hmac-file-server/UPLOAD_COMPLETION_FIX.md

Upload Completion Issue - Diagnostic & Fix

Problem Analysis

User Report

• ✅ Upload starts correctly: HMAC validation working
• ✅ Transfer completes: File uploads without "endless encryption" delay
• ❌ Final step fails: "Not found" error after upload completion

Root Cause Identified

The issue occurs in the final storage step, specifically in the deduplication process:

Deduplication Process Steps

1. File Upload: ✅ Completes successfully
2. SHA256 Computation: ✅ Working (now skipped for files >1GB)
3. File Movement: ❌ os.Rename() and os.Link() operations failing
4. Hard Link Creation: ❌ Causing "not found" response

Technical Details

// From helpers.go - Deduplication process
if err := os.Rename(absFilename, existingPath); err != nil {
    log.Warnf("Failed to move file for deduplication: %v", err)
    return nil // Don't fail upload - BUT THIS MIGHT STILL CAUSE ISSUES
}

if err := os.Link(existingPath, absFilename); err != nil {
    log.Warnf("Failed to create link after deduplication: %v", err)
    // File restoration attempt may fail
    return nil
}

Fix Applied

Immediate Solution

# Temporarily disabled deduplication to isolate the issue
deduplication_enabled = false

Testing Strategy

1. Upload with deduplication disabled: Should complete successfully
2. Monitor file storage: Verify files appear in upload directory
3. Check for "not found" errors: Should be eliminated
4. Confirm client success: XMPP clients should show successful upload

Expected Results

Before Fix (with deduplication)

Upload Process:
1. HMAC validation: ✅ Success
2. File transfer: ✅ Success  
3. File created: ✅ Success
4. Deduplication: ❌ Hard link failure
5. Client response: ❌ "Not found"

After Fix (deduplication disabled)

Upload Process:
1. HMAC validation: ✅ Success
2. File transfer: ✅ Success
3. File stored directly: ✅ Success
4. Deduplication: ⏭️ Skipped
5. Client response: ✅ Success

Long-term Solution Options

Option 1: Fix Deduplication Hard Links

• Investigate NFS hard link limitations
• Implement fallback to file copying instead of linking
• Add better error handling for link failures

Option 2: Disable Deduplication for Large Files Only

• Keep deduplication for small files (where it works)
• Disable only for large files that were causing issues
• Maintains storage efficiency for smaller files

Option 3: Alternative Deduplication Strategy

• Use symbolic links instead of hard links
• Implement reference counting system
• Store deduplicated files in separate location

Monitoring & Verification

Test Script Created

/root/hmac-file-server/test_upload_completion.sh

Real-time Monitoring

• nginx access logs
• HMAC server logs
• Upload directory file creation
• Client response verification

Current Status

✅ Deduplication disabled to eliminate the storage failure
✅ Upload speed optimized (1GB limit prevents SHA256 delays)
✅ Server running with simplified storage process
🔄 Testing phase to confirm fix resolves "not found" issue

Next Steps

1. Test upload completion with current configuration
2. Verify client success (no more "not found" errors)
3. Decide on long-term deduplication strategy based on test results
4. Re-enable optimized deduplication if hard link issues can be resolved

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Issue: Final storage step failing in deduplication process
Fix: Deduplication temporarily disabled
Status: Testing upload completion