Don't bail out just because a node couldn't be read.

* Added a new CachedNode::SetTo() variant that actually returns an error code.
* Only bail out if there was an actual I/O error, not already if the offset
  was invalid.
* This should help fixing some corruption corner cases.

src/add-ons/kernel/file_systems/bfs/BPlusTree.cpp

@@ -268,11 +268,20 @@ CachedNode::Unset()
 const bplustree_node*
 CachedNode::SetTo(off_t offset, bool check)
 {
-	if (fTree == NULL || fTree->fStream == NULL) {
+	const bplustree_node* node;
-		REPORT_ERROR(B_BAD_VALUE);
+	if (SetTo(offset, &node, check) == B_OK)
+		return node;
+
 	return NULL;
 }
 
+
+status_t
+CachedNode::SetTo(off_t offset, const bplustree_node** _node, bool check)
+{
+	if (fTree == NULL || fTree->fStream == NULL)
+		RETURN_ERROR(B_BAD_VALUE);
+
 	Unset();
 
 	// You can only ask for nodes at valid positions - you can't
@@ -281,7 +290,7 @@ CachedNode::SetTo(off_t offset, bool check)
 	if (offset > fTree->fHeader.MaximumSize() - fTree->fNodeSize
 		|| offset <= 0
 		|| (offset % fTree->fNodeSize) != 0)
-		return NULL;
+		RETURN_ERROR(B_BAD_VALUE);
 
 	if (InternalSetTo(NULL, offset) != NULL && check) {
 		// sanity checks (links, all_key_count)
@@ -289,10 +298,12 @@ CachedNode::SetTo(off_t offset, bool check)
 			FATAL(("invalid node [%p] read from offset %" B_PRIdOFF " (block %"
 				B_PRIdOFF "), inode at %" B_PRIdINO "\n", fNode, offset,
 				fBlockNumber, fTree->fStream->ID()));
-			return NULL;
+			return B_BAD_DATA;
 		}
 	}
-	return fNode;
+
+	*_node = fNode;
+	return B_OK;
 }
 
 
@@ -702,10 +713,19 @@ BPlusTree::Validate(bool repair, bool& _errorsFound)
 	CachedNode cached(this);
 	off_t freeOffset = fHeader.FreeNode();
 	while (freeOffset > 0) {
-		const bplustree_node* node = cached.SetTo(freeOffset, false);
+		const bplustree_node* node;
-		if (node == NULL)
+		status_t status = cached.SetTo(freeOffset, &node, false);
+		if (status != B_OK) {
+			if (status == B_IO_ERROR)
 				return B_IO_ERROR;
 
+			dprintf("inode %" B_PRIdOFF ": free node at %" B_PRIdOFF " could "
+				"not be read: %s\n", fStream->ID(), freeOffset,
+				strerror(status));
+			check.FoundError();
+			break;
+		}
+
 		if (check.Visited(freeOffset)) {
 			dprintf("inode %" B_PRIdOFF ": free node at %" B_PRIdOFF
 				" circular!\n", fStream->ID(), freeOffset);
@@ -726,12 +746,12 @@ BPlusTree::Validate(bool repair, bool& _errorsFound)
 
 	// Iterate over the complete tree recursively
 
-	const bplustree_node* root = cached.SetTo(fHeader.RootNode(), true);
+	const bplustree_node* root;
-	if (root == NULL)
+	status_t status = cached.SetTo(fHeader.RootNode(), &root, true);
-		return B_IO_ERROR;
+	if (status != B_OK)
+		return status;
 
-	status_t status = _ValidateChildren(check, 0, fHeader.RootNode(), NULL, 0,
+	status = _ValidateChildren(check, 0, fHeader.RootNode(), NULL, 0, root);
-		root);
 
 	if (check.ErrorsFound())
 		_errorsFound = true;
@@ -2292,11 +2312,19 @@ BPlusTree::_ValidateChildren(TreeCheck& check, uint32 level, off_t offset,
 			off_t lastDuplicateOffset = BPLUSTREE_NULL;
 
 			while (duplicateOffset != BPLUSTREE_NULL) {
-				const bplustree_node* node
+				const bplustree_node* node;
-					= cached.SetTo(duplicateOffset, false);
+				status_t status = cached.SetTo(duplicateOffset, &node, false);
-				if (node == NULL)
+				if (status != B_OK) {
+					if (status == B_IO_ERROR)
 						return B_IO_ERROR;
 
+					dprintf("inode %" B_PRIdOFF ": duplicate node at %"
+						B_PRIdOFF " could not be read: %s\n", fStream->ID(),
+						duplicateOffset, strerror(status));
+					check.FoundError();
+					break;
+				}
+
 				bool isFragmentNode = bplustree_node::LinkType(childOffset)
 					== BPLUSTREE_DUPLICATE_FRAGMENT;
 				bool isKnownFragment = isFragmentNode
@@ -2419,10 +2447,18 @@ BPlusTree::_ValidateChild(TreeCheck& check, CachedNode& cached, uint32 level,
 	off_t offset, off_t lastOffset, off_t nextOffset,
 	const uint8* key, uint16 keyLength)
 {
-	const bplustree_node* node = cached.SetTo(offset, true);
+	const bplustree_node* node;
-	if (node == NULL)
+	status_t status = cached.SetTo(offset, &node, true);
+	if (status != B_OK) {
+		if (status == B_IO_ERROR)
 			return B_IO_ERROR;
 
+		dprintf("inode %" B_PRIdOFF ": node at %" B_PRIdOFF " could not be "
+			"read: %s\n", fStream->ID(), offset, strerror(status));
+		check.FoundError();
+		return B_OK;
+	}
+
 	if (node->LeftLink() != lastOffset) {
 		dprintf("inode %" B_PRIdOFF ": node at %" B_PRIdOFF " has "
 			"wrong left link %" B_PRIdOFF ", expected %" B_PRIdOFF

src/add-ons/kernel/file_systems/bfs/BPlusTree.h

@@ -169,6 +169,9 @@ public:
 	}
 
 			const bplustree_node* SetTo(off_t offset, bool check = true);
+			status_t			SetTo(off_t offset,
+									const bplustree_node** _node,
+									bool check = true);
 			bplustree_node*		SetToWritable(Transaction& transaction,
 									off_t offset, bool check = true);
 			bplustree_node*		MakeWritable(Transaction& transaction);