[PATCH proxmox-backup] snapshot locking: improve error contexts

["Fabian Grünbichler" <f.gruenbichler@proxmox.com>]

having the struct-debug representation logged is rather noisy, the relative
path contains all the relevant information.

Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
---

Notes:
    this is still often redundant, since context higher up might contain the
    API-type BackupDir, and the error itself might contain multiple copies of the
    lock path, but it's still an improvement..

 pbs-datastore/src/datastore.rs | 9 ++++++---
 src/api2/reader/mod.rs         | 4 ++--
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/pbs-datastore/src/datastore.rs b/pbs-datastore/src/datastore.rs
index d6dcce77f..665333f52 100644
--- a/pbs-datastore/src/datastore.rs
+++ b/pbs-datastore/src/datastore.rs
@@ -1870,14 +1870,14 @@ impl DataStore {
         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:?}'")
+                    format!("while creating new locked snapshot {relative_path:?}")
                 })?;
                 Ok((relative_path, true, guard))
             }
             Err(ref e) if e.kind() == io::ErrorKind::AlreadyExists => {
                 let guard = backup_dir
                     .lock()
-                    .with_context(|| format!("while creating locked snapshot '{backup_dir:?}'"))?;
+                    .with_context(|| format!("while creating locked snapshot {relative_path:?}"))?;
                 Ok((relative_path, false, guard))
             }
             Err(e) => Err(e.into()),
@@ -2838,7 +2838,10 @@ impl DataStore {
         }
 
         let _guard = backup_dir.lock().with_context(|| {
-            format!("while updating the protection status of snapshot '{backup_dir:?}'")
+            format!(
+                "while updating the protection status of snapshot {:?}",
+                backup_dir.relative_path()
+            )
         })?;
 
         let protected_path = backup_dir.protected_file();
diff --git a/src/api2/reader/mod.rs b/src/api2/reader/mod.rs
index 4321d2286..29c00e74c 100644
--- a/src/api2/reader/mod.rs
+++ b/src/api2/reader/mod.rs
@@ -131,12 +131,12 @@ fn upgrade_to_backup_reader_protocol(
         }
 
         if !backup_dir.full_path().exists() {
-            bail!("snapshot {} does not exist.", backup_dir.dir());
+            bail!("snapshot {:?} does not exist.", backup_dir.relative_path());
         }
 
         let _guard = backup_dir
             .lock_shared()
-            .with_context(|| format!("while reading snapshot '{backup_dir:?}'"))?;
+            .with_context(|| format!("while reading snapshot {:?}", backup_dir.relative_path()))?;
 
         let path = datastore.base_path();
 
-- 
2.47.3