+ return retVal;
+}
+
+/*
+ * FindBlockForgarbageCollection is used to select the dirtiest block (or close enough)
+ * for garbage collection.
+ */
+
+static unsigned yaffs_FindBlockForGarbageCollection(yaffs_Device *dev,
+ int aggressive,
+ int background)
+{
+ int i;
+ int iterations;
+ unsigned selected = 0;
+ int prioritised = 0;
+ int prioritisedExists = 0;
+ yaffs_BlockInfo *bi;
+ int threshold;
+
+ /* First let's see if we need to grab a prioritised block */
+ if (dev->hasPendingPrioritisedGCs && !aggressive) {
+ dev->gcDirtiest = 0;
+ bi = dev->blockInfo;
+ for (i = dev->internalStartBlock;
+ i <= dev->internalEndBlock && !selected;
+ i++) {
+
+ if (bi->gcPrioritise) {
+ prioritisedExists = 1;
+ if (bi->blockState == YAFFS_BLOCK_STATE_FULL &&
+ yaffs_BlockNotDisqualifiedFromGC(dev, bi)) {
+ selected = i;
+ prioritised = 1;
+ }
+ }
+ bi++;
+ }
+
+ /*
+ * If there is a prioritised block and none was selected then
+ * this happened because there is at least one old dirty block gumming
+ * up the works. Let's gc the oldest dirty block.
+ */
+
+ if(prioritisedExists &&
+ !selected &&
+ dev->oldestDirtyBlock > 0)
+ selected = dev->oldestDirtyBlock;
+
+ if (!prioritisedExists) /* None found, so we can clear this */
+ dev->hasPendingPrioritisedGCs = 0;
+ }
+
+ /* If we're doing aggressive GC then we are happy to take a less-dirty block, and
+ * search harder.
+ * else (we're doing a leasurely gc), then we only bother to do this if the
+ * block has only a few pages in use.
+ */
+
+ if (!selected){
+ int pagesUsed;
+ int nBlocks = dev->internalEndBlock - dev->internalStartBlock + 1;
+ if (aggressive){
+ threshold = dev->param.nChunksPerBlock;
+ iterations = nBlocks;
+ } else {
+ int maxThreshold = dev->param.nChunksPerBlock/2;
+ threshold = background ?
+ (dev->gcNotDone + 2) * 2 : 0;
+ if(threshold <YAFFS_GC_PASSIVE_THRESHOLD)
+ threshold = YAFFS_GC_PASSIVE_THRESHOLD;
+ if(threshold > maxThreshold)
+ threshold = maxThreshold;
+
+ iterations = nBlocks / 16 + 1;
+ if (iterations > 100)
+ iterations = 100;
+ }
+
+ for (i = 0;
+ i < iterations &&
+ (dev->gcDirtiest < 1 ||
+ dev->gcPagesInUse > YAFFS_GC_GOOD_ENOUGH);
+ i++) {
+ dev->gcBlockFinder++;
+ if (dev->gcBlockFinder < dev->internalStartBlock ||
+ dev->gcBlockFinder > dev->internalEndBlock)
+ dev->gcBlockFinder = dev->internalStartBlock;
+
+ bi = yaffs_GetBlockInfo(dev, dev->gcBlockFinder);
+
+ pagesUsed = bi->pagesInUse - bi->softDeletions;
+
+ if (bi->blockState == YAFFS_BLOCK_STATE_FULL &&
+ pagesUsed < dev->param.nChunksPerBlock &&
+ (dev->gcDirtiest < 1 || pagesUsed < dev->gcPagesInUse) &&
+ yaffs_BlockNotDisqualifiedFromGC(dev, bi)) {
+ dev->gcDirtiest = dev->gcBlockFinder;
+ dev->gcPagesInUse = pagesUsed;
+ }
+ }
+
+ if(dev->gcDirtiest > 0 && dev->gcPagesInUse <= threshold)
+ selected = dev->gcDirtiest;
+ }
+
+ /*
+ * If nothing has been selected for a while, try selecting the oldest dirty
+ * because that's gumming up the works.
+ */
+
+ if(!selected && dev->param.isYaffs2 &&
+ dev->gcNotDone >= ( background ? 10 : 20)){
+ yaffs_FindOldestDirtySequence(dev);
+ if(dev->oldestDirtyBlock > 0) {
+ selected = dev->oldestDirtyBlock;
+ dev->gcDirtiest = selected;
+ dev->oldestDirtyGCs++;
+ bi = yaffs_GetBlockInfo(dev, selected);
+ dev->gcPagesInUse = bi->pagesInUse - bi->softDeletions;
+ } else
+ dev->gcNotDone = 0;
+ }
+
+ if(selected){
+ T(YAFFS_TRACE_GC,
+ (TSTR("GC Selected block %d with %d free, prioritised:%d" TENDSTR),
+ selected,
+ dev->param.nChunksPerBlock - dev->gcPagesInUse,
+ prioritised));
+
+ if(background)
+ dev->backgroundGCs++;
+ dev->gcDirtiest = 0;
+ dev->gcPagesInUse = 0;
+ dev->gcNotDone = 0;
+ if(dev->refreshSkip > 0)
+ dev->refreshSkip--;
+ } else{
+ dev->gcNotDone++;
+ T(YAFFS_TRACE_GC,
+ (TSTR("GC none: finder %d skip %d threshold %d dirtiest %d using %d oldest %d%s" TENDSTR),
+ dev->gcBlockFinder, dev->gcNotDone,
+ threshold,
+ dev->gcDirtiest, dev->gcPagesInUse,
+ dev->oldestDirtyBlock,
+ background ? " bg" : ""));
+ }
+
+ return selected;