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* [pbs-devel] [PATCH proxmox-backup v9 0/4] refactor datastore locking to use tmpfs
@ 2025-03-26 11:44 Shannon Sterz
  2025-03-26 11:44 ` [pbs-devel] [PATCH proxmox-backup v9 1/4] datastore/api/backup: prepare for fix of #3935 by adding lock helpers Shannon Sterz
                   ` (4 more replies)
  0 siblings, 5 replies; 11+ messages in thread
From: Shannon Sterz @ 2025-03-26 11:44 UTC (permalink / raw)
  To: pbs-devel

The goal of this series is to make it safer to remove backup groups &
snapshots by separating the corresponding directories from their lock
files. By moving the lock files to the tmpfs-backed '/run' directory,
we also make sure that the lock files get cleaned up when the system
reboots.

This series refactors the locking mechanism inside the `DataStore`,
`BackupDir` and `BackupGroup` traits. In a first step locking methods
are added and the existing code is refactored to use them. Commit two
derives a lock file name under '/run' for each group/snapshot. It also
adds double stat'ing. To avoid issues when upgrading, the file
`/run/proxmox-backup/old-locking` is created through a post-install
hook which is used to determine whether the system has been rebooted
and we can safely use the new locking mechanism.

The third commit refactors locking for manifests and brings it in-line
with the group/snapshot locks. Finally, the last commit fixes a race
condition when changing the owner of a datastore.

----
changes from v8 (thanks @ Christian Ebner & Wolfgang Bumiller):
* switch to use `with_context` instead of `map_err` which would swallow
  existing context
* add a reminder to update the version number in postinst to avoid
  building broken packages

changes from v7 (thanks @ Christian Ebner):
* use anyhow's `Context` to provide more context on the call site of a
  locking helper call
* rebase on top of current master to apply cleanly again

changes from v6:
* add old locking safe guards to avoid different versions of the locking
  mechanism being used at the same time (see discussion here [2]).

[2]: https://lore.proxmox.com/pbs-devel/20250306120810.361035-1-m.sandoval@proxmox.com/T/#u

changes from v5:
* re-phrase commit messages to make it clear which commit actually
  fixes the issue and what the commit implies in-terms of semantic
  changes for error messages (thanks @ Thomas Lamprecht)
* make it so the series applies cleanly again and clean up a newly
  added usage of `lock_dir_noblock`

changes from v4 (thanks @ Wolfgang Bumiller):
* stop using `to_string_lossy()`
* switch funtion signature of `create_locked_backup_group()` and
  `create_locked_backup_dir` to use the `Arc` version of a datastore.
* smaller clippy fixes
* rebased on current master

changes from v3:
* moved patch 2 to the front so it can be applied separatelly more
  easily
* rebased on current master

changes from v2:
* different encoding scheme for lock file names
* refactored locking methods to be used by the new BackupDir and
  BackupGroup traits
* adapted lock file names to include namespaces

changes from v1 (thanks @ Wolfgang Bumiller & Thomas Lamprecht):
* split adding locking helpers and move '/run' into two commits
* instead of stat'ing the path of lock file twice, only use the file
  descriptor for one of the stat'ing procedures instead
* several improvements to helper functions and documentation



Shannon Sterz (4):
  datastore/api/backup: prepare for fix of #3935 by adding lock helpers
  fix #3935: datastore/api/backup: move datastore locking to '/run'
  fix #3935: datastore: move manifest locking to new locking method
  fix: api: avoid race condition in set_backup_owner

 Cargo.toml                           |   2 +-
 debian/postinst                      |   5 +
 debian/rules                         |   2 +
 pbs-config/src/lib.rs                |  32 +++-
 pbs-datastore/Cargo.toml             |   1 +
 pbs-datastore/src/backup_info.rs     | 235 ++++++++++++++++++++++++---
 pbs-datastore/src/datastore.rs       |  86 +++++-----
 pbs-datastore/src/snapshot_reader.rs |  20 ++-
 src/api2/admin/datastore.rs          |  13 +-
 src/api2/backup/environment.rs       |  21 +--
 src/api2/backup/mod.rs               |  13 +-
 src/api2/reader/mod.rs               |  11 +-
 src/backup/verify.rs                 |  12 +-
 src/server/sync.rs                   |  13 +-
 14 files changed, 342 insertions(+), 124 deletions(-)

--
2.39.5



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^ permalink raw reply	[flat|nested] 11+ messages in thread
* [pbs-devel] [PATCH proxmox-backup v9 1/4] datastore/api/backup: prepare for fix of #3935 by adding lock helpers
  2025-03-26 11:44 [pbs-devel] [PATCH proxmox-backup v9 0/4] refactor datastore locking to use tmpfs Shannon Sterz
@ 2025-03-26 11:44 ` Shannon Sterz
  2025-03-26 11:44 ` [pbs-devel] [PATCH proxmox-backup v9 2/4] fix #3935: datastore/api/backup: move datastore locking to '/run' Shannon Sterz
                   ` (3 subsequent siblings)
  4 siblings, 0 replies; 11+ messages in thread
From: Shannon Sterz @ 2025-03-26 11:44 UTC (permalink / raw)
  To: pbs-devel

to avoid duplicate code, add helpers for locking groups and snapshots
to the BackupGroup and BackupDir traits respectively and refactor
existing code to use them.

this also adapts error handling by adding relevant context to each
locking helper call site. otherwise, we might loose valuable
information useful for debugging. note, however, that users that
relied on specific error messages will break.

Signed-off-by: Shannon Sterz <s.sterz@proxmox.com>
---
 pbs-datastore/src/backup_info.rs     | 45 ++++++++++++---
 pbs-datastore/src/datastore.rs       | 82 +++++++++++++---------------
 pbs-datastore/src/snapshot_reader.rs |  9 ++-
 src/api2/backup/environment.rs       | 16 +++---
 src/api2/backup/mod.rs               | 13 ++---
 src/api2/reader/mod.rs               | 11 ++--
 src/backup/verify.rs                 | 12 ++--
 src/server/sync.rs                   | 13 ++---
 8 files changed, 106 insertions(+), 95 deletions(-)

diff --git a/pbs-datastore/src/backup_info.rs b/pbs-datastore/src/backup_info.rs
index ef2b982c..c7f7ed53 100644
--- a/pbs-datastore/src/backup_info.rs
+++ b/pbs-datastore/src/backup_info.rs
@@ -3,9 +3,11 @@ use std::os::unix::io::RawFd;
 use std::path::PathBuf;
 use std::sync::Arc;
 
-use anyhow::{bail, format_err, Error};
+use anyhow::{bail, format_err, Context, Error};
 
-use proxmox_sys::fs::{lock_dir_noblock, replace_file, CreateOptions};
+use proxmox_sys::fs::{
+    lock_dir_noblock, lock_dir_noblock_shared, replace_file, CreateOptions, DirLockGuard,
+};
 
 use pbs_api_types::{
     Authid, BackupGroupDeleteStats, BackupNamespace, BackupType, GroupFilter, VerifyState,
@@ -199,9 +201,10 @@ impl BackupGroup {
     /// Returns `BackupGroupDeleteStats`, containing the number of deleted snapshots
     /// and number of protected snaphsots, which therefore were not removed.
     pub fn destroy(&self) -> Result<BackupGroupDeleteStats, Error> {
+        let _guard = self
+            .lock()
+            .with_context(|| format!("while destroying group '{self:?}'"))?;
         let path = self.full_group_path();
-        let _guard =
-            proxmox_sys::fs::lock_dir_noblock(&path, "backup group", "possible running backup")?;
 
         log::info!("removing backup group {:?}", path);
         let mut delete_stats = BackupGroupDeleteStats::default();
@@ -237,6 +240,15 @@ impl BackupGroup {
         self.store
             .set_owner(&self.ns, self.as_ref(), auth_id, force)
     }
+
+    /// Lock a group exclusively
+    pub fn lock(&self) -> Result<DirLockGuard, Error> {
+        lock_dir_noblock(
+            &self.full_group_path(),
+            "backup group",
+            "possible running backup",
+        )
+    }
 }
 
 impl AsRef<pbs_api_types::BackupNamespace> for BackupGroup {
@@ -442,15 +454,33 @@ impl BackupDir {
             .map_err(|err| format_err!("unable to acquire manifest lock {:?} - {}", &path, err))
     }
 
+    /// Lock this snapshot exclusively
+    pub fn lock(&self) -> Result<DirLockGuard, Error> {
+        lock_dir_noblock(
+            &self.full_path(),
+            "snapshot",
+            "backup is running or snapshot is in use",
+        )
+    }
+
+    /// Acquire a shared lock on this snapshot
+    pub fn lock_shared(&self) -> Result<DirLockGuard, Error> {
+        lock_dir_noblock_shared(
+            &self.full_path(),
+            "snapshot",
+            "backup is running or snapshot is in use, could not acquire shared lock",
+        )
+    }
+
     /// Destroy the whole snapshot, bails if it's protected
     ///
     /// Setting `force` to true skips locking and thus ignores if the backup is currently in use.
     pub fn destroy(&self, force: bool) -> Result<(), Error> {
-        let full_path = self.full_path();
-
         let (_guard, _manifest_guard);
         if !force {
-            _guard = lock_dir_noblock(&full_path, "snapshot", "possibly running or in use")?;
+            _guard = self
+                .lock()
+                .with_context(|| format!("while destroying snapshot '{self:?}'"))?;
             _manifest_guard = self.lock_manifest()?;
         }
 
@@ -458,6 +488,7 @@ impl BackupDir {
             bail!("cannot remove protected snapshot"); // use special error type?
         }
 
+        let full_path = self.full_path();
         log::info!("removing backup snapshot {:?}", full_path);
         std::fs::remove_dir_all(&full_path).map_err(|err| {
             format_err!("removing backup snapshot {:?} failed - {}", full_path, err,)
diff --git a/pbs-datastore/src/datastore.rs b/pbs-datastore/src/datastore.rs
index a6a91ca7..1cbd0038 100644
--- a/pbs-datastore/src/datastore.rs
+++ b/pbs-datastore/src/datastore.rs
@@ -5,7 +5,7 @@ use std::os::unix::io::AsRawFd;
 use std::path::{Path, PathBuf};
 use std::sync::{Arc, LazyLock, Mutex};
 
-use anyhow::{bail, format_err, Error};
+use anyhow::{bail, format_err, Context, Error};
 use nix::unistd::{unlinkat, UnlinkatFlags};
 use tracing::{info, warn};
 
@@ -13,8 +13,8 @@ use proxmox_human_byte::HumanByte;
 use proxmox_schema::ApiType;
 
 use proxmox_sys::error::SysError;
+use proxmox_sys::fs::DirLockGuard;
 use proxmox_sys::fs::{file_read_optional_string, replace_file, CreateOptions};
-use proxmox_sys::fs::{lock_dir_noblock, DirLockGuard};
 use proxmox_sys::linux::procfs::MountInfo;
 use proxmox_sys::process_locker::ProcessLockSharedGuard;
 use proxmox_worker_task::WorkerTaskContext;
@@ -774,41 +774,35 @@ impl DataStore {
     ///
     /// This also acquires an exclusive lock on the directory and returns the lock guard.
     pub fn create_locked_backup_group(
-        &self,
+        self: &Arc<Self>,
         ns: &BackupNamespace,
         backup_group: &pbs_api_types::BackupGroup,
         auth_id: &Authid,
     ) -> Result<(Authid, DirLockGuard), Error> {
-        // create intermediate path first:
-        let mut full_path = self.base_path();
-        for ns in ns.components() {
-            full_path.push("ns");
-            full_path.push(ns);
-        }
-        full_path.push(backup_group.ty.as_str());
-        std::fs::create_dir_all(&full_path)?;
+        let backup_group = self.backup_group(ns.clone(), backup_group.clone());
 
-        full_path.push(&backup_group.id);
+        // create intermediate path first
+        let full_path = backup_group.full_group_path();
 
-        // create the last component now
+        std::fs::create_dir_all(full_path.parent().ok_or_else(|| {
+            format_err!("could not construct parent path for group {backup_group:?}")
+        })?)?;
+
+        // now create the group, this allows us to check whether it existed before
         match std::fs::create_dir(&full_path) {
             Ok(_) => {
-                let guard = lock_dir_noblock(
-                    &full_path,
-                    "backup group",
-                    "another backup is already running",
-                )?;
-                self.set_owner(ns, backup_group, auth_id, false)?;
-                let owner = self.get_owner(ns, backup_group)?; // just to be sure
+                let guard = backup_group.lock().with_context(|| {
+                    format!("while creating new locked backup group '{backup_group:?}'")
+                })?;
+                self.set_owner(ns, backup_group.group(), auth_id, false)?;
+                let owner = self.get_owner(ns, backup_group.group())?; // just to be sure
                 Ok((owner, guard))
             }
             Err(ref err) if err.kind() == io::ErrorKind::AlreadyExists => {
-                let guard = lock_dir_noblock(
-                    &full_path,
-                    "backup group",
-                    "another backup is already running",
-                )?;
-                let owner = self.get_owner(ns, backup_group)?; // just to be sure
+                let guard = backup_group.lock().with_context(|| {
+                    format!("while creating locked backup group '{backup_group:?}'")
+                })?;
+                let owner = self.get_owner(ns, backup_group.group())?; // just to be sure
                 Ok((owner, guard))
             }
             Err(err) => bail!("unable to create backup group {:?} - {}", full_path, err),
@@ -819,29 +813,25 @@ impl DataStore {
     ///
     /// The BackupGroup directory needs to exist.
     pub fn create_locked_backup_dir(
-        &self,
+        self: &Arc<Self>,
         ns: &BackupNamespace,
         backup_dir: &pbs_api_types::BackupDir,
     ) -> Result<(PathBuf, bool, DirLockGuard), Error> {
-        let full_path = self.snapshot_path(ns, backup_dir);
-        let relative_path = full_path.strip_prefix(self.base_path()).map_err(|err| {
-            format_err!(
-                "failed to produce correct path for backup {backup_dir} in namespace {ns}: {err}"
-            )
-        })?;
+        let backup_dir = self.backup_dir(ns.clone(), backup_dir.clone())?;
+        let relative_path = backup_dir.relative_path();
 
-        let lock = || {
-            lock_dir_noblock(
-                &full_path,
-                "snapshot",
-                "internal error - tried creating snapshot that's already in use",
-            )
-        };
-
-        match std::fs::create_dir(&full_path) {
-            Ok(_) => Ok((relative_path.to_owned(), true, lock()?)),
+        match std::fs::create_dir(backup_dir.full_path()) {
+            Ok(_) => {
+                let guard = backup_dir.lock().with_context(|| {
+                    format!("while creating new locked snapshot '{backup_dir:?}'")
+                })?;
+                Ok((relative_path, true, guard))
+            }
             Err(ref e) if e.kind() == io::ErrorKind::AlreadyExists => {
-                Ok((relative_path.to_owned(), false, lock()?))
+                let guard = backup_dir
+                    .lock()
+                    .with_context(|| format!("while creating locked snapshot '{backup_dir:?}'"))?;
+                Ok((relative_path, false, guard))
             }
             Err(e) => Err(e.into()),
         }
@@ -1305,7 +1295,9 @@ impl DataStore {
             bail!("snapshot {} does not exist!", backup_dir.dir());
         }
 
-        let _guard = lock_dir_noblock(&full_path, "snapshot", "possibly running or in use")?;
+        let _guard = backup_dir.lock().with_context(|| {
+            format!("while updating the protection status of snapshot '{backup_dir:?}'")
+        })?;
 
         let protected_path = backup_dir.protected_file();
         if protection {
diff --git a/pbs-datastore/src/snapshot_reader.rs b/pbs-datastore/src/snapshot_reader.rs
index 99ae1180..edff19ef 100644
--- a/pbs-datastore/src/snapshot_reader.rs
+++ b/pbs-datastore/src/snapshot_reader.rs
@@ -4,11 +4,9 @@ use std::path::Path;
 use std::rc::Rc;
 use std::sync::Arc;
 
-use anyhow::{bail, Error};
+use anyhow::{bail, Context, Error};
 use nix::dir::Dir;
 
-use proxmox_sys::fs::lock_dir_noblock_shared;
-
 use pbs_api_types::{
     print_store_and_ns, ArchiveType, BackupNamespace, Operation, CLIENT_LOG_BLOB_NAME,
     MANIFEST_BLOB_NAME,
@@ -48,8 +46,9 @@ impl SnapshotReader {
             bail!("snapshot {} does not exist!", snapshot.dir());
         }
 
-        let locked_dir =
-            lock_dir_noblock_shared(&snapshot_path, "snapshot", "locked by another operation")?;
+        let locked_dir = snapshot
+            .lock_shared()
+            .with_context(|| format!("while trying to read snapshot '{snapshot:?}'"))?;
 
         let datastore_name = datastore.name().to_string();
         let manifest = match snapshot.load_manifest() {
diff --git a/src/api2/backup/environment.rs b/src/api2/backup/environment.rs
index 99d885e2..7943b576 100644
--- a/src/api2/backup/environment.rs
+++ b/src/api2/backup/environment.rs
@@ -1,4 +1,4 @@
-use anyhow::{bail, format_err, Error};
+use anyhow::{bail, format_err, Context, Error};
 use nix::dir::Dir;
 use std::collections::HashMap;
 use std::sync::{Arc, Mutex};
@@ -8,7 +8,7 @@ use ::serde::Serialize;
 use serde_json::{json, Value};
 
 use proxmox_router::{RpcEnvironment, RpcEnvironmentType};
-use proxmox_sys::fs::{lock_dir_noblock_shared, replace_file, CreateOptions};
+use proxmox_sys::fs::{replace_file, CreateOptions};
 
 use pbs_api_types::Authid;
 use pbs_datastore::backup_info::{BackupDir, BackupInfo};
@@ -645,12 +645,12 @@ impl BackupEnvironment {
 
         // Downgrade to shared lock, the backup itself is finished
         drop(excl_snap_lock);
-        let snap_lock = lock_dir_noblock_shared(
-            &self.backup_dir.full_path(),
-            "snapshot",
-            "snapshot is already locked by another operation",
-        )?;
-
+        let snap_lock = self.backup_dir.lock_shared().with_context(|| {
+            format!(
+                "while trying to verify snapshot '{:?}' after completion",
+                self.backup_dir
+            )
+        })?;
         let worker_id = format!(
             "{}:{}/{}/{:08X}",
             self.datastore.name(),
diff --git a/src/api2/backup/mod.rs b/src/api2/backup/mod.rs
index efc97a1f..344c80d4 100644
--- a/src/api2/backup/mod.rs
+++ b/src/api2/backup/mod.rs
@@ -1,6 +1,6 @@
 //! Backup protocol (HTTP2 upgrade)
 
-use anyhow::{bail, format_err, Error};
+use anyhow::{bail, format_err, Context, Error};
 use futures::*;
 use hex::FromHex;
 use hyper::header::{HeaderValue, CONNECTION, UPGRADE};
@@ -17,7 +17,6 @@ use proxmox_router::{
 };
 use proxmox_schema::*;
 use proxmox_sortable_macro::sortable;
-use proxmox_sys::fs::lock_dir_noblock_shared;
 
 use pbs_api_types::{
     ArchiveType, Authid, BackupNamespace, BackupType, Operation, VerifyState,
@@ -186,12 +185,10 @@ fn upgrade_to_backup_protocol(
             }
 
             // lock last snapshot to prevent forgetting/pruning it during backup
-            let full_path = last.backup_dir.full_path();
-            Some(lock_dir_noblock_shared(
-                &full_path,
-                "snapshot",
-                "base snapshot is already locked by another operation",
-            )?)
+            let guard = last.backup_dir
+                .lock_shared()
+                .with_context(|| format!("while locking last snapshot during backup '{last:?}'"))?;
+            Some(guard)
         } else {
             None
         };
diff --git a/src/api2/reader/mod.rs b/src/api2/reader/mod.rs
index 1713f182..cc791299 100644
--- a/src/api2/reader/mod.rs
+++ b/src/api2/reader/mod.rs
@@ -1,6 +1,6 @@
 //! Backup reader/restore protocol (HTTP2 upgrade)
 
-use anyhow::{bail, format_err, Error};
+use anyhow::{bail, format_err, Context, Error};
 use futures::*;
 use hex::FromHex;
 use hyper::header::{self, HeaderValue, CONNECTION, UPGRADE};
@@ -16,7 +16,6 @@ use proxmox_router::{
 };
 use proxmox_schema::{BooleanSchema, ObjectSchema};
 use proxmox_sortable_macro::sortable;
-use proxmox_sys::fs::lock_dir_noblock_shared;
 
 use pbs_api_types::{
     ArchiveType, Authid, Operation, BACKUP_ARCHIVE_NAME_SCHEMA, BACKUP_ID_SCHEMA,
@@ -129,11 +128,9 @@ fn upgrade_to_backup_reader_protocol(
             bail!("snapshot {} does not exist.", backup_dir.dir());
         }
 
-        let _guard = lock_dir_noblock_shared(
-            &backup_dir.full_path(),
-            "snapshot",
-            "locked by another operation",
-        )?;
+        let _guard = backup_dir
+            .lock_shared()
+            .with_context(|| format!("while reading snapshot '{backup_dir:?}'"))?;
 
         let path = datastore.base_path();
 
diff --git a/src/backup/verify.rs b/src/backup/verify.rs
index f652c262..10a64fda 100644
--- a/src/backup/verify.rs
+++ b/src/backup/verify.rs
@@ -4,10 +4,9 @@ use std::sync::{Arc, Mutex};
 use std::time::Instant;
 
 use anyhow::{bail, Error};
-use nix::dir::Dir;
+use proxmox_sys::fs::DirLockGuard;
 use tracing::{error, info, warn};
 
-use proxmox_sys::fs::lock_dir_noblock_shared;
 use proxmox_worker_task::WorkerTaskContext;
 
 use pbs_api_types::{
@@ -307,11 +306,8 @@ pub fn verify_backup_dir(
         return Ok(true);
     }
 
-    let snap_lock = lock_dir_noblock_shared(
-        &backup_dir.full_path(),
-        "snapshot",
-        "locked by another operation",
-    );
+    let snap_lock = backup_dir.lock_shared();
+
     match snap_lock {
         Ok(snap_lock) => {
             verify_backup_dir_with_lock(verify_worker, backup_dir, upid, filter, snap_lock)
@@ -334,7 +330,7 @@ pub fn verify_backup_dir_with_lock(
     backup_dir: &BackupDir,
     upid: UPID,
     filter: Option<&dyn Fn(&BackupManifest) -> bool>,
-    _snap_lock: Dir,
+    _snap_lock: DirLockGuard,
 ) -> Result<bool, Error> {
     let datastore_name = verify_worker.datastore.name();
     let backup_dir_name = backup_dir.dir();
diff --git a/src/server/sync.rs b/src/server/sync.rs
index 4dd46c5a..b6852aff 100644
--- a/src/server/sync.rs
+++ b/src/server/sync.rs
@@ -10,6 +10,7 @@ use std::time::Duration;
 use anyhow::{bail, format_err, Context, Error};
 use futures::{future::FutureExt, select};
 use hyper::http::StatusCode;
+use proxmox_sys::fs::DirLockGuard;
 use serde_json::json;
 use tracing::{info, warn};
 
@@ -105,7 +106,7 @@ pub(crate) struct RemoteSourceReader {
 }
 
 pub(crate) struct LocalSourceReader {
-    pub(crate) _dir_lock: Arc<Mutex<proxmox_sys::fs::DirLockGuard>>,
+    pub(crate) _dir_lock: Arc<Mutex<DirLockGuard>>,
     pub(crate) path: PathBuf,
     pub(crate) datastore: Arc<DataStore>,
 }
@@ -478,13 +479,11 @@ impl SyncSource for LocalSource {
         dir: &BackupDir,
     ) -> Result<Arc<dyn SyncSourceReader>, Error> {
         let dir = self.store.backup_dir(ns.clone(), dir.clone())?;
-        let dir_lock = proxmox_sys::fs::lock_dir_noblock_shared(
-            &dir.full_path(),
-            "snapshot",
-            "locked by another operation",
-        )?;
+        let guard = dir
+            .lock()
+            .with_context(|| format!("while reading snapshot '{dir:?}' for a sync job"))?;
         Ok(Arc::new(LocalSourceReader {
-            _dir_lock: Arc::new(Mutex::new(dir_lock)),
+            _dir_lock: Arc::new(Mutex::new(guard)),
             path: dir.full_path(),
             datastore: dir.datastore().clone(),
         }))
-- 
2.39.5



_______________________________________________
pbs-devel mailing list
pbs-devel@lists.proxmox.com
https://lists.proxmox.com/cgi-bin/mailman/listinfo/pbs-devel


^ permalink raw reply	[flat|nested] 11+ messages in thread
* [pbs-devel] [PATCH proxmox-backup v9 2/4] fix #3935: datastore/api/backup: move datastore locking to '/run'
  2025-03-26 11:44 [pbs-devel] [PATCH proxmox-backup v9 0/4] refactor datastore locking to use tmpfs Shannon Sterz
  2025-03-26 11:44 ` [pbs-devel] [PATCH proxmox-backup v9 1/4] datastore/api/backup: prepare for fix of #3935 by adding lock helpers Shannon Sterz
@ 2025-03-26 11:44 ` Shannon Sterz
  2025-03-26 15:14   ` Thomas Lamprecht
  2025-03-26 15:22   ` Thomas Lamprecht
  2025-03-26 11:44 ` [pbs-devel] [PATCH proxmox-backup v9 3/4] fix #3935: datastore: move manifest locking to new locking method Shannon Sterz
                   ` (2 subsequent siblings)
  4 siblings, 2 replies; 11+ messages in thread
From: Shannon Sterz @ 2025-03-26 11:44 UTC (permalink / raw)
  To: pbs-devel

to avoid issues when removing a group or snapshot directory where two
threads hold a lock to the same directory, move locking to the tmpfs
backed '/run' directory. also adds double stat'ing to make it possible
to remove locks without certain race condition issues.

this new mechanism is only employed when we can be sure, that a reboot
has occured so that all processes are using the new locking mechanism.
otherwise, two separate process could assume they have exclusive
rights to a group or snapshot.

bumps the rust version to 1.81 so we can use `std::fs::exists` without
issue.

Signed-off-by: Shannon Sterz <s.sterz@proxmox.com>
---
 Cargo.toml                           |   2 +-
 debian/postinst                      |   5 +
 debian/rules                         |   2 +
 pbs-config/src/lib.rs                |  32 ++++-
 pbs-datastore/Cargo.toml             |   1 +
 pbs-datastore/src/backup_info.rs     | 195 +++++++++++++++++++++++----
 pbs-datastore/src/datastore.rs       |   6 +-
 pbs-datastore/src/snapshot_reader.rs |  15 ++-
 src/api2/backup/environment.rs       |   5 +-
 src/backup/verify.rs                 |   4 +-
 src/server/sync.rs                   |   4 +-
 11 files changed, 229 insertions(+), 42 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 306d50e9..645f2d81 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,7 +13,7 @@ authors = [
 edition = "2021"
 license = "AGPL-3"
 repository = "https://git.proxmox.com/?p=proxmox-backup.git"
-rust-version = "1.80"
+rust-version = "1.81"
 
 [package]
 name = "proxmox-backup"
diff --git a/debian/postinst b/debian/postinst
index 0485ca34..81c15826 100644
--- a/debian/postinst
+++ b/debian/postinst
@@ -80,6 +80,11 @@ EOF
 				update_sync_job "$prev_job"
 			fi
 		fi
+
+		if dpkg --compare-versions "$2" 'lt' '3.3.4~'; then
+			# ensure old locking is used by the daemon until a reboot happened
+			touch "/run/proxmox-backup/old-locking"
+		fi
 	fi
     ;;
 
diff --git a/debian/rules b/debian/rules
index a03fe11b..6e1844e1 100755
--- a/debian/rules
+++ b/debian/rules
@@ -22,6 +22,8 @@ ifneq ("$(wildcard .repoid)","")
 endif
 
 %:
+	@echo "fix locking version in postinst"
+	false
 	dh $@ --with=bash-completion
 
 override_dh_auto_configure:
diff --git a/pbs-config/src/lib.rs b/pbs-config/src/lib.rs
index 20a8238d..9c4d77c2 100644
--- a/pbs-config/src/lib.rs
+++ b/pbs-config/src/lib.rs
@@ -22,6 +22,8 @@ pub use config_version_cache::ConfigVersionCache;
 
 use anyhow::{format_err, Error};
 use nix::unistd::{Gid, Group, Uid, User};
+use proxmox_sys::fs::DirLockGuard;
+use std::os::unix::prelude::AsRawFd;
 
 pub use pbs_buildcfg::{BACKUP_GROUP_NAME, BACKUP_USER_NAME};
 
@@ -46,13 +48,34 @@ pub fn backup_group() -> Result<nix::unistd::Group, Error> {
 }
 
 pub struct BackupLockGuard {
-    _file: Option<std::fs::File>,
+    file: Option<std::fs::File>,
+    // TODO: Remove `_legacy_dir` with PBS 5
+    _legacy_dir: Option<DirLockGuard>,
+}
+
+impl AsRawFd for BackupLockGuard {
+    fn as_raw_fd(&self) -> i32 {
+        self.file.as_ref().map_or(-1, |f| f.as_raw_fd())
+    }
+}
+
+// TODO: Remove with PBS 5
+impl From<DirLockGuard> for BackupLockGuard {
+    fn from(value: DirLockGuard) -> Self {
+        Self {
+            file: None,
+            _legacy_dir: Some(value),
+        }
+    }
 }
 
 #[doc(hidden)]
 /// Note: do not use for production code, this is only intended for tests
 pub unsafe fn create_mocked_lock() -> BackupLockGuard {
-    BackupLockGuard { _file: None }
+    BackupLockGuard {
+        file: None,
+        _legacy_dir: None,
+    }
 }
 
 /// Open or create a lock file owned by user "backup" and lock it.
@@ -76,7 +99,10 @@ pub fn open_backup_lockfile<P: AsRef<std::path::Path>>(
     let timeout = timeout.unwrap_or(std::time::Duration::new(10, 0));
 
     let file = proxmox_sys::fs::open_file_locked(&path, timeout, exclusive, options)?;
-    Ok(BackupLockGuard { _file: Some(file) })
+    Ok(BackupLockGuard {
+        file: Some(file),
+        _legacy_dir: None,
+    })
 }
 
 /// Atomically write data to file owned by "root:backup" with permission "0640"
diff --git a/pbs-datastore/Cargo.toml b/pbs-datastore/Cargo.toml
index 4ebc5fdc..7623adc2 100644
--- a/pbs-datastore/Cargo.toml
+++ b/pbs-datastore/Cargo.toml
@@ -35,6 +35,7 @@ proxmox-lang.workspace=true
 proxmox-schema = { workspace = true, features = [ "api-macro" ] }
 proxmox-serde = { workspace = true, features = [ "serde_json" ] }
 proxmox-sys.workspace = true
+proxmox-systemd.workspace = true
 proxmox-time.workspace = true
 proxmox-uuid.workspace = true
 proxmox-worker-task.workspace = true
diff --git a/pbs-datastore/src/backup_info.rs b/pbs-datastore/src/backup_info.rs
index c7f7ed53..4e381142 100644
--- a/pbs-datastore/src/backup_info.rs
+++ b/pbs-datastore/src/backup_info.rs
@@ -1,13 +1,15 @@
 use std::fmt;
-use std::os::unix::io::RawFd;
+use std::os::unix::io::{AsRawFd, RawFd};
+use std::os::unix::prelude::OsStrExt;
+use std::path::Path;
 use std::path::PathBuf;
-use std::sync::Arc;
+use std::sync::{Arc, LazyLock};
+use std::time::Duration;
 
 use anyhow::{bail, format_err, Context, Error};
 
-use proxmox_sys::fs::{
-    lock_dir_noblock, lock_dir_noblock_shared, replace_file, CreateOptions, DirLockGuard,
-};
+use proxmox_sys::fs::{lock_dir_noblock, lock_dir_noblock_shared, replace_file, CreateOptions};
+use proxmox_systemd::escape_unit;
 
 use pbs_api_types::{
     Authid, BackupGroupDeleteStats, BackupNamespace, BackupType, GroupFilter, VerifyState,
@@ -18,6 +20,18 @@ use pbs_config::{open_backup_lockfile, BackupLockGuard};
 use crate::manifest::{BackupManifest, MANIFEST_LOCK_NAME};
 use crate::{DataBlob, DataStore};
 
+pub const DATASTORE_LOCKS_DIR: &str = "/run/proxmox-backup/locks";
+
+// TODO: Remove with PBS 5
+// Note: The `expect()` call here will only happen if we can neither confirm nor deny the existence
+// of the file. this should only happen if a user messes with the `/run/proxmox-backup` directory.
+// if that happens, a lot more should fail as we rely on the existence of the directory throughout
+// the code. so just panic with a reasonable message.
+static OLD_LOCKING: LazyLock<bool> = LazyLock::new(|| {
+    std::fs::exists("/run/proxmox-backup/old-locking")
+        .expect("cannot read `/run/proxmox-backup`, please check permissions")
+});
+
 /// BackupGroup is a directory containing a list of BackupDir
 #[derive(Clone)]
 pub struct BackupGroup {
@@ -225,6 +239,7 @@ impl BackupGroup {
             delete_stats.increment_removed_groups();
         }
 
+        let _ = std::fs::remove_file(self.lock_path());
         Ok(delete_stats)
     }
 
@@ -241,13 +256,34 @@ impl BackupGroup {
             .set_owner(&self.ns, self.as_ref(), auth_id, force)
     }
 
-    /// Lock a group exclusively
-    pub fn lock(&self) -> Result<DirLockGuard, Error> {
-        lock_dir_noblock(
-            &self.full_group_path(),
-            "backup group",
-            "possible running backup",
-        )
+    /// Returns a file name for locking a group.
+    ///
+    /// The lock file will be located in:
+    /// `${DATASTORE_LOCKS_DIR}/${datastore name}/${lock_file_path_helper(rpath)}`
+    /// where `rpath` is the relative path of the group.
+    fn lock_path(&self) -> PathBuf {
+        let path = Path::new(DATASTORE_LOCKS_DIR).join(self.store.name());
+
+        let rpath = Path::new(self.group.ty.as_str()).join(&self.group.id);
+
+        path.join(lock_file_path_helper(&self.ns, rpath))
+    }
+
+    /// Locks a group exclusively.
+    pub fn lock(&self) -> Result<BackupLockGuard, Error> {
+        if *OLD_LOCKING {
+            lock_dir_noblock(
+                &self.full_group_path(),
+                "backup group",
+                "possible runing backup, group is in use",
+            )
+            .map(BackupLockGuard::from)
+        } else {
+            lock_helper(self.store.name(), &self.lock_path(), |p| {
+                open_backup_lockfile(p, Some(Duration::from_secs(0)), true)
+                    .with_context(|| format!("unable to acquire backup group lock {p:?}"))
+            })
+        }
     }
 }
 
@@ -454,22 +490,53 @@ impl BackupDir {
             .map_err(|err| format_err!("unable to acquire manifest lock {:?} - {}", &path, err))
     }
 
-    /// Lock this snapshot exclusively
-    pub fn lock(&self) -> Result<DirLockGuard, Error> {
-        lock_dir_noblock(
-            &self.full_path(),
-            "snapshot",
-            "backup is running or snapshot is in use",
-        )
+    /// Returns a file name for locking a snapshot.
+    ///
+    /// The lock file will be located in:
+    /// `${DATASTORE_LOCKS_DIR}/${datastore name}/${lock_file_path_helper(rpath)}`
+    /// where `rpath` is the relative path of the snapshot.
+    fn lock_path(&self) -> PathBuf {
+        let path = Path::new(DATASTORE_LOCKS_DIR).join(self.store.name());
+
+        let rpath = Path::new(self.dir.group.ty.as_str())
+            .join(&self.dir.group.id)
+            .join(&self.backup_time_string);
+
+        path.join(lock_file_path_helper(&self.ns, rpath))
     }
 
-    /// Acquire a shared lock on this snapshot
-    pub fn lock_shared(&self) -> Result<DirLockGuard, Error> {
-        lock_dir_noblock_shared(
-            &self.full_path(),
-            "snapshot",
-            "backup is running or snapshot is in use, could not acquire shared lock",
-        )
+    /// Locks a snapshot exclusively.
+    pub fn lock(&self) -> Result<BackupLockGuard, Error> {
+        if *OLD_LOCKING {
+            lock_dir_noblock(
+                &self.full_path(),
+                "snapshot",
+                "backup is running or snapshot is in use",
+            )
+            .map(BackupLockGuard::from)
+        } else {
+            lock_helper(self.store.name(), &self.lock_path(), |p| {
+                open_backup_lockfile(p, Some(Duration::from_secs(0)), true)
+                    .with_context(|| format!("unable to acquire snapshot lock {p:?}"))
+            })
+        }
+    }
+
+    /// Acquires a shared lock on a snapshot.
+    pub fn lock_shared(&self) -> Result<BackupLockGuard, Error> {
+        if *OLD_LOCKING {
+            lock_dir_noblock_shared(
+                &self.full_path(),
+                "snapshot",
+                "backup is running or snapshot is in use, could not acquire shared lock",
+            )
+            .map(BackupLockGuard::from)
+        } else {
+            lock_helper(self.store.name(), &self.lock_path(), |p| {
+                open_backup_lockfile(p, Some(Duration::from_secs(0)), false)
+                    .with_context(|| format!("unable to acquire shared snapshot lock {p:?}"))
+            })
+        }
     }
 
     /// Destroy the whole snapshot, bails if it's protected
@@ -494,11 +561,13 @@ impl BackupDir {
             format_err!("removing backup snapshot {:?} failed - {}", full_path, err,)
         })?;
 
-        // the manifest doesn't exist anymore, no need to keep the lock (already done by guard?)
+        // remove no longer needed lock files
         if let Ok(path) = self.manifest_lock_path() {
             let _ = std::fs::remove_file(path); // ignore errors
         }
 
+        let _ = std::fs::remove_file(self.lock_path()); // ignore errors
+
         Ok(())
     }
 
@@ -692,3 +761,75 @@ fn list_backup_files<P: ?Sized + nix::NixPath>(
 
     Ok(files)
 }
+
+/// Creates a path to a lock file depending on the relative path of an object (snapshot, group,
+/// manifest) in a datastore. First all namespaces will be concatenated with a colon (ns-folder).
+/// Then the actual file name will depend on the length of the relative path without namespaces. If
+/// it is shorter than 255 characters in its unit encoded form, than the unit encoded form will be
+/// used directly. If not, the file name will consist of the first 80 character, the last 80
+/// characters and the hash of the unit encoded relative path without namespaces. It will also be
+/// placed into a "hashed" subfolder in the namespace folder.
+///
+/// Examples:
+///
+/// - vm-100
+/// - vm-100-2022\x2d05\x2d02T08\x3a11\x3a33Z
+/// - ns1:ns2:ns3:ns4:ns5:ns6:ns7/vm-100-2022\x2d05\x2d02T08\x3a11\x3a33Z
+///
+/// A "hashed" lock file would look like this:
+/// - ns1:ns2:ns3/hashed/$first_eighty...$last_eighty-$hash
+fn lock_file_path_helper(ns: &BackupNamespace, path: PathBuf) -> PathBuf {
+    let to_return = PathBuf::from(
+        ns.components()
+            .map(String::from)
+            .reduce(|acc, n| format!("{acc}:{n}"))
+            .unwrap_or_default(),
+    );
+
+    let path_bytes = path.as_os_str().as_bytes();
+
+    let enc = escape_unit(path_bytes, true);
+
+    if enc.len() < 255 {
+        return to_return.join(enc);
+    }
+
+    let to_return = to_return.join("hashed");
+
+    let first_eigthy = &enc[..80];
+    let last_eighty = &enc[enc.len() - 80..];
+    let hash = hex::encode(openssl::sha::sha256(path_bytes));
+
+    to_return.join(format!("{first_eigthy}...{last_eighty}-{hash}"))
+}
+
+/// Helps implement the double stat'ing procedure. It avoids certain race conditions upon lock
+/// deletion.
+///
+/// It also creates the base directory for lock files.
+fn lock_helper<F>(
+    store_name: &str,
+    path: &std::path::Path,
+    lock_fn: F,
+) -> Result<BackupLockGuard, Error>
+where
+    F: Fn(&std::path::Path) -> Result<BackupLockGuard, Error>,
+{
+    let mut lock_dir = Path::new(DATASTORE_LOCKS_DIR).join(store_name);
+
+    if let Some(parent) = path.parent() {
+        lock_dir = lock_dir.join(parent);
+    };
+
+    std::fs::create_dir_all(&lock_dir)?;
+
+    let lock = lock_fn(path)?;
+
+    let inode = nix::sys::stat::fstat(lock.as_raw_fd())?.st_ino;
+
+    if nix::sys::stat::stat(path).map_or(true, |st| inode != st.st_ino) {
+        bail!("could not acquire lock, another thread modified the lock file");
+    }
+
+    Ok(lock)
+}
diff --git a/pbs-datastore/src/datastore.rs b/pbs-datastore/src/datastore.rs
index 1cbd0038..1e6157c0 100644
--- a/pbs-datastore/src/datastore.rs
+++ b/pbs-datastore/src/datastore.rs
@@ -13,7 +13,6 @@ use proxmox_human_byte::HumanByte;
 use proxmox_schema::ApiType;
 
 use proxmox_sys::error::SysError;
-use proxmox_sys::fs::DirLockGuard;
 use proxmox_sys::fs::{file_read_optional_string, replace_file, CreateOptions};
 use proxmox_sys::linux::procfs::MountInfo;
 use proxmox_sys::process_locker::ProcessLockSharedGuard;
@@ -24,6 +23,7 @@ use pbs_api_types::{
     DataStoreConfig, DatastoreFSyncLevel, DatastoreTuning, GarbageCollectionStatus,
     MaintenanceMode, MaintenanceType, Operation, UPID,
 };
+use pbs_config::BackupLockGuard;
 
 use crate::backup_info::{BackupDir, BackupGroup};
 use crate::chunk_store::ChunkStore;
@@ -778,7 +778,7 @@ impl DataStore {
         ns: &BackupNamespace,
         backup_group: &pbs_api_types::BackupGroup,
         auth_id: &Authid,
-    ) -> Result<(Authid, DirLockGuard), Error> {
+    ) -> Result<(Authid, BackupLockGuard), Error> {
         let backup_group = self.backup_group(ns.clone(), backup_group.clone());
 
         // create intermediate path first
@@ -816,7 +816,7 @@ impl DataStore {
         self: &Arc<Self>,
         ns: &BackupNamespace,
         backup_dir: &pbs_api_types::BackupDir,
-    ) -> Result<(PathBuf, bool, DirLockGuard), Error> {
+    ) -> Result<(PathBuf, bool, BackupLockGuard), Error> {
         let backup_dir = self.backup_dir(ns.clone(), backup_dir.clone())?;
         let relative_path = backup_dir.relative_path();
 
diff --git a/pbs-datastore/src/snapshot_reader.rs b/pbs-datastore/src/snapshot_reader.rs
index edff19ef..07601df8 100644
--- a/pbs-datastore/src/snapshot_reader.rs
+++ b/pbs-datastore/src/snapshot_reader.rs
@@ -4,8 +4,11 @@ use std::path::Path;
 use std::rc::Rc;
 use std::sync::Arc;
 
-use anyhow::{bail, Context, Error};
+use anyhow::{bail, format_err, Context, Error};
 use nix::dir::Dir;
+use nix::fcntl::OFlag;
+use nix::sys::stat::Mode;
+use pbs_config::BackupLockGuard;
 
 use pbs_api_types::{
     print_store_and_ns, ArchiveType, BackupNamespace, Operation, CLIENT_LOG_BLOB_NAME,
@@ -26,6 +29,10 @@ pub struct SnapshotReader {
     datastore_name: String,
     file_list: Vec<String>,
     locked_dir: Dir,
+
+    // while this is never read, the lock needs to be kept until the
+    // reader is dropped to ensure valid locking semantics
+    _lock: BackupLockGuard,
 }
 
 impl SnapshotReader {
@@ -46,10 +53,13 @@ impl SnapshotReader {
             bail!("snapshot {} does not exist!", snapshot.dir());
         }
 
-        let locked_dir = snapshot
+        let lock = snapshot
             .lock_shared()
             .with_context(|| format!("while trying to read snapshot '{snapshot:?}'"))?;
 
+        let locked_dir = Dir::open(&snapshot_path, OFlag::O_RDONLY, Mode::empty())
+            .with_context(|| format!("unable to open snapshot directory {snapshot_path:?}"))?;
+
         let datastore_name = datastore.name().to_string();
         let manifest = match snapshot.load_manifest() {
             Ok((manifest, _)) => manifest,
@@ -79,6 +89,7 @@ impl SnapshotReader {
             datastore_name,
             file_list,
             locked_dir,
+            _lock: lock,
         })
     }
 
diff --git a/src/api2/backup/environment.rs b/src/api2/backup/environment.rs
index 7943b576..3d541b46 100644
--- a/src/api2/backup/environment.rs
+++ b/src/api2/backup/environment.rs
@@ -1,5 +1,6 @@
 use anyhow::{bail, format_err, Context, Error};
-use nix::dir::Dir;
+use pbs_config::BackupLockGuard;
+
 use std::collections::HashMap;
 use std::sync::{Arc, Mutex};
 use tracing::info;
@@ -635,7 +636,7 @@ impl BackupEnvironment {
     /// If verify-new is set on the datastore, this will run a new verify task
     /// for the backup. If not, this will return and also drop the passed lock
     /// immediately.
-    pub fn verify_after_complete(&self, excl_snap_lock: Dir) -> Result<(), Error> {
+    pub fn verify_after_complete(&self, excl_snap_lock: BackupLockGuard) -> Result<(), Error> {
         self.ensure_finished()?;
 
         if !self.datastore.verify_new() {
diff --git a/src/backup/verify.rs b/src/backup/verify.rs
index 10a64fda..3d2cba8a 100644
--- a/src/backup/verify.rs
+++ b/src/backup/verify.rs
@@ -1,10 +1,10 @@
+use pbs_config::BackupLockGuard;
 use std::collections::HashSet;
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::{Arc, Mutex};
 use std::time::Instant;
 
 use anyhow::{bail, Error};
-use proxmox_sys::fs::DirLockGuard;
 use tracing::{error, info, warn};
 
 use proxmox_worker_task::WorkerTaskContext;
@@ -330,7 +330,7 @@ pub fn verify_backup_dir_with_lock(
     backup_dir: &BackupDir,
     upid: UPID,
     filter: Option<&dyn Fn(&BackupManifest) -> bool>,
-    _snap_lock: DirLockGuard,
+    _snap_lock: BackupLockGuard,
 ) -> Result<bool, Error> {
     let datastore_name = verify_worker.datastore.name();
     let backup_dir_name = backup_dir.dir();
diff --git a/src/server/sync.rs b/src/server/sync.rs
index b6852aff..10804b14 100644
--- a/src/server/sync.rs
+++ b/src/server/sync.rs
@@ -10,7 +10,7 @@ use std::time::Duration;
 use anyhow::{bail, format_err, Context, Error};
 use futures::{future::FutureExt, select};
 use hyper::http::StatusCode;
-use proxmox_sys::fs::DirLockGuard;
+use pbs_config::BackupLockGuard;
 use serde_json::json;
 use tracing::{info, warn};
 
@@ -106,7 +106,7 @@ pub(crate) struct RemoteSourceReader {
 }
 
 pub(crate) struct LocalSourceReader {
-    pub(crate) _dir_lock: Arc<Mutex<DirLockGuard>>,
+    pub(crate) _dir_lock: Arc<Mutex<BackupLockGuard>>,
     pub(crate) path: PathBuf,
     pub(crate) datastore: Arc<DataStore>,
 }
-- 
2.39.5



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^ permalink raw reply	[flat|nested] 11+ messages in thread
* [pbs-devel] [PATCH proxmox-backup v9 3/4] fix #3935: datastore: move manifest locking to new locking method
  2025-03-26 11:44 [pbs-devel] [PATCH proxmox-backup v9 0/4] refactor datastore locking to use tmpfs Shannon Sterz
  2025-03-26 11:44 ` [pbs-devel] [PATCH proxmox-backup v9 1/4] datastore/api/backup: prepare for fix of #3935 by adding lock helpers Shannon Sterz
  2025-03-26 11:44 ` [pbs-devel] [PATCH proxmox-backup v9 2/4] fix #3935: datastore/api/backup: move datastore locking to '/run' Shannon Sterz
@ 2025-03-26 11:44 ` Shannon Sterz
  2025-03-26 11:44 ` [pbs-devel] [PATCH proxmox-backup v9 4/4] fix: api: avoid race condition in set_backup_owner Shannon Sterz
  2025-03-26 15:36 ` [pbs-devel] applied-series: [PATCH proxmox-backup v9 0/4] refactor datastore locking to use tmpfs Thomas Lamprecht
  4 siblings, 0 replies; 11+ messages in thread
From: Shannon Sterz @ 2025-03-26 11:44 UTC (permalink / raw)
  To: pbs-devel

adds double stat'ing and removes directory hierarchy to bring manifest
locking in-line with other locks used by the BackupDir trait.

if the old locking mechanism is still supposed to be used, this still
falls back to the previous lock file. however, we already add double
stat'ing since it is trivial to do here and should only provide better
safety when it comes to removing locks.

Signed-off-by: Shannon Sterz <s.sterz@proxmox.com>
---
 pbs-datastore/src/backup_info.rs | 45 ++++++++++++++++++++------------
 1 file changed, 29 insertions(+), 16 deletions(-)

diff --git a/pbs-datastore/src/backup_info.rs b/pbs-datastore/src/backup_info.rs
index 4e381142..396b6bde 100644
--- a/pbs-datastore/src/backup_info.rs
+++ b/pbs-datastore/src/backup_info.rs
@@ -469,25 +469,41 @@ impl BackupDir {
     /// Returns the filename to lock a manifest
     ///
     /// Also creates the basedir. The lockfile is located in
-    /// '/run/proxmox-backup/locks/{datastore}/[ns/{ns}/]+{type}/{id}/{timestamp}.index.json.lck'
-    fn manifest_lock_path(&self) -> Result<PathBuf, Error> {
-        let mut path = PathBuf::from(&format!("/run/proxmox-backup/locks/{}", self.store.name()));
-        path.push(self.relative_path());
+    /// `${DATASTORE_LOCKS_DIR}/${datastore name}/${lock_file_path_helper(rpath)}.index.json.lck`
+    /// where rpath is the relative path of the snapshot.
+    fn manifest_lock_path(&self) -> PathBuf {
+        let path = Path::new(DATASTORE_LOCKS_DIR).join(self.store.name());
 
-        std::fs::create_dir_all(&path)?;
-        let ts = self.backup_time_string();
-        path.push(format!("{ts}{MANIFEST_LOCK_NAME}"));
+        let rpath = Path::new(self.dir.group.ty.as_str())
+            .join(&self.dir.group.id)
+            .join(&self.backup_time_string)
+            .join(MANIFEST_LOCK_NAME);
 
-        Ok(path)
+        path.join(lock_file_path_helper(&self.ns, rpath))
     }
 
     /// Locks the manifest of a snapshot, for example, to update or delete it.
     pub(crate) fn lock_manifest(&self) -> Result<BackupLockGuard, Error> {
-        let path = self.manifest_lock_path()?;
+        let path = if *OLD_LOCKING {
+            // old manifest lock path
+            let path = Path::new(DATASTORE_LOCKS_DIR)
+                .join(self.store.name())
+                .join(self.relative_path());
 
-        // actions locking the manifest should be relatively short, only wait a few seconds
-        open_backup_lockfile(&path, Some(std::time::Duration::from_secs(5)), true)
-            .map_err(|err| format_err!("unable to acquire manifest lock {:?} - {}", &path, err))
+            std::fs::create_dir_all(&path)?;
+
+            path.join(format!("{}{MANIFEST_LOCK_NAME}", self.backup_time_string()))
+        } else {
+            self.manifest_lock_path()
+        };
+
+        lock_helper(self.store.name(), &path, |p| {
+            // 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
+            open_backup_lockfile(p, Some(Duration::from_secs(5)), true)
+                .with_context(|| format_err!("unable to acquire manifest lock {p:?}"))
+        })
     }
 
     /// Returns a file name for locking a snapshot.
@@ -562,10 +578,7 @@ impl BackupDir {
         })?;
 
         // remove no longer needed lock files
-        if let Ok(path) = self.manifest_lock_path() {
-            let _ = std::fs::remove_file(path); // ignore errors
-        }
-
+        let _ = std::fs::remove_file(self.manifest_lock_path()); // ignore errors
         let _ = std::fs::remove_file(self.lock_path()); // ignore errors
 
         Ok(())
-- 
2.39.5



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^ permalink raw reply	[flat|nested] 11+ messages in thread
* [pbs-devel] [PATCH proxmox-backup v9 4/4] fix: api: avoid race condition in set_backup_owner
  2025-03-26 11:44 [pbs-devel] [PATCH proxmox-backup v9 0/4] refactor datastore locking to use tmpfs Shannon Sterz
                   ` (2 preceding siblings ...)
  2025-03-26 11:44 ` [pbs-devel] [PATCH proxmox-backup v9 3/4] fix #3935: datastore: move manifest locking to new locking method Shannon Sterz
@ 2025-03-26 11:44 ` Shannon Sterz
  2025-03-26 15:36 ` [pbs-devel] applied-series: [PATCH proxmox-backup v9 0/4] refactor datastore locking to use tmpfs Thomas Lamprecht
  4 siblings, 0 replies; 11+ messages in thread
From: Shannon Sterz @ 2025-03-26 11:44 UTC (permalink / raw)
  To: pbs-devel

when two clients change the owner of a backup store, a race condition
arose. add locking to avoid this.

Signed-off-by: Shannon Sterz <s.sterz@proxmox.com>
---
 src/api2/admin/datastore.rs | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/api2/admin/datastore.rs b/src/api2/admin/datastore.rs
index 483e595c..3e532636 100644
--- a/src/api2/admin/datastore.rs
+++ b/src/api2/admin/datastore.rs
@@ -7,7 +7,7 @@ use std::os::unix::ffi::OsStrExt;
 use std::path::{Path, PathBuf};
 use std::sync::Arc;
 
-use anyhow::{bail, format_err, Error};
+use anyhow::{bail, format_err, Context, Error};
 use futures::*;
 use hyper::http::request::Parts;
 use hyper::{header, Body, Response, StatusCode};
@@ -2347,10 +2347,9 @@ pub async fn set_backup_owner(
         let datastore = DataStore::lookup_datastore(&store, Some(Operation::Write))?;
 
         let backup_group = datastore.backup_group(ns, backup_group);
+        let owner = backup_group.get_owner()?;
 
         if owner_check_required {
-            let owner = backup_group.get_owner()?;
-
             let allowed = match (owner.is_token(), new_owner.is_token()) {
                 (true, true) => {
                     // API token to API token, owned by same user
@@ -2397,6 +2396,14 @@ pub async fn set_backup_owner(
             );
         }
 
+        let _guard = backup_group
+            .lock()
+            .with_context(|| format!("while setting the owner of group '{backup_group:?}'"))?;
+
+        if owner != backup_group.get_owner()? {
+            bail!("{owner} does not own this group anymore");
+        }
+
         backup_group.set_owner(&new_owner, true)?;
 
         Ok(())
-- 
2.39.5



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^ permalink raw reply	[flat|nested] 11+ messages in thread
* Re: [pbs-devel] [PATCH proxmox-backup v9 2/4] fix #3935: datastore/api/backup: move datastore locking to '/run'
  2025-03-26 11:44 ` [pbs-devel] [PATCH proxmox-backup v9 2/4] fix #3935: datastore/api/backup: move datastore locking to '/run' Shannon Sterz
@ 2025-03-26 15:14   ` Thomas Lamprecht
  2025-03-26 15:22   ` Thomas Lamprecht
  1 sibling, 0 replies; 11+ messages in thread
From: Thomas Lamprecht @ 2025-03-26 15:14 UTC (permalink / raw)
  To: Proxmox Backup Server development discussion, Shannon Sterz

Am 26.03.25 um 12:44 schrieb Shannon Sterz:
> to avoid issues when removing a group or snapshot directory where two
> threads hold a lock to the same directory, move locking to the tmpfs
> backed '/run' directory. also adds double stat'ing to make it possible
> to remove locks without certain race condition issues.
> 
> this new mechanism is only employed when we can be sure, that a reboot
> has occured so that all processes are using the new locking mechanism.
> otherwise, two separate process could assume they have exclusive
> rights to a group or snapshot.
> 
> bumps the rust version to 1.81 so we can use `std::fs::exists` without
> issue.
> 
> Signed-off-by: Shannon Sterz <s.sterz@proxmox.com>
> ---
>  Cargo.toml                           |   2 +-
>  debian/postinst                      |   5 +
>  debian/rules                         |   2 +
>  pbs-config/src/lib.rs                |  32 ++++-
>  pbs-datastore/Cargo.toml             |   1 +
>  pbs-datastore/src/backup_info.rs     | 195 +++++++++++++++++++++++----
>  pbs-datastore/src/datastore.rs       |   6 +-
>  pbs-datastore/src/snapshot_reader.rs |  15 ++-
>  src/api2/backup/environment.rs       |   5 +-
>  src/backup/verify.rs                 |   4 +-
>  src/server/sync.rs                   |   4 +-
>  11 files changed, 229 insertions(+), 42 deletions(-)
> 
> diff --git a/Cargo.toml b/Cargo.toml
> index 306d50e9..645f2d81 100644
> --- a/Cargo.toml
> +++ b/Cargo.toml
> @@ -13,7 +13,7 @@ authors = [
>  edition = "2021"
>  license = "AGPL-3"
>  repository = "https://git.proxmox.com/?p=proxmox-backup.git"
> -rust-version = "1.80"
> +rust-version = "1.81"
>  
>  [package]
>  name = "proxmox-backup"
> diff --git a/debian/postinst b/debian/postinst
> index 0485ca34..81c15826 100644
> --- a/debian/postinst
> +++ b/debian/postinst
> @@ -80,6 +80,11 @@ EOF
>  				update_sync_job "$prev_job"
>  			fi
>  		fi
> +
> +		if dpkg --compare-versions "$2" 'lt' '3.3.4~'; then
> +			# ensure old locking is used by the daemon until a reboot happened
> +			touch "/run/proxmox-backup/old-locking"
> +		fi
>  	fi
>      ;;
>  
> diff --git a/debian/rules b/debian/rules
> index a03fe11b..6e1844e1 100755
> --- a/debian/rules
> +++ b/debian/rules
> @@ -22,6 +22,8 @@ ifneq ("$(wildcard .repoid)","")
>  endif
>  
>  %:
> +	@echo "fix locking version in postinst"
> +	false
>  	dh $@ --with=bash-completion
>  
>  override_dh_auto_configure:
> diff --git a/pbs-config/src/lib.rs b/pbs-config/src/lib.rs
> index 20a8238d..9c4d77c2 100644
> --- a/pbs-config/src/lib.rs
> +++ b/pbs-config/src/lib.rs
> @@ -22,6 +22,8 @@ pub use config_version_cache::ConfigVersionCache;
>  
>  use anyhow::{format_err, Error};
>  use nix::unistd::{Gid, Group, Uid, User};
> +use proxmox_sys::fs::DirLockGuard;
> +use std::os::unix::prelude::AsRawFd;
>  
>  pub use pbs_buildcfg::{BACKUP_GROUP_NAME, BACKUP_USER_NAME};
>  
> @@ -46,13 +48,34 @@ pub fn backup_group() -> Result<nix::unistd::Group, Error> {
>  }
>  
>  pub struct BackupLockGuard {
> -    _file: Option<std::fs::File>,
> +    file: Option<std::fs::File>,
> +    // TODO: Remove `_legacy_dir` with PBS 5
> +    _legacy_dir: Option<DirLockGuard>,
> +}
> +
> +impl AsRawFd for BackupLockGuard {
> +    fn as_raw_fd(&self) -> i32 {
> +        self.file.as_ref().map_or(-1, |f| f.as_raw_fd())
> +    }
> +}
> +
> +// TODO: Remove with PBS 5
> +impl From<DirLockGuard> for BackupLockGuard {
> +    fn from(value: DirLockGuard) -> Self {
> +        Self {
> +            file: None,
> +            _legacy_dir: Some(value),
> +        }
> +    }
>  }
>  
>  #[doc(hidden)]
>  /// Note: do not use for production code, this is only intended for tests
>  pub unsafe fn create_mocked_lock() -> BackupLockGuard {
> -    BackupLockGuard { _file: None }
> +    BackupLockGuard {
> +        file: None,
> +        _legacy_dir: None,
> +    }
>  }
>  
>  /// Open or create a lock file owned by user "backup" and lock it.
> @@ -76,7 +99,10 @@ pub fn open_backup_lockfile<P: AsRef<std::path::Path>>(
>      let timeout = timeout.unwrap_or(std::time::Duration::new(10, 0));
>  
>      let file = proxmox_sys::fs::open_file_locked(&path, timeout, exclusive, options)?;
> -    Ok(BackupLockGuard { _file: Some(file) })
> +    Ok(BackupLockGuard {
> +        file: Some(file),
> +        _legacy_dir: None,
> +    })
>  }
>  
>  /// Atomically write data to file owned by "root:backup" with permission "0640"
> diff --git a/pbs-datastore/Cargo.toml b/pbs-datastore/Cargo.toml
> index 4ebc5fdc..7623adc2 100644
> --- a/pbs-datastore/Cargo.toml
> +++ b/pbs-datastore/Cargo.toml
> @@ -35,6 +35,7 @@ proxmox-lang.workspace=true
>  proxmox-schema = { workspace = true, features = [ "api-macro" ] }
>  proxmox-serde = { workspace = true, features = [ "serde_json" ] }
>  proxmox-sys.workspace = true
> +proxmox-systemd.workspace = true
>  proxmox-time.workspace = true
>  proxmox-uuid.workspace = true
>  proxmox-worker-task.workspace = true
> diff --git a/pbs-datastore/src/backup_info.rs b/pbs-datastore/src/backup_info.rs
> index c7f7ed53..4e381142 100644
> --- a/pbs-datastore/src/backup_info.rs
> +++ b/pbs-datastore/src/backup_info.rs
> @@ -1,13 +1,15 @@
>  use std::fmt;
> -use std::os::unix::io::RawFd;
> +use std::os::unix::io::{AsRawFd, RawFd};
> +use std::os::unix::prelude::OsStrExt;
> +use std::path::Path;
>  use std::path::PathBuf;
> -use std::sync::Arc;
> +use std::sync::{Arc, LazyLock};
> +use std::time::Duration;
>  
>  use anyhow::{bail, format_err, Context, Error};
>  
> -use proxmox_sys::fs::{
> -    lock_dir_noblock, lock_dir_noblock_shared, replace_file, CreateOptions, DirLockGuard,
> -};
> +use proxmox_sys::fs::{lock_dir_noblock, lock_dir_noblock_shared, replace_file, CreateOptions};
> +use proxmox_systemd::escape_unit;
>  
>  use pbs_api_types::{
>      Authid, BackupGroupDeleteStats, BackupNamespace, BackupType, GroupFilter, VerifyState,
> @@ -18,6 +20,18 @@ use pbs_config::{open_backup_lockfile, BackupLockGuard};
>  use crate::manifest::{BackupManifest, MANIFEST_LOCK_NAME};
>  use crate::{DataBlob, DataStore};
>  
> +pub const DATASTORE_LOCKS_DIR: &str = "/run/proxmox-backup/locks";

I was shortly tempted to question if this should be in /run/lock/proxmox-backup,
but we already keep the index manifest locks in there, so it's probably fine
and might be even stranger if we would move just these new lock paths to
/run/lock/proxmox-backup I think. We could always create a symlink that points
/run/lock/proxmox-backup -> /run/proxmox-backup/locks if one really questions this.

So just to vent this thought out, it's fine as is.


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^ permalink raw reply	[flat|nested] 11+ messages in thread
* Re: [pbs-devel] [PATCH proxmox-backup v9 2/4] fix #3935: datastore/api/backup: move datastore locking to '/run'
  2025-03-26 11:44 ` [pbs-devel] [PATCH proxmox-backup v9 2/4] fix #3935: datastore/api/backup: move datastore locking to '/run' Shannon Sterz
  2025-03-26 15:14   ` Thomas Lamprecht
@ 2025-03-26 15:22   ` Thomas Lamprecht
  1 sibling, 0 replies; 11+ messages in thread
From: Thomas Lamprecht @ 2025-03-26 15:22 UTC (permalink / raw)
  To: Proxmox Backup Server development discussion, Shannon Sterz

Am 26.03.25 um 12:44 schrieb Shannon Sterz:
> diff --git a/pbs-datastore/src/snapshot_reader.rs b/pbs-datastore/src/snapshot_reader.rs
> index edff19ef..07601df8 100644
> --- a/pbs-datastore/src/snapshot_reader.rs
> +++ b/pbs-datastore/src/snapshot_reader.rs
> @@ -4,8 +4,11 @@ use std::path::Path;
>  use std::rc::Rc;
>  use std::sync::Arc;
>  
> -use anyhow::{bail, Context, Error};
> +use anyhow::{bail, format_err, Context, Error};

The format_err use statement resulted in an "unused import" warning, as it
was just a minor oversight I fixed that up directly in the respective commit.


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^ permalink raw reply	[flat|nested] 11+ messages in thread
* [pbs-devel] applied-series: [PATCH proxmox-backup v9 0/4] refactor datastore locking to use tmpfs
  2025-03-26 11:44 [pbs-devel] [PATCH proxmox-backup v9 0/4] refactor datastore locking to use tmpfs Shannon Sterz
                   ` (3 preceding siblings ...)
  2025-03-26 11:44 ` [pbs-devel] [PATCH proxmox-backup v9 4/4] fix: api: avoid race condition in set_backup_owner Shannon Sterz
@ 2025-03-26 15:36 ` Thomas Lamprecht
  2025-03-27 10:02   ` Shannon Sterz
  4 siblings, 1 reply; 11+ messages in thread
From: Thomas Lamprecht @ 2025-03-26 15:36 UTC (permalink / raw)
  To: Proxmox Backup Server development discussion, Shannon Sterz

Am 26.03.25 um 12:44 schrieb Shannon Sterz:> The goal of this series is to make it safer to remove backup groups &
> snapshots by separating the corresponding directories from their lock
> files. By moving the lock files to the tmpfs-backed '/run' directory,
> we also make sure that the lock files get cleaned up when the system
> reboots.
> 
> This series refactors the locking mechanism inside the `DataStore`,
> `BackupDir` and `BackupGroup` traits. In a first step locking methods
> are added and the existing code is refactored to use them. Commit two
> derives a lock file name under '/run' for each group/snapshot. It also
> adds double stat'ing. To avoid issues when upgrading, the file
> `/run/proxmox-backup/old-locking` is created through a post-install
> hook which is used to determine whether the system has been rebooted
> and we can safely use the new locking mechanism.
> 
> The third commit refactors locking for manifests and brings it in-line
> with the group/snapshot locks. Finally, the last commit fixes a race
> condition when changing the owner of a datastore.
 
> Shannon Sterz (4):
>   datastore/api/backup: prepare for fix of #3935 by adding lock helpers
>   fix #3935: datastore/api/backup: move datastore locking to '/run'
>   fix #3935: datastore: move manifest locking to new locking method
>   fix: api: avoid race condition in set_backup_owner
> 

applied series, added Wolfgang's Acked-by – feel encouraged to pick such
things up already for a new revision, especially an A-b is less problematic
with minor changes as long as the overall design stays the same – and also
fixed a minor compile warning about an unused import that stemmed from
intra-revision changes, thanks!


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^ permalink raw reply	[flat|nested] 11+ messages in thread
* Re: [pbs-devel] applied-series: [PATCH proxmox-backup v9 0/4] refactor datastore locking to use tmpfs
  2025-03-26 15:36 ` [pbs-devel] applied-series: [PATCH proxmox-backup v9 0/4] refactor datastore locking to use tmpfs Thomas Lamprecht
@ 2025-03-27 10:02   ` Shannon Sterz
  2025-03-28  7:51     ` Wolfgang Bumiller
  0 siblings, 1 reply; 11+ messages in thread
From: Shannon Sterz @ 2025-03-27 10:02 UTC (permalink / raw)
  To: Thomas Lamprecht, Proxmox Backup Server development discussion

On Wed Mar 26, 2025 at 4:36 PM CET, Thomas Lamprecht wrote:
> Am 26.03.25 um 12:44 schrieb Shannon Sterz:> The goal of this series is to make it safer to remove backup groups &
>> snapshots by separating the corresponding directories from their lock
>> files. By moving the lock files to the tmpfs-backed '/run' directory,
>> we also make sure that the lock files get cleaned up when the system
>> reboots.
>>
>> This series refactors the locking mechanism inside the `DataStore`,
>> `BackupDir` and `BackupGroup` traits. In a first step locking methods
>> are added and the existing code is refactored to use them. Commit two
>> derives a lock file name under '/run' for each group/snapshot. It also
>> adds double stat'ing. To avoid issues when upgrading, the file
>> `/run/proxmox-backup/old-locking` is created through a post-install
>> hook which is used to determine whether the system has been rebooted
>> and we can safely use the new locking mechanism.
>>
>> The third commit refactors locking for manifests and brings it in-line
>> with the group/snapshot locks. Finally, the last commit fixes a race
>> condition when changing the owner of a datastore.
>
>> Shannon Sterz (4):
>>   datastore/api/backup: prepare for fix of #3935 by adding lock helpers
>>   fix #3935: datastore/api/backup: move datastore locking to '/run'
>>   fix #3935: datastore: move manifest locking to new locking method
>>   fix: api: avoid race condition in set_backup_owner
>>
>
> applied series, added Wolfgang's Acked-by – feel encouraged to pick such
> things up already for a new revision, especially an A-b is less problematic
> with minor changes as long as the overall design stays the same – and also
> fixed a minor compile warning about an unused import that stemmed from
> intra-revision changes, thanks!

thanks a bunch! should i always add all trailers mentioned on list?
wasn't sure about the `Acked-by` tbh ^^'


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^ permalink raw reply	[flat|nested] 11+ messages in thread
* Re: [pbs-devel] applied-series: [PATCH proxmox-backup v9 0/4] refactor datastore locking to use tmpfs
  2025-03-27 10:02   ` Shannon Sterz
@ 2025-03-28  7:51     ` Wolfgang Bumiller
  2025-03-28  8:17       ` Shannon Sterz
  0 siblings, 1 reply; 11+ messages in thread
From: Wolfgang Bumiller @ 2025-03-28  7:51 UTC (permalink / raw)
  To: Shannon Sterz
  Cc: Thomas Lamprecht, Proxmox Backup Server development discussion

On Thu, Mar 27, 2025 at 11:02:35AM +0100, Shannon Sterz wrote:
> On Wed Mar 26, 2025 at 4:36 PM CET, Thomas Lamprecht wrote:
> > Am 26.03.25 um 12:44 schrieb Shannon Sterz:> The goal of this series is to make it safer to remove backup groups &
> >> snapshots by separating the corresponding directories from their lock
> >> files. By moving the lock files to the tmpfs-backed '/run' directory,
> >> we also make sure that the lock files get cleaned up when the system
> >> reboots.
> >>
> >> This series refactors the locking mechanism inside the `DataStore`,
> >> `BackupDir` and `BackupGroup` traits. In a first step locking methods
> >> are added and the existing code is refactored to use them. Commit two
> >> derives a lock file name under '/run' for each group/snapshot. It also
> >> adds double stat'ing. To avoid issues when upgrading, the file
> >> `/run/proxmox-backup/old-locking` is created through a post-install
> >> hook which is used to determine whether the system has been rebooted
> >> and we can safely use the new locking mechanism.
> >>
> >> The third commit refactors locking for manifests and brings it in-line
> >> with the group/snapshot locks. Finally, the last commit fixes a race
> >> condition when changing the owner of a datastore.
> >
> >> Shannon Sterz (4):
> >>   datastore/api/backup: prepare for fix of #3935 by adding lock helpers
> >>   fix #3935: datastore/api/backup: move datastore locking to '/run'
> >>   fix #3935: datastore: move manifest locking to new locking method
> >>   fix: api: avoid race condition in set_backup_owner
> >>
> >
> > applied series, added Wolfgang's Acked-by – feel encouraged to pick such
> > things up already for a new revision, especially an A-b is less problematic
> > with minor changes as long as the overall design stays the same – and also
> > fixed a minor compile warning about an unused import that stemmed from
> > intra-revision changes, thanks!
> 
> thanks a bunch! should i always add all trailers mentioned on list?
> wasn't sure about the `Acked-by` tbh ^^'

At the very least any commits with no changes can accumulate all the
trailers.

For any changed commits you'll need to gauge whether or not another look
is warranted.
Eg. obviously typo or small rustfmt fixes are fine.
In the previous series I also specifically stated that my Ack includes
the proposed changes as I figured they'd be small enough to not require
another complete review, so as a review I would've just done a git-diff
between the 2 completely-applied versions rather than looked at the
individual patches first. (I don't necessarily do this between versions,
depending on how the changes are described in the emails, since with
regular read-throughs I'll usually pick up more things which I might
have missed in earlier versions.)


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^ permalink raw reply	[flat|nested] 11+ messages in thread
* Re: [pbs-devel] applied-series: [PATCH proxmox-backup v9 0/4] refactor datastore locking to use tmpfs
  2025-03-28  7:51     ` Wolfgang Bumiller
@ 2025-03-28  8:17       ` Shannon Sterz
  0 siblings, 0 replies; 11+ messages in thread
From: Shannon Sterz @ 2025-03-28  8:17 UTC (permalink / raw)
  To: Wolfgang Bumiller
  Cc: Thomas Lamprecht, Proxmox Backup Server development discussion

On Fri Mar 28, 2025 at 8:51 AM CET, Wolfgang Bumiller wrote:
> On Thu, Mar 27, 2025 at 11:02:35AM +0100, Shannon Sterz wrote:
>> On Wed Mar 26, 2025 at 4:36 PM CET, Thomas Lamprecht wrote:
>> > Am 26.03.25 um 12:44 schrieb Shannon Sterz:> The goal of this series is to make it safer to remove backup groups &
>> >> snapshots by separating the corresponding directories from their lock
>> >> files. By moving the lock files to the tmpfs-backed '/run' directory,
>> >> we also make sure that the lock files get cleaned up when the system
>> >> reboots.
>> >>
>> >> This series refactors the locking mechanism inside the `DataStore`,
>> >> `BackupDir` and `BackupGroup` traits. In a first step locking methods
>> >> are added and the existing code is refactored to use them. Commit two
>> >> derives a lock file name under '/run' for each group/snapshot. It also
>> >> adds double stat'ing. To avoid issues when upgrading, the file
>> >> `/run/proxmox-backup/old-locking` is created through a post-install
>> >> hook which is used to determine whether the system has been rebooted
>> >> and we can safely use the new locking mechanism.
>> >>
>> >> The third commit refactors locking for manifests and brings it in-line
>> >> with the group/snapshot locks. Finally, the last commit fixes a race
>> >> condition when changing the owner of a datastore.
>> >
>> >> Shannon Sterz (4):
>> >>   datastore/api/backup: prepare for fix of #3935 by adding lock helpers
>> >>   fix #3935: datastore/api/backup: move datastore locking to '/run'
>> >>   fix #3935: datastore: move manifest locking to new locking method
>> >>   fix: api: avoid race condition in set_backup_owner
>> >>
>> >
>> > applied series, added Wolfgang's Acked-by – feel encouraged to pick such
>> > things up already for a new revision, especially an A-b is less problematic
>> > with minor changes as long as the overall design stays the same – and also
>> > fixed a minor compile warning about an unused import that stemmed from
>> > intra-revision changes, thanks!
>>
>> thanks a bunch! should i always add all trailers mentioned on list?
>> wasn't sure about the `Acked-by` tbh ^^'
>
> At the very least any commits with no changes can accumulate all the
> trailers.
>
> For any changed commits you'll need to gauge whether or not another look
> is warranted.
> Eg. obviously typo or small rustfmt fixes are fine.
> In the previous series I also specifically stated that my Ack includes
> the proposed changes as I figured they'd be small enough to not require
> another complete review, so as a review I would've just done a git-diff
> between the 2 completely-applied versions rather than looked at the
> individual patches first. (I don't necessarily do this between versions,
> depending on how the changes are described in the emails, since with
> regular read-throughs I'll usually pick up more things which I might
> have missed in earlier versions.)

makes sense, thanks! i'll try to keep that in mind an do better on
adding trailers in the future!


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^ permalink raw reply	[flat|nested] 11+ messages in thread
end of thread, other threads:[~2025-03-28  8:18 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2025-03-26 11:44 [pbs-devel] [PATCH proxmox-backup v9 0/4] refactor datastore locking to use tmpfs Shannon Sterz
2025-03-26 11:44 ` [pbs-devel] [PATCH proxmox-backup v9 1/4] datastore/api/backup: prepare for fix of #3935 by adding lock helpers Shannon Sterz
2025-03-26 11:44 ` [pbs-devel] [PATCH proxmox-backup v9 2/4] fix #3935: datastore/api/backup: move datastore locking to '/run' Shannon Sterz
2025-03-26 15:14   ` Thomas Lamprecht
2025-03-26 15:22   ` Thomas Lamprecht
2025-03-26 11:44 ` [pbs-devel] [PATCH proxmox-backup v9 3/4] fix #3935: datastore: move manifest locking to new locking method Shannon Sterz
2025-03-26 11:44 ` [pbs-devel] [PATCH proxmox-backup v9 4/4] fix: api: avoid race condition in set_backup_owner Shannon Sterz
2025-03-26 15:36 ` [pbs-devel] applied-series: [PATCH proxmox-backup v9 0/4] refactor datastore locking to use tmpfs Thomas Lamprecht
2025-03-27 10:02   ` Shannon Sterz
2025-03-28  7:51     ` Wolfgang Bumiller
2025-03-28  8:17       ` Shannon Sterz

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