From: "Fabian Grünbichler" <f.gruenbichler@proxmox.com>
To: Proxmox Backup Server development discussion
<pbs-devel@lists.proxmox.com>
Subject: Re: [pbs-devel] [PATCH] datastore: fix problem with operations counting
Date: Thu, 25 Apr 2024 10:41:46 +0200 [thread overview]
Message-ID: <1714034383.t1rdpl0dov.astroid@yuna.none> (raw)
In-Reply-To: <20240425083211.60986-1-h.laimer@proxmox.com>
On April 25, 2024 10:32 am, Hannes Laimer wrote:
> ... if `.chunks/` is not available(deleted/moved) ChunkStore::open
> fails, but that would happen after updating the active operations on the
> datastore, so no reference that could be dropped is returned. Leading to
> the operations counter to always increase. This only updates the counter
> when a reference is returned, not before.
>
> Signed-off-by: Hannes Laimer <h.laimer@proxmox.com>
> ---
> pbs-datastore/src/datastore.rs | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/pbs-datastore/src/datastore.rs b/pbs-datastore/src/datastore.rs
> index f95da761..2f8952ae 100644
> --- a/pbs-datastore/src/datastore.rs
> +++ b/pbs-datastore/src/datastore.rs
> @@ -158,10 +158,6 @@ impl DataStore {
> }
> }
>
> - if let Some(operation) = operation {
> - update_active_operations(name, operation, 1)?;
> - }
> -
> // Our operation is registered, unlock the config.
> drop(config_lock);
this comment here, and the bigger one just out of context at the start
of this fn:
// Avoid TOCTOU between checking maintenance mode and updating active operation counter, as
// we use it to decide whether it is okay to delete the datastore.
let config_lock = pbs_config::datastore::lock_config()?;
make me think that this commit at least lacks a rationale why this
change is safe, but possibly means that we would need to hold the config
lock longer here?
>
> @@ -172,6 +168,9 @@ impl DataStore {
> let chunk_store = if let Some(datastore) = &entry {
> let last_digest = datastore.last_digest.as_ref();
> if let Some(true) = last_digest.map(|last_digest| last_digest == &digest) {
> + if let Some(operation) = operation {
> + update_active_operations(name, operation, 1)?;
> + }
> return Ok(Arc::new(Self {
> inner: Arc::clone(datastore),
> operation,
> @@ -195,6 +194,10 @@ impl DataStore {
> let datastore = Arc::new(datastore);
> datastore_cache.insert(name.to_string(), datastore.clone());
>
> + if let Some(operation) = operation {
> + update_active_operations(name, operation, 1)?;
> + }
> +
> Ok(Arc::new(Self {
> inner: datastore,
> operation,
> --
> 2.39.2
>
>
>
> _______________________________________________
> pbs-devel mailing list
> pbs-devel@lists.proxmox.com
> https://lists.proxmox.com/cgi-bin/mailman/listinfo/pbs-devel
>
>
>
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next prev parent reply other threads:[~2024-04-25 8:42 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-25 8:32 Hannes Laimer
2024-04-25 8:41 ` Fabian Grünbichler [this message]
2024-04-25 8:55 ` Hannes Laimer
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