5b15e2ecaf
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>
77 lines
2.7 KiB
Diff
77 lines
2.7 KiB
Diff
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, 25 May 2022 13:59:38 +0200
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Subject: [PATCH] PVE-Backup: ensure jobs in di_list are referenced
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Ensures that qmp_backup_cancel doesn't pick a job that's already been
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freed. With unlucky timings it seems possible that:
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1. job_exit -> job_completed -> job_finalize_single starts
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2. pvebackup_co_complete_stream gets spawned in completion callback
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3. job finalize_single finishes -> job's refcount hits zero -> job is
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freed
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4. qmp_backup_cancel comes in and locks backup_state.backup_mutex
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before pvebackup_co_complete_stream can remove the job from the
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di_list
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5. qmp_backup_cancel will pick a job that's already been freed
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Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
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Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
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---
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pve-backup.c | 25 ++++++++++++++++++++-----
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1 file changed, 20 insertions(+), 5 deletions(-)
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diff --git a/pve-backup.c b/pve-backup.c
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index 5bed6f4014..0c34428713 100644
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--- a/pve-backup.c
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+++ b/pve-backup.c
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@@ -316,6 +316,14 @@ static void coroutine_fn pvebackup_co_complete_stream(void *opaque)
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}
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}
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+ if (di->job) {
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+ AioContext *ctx = di->job->job.aio_context;
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+ aio_context_acquire(ctx);
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+ job_unref(&di->job->job);
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+ di->job = NULL;
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+ aio_context_release(ctx);
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+ }
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+
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// remove self from job list
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backup_state.di_list = g_list_remove(backup_state.di_list, di);
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@@ -491,9 +499,12 @@ static void create_backup_jobs_bh(void *opaque) {
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bitmap_mode, false, NULL, &perf, BLOCKDEV_ON_ERROR_REPORT, BLOCKDEV_ON_ERROR_REPORT,
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JOB_DEFAULT, pvebackup_complete_cb, di, backup_state.txn, &local_err);
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- aio_context_release(aio_context);
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-
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di->job = job;
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+ if (job) {
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+ job_ref(&job->job);
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+ }
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+
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+ aio_context_release(aio_context);
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if (!job || local_err) {
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error_setg(errp, "backup_job_create failed: %s",
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@@ -521,12 +532,16 @@ static void create_backup_jobs_bh(void *opaque) {
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di->target = NULL;
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}
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- if (!canceled && di->job) {
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+ if (di->job) {
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AioContext *ctx = di->job->job.aio_context;
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aio_context_acquire(ctx);
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- job_cancel_sync(&di->job->job, true);
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+ if (!canceled) {
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+ job_cancel_sync(&di->job->job, true);
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+ canceled = true;
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+ }
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+ job_unref(&di->job->job);
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+ di->job = NULL;
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aio_context_release(ctx);
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- canceled = true;
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}
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}
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}
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