[ISSUE #9713] Improve data consistency in DefaultMappedFile flush method

- Move FLUSHED_POSITION_UPDATER.set() inside try block
- Prevent false positive flush success when actual flush operation fails
- Ensure data consistency and prevent potential data loss on system crash

Previously, flushed position was updated even when flush operation failed,
which could lead to data loss as the system would incorrectly assume
data was persisted to disk when it was still in memory.

Co-authored-by: guyinyou <guyinyou.gyy@alibaba-inc.com>

Author: guyinyou

store/src/main/java/org/apache/rocketmq/store/logfile/DefaultMappedFile.java

@@ -123,6 +123,7 @@ public class DefaultMappedFile extends AbstractMappedFile {
     private static final SharedByteBuffer[] SHARED_BYTE_BUFFER;
 
     protected RunningFlags runningFlags;
+
     static class SharedByteBuffer {
         private final ReentrantLock lock;
         private final ByteBuffer buffer;
@@ -532,14 +533,13 @@ public boolean appendMessageUsingFileChannel(byte[] data) {
      */
     @Override
     public int flush(final int flushLeastPages) {
+        if (!isWriteable()) {
+            return this.getFlushedPosition();
+        }
         if (this.isAbleToFlush(flushLeastPages)) {
             if (this.hold()) {
                 int value = getReadPosition();
 
-                if (!isWriteable()) {
-                    return this.getFlushedPosition();
-                }
-
                 try {
                     this.mappedByteBufferAccessCountSinceLastSwap++;
 
@@ -555,14 +555,13 @@ public int flush(final int flushLeastPages) {
                         }
                     }
                     this.lastFlushTime = System.currentTimeMillis();
+                    FLUSHED_POSITION_UPDATER.set(this, value);
                 } catch (Throwable e) {
                     if (e instanceof IOException) {
                         getAndMakeNotWriteable();
                     }
                     log.error("Error occurred when force data to disk.", e);
                 }
-
-                FLUSHED_POSITION_UPDATER.set(this, value);
                 this.release();
             } else {
                 log.warn("in flush, hold failed, flush offset = " + FLUSHED_POSITION_UPDATER.get(this));