fix: bad read by wrong data region

    User io may involve discontinuous segments in different chunks. Bad
    read is produced by merging them into continuous one. That is what
    Region does. This pr separate discontinuous segments into different
    regions, avoiding merging forcibly.

Signed-off-by: 泰友 <[email protected]>

storage/src/cache/cachedfile.rs

@@ -1662,6 +1662,20 @@ impl FileIoMergeState {
         tag: BlobIoTag,
         chunk: Option<Arc<dyn BlobChunkInfo>>,
     ) -> Result<()> {
+        // Make sure user io of same region continuous
+        if !self.regions.is_empty() && self.joinable(region_type) {
+            let region = &self.regions[self.regions.len() - 1];
+            if !region.seg.is_empty() && tag.is_user_io() {
+                if let BlobIoTag::User(ref seg) = tag {
+                    if seg.offset as u64 + start
+                        != region.blob_address + region.seg.offset as u64 + region.seg.len as u64
+                    {
+                        self.commit();
+                    }
+                }
+            }
+        }
+
         if self.regions.is_empty() || !self.joinable(region_type) {
             self.regions.push(Region::new(region_type));
             self.last_region_joinable = true;
@@ -1793,7 +1807,7 @@ mod tests {
 
         let tag = BlobIoTag::User(BlobIoSegment {
             offset: 0x1800,
-            len: 0x1800,
+            len: 0x800,
         });
         state
             .push(RegionType::CacheFast, 0x1000, 0x2000, tag, None)
@@ -1810,8 +1824,8 @@ mod tests {
         assert_eq!(state.regions.len(), 1);
 
         let tag = BlobIoTag::User(BlobIoSegment {
-            offset: 0x0000,
-            len: 0x2000,
+            offset: 0x0001,
+            len: 0x1fff,
         });
         state
             .push(RegionType::CacheSlow, 0x5000, 0x2000, tag, None)