From: Dominik Csapak <d.csapak@proxmox.com>
To: Wolfgang Bumiller <w.bumiller@proxmox.com>
Cc: pbs-devel@lists.proxmox.com
Subject: Re: [pbs-devel] [PATCH proxmox-backup 2/2] backup/datastore: move manifest locking to /run
Date: Wed, 2 Dec 2020 14:58:12 +0100 [thread overview]
Message-ID: <57c91b8c-ef08-2b28-595c-20db7cb8d8da@proxmox.com> (raw)
In-Reply-To: <20201202135000.nxcyky5lhnxddi6a@wobu-vie.proxmox.com>
On 12/2/20 2:50 PM, Wolfgang Bumiller wrote:
> On Wed, Dec 02, 2020 at 02:19:57PM +0100, Dominik Csapak wrote:
>> this fixes the issue that on some filesystems, you cannot recursively
>> remove a directory when you hold a lock on a file inside (e.g. nfs/cifs)
>>
>> it is not really backwards compatible (so during an upgrade, there
>> could be two daemons have the lock), but since the locking was
>> broken before (see previous patch) it should not really matter
>> (also it seems very unlikely that someone will trigger this)
>>
>> Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
>> ---
>> src/backup/datastore.rs | 26 +++++++++++++++++++++++---
>> 1 file changed, 23 insertions(+), 3 deletions(-)
>>
>> diff --git a/src/backup/datastore.rs b/src/backup/datastore.rs
>> index 0f74ac3c..9cc88906 100644
>> --- a/src/backup/datastore.rs
>> +++ b/src/backup/datastore.rs
>> @@ -257,6 +257,12 @@ impl DataStore {
>> )
>> })?;
>>
>> + // the manifest does not exists anymore, we do not need to keep the lock
>> + if let Ok(path) = self.manifest_lock_path(backup_dir) {
>> + // ignore errors
>> + let _ = std::fs::remove_file(path);
>> + }
>> +
>> Ok(())
>> }
>>
>> @@ -698,13 +704,27 @@ impl DataStore {
>> ))
>> }
>>
>
> please describe the path in a doc comment here
ok, but even in a private api?
>
>> + fn manifest_lock_path(
>> + &self,
>> + backup_dir: &BackupDir,
>> + ) -> Result<PathBuf, Error> {
>> +
>> + let mut path = PathBuf::from("/run/proxmox-backup/.locks/");
>
> why `.locks` and not just `locks`? I don't see the benefit in "hidden"
> files in `/run`?
yeah you're right, no sense in making this hidden
>
>> + path.push(self.name());
>> + path.push(backup_dir.group().backup_type());
>> + path.push(backup_dir.group().backup_id());
>> + std::fs::create_dir_all(&path)?;
>
> Is there a particular reason you use a `PathBuf` here this way? Looks
> like you could just `format!()` it all the same? Since none of these
> types are `Path`s to begin with anyway.
>
> Since those components are all strings, IMO you could work with a
> `String` from the start and only convert to PathBuf at the end.
>
> Would save you the extra String allocation below.
ok will do
>
> So if I see this right, the file will then be
> /run/proxmox-backup/.locks/$store/${type}/${id}/${timestamp}.index.json.lck
>
> seems reasonable apart from the dot in `.locks` ;-)
>
> However, do we really need the directory structure here?
> Shouldn't a flat `.../locks/${type}.${id}.${timestamp}.index.json` be
> fine as well? (I don't really mind, it would just be less code ;-) )
for now, ids do not really have a length limit besides the fs filename
limit of 255 bytes
and since i had to factor that out, i did for datastore/type as well
(would look even weirder to use something like:
.../locks/${datastore}.${type}/${id}/${timestamp}.index.json.lck
)
though we probably should limit the id length anyway...
>
>> +
>> + path.push(format!( "{}{}", backup_dir.backup_time_string(), &MANIFEST_LOCK_NAME));
>> +
>> + Ok(path)
>> + }
>> +
>> fn lock_manifest(
>> &self,
>> backup_dir: &BackupDir,
>> ) -> Result<File, Error> {
>> - let mut path = self.base_path();
>> - path.push(backup_dir.relative_path());
>> - path.push(&MANIFEST_LOCK_NAME);
>> + let path = self.manifest_lock_path(backup_dir)?;
>>
>> // update_manifest should never take a long time, so if someone else has
>> // the lock we can simply block a bit and should get it soon
>> --
>> 2.20.1
next prev parent reply other threads:[~2020-12-02 13:58 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-02 13:19 [pbs-devel] [PATCH proxmox-backup 1/2] backup/datastore: really lock manifest on delete Dominik Csapak
2020-12-02 13:19 ` [pbs-devel] [PATCH proxmox-backup 2/2] backup/datastore: move manifest locking to /run Dominik Csapak
2020-12-02 13:50 ` Wolfgang Bumiller
2020-12-02 13:58 ` Dominik Csapak [this message]
2020-12-02 14:07 ` Wolfgang Bumiller
2020-12-02 13:40 ` [pbs-devel] applied: [PATCH proxmox-backup 1/2] backup/datastore: really lock manifest on delete Wolfgang Bumiller
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=57c91b8c-ef08-2b28-595c-20db7cb8d8da@proxmox.com \
--to=d.csapak@proxmox.com \
--cc=pbs-devel@lists.proxmox.com \
--cc=w.bumiller@proxmox.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.
Service provided by Proxmox Server Solutions GmbH | Privacy | Legal