2022-03-02 12:05:16 +03:00
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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Fabian Ebner <f.ebner@proxmox.com>
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Date: Wed, 2 Mar 2022 08:35:05 +0100
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Subject: [PATCH] block/backup: move bcs bitmap initialization to job creation
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For backing up the state of multiple disks from the same time, a job
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for each disk has to be created. It's convenient if the jobs don't
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have to be started at the same time and if operation of the VM can be
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resumed after job creation. This would lead to a window between job
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creation and running the job, where writes can happen. But no writes
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should happen between setting up the copy-before-write filter and
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setting up the block copy state bitmap, because then new writes would
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just pass through.
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Commit 06e0a9c16405c0a4c1eca33cf286cc04c42066a2 moved initalization of
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the bitmap to setting up the copy-before-write filter when sync_mode
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is not MIRROR_SYNC_MODE_BITMAP. Ensure that the bitmap is initialized
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upon job creation for the remaining case too, by moving the
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backup_init_bcs_bitmap call to backup_job_create.
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Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
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2022-04-25 11:07:01 +03:00
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Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
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2022-03-02 12:05:16 +03:00
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---
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block/backup.c | 8 ++++----
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1 file changed, 4 insertions(+), 4 deletions(-)
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diff --git a/block/backup.c b/block/backup.c
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2022-12-14 17:16:32 +03:00
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index 6a9ad97a53..9b0151c5be 100644
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2022-03-02 12:05:16 +03:00
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--- a/block/backup.c
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+++ b/block/backup.c
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update submodule and patches to 7.1.0
Notable changes:
* The only big change is the switch to using a custom QIOChannel for
savevm-async, because the previously used QEMUFileOps was dropped.
Changes to the current implementation:
* Switch to vector based methods as required for an IO channel. For
short reads the passed-in IO vector is stuffed with zeroes at the
end, just to be sure.
* For reading: The documentation in include/io/channel.h states that
at least one byte should be read, so also error out when whe are
at the very end instead of returning 0.
* For reading: Fix off-by-one error when request goes beyond end.
The wrong code piece was:
if ((pos + size) > maxlen) {
size = maxlen - pos - 1;
}
Previously, the last byte would not be read. It's actually
possible to get a snapshot .raw file that has content all the way
up the final 512 byte (= BDRV_SECTOR_SIZE) boundary without any
trailing zero bytes (I wrote a script to do it).
Luckily, it didn't cause a real issue, because qemu_loadvm_state()
is not interested in the final (i.e. QEMU_VM_VMDESCRIPTION)
section. The buffer for reading it is simply freed up afterwards
and the function will assume that it read the whole section, even
if that's not the case.
* For writing: Make use of the generated blk_pwritev() wrapper
instead of manually wrapping the coroutine to simplify and save a
few lines.
* Adapt to changed interfaces for blk_{pread,pwrite}:
* a9262f551e ("block: Change blk_{pread,pwrite}() param order")
* 3b35d4542c ("block: Add a 'flags' param to blk_pread()")
* bf5b16fa40 ("block: Make blk_{pread,pwrite}() return 0 on success")
Those changes especially affected the qemu-img dd patches, because
the context also changed, but also some of our block drivers used
the functions.
* Drop qemu-common.h include: it got renamed after essentially
everything was moved to other headers. The only remaining user I
could find for things dropped from the header between 7.0 and 7.1
was qemu_get_vm_name() in the iscsi-initiatorname patch, but it
already includes the header to which the function was moved.
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
2022-10-14 15:07:13 +03:00
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@@ -237,8 +237,8 @@ static void backup_init_bcs_bitmap(BackupBlockJob *job)
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true);
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2022-03-02 12:05:16 +03:00
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} else if (job->sync_mode == MIRROR_SYNC_MODE_TOP) {
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/*
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- * We can't hog the coroutine to initialize this thoroughly.
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- * Set a flag and resume work when we are able to yield safely.
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+ * Initialization is costly here. Simply set a flag and let the
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+ * backup_run coroutine resume work once it can yield safely.
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*/
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block_copy_set_skip_unallocated(job->bcs, true);
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}
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update submodule and patches to 7.1.0
Notable changes:
* The only big change is the switch to using a custom QIOChannel for
savevm-async, because the previously used QEMUFileOps was dropped.
Changes to the current implementation:
* Switch to vector based methods as required for an IO channel. For
short reads the passed-in IO vector is stuffed with zeroes at the
end, just to be sure.
* For reading: The documentation in include/io/channel.h states that
at least one byte should be read, so also error out when whe are
at the very end instead of returning 0.
* For reading: Fix off-by-one error when request goes beyond end.
The wrong code piece was:
if ((pos + size) > maxlen) {
size = maxlen - pos - 1;
}
Previously, the last byte would not be read. It's actually
possible to get a snapshot .raw file that has content all the way
up the final 512 byte (= BDRV_SECTOR_SIZE) boundary without any
trailing zero bytes (I wrote a script to do it).
Luckily, it didn't cause a real issue, because qemu_loadvm_state()
is not interested in the final (i.e. QEMU_VM_VMDESCRIPTION)
section. The buffer for reading it is simply freed up afterwards
and the function will assume that it read the whole section, even
if that's not the case.
* For writing: Make use of the generated blk_pwritev() wrapper
instead of manually wrapping the coroutine to simplify and save a
few lines.
* Adapt to changed interfaces for blk_{pread,pwrite}:
* a9262f551e ("block: Change blk_{pread,pwrite}() param order")
* 3b35d4542c ("block: Add a 'flags' param to blk_pread()")
* bf5b16fa40 ("block: Make blk_{pread,pwrite}() return 0 on success")
Those changes especially affected the qemu-img dd patches, because
the context also changed, but also some of our block drivers used
the functions.
* Drop qemu-common.h include: it got renamed after essentially
everything was moved to other headers. The only remaining user I
could find for things dropped from the header between 7.0 and 7.1
was qemu_get_vm_name() in the iscsi-initiatorname patch, but it
already includes the header to which the function was moved.
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
2022-10-14 15:07:13 +03:00
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@@ -252,8 +252,6 @@ static int coroutine_fn backup_run(Job *job, Error **errp)
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2022-03-02 12:05:16 +03:00
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BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
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int ret;
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- backup_init_bcs_bitmap(s);
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-
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if (s->sync_mode == MIRROR_SYNC_MODE_TOP) {
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int64_t offset = 0;
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int64_t count;
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update submodule and patches to 7.1.0
Notable changes:
* The only big change is the switch to using a custom QIOChannel for
savevm-async, because the previously used QEMUFileOps was dropped.
Changes to the current implementation:
* Switch to vector based methods as required for an IO channel. For
short reads the passed-in IO vector is stuffed with zeroes at the
end, just to be sure.
* For reading: The documentation in include/io/channel.h states that
at least one byte should be read, so also error out when whe are
at the very end instead of returning 0.
* For reading: Fix off-by-one error when request goes beyond end.
The wrong code piece was:
if ((pos + size) > maxlen) {
size = maxlen - pos - 1;
}
Previously, the last byte would not be read. It's actually
possible to get a snapshot .raw file that has content all the way
up the final 512 byte (= BDRV_SECTOR_SIZE) boundary without any
trailing zero bytes (I wrote a script to do it).
Luckily, it didn't cause a real issue, because qemu_loadvm_state()
is not interested in the final (i.e. QEMU_VM_VMDESCRIPTION)
section. The buffer for reading it is simply freed up afterwards
and the function will assume that it read the whole section, even
if that's not the case.
* For writing: Make use of the generated blk_pwritev() wrapper
instead of manually wrapping the coroutine to simplify and save a
few lines.
* Adapt to changed interfaces for blk_{pread,pwrite}:
* a9262f551e ("block: Change blk_{pread,pwrite}() param order")
* 3b35d4542c ("block: Add a 'flags' param to blk_pread()")
* bf5b16fa40 ("block: Make blk_{pread,pwrite}() return 0 on success")
Those changes especially affected the qemu-img dd patches, because
the context also changed, but also some of our block drivers used
the functions.
* Drop qemu-common.h include: it got renamed after essentially
everything was moved to other headers. The only remaining user I
could find for things dropped from the header between 7.0 and 7.1
was qemu_get_vm_name() in the iscsi-initiatorname patch, but it
already includes the header to which the function was moved.
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
2022-10-14 15:07:13 +03:00
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@@ -492,6 +490,8 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
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2022-03-02 12:05:16 +03:00
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block_job_add_bdrv(&job->common, "target", target, 0, BLK_PERM_ALL,
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&error_abort);
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+ backup_init_bcs_bitmap(job);
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+
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return &job->common;
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error:
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