storage: fix chunk map compatibility

The blob cache file of nydusd v2.2 and <=v2.1 are in different
formats, which are not compatible. Should use different chunk map
files for them, in order to upgrade or downgrade smoothly.

For the nydusd <=v2.1, the files in blob cache directory:

```
$blob_id
$blob_id.chunk_map
```

For the nydusd =v2.2, the files in blob cache directory:

```
$blob_id.blob.data
$blob_id.chunk_map
```

NOTE: nydusd (v2.2) maybe use the chunk map file of nydusd(<=v2.1),
it will cause the corrupted blob cache data to be read.

For the nydusd of current patch, the files in blob cache directory:

```
$blob_id.blob.data
$blob_id.blob.data.chunk_map
```

NOTE: this will discard the old blob cache data and chunk map files.

Signed-off-by: Yan Song <[email protected]>

storage/src/cache/filecache/mod.rs

@@ -25,6 +25,9 @@ use crate::cache::{BlobCache, BlobCacheMgr};
 use crate::device::{BlobFeatures, BlobInfo};
 use crate::RAFS_DEFAULT_CHUNK_SIZE;
 
+pub const BLOB_RAW_FILE_SUFFIX: &str = ".blob.raw";
+pub const BLOB_DATA_FILE_SUFFIX: &str = ".blob.data";
+
 /// An implementation of [BlobCacheMgr](../trait.BlobCacheMgr.html) to improve performance by
 /// caching uncompressed blob with local storage.
 #[derive(Clone)]
@@ -107,7 +110,7 @@ impl FileCacheMgr {
                 .underlying_files
                 .lock()
                 .unwrap()
-                .insert(blob_id);
+                .insert(blob_id + BLOB_DATA_FILE_SUFFIX);
             Ok(entry)
         }
     }
@@ -236,9 +239,9 @@ impl FileCacheEntry {
                 && !is_legacy_stargz;
             // Set cache file to its expected size.
             let suffix = if mgr.cache_raw_data {
-                ".blob.raw"
+                BLOB_RAW_FILE_SUFFIX
             } else {
-                ".blob.data"
+                BLOB_DATA_FILE_SUFFIX
             };
             let blob_data_file_path = blob_file_path.clone() + suffix;
             let file = OpenOptions::new()
@@ -358,7 +361,7 @@ impl FileCacheEntry {
             Arc::new(BlobStateMap::from(DigestedChunkMap::new()))
         } else {
             Arc::new(BlobStateMap::from(IndexedChunkMap::new(
-                blob_file,
+                &format!("{}{}", blob_file, BLOB_DATA_FILE_SUFFIX),
                 blob_info.chunk_count(),
                 true,
             )?))

storage/src/cache/fscache/mod.rs

@@ -22,6 +22,8 @@ use crate::device::{BlobFeatures, BlobInfo, BlobObject};
 use crate::factory::BLOB_FACTORY;
 use crate::RAFS_DEFAULT_CHUNK_SIZE;
 
+use crate::cache::filecache::BLOB_DATA_FILE_SUFFIX;
+
 const FSCACHE_BLOBS_CHECK_NUM: u8 = 1;
 
 /// An implementation of [BlobCacheMgr](../trait.BlobCacheMgr.html) to improve performance by
@@ -104,7 +106,7 @@ impl FsCacheMgr {
                 .underlying_files
                 .lock()
                 .unwrap()
-                .insert(blob_id);
+                .insert(blob_id + BLOB_DATA_FILE_SUFFIX);
             Ok(entry)
         }
     }
@@ -256,7 +258,7 @@ impl FileCacheEntry {
         };
 
         let chunk_map = Arc::new(BlobStateMap::from(IndexedChunkMap::new(
-            &blob_file_path,
+            &format!("{}{}", blob_file_path, BLOB_DATA_FILE_SUFFIX),
             blob_info.chunk_count(),
             false,
         )?));

storage/src/cache/state/indexed_chunk_map.rs

@@ -12,7 +12,7 @@ use std::io::Result;
 
 use crate::cache::state::persist_map::PersistMap;
 use crate::cache::state::{ChunkIndexGetter, ChunkMap, RangeMap};
-use crate::device::{BlobChunkInfo, BlobInfo};
+use crate::device::BlobChunkInfo;
 
 /// The name suffix of blob chunk_map file, named $blob_id.chunk_map.
 const FILE_SUFFIX: &str = "chunk_map";
@@ -39,14 +39,6 @@ impl IndexedChunkMap {
 
         PersistMap::open(&filename, chunk_count, true, persist).map(|map| IndexedChunkMap { map })
     }
-
-    /// Create a new instance of `IndexedChunkMap` from an existing chunk map file.
-    pub fn open(blob_info: &BlobInfo, workdir: &str) -> Result<Self> {
-        let filename = format!("{}/{}.{}", workdir, blob_info.blob_id(), FILE_SUFFIX);
-
-        PersistMap::open(&filename, blob_info.chunk_count(), false, true)
-            .map(|map| IndexedChunkMap { map })
-    }
 }
 
 impl ChunkMap for IndexedChunkMap {

utils/src/metrics.rs

@@ -714,6 +714,8 @@ pub struct BlobcacheMetrics {
     id: String,
     // Prefer to let external tool get file's state like file size and disk usage.
     // Because stat(2) file may get blocked.
+    // It should include the real blob cache file names, so that the external GC
+    // process can handle it directly.
     pub underlying_files: Mutex<HashSet<String>>,
     pub store_path: String,
     // Cache hit percentage = (partial_hits + whole_hits) / total