xnu-1456.1.26.tar.gz

[apple/xnu.git] / bsd / hfs / hfscommon / BTree / BTreeAllocate.c

diff --git a/bsd/hfs/hfscommon/BTree/BTreeAllocate.c b/bsd/hfs/hfscommon/BTree/BTreeAllocate.c
index 41adf88635b5b6aff2b67ffdced38343329ee359..64c7b86f0cde969922909410077f313f9b1470d7 100644 (file)
--- a/bsd/hfs/hfscommon/BTree/BTreeAllocate.c
+++ b/bsd/hfs/hfscommon/BTree/BTreeAllocate.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000-2003, 2005-2008 Apple Inc. All rights reserved.
+ * Copyright (c) 2000-2003, 2005-2009 Apple Inc. All rights reserved.
  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  * 
@@ -359,7 +359,7 @@ OSStatus    ExtendBTree     (BTreeControlBlockPtr   btreePtr,
        } while ( ((BTNodeDescriptor*)mapNode.buffer)->fLink != 0 );
 
        if (DEBUG_BUILD && totalMapBits != CalcMapBits (btreePtr))
-               Panic ("\pExtendBTree: totalMapBits != CalcMapBits");
+               Panic ("ExtendBTree: totalMapBits != CalcMapBits");
                
        /////////////////////// Extend LEOF If Necessary ////////////////////////////
 
@@ -464,7 +464,7 @@ OSStatus    ExtendBTree     (BTreeControlBlockPtr   btreePtr,
                        
                        if (DEBUG_BUILD && mapSize != M_MapRecordSize (btreePtr->nodeSize) )
                        {
-                               Panic ("\pExtendBTree: mapSize != M_MapRecordSize");
+                               Panic ("ExtendBTree: mapSize != M_MapRecordSize");
                        }
                        
                        mapBits         = mapSize << 3;         // mapSize (in bytes) * 8
@@ -614,3 +614,112 @@ u_int32_t         CalcMapBits     (BTreeControlBlockPtr    btreePtr)
        
        return  mapBits;
 }
+
+
+/*-------------------------------------------------------------------------------
+Routine:       BTZeroUnusedNodes
+
+Function:      Write zeros to all nodes in the B-tree that are not currently in use.
+-------------------------------------------------------------------------------*/
+__private_extern__
+int
+BTZeroUnusedNodes(FCB *filePtr)
+{
+       int                                             err;
+       vnode_t                                 vp;
+       BTreeControlBlockPtr    btreePtr;
+       BlockDescriptor                 mapNode;
+       buf_t                                   bp;
+       u_int32_t                               nodeNumber;
+       u_int16_t                               *mapPtr, *pos;
+       u_int16_t                               mapSize, size;
+       u_int16_t                               mask;
+       u_int16_t                               bitNumber;
+       u_int16_t                               word;
+       int                                             numWritten;
+       
+       vp = FTOV(filePtr);
+       btreePtr = (BTreeControlBlockPtr) filePtr->fcbBTCBPtr;
+       bp = NULL;
+       nodeNumber = 0;
+       mapNode.buffer = nil;
+       mapNode.blockHeader = nil;
+       numWritten = 0;
+       
+       /* Iterate over map nodes. */
+       while (true)
+       {
+               err = GetMapNode (btreePtr, &mapNode, &mapPtr, &mapSize);
+               if (err)
+               {
+                       err = MacToVFSError(err);
+                       goto ErrorExit;
+               }
+               
+               pos             = mapPtr;
+               size    = mapSize;
+               size  >>= 1;                                    /* convert to number of 16-bit words */
+
+               /* Iterate over 16-bit words in the map record. */
+               while (size--)
+               {
+                       if (*pos != 0xFFFF)                     /* Anything free in this word? */
+                       {
+                               word = SWAP_BE16(*pos);
+                               
+                               /* Iterate over bits in the word. */
+                               for (bitNumber = 0, mask = 0x8000;
+                                    bitNumber < 16;
+                                    ++bitNumber, mask >>= 1)
+                               {
+                                       if (word & mask)
+                                               continue;                               /* This node is in use. */
+                                       
+                                       if (nodeNumber + bitNumber >= btreePtr->totalNodes)
+                                       {
+                                               /* We've processed all of the nodes. */
+                                               goto done;
+                                       }
+                                       
+                                       /*
+                                        * Get a buffer full of zeros and write it to the unused
+                                        * node.  Since we'll probably be writing a lot of nodes,
+                                        * bypass the journal (to avoid a transaction that's too
+                                        * big).  Instead, this behaves more like clearing out
+                                        * nodes when extending a B-tree (eg., ClearBTNodes).
+                                        */
+                                       bp = buf_getblk(vp, nodeNumber + bitNumber, btreePtr->nodeSize, 0, 0, BLK_META);
+                                       if (bp == NULL)
+                                       {
+                                               printf("hfs: BTZeroUnusedNodes: unable to read node %u\n", nodeNumber + bitNumber);
+                                               err = EIO;
+                                               goto ErrorExit;
+                                       }
+                                       
+                                       buf_clear(bp);
+                                       buf_markaged(bp);
+                                       
+                                       /*
+                                        * Try not to hog the buffer cache.  Wait for the write
+                                        * every 32 nodes.
+                                        */
+                                       ++numWritten;
+                                       if (numWritten % 32 == 0)
+                                               VNOP_BWRITE(bp);
+                                       else
+                                               buf_bawrite(bp);
+                               }
+                       }
+                       
+                       /* Go to the next word in the bitmap */
+                       ++pos;
+                       nodeNumber += 16;
+               }
+       }
+
+ErrorExit:
+done:
+       (void) ReleaseNode(btreePtr, &mapNode);
+       
+       return err;
+}