diff --git a/buffer/src/main/java/io/netty/buffer/AbstractByteBuf.java b/buffer/src/main/java/io/netty/buffer/AbstractByteBuf.java
index fe880c7efd1..3a19f85c21a 100644
--- a/buffer/src/main/java/io/netty/buffer/AbstractByteBuf.java
+++ b/buffer/src/main/java/io/netty/buffer/AbstractByteBuf.java
@@ -1417,6 +1417,13 @@ protected final void checkDstIndex(int index, int length, int dstIndex, int dstC
         }
     }
 
+    protected final void checkDstIndex(int length, int dstIndex, int dstCapacity) {
+        checkReadableBytes(length);
+        if (checkBounds) {
+            checkRangeBounds("dstIndex", dstIndex, length, dstCapacity);
+        }
+    }
+
     /**
      * Throws an {@link IndexOutOfBoundsException} if the current
      * {@linkplain #readableBytes() readable bytes} of this buffer is less
diff --git a/buffer/src/main/java/io/netty/buffer/PooledByteBuf.java b/buffer/src/main/java/io/netty/buffer/PooledByteBuf.java
index 3b42709a6e5..8c2d54674db 100644
--- a/buffer/src/main/java/io/netty/buffer/PooledByteBuf.java
+++ b/buffer/src/main/java/io/netty/buffer/PooledByteBuf.java
@@ -19,8 +19,13 @@
 import io.netty.util.Recycler;
 import io.netty.util.Recycler.Handle;
 
+import java.io.IOException;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
+import java.nio.channels.ClosedChannelException;
+import java.nio.channels.FileChannel;
+import java.nio.channels.GatheringByteChannel;
+import java.nio.channels.ScatteringByteChannel;
 
 abstract class PooledByteBuf<T> extends AbstractReferenceCountedByteBuf {
 
@@ -89,34 +94,23 @@ public int maxFastWritableBytes() {
 
     @Override
     public final ByteBuf capacity(int newCapacity) {
+        if (newCapacity == length) {
+            ensureAccessible();
+            return this;
+        }
         checkNewCapacity(newCapacity);
-
-        // If the request capacity does not require reallocation, just update the length of the memory.
-        if (chunk.unpooled) {
-            if (newCapacity == length) {
-                return this;
-            }
-        } else {
+        if (!chunk.unpooled) {
+            // If the request capacity does not require reallocation, just update the length of the memory.
             if (newCapacity > length) {
                 if (newCapacity <= maxLength) {
                     length = newCapacity;
                     return this;
                 }
-            } else if (newCapacity < length) {
-                if (newCapacity > maxLength >>> 1) {
-                    if (maxLength <= 512) {
-                        if (newCapacity > maxLength - 16) {
-                            length = newCapacity;
-                            setIndex(Math.min(readerIndex(), newCapacity), Math.min(writerIndex(), newCapacity));
-                            return this;
-                        }
-                    } else { // > 512 (i.e. >= 1024)
-                        length = newCapacity;
-                        setIndex(Math.min(readerIndex(), newCapacity), Math.min(writerIndex(), newCapacity));
-                        return this;
-                    }
-                }
-            } else {
+            } else if (newCapacity > maxLength >>> 1 &&
+                    (maxLength > 512 || newCapacity > maxLength - 16)) {
+                // here newCapacity < length
+                length = newCapacity;
+                setIndex(Math.min(readerIndex(), newCapacity), Math.min(writerIndex(), newCapacity));
                 return this;
             }
         }
@@ -187,4 +181,81 @@ private void recycle() {
     protected final int idx(int index) {
         return offset + index;
     }
+
+    final ByteBuffer _internalNioBuffer(int index, int length, boolean duplicate) {
+        index = idx(index);
+        ByteBuffer buffer = duplicate ? newInternalNioBuffer(memory) : internalNioBuffer();
+        buffer.limit(index + length).position(index);
+        return buffer;
+    }
+
+    ByteBuffer duplicateInternalNioBuffer(int index, int length) {
+        checkIndex(index, length);
+        return _internalNioBuffer(index, length, true);
+    }
+
+    @Override
+    public final ByteBuffer internalNioBuffer(int index, int length) {
+        checkIndex(index, length);
+        return _internalNioBuffer(index, length, false);
+    }
+
+    @Override
+    public final int nioBufferCount() {
+        return 1;
+    }
+
+    @Override
+    public final ByteBuffer nioBuffer(int index, int length) {
+        return duplicateInternalNioBuffer(index, length).slice();
+    }
+
+    @Override
+    public final ByteBuffer[] nioBuffers(int index, int length) {
+        return new ByteBuffer[] { nioBuffer(index, length) };
+    }
+
+    @Override
+    public final int getBytes(int index, GatheringByteChannel out, int length) throws IOException {
+        return out.write(duplicateInternalNioBuffer(index, length));
+    }
+
+    @Override
+    public final int readBytes(GatheringByteChannel out, int length) throws IOException {
+        checkReadableBytes(length);
+        int readBytes = out.write(_internalNioBuffer(readerIndex, length, false));
+        readerIndex += readBytes;
+        return readBytes;
+    }
+
+    @Override
+    public final int getBytes(int index, FileChannel out, long position, int length) throws IOException {
+        return out.write(duplicateInternalNioBuffer(index, length), position);
+    }
+
+    @Override
+    public final int readBytes(FileChannel out, long position, int length) throws IOException {
+        checkReadableBytes(length);
+        int readBytes = out.write(_internalNioBuffer(readerIndex, length, false), position);
+        readerIndex += readBytes;
+        return readBytes;
+    }
+
+    @Override
+    public final int setBytes(int index, ScatteringByteChannel in, int length) throws IOException {
+        try {
+            return in.read(internalNioBuffer(index, length));
+        } catch (ClosedChannelException ignored) {
+            return -1;
+        }
+    }
+
+    @Override
+    public final int setBytes(int index, FileChannel in, long position, int length) throws IOException {
+        try {
+            return in.read(internalNioBuffer(index, length), position);
+        } catch (ClosedChannelException ignored) {
+            return -1;
+        }
+    }
 }
diff --git a/buffer/src/main/java/io/netty/buffer/PooledDirectByteBuf.java b/buffer/src/main/java/io/netty/buffer/PooledDirectByteBuf.java
index 9601150b319..f05ab4bdb9a 100644
--- a/buffer/src/main/java/io/netty/buffer/PooledDirectByteBuf.java
+++ b/buffer/src/main/java/io/netty/buffer/PooledDirectByteBuf.java
@@ -22,10 +22,6 @@
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.nio.ByteBuffer;
-import java.nio.channels.ClosedChannelException;
-import java.nio.channels.FileChannel;
-import java.nio.channels.GatheringByteChannel;
-import java.nio.channels.ScatteringByteChannel;
 
 final class PooledDirectByteBuf extends PooledByteBuf<ByteBuffer> {
 
@@ -126,55 +122,30 @@ public ByteBuf getBytes(int index, ByteBuf dst, int dstIndex, int length) {
 
     @Override
     public ByteBuf getBytes(int index, byte[] dst, int dstIndex, int length) {
-        getBytes(index, dst, dstIndex, length, false);
-        return this;
-    }
-
-    private void getBytes(int index, byte[] dst, int dstIndex, int length, boolean internal) {
         checkDstIndex(index, length, dstIndex, dst.length);
-        ByteBuffer tmpBuf;
-        if (internal) {
-            tmpBuf = internalNioBuffer();
-        } else {
-            tmpBuf = memory.duplicate();
-        }
-        index = idx(index);
-        tmpBuf.clear().position(index).limit(index + length);
-        tmpBuf.get(dst, dstIndex, length);
+        _internalNioBuffer(index, length, true).get(dst, dstIndex, length);
+        return this;
     }
 
     @Override
     public ByteBuf readBytes(byte[] dst, int dstIndex, int length) {
-        checkReadableBytes(length);
-        getBytes(readerIndex, dst, dstIndex, length, true);
+        checkDstIndex(length, dstIndex, dst.length);
+        _internalNioBuffer(readerIndex, length, false).get(dst, dstIndex, length);
         readerIndex += length;
         return this;
     }
 
     @Override
     public ByteBuf getBytes(int index, ByteBuffer dst) {
-        getBytes(index, dst, false);
+        dst.put(duplicateInternalNioBuffer(index, dst.remaining()));
         return this;
     }
 
-    private void getBytes(int index, ByteBuffer dst, boolean internal) {
-        checkIndex(index, dst.remaining());
-        ByteBuffer tmpBuf;
-        if (internal) {
-            tmpBuf = internalNioBuffer();
-        } else {
-            tmpBuf = memory.duplicate();
-        }
-        index = idx(index);
-        tmpBuf.clear().position(index).limit(index + dst.remaining());
-        dst.put(tmpBuf);
-    }
-
     @Override
     public ByteBuf readBytes(ByteBuffer dst) {
         int length = dst.remaining();
         checkReadableBytes(length);
-        getBytes(readerIndex, dst, true);
+        dst.put(_internalNioBuffer(readerIndex, length, false));
         readerIndex += length;
         return this;
     }
@@ -201,61 +172,6 @@ public ByteBuf readBytes(OutputStream out, int length) throws IOException {
         return this;
     }
 
-    @Override
-    public int getBytes(int index, GatheringByteChannel out, int length) throws IOException {
-        return getBytes(index, out, length, false);
-    }
-
-    private int getBytes(int index, GatheringByteChannel out, int length, boolean internal) throws IOException {
-        checkIndex(index, length);
-        if (length == 0) {
-            return 0;
-        }
-
-        ByteBuffer tmpBuf;
-        if (internal) {
-            tmpBuf = internalNioBuffer();
-        } else {
-            tmpBuf = memory.duplicate();
-        }
-        index = idx(index);
-        tmpBuf.clear().position(index).limit(index + length);
-        return out.write(tmpBuf);
-    }
-
-    @Override
-    public int getBytes(int index, FileChannel out, long position, int length) throws IOException {
-        return getBytes(index, out, position, length, false);
-    }
-
-    private int getBytes(int index, FileChannel out, long position, int length, boolean internal) throws IOException {
-        checkIndex(index, length);
-        if (length == 0) {
-            return 0;
-        }
-
-        ByteBuffer tmpBuf = internal ? internalNioBuffer() : memory.duplicate();
-        index = idx(index);
-        tmpBuf.clear().position(index).limit(index + length);
-        return out.write(tmpBuf, position);
-    }
-
-    @Override
-    public int readBytes(GatheringByteChannel out, int length) throws IOException {
-        checkReadableBytes(length);
-        int readBytes = getBytes(readerIndex, out, length, true);
-        readerIndex += readBytes;
-        return readBytes;
-    }
-
-    @Override
-    public int readBytes(FileChannel out, long position, int length) throws IOException {
-        checkReadableBytes(length);
-        int readBytes = getBytes(readerIndex, out, position, length, true);
-        readerIndex += readBytes;
-        return readBytes;
-    }
-
     @Override
     protected void _setByte(int index, int value) {
         memory.put(idx(index), (byte) value);
@@ -327,23 +243,21 @@ public ByteBuf setBytes(int index, ByteBuf src, int srcIndex, int length) {
     @Override
     public ByteBuf setBytes(int index, byte[] src, int srcIndex, int length) {
         checkSrcIndex(index, length, srcIndex, src.length);
-        ByteBuffer tmpBuf = internalNioBuffer();
-        index = idx(index);
-        tmpBuf.clear().position(index).limit(index + length);
-        tmpBuf.put(src, srcIndex, length);
+        _internalNioBuffer(index, length, false).put(src, srcIndex, length);
         return this;
     }
 
     @Override
     public ByteBuf setBytes(int index, ByteBuffer src) {
-        checkIndex(index, src.remaining());
+        int length = src.remaining();
+        checkIndex(index, length);
         ByteBuffer tmpBuf = internalNioBuffer();
         if (src == tmpBuf) {
             src = src.duplicate();
         }
 
         index = idx(index);
-        tmpBuf.clear().position(index).limit(index + src.remaining());
+        tmpBuf.clear().position(index).limit(index + length);
         tmpBuf.put(src);
         return this;
     }
@@ -362,62 +276,11 @@ public int setBytes(int index, InputStream in, int length) throws IOException {
         return readBytes;
     }
 
-    @Override
-    public int setBytes(int index, ScatteringByteChannel in, int length) throws IOException {
-        checkIndex(index, length);
-        ByteBuffer tmpBuf = internalNioBuffer();
-        index = idx(index);
-        tmpBuf.clear().position(index).limit(index + length);
-        try {
-            return in.read(tmpBuf);
-        } catch (ClosedChannelException ignored) {
-            return -1;
-        }
-    }
-
-    @Override
-    public int setBytes(int index, FileChannel in, long position, int length) throws IOException {
-        checkIndex(index, length);
-        ByteBuffer tmpBuf = internalNioBuffer();
-        index = idx(index);
-        tmpBuf.clear().position(index).limit(index + length);
-        try {
-            return in.read(tmpBuf, position);
-        } catch (ClosedChannelException ignored) {
-            return -1;
-        }
-    }
-
     @Override
     public ByteBuf copy(int index, int length) {
         checkIndex(index, length);
         ByteBuf copy = alloc().directBuffer(length, maxCapacity());
-        copy.writeBytes(this, index, length);
-        return copy;
-    }
-
-    @Override
-    public int nioBufferCount() {
-        return 1;
-    }
-
-    @Override
-    public ByteBuffer nioBuffer(int index, int length) {
-        checkIndex(index, length);
-        index = idx(index);
-        return ((ByteBuffer) memory.duplicate().position(index).limit(index + length)).slice();
-    }
-
-    @Override
-    public ByteBuffer[] nioBuffers(int index, int length) {
-        return new ByteBuffer[] { nioBuffer(index, length) };
-    }
-
-    @Override
-    public ByteBuffer internalNioBuffer(int index, int length) {
-        checkIndex(index, length);
-        index = idx(index);
-        return (ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length);
+        return copy.writeBytes(this, index, length);
     }
 
     @Override
diff --git a/buffer/src/main/java/io/netty/buffer/PooledHeapByteBuf.java b/buffer/src/main/java/io/netty/buffer/PooledHeapByteBuf.java
index 467bde09cc9..bc740c01680 100644
--- a/buffer/src/main/java/io/netty/buffer/PooledHeapByteBuf.java
+++ b/buffer/src/main/java/io/netty/buffer/PooledHeapByteBuf.java
@@ -21,10 +21,6 @@
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.nio.ByteBuffer;
-import java.nio.channels.ClosedChannelException;
-import java.nio.channels.FileChannel;
-import java.nio.channels.GatheringByteChannel;
-import java.nio.channels.ScatteringByteChannel;
 
 class PooledHeapByteBuf extends PooledByteBuf<byte[]> {
 
@@ -117,8 +113,9 @@ public final ByteBuf getBytes(int index, byte[] dst, int dstIndex, int length) {
 
     @Override
     public final ByteBuf getBytes(int index, ByteBuffer dst) {
-        checkIndex(index, dst.remaining());
-        dst.put(memory, idx(index), dst.remaining());
+        int length = dst.remaining();
+        checkIndex(index, length);
+        dst.put(memory, idx(index), length);
         return this;
     }
 
@@ -129,51 +126,6 @@ public final ByteBuf getBytes(int index, OutputStream out, int length) throws IO
         return this;
     }
 
-    @Override
-    public final int getBytes(int index, GatheringByteChannel out, int length) throws IOException {
-        return getBytes(index, out, length, false);
-    }
-
-    private int getBytes(int index, GatheringByteChannel out, int length, boolean internal) throws IOException {
-        checkIndex(index, length);
-        index = idx(index);
-        ByteBuffer tmpBuf;
-        if (internal) {
-            tmpBuf = internalNioBuffer();
-        } else {
-            tmpBuf = ByteBuffer.wrap(memory);
-        }
-        return out.write((ByteBuffer) tmpBuf.clear().position(index).limit(index + length));
-    }
-
-    @Override
-    public final int getBytes(int index, FileChannel out, long position, int length) throws IOException {
-        return getBytes(index, out, position, length, false);
-    }
-
-    private int getBytes(int index, FileChannel out, long position, int length, boolean internal) throws IOException {
-        checkIndex(index, length);
-        index = idx(index);
-        ByteBuffer tmpBuf = internal ? internalNioBuffer() : ByteBuffer.wrap(memory);
-        return out.write((ByteBuffer) tmpBuf.clear().position(index).limit(index + length), position);
-    }
-
-    @Override
-    public final int readBytes(GatheringByteChannel out, int length) throws IOException {
-        checkReadableBytes(length);
-        int readBytes = getBytes(readerIndex, out, length, true);
-        readerIndex += readBytes;
-        return readBytes;
-    }
-
-    @Override
-    public final int readBytes(FileChannel out, long position, int length) throws IOException {
-        checkReadableBytes(length);
-        int readBytes = getBytes(readerIndex, out, position, length, true);
-        readerIndex += readBytes;
-        return readBytes;
-    }
-
     @Override
     protected void _setByte(int index, int value) {
         HeapByteBufUtil.setByte(memory, idx(index), value);
@@ -253,59 +205,17 @@ public final int setBytes(int index, InputStream in, int length) throws IOExcept
         return in.read(memory, idx(index), length);
     }
 
-    @Override
-    public final int setBytes(int index, ScatteringByteChannel in, int length) throws IOException {
-        checkIndex(index, length);
-        index = idx(index);
-        try {
-            return in.read((ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length));
-        } catch (ClosedChannelException ignored) {
-            return -1;
-        }
-    }
-
-    @Override
-    public final int setBytes(int index, FileChannel in, long position, int length) throws IOException {
-        checkIndex(index, length);
-        index = idx(index);
-        try {
-            return in.read((ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length), position);
-        } catch (ClosedChannelException ignored) {
-            return -1;
-        }
-    }
-
     @Override
     public final ByteBuf copy(int index, int length) {
         checkIndex(index, length);
         ByteBuf copy = alloc().heapBuffer(length, maxCapacity());
-        copy.writeBytes(memory, idx(index), length);
-        return copy;
-    }
-
-    @Override
-    public final int nioBufferCount() {
-        return 1;
-    }
-
-    @Override
-    public final ByteBuffer[] nioBuffers(int index, int length) {
-        return new ByteBuffer[] { nioBuffer(index, length) };
-    }
-
-    @Override
-    public final ByteBuffer nioBuffer(int index, int length) {
-        checkIndex(index, length);
-        index = idx(index);
-        ByteBuffer buf =  ByteBuffer.wrap(memory, index, length);
-        return buf.slice();
+        return copy.writeBytes(memory, idx(index), length);
     }
 
     @Override
-    public final ByteBuffer internalNioBuffer(int index, int length) {
+    final ByteBuffer duplicateInternalNioBuffer(int index, int length) {
         checkIndex(index, length);
-        index = idx(index);
-        return (ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length);
+        return ByteBuffer.wrap(memory, idx(index), length).slice();
     }
 
     @Override
diff --git a/buffer/src/main/java/io/netty/buffer/PooledUnsafeDirectByteBuf.java b/buffer/src/main/java/io/netty/buffer/PooledUnsafeDirectByteBuf.java
index e2dc22cb07d..e5a335d6d9b 100644
--- a/buffer/src/main/java/io/netty/buffer/PooledUnsafeDirectByteBuf.java
+++ b/buffer/src/main/java/io/netty/buffer/PooledUnsafeDirectByteBuf.java
@@ -23,10 +23,6 @@
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.nio.ByteBuffer;
-import java.nio.channels.ClosedChannelException;
-import java.nio.channels.FileChannel;
-import java.nio.channels.GatheringByteChannel;
-import java.nio.channels.ScatteringByteChannel;
 
 final class PooledUnsafeDirectByteBuf extends PooledByteBuf<ByteBuffer> {
     private static final Recycler<PooledUnsafeDirectByteBuf> RECYCLER = new Recycler<PooledUnsafeDirectByteBuf>() {
@@ -138,78 +134,12 @@ public ByteBuf getBytes(int index, ByteBuffer dst) {
         return this;
     }
 
-    @Override
-    public ByteBuf readBytes(ByteBuffer dst) {
-        int length = dst.remaining();
-        checkReadableBytes(length);
-        getBytes(readerIndex, dst);
-        readerIndex += length;
-        return this;
-    }
-
     @Override
     public ByteBuf getBytes(int index, OutputStream out, int length) throws IOException {
         UnsafeByteBufUtil.getBytes(this, addr(index), index, out, length);
         return this;
     }
 
-    @Override
-    public int getBytes(int index, GatheringByteChannel out, int length) throws IOException {
-        return getBytes(index, out, length, false);
-    }
-
-    private int getBytes(int index, GatheringByteChannel out, int length, boolean internal) throws IOException {
-        checkIndex(index, length);
-        if (length == 0) {
-            return 0;
-        }
-
-        ByteBuffer tmpBuf;
-        if (internal) {
-            tmpBuf = internalNioBuffer();
-        } else {
-            tmpBuf = memory.duplicate();
-        }
-        index = idx(index);
-        tmpBuf.clear().position(index).limit(index + length);
-        return out.write(tmpBuf);
-    }
-
-    @Override
-    public int getBytes(int index, FileChannel out, long position, int length) throws IOException {
-        return getBytes(index, out, position, length, false);
-    }
-
-    private int getBytes(int index, FileChannel out, long position, int length, boolean internal) throws IOException {
-        checkIndex(index, length);
-        if (length == 0) {
-            return 0;
-        }
-
-        ByteBuffer tmpBuf = internal ? internalNioBuffer() : memory.duplicate();
-        index = idx(index);
-        tmpBuf.clear().position(index).limit(index + length);
-        return out.write(tmpBuf, position);
-    }
-
-    @Override
-    public int readBytes(GatheringByteChannel out, int length)
-            throws IOException {
-        checkReadableBytes(length);
-        int readBytes = getBytes(readerIndex, out, length, true);
-        readerIndex += readBytes;
-        return readBytes;
-    }
-
-    @Override
-    public int readBytes(FileChannel out, long position, int length)
-            throws IOException {
-        checkReadableBytes(length);
-        int readBytes = getBytes(readerIndex, out, position, length, true);
-        readerIndex += readBytes;
-        return readBytes;
-    }
-
     @Override
     protected void _setByte(int index, int value) {
         UnsafeByteBufUtil.setByte(addr(index), (byte) value);
@@ -278,61 +208,11 @@ public int setBytes(int index, InputStream in, int length) throws IOException {
         return UnsafeByteBufUtil.setBytes(this, addr(index), index, in, length);
     }
 
-    @Override
-    public int setBytes(int index, ScatteringByteChannel in, int length) throws IOException {
-        checkIndex(index, length);
-        ByteBuffer tmpBuf = internalNioBuffer();
-        index = idx(index);
-        tmpBuf.clear().position(index).limit(index + length);
-        try {
-            return in.read(tmpBuf);
-        } catch (ClosedChannelException ignored) {
-            return -1;
-        }
-    }
-
-    @Override
-    public int setBytes(int index, FileChannel in, long position, int length) throws IOException {
-        checkIndex(index, length);
-        ByteBuffer tmpBuf = internalNioBuffer();
-        index = idx(index);
-        tmpBuf.clear().position(index).limit(index + length);
-        try {
-            return in.read(tmpBuf, position);
-        } catch (ClosedChannelException ignored) {
-            return -1;
-        }
-    }
-
     @Override
     public ByteBuf copy(int index, int length) {
         return UnsafeByteBufUtil.copy(this, addr(index), index, length);
     }
 
-    @Override
-    public int nioBufferCount() {
-        return 1;
-    }
-
-    @Override
-    public ByteBuffer[] nioBuffers(int index, int length) {
-        return new ByteBuffer[] { nioBuffer(index, length) };
-    }
-
-    @Override
-    public ByteBuffer nioBuffer(int index, int length) {
-        checkIndex(index, length);
-        index = idx(index);
-        return ((ByteBuffer) memory.duplicate().position(index).limit(index + length)).slice();
-    }
-
-    @Override
-    public ByteBuffer internalNioBuffer(int index, int length) {
-        checkIndex(index, length);
-        index = idx(index);
-        return (ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length);
-    }
-
     @Override
     public boolean hasArray() {
         return false;