[PATCH v2 proxmox-backup 2/2] datastore: rephrase error messages for failed chunk insert

[Robert Obkircher <r.obkircher@proxmox.com>]

The "not allowed" phrasing sounds like an access-right problem, when
the actual problem is likely file corruption.

Link: https://forum.proxmox.com/threads/184140
Signed-off-by: Robert Obkircher <r.obkircher@proxmox.com>
---
 pbs-datastore/src/chunk_store.rs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/pbs-datastore/src/chunk_store.rs b/pbs-datastore/src/chunk_store.rs
index e5cfd130f..a3cc47d54 100644
--- a/pbs-datastore/src/chunk_store.rs
+++ b/pbs-datastore/src/chunk_store.rs
@@ -718,15 +718,16 @@ impl ChunkStore {
                 // includes data derived from the encryption key
                 if magic == UNCOMPRESSED_BLOB_MAGIC_1_0 || magic == COMPRESSED_BLOB_MAGIC_1_0 {
                     bail!(
-                        "Overwriting unencrypted chunk '{digest_str}' on store '{name}' with encrypted chunk with same digest not allowed!"
+                        "Cannot overwrite existing unencrypted chunk '{digest_str}' on store '{name}' with encrypted chunk."
                     );
                 }
 
                 // if both chunks are uncompressed and encrypted and have the same digest, but
                 // their sizes are different, one of them *must* be invalid
                 if magic == ENCRYPTED_BLOB_MAGIC_1_0 && !chunk.is_compressed() {
+                    // gc is also mentioned because verification doesn't check unreferenced chunks
                     bail!(
-                        "Overwriting existing (encrypted) chunk '{digest_str}' on store '{name}' is not allowed!"
+                        "Found existing encrypted chunk '{digest_str}' of different size on store '{name}'. Verify and garbage-collect the full datastore to clean up possibly corrupted chunks.",
                     )
                 }
 
-- 
2.47.3