posix: Add 'locking' option, Fam Zheng, 2017/05/02
- [Qemu-devel] [PATCH v17 16/23] file-win32: Error out if locking=on, Fam Zheng, 2017/05/02
- [Qemu-devel] [PATCH v17 17/23] tests: Disable image lock in test-replication, Fam Zheng, 2017/05/02
- [Qemu-devel] [PATCH v17 18/23] block: Reuse bs as backing hd for drive-backup sync=none,
Fam Zheng <=
- [Qemu-devel] [PATCH v17 19/23] osdep: Add qemu_lock_fd and qemu_unlock_fd, Fam Zheng, 2017/05/02
- [Qemu-devel] [PATCH v17 20/23] osdep: Fall back to posix lock when OFD lock is unavailable, Fam Zheng, 2017/05/02
- [Qemu-devel] [PATCH v17 21/23] file-posix: Add image locking to perm operations, Fam Zheng, 2017/05/02
- [Qemu-devel] [PATCH v17 23/23] tests: Add POSIX image locking test case 182, Fam Zheng, 2017/05/02
- [Qemu-devel] [PATCH v17 22/23] qemu-iotests: Add test case 153 for image locking, Fam Zheng, 2017/05/02
- Re: [Qemu-devel] [PATCH v17 00/23] block: Image locking series, Kevin Wolf, 2017/05/04