Btrfs: allocate extent state and check the result properly

It doesn't allocate extent_state and check the result properly: - in set_extent_bit, it doesn't allocate extent_state if the path is not allowed wait - in clear_extent_bit, it doesn't check the result after atomic-ly allocate, we trigger BUG_ON() if it's fail - if allocate fail, we trigger BUG_ON instead of returning -ENOMEM since the return value of clear_extent_bit() is ignored by many callers Signed-off-by: Xiao Guangrong <[email protected]> Signed-off-by: Chris Mason <[email protected]>
nrgmilk · May 23, 2011 · 8233767 · 8233767
1 parent b083916
commit 8233767
Showing 1 changed file with 26 additions and 8 deletions.
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
@@ -439,6 +439,15 @@ static int clear_state_bit(struct extent_io_tree *tree,
 	return ret;
 }
 
+static struct extent_state *
+alloc_extent_state_atomic(struct extent_state *prealloc)
+{
+	if (!prealloc)
+		prealloc = alloc_extent_state(GFP_ATOMIC);
+
+	return prealloc;
+}
+
 /*
  * clear some bits on a range in the tree.  This may require splitting
  * or inserting elements in the tree, so the gfp mask is used to
@@ -476,8 +485,7 @@ int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 again:
 	if (!prealloc && (mask & __GFP_WAIT)) {
 		prealloc = alloc_extent_state(mask);
-		if (!prealloc)
-			return -ENOMEM;
+		BUG_ON(!prealloc);
 	}
 
 	spin_lock(&tree->lock);
@@ -529,8 +537,8 @@ int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 	 */
 
 	if (state->start < start) {
-		if (!prealloc)
-			prealloc = alloc_extent_state(GFP_ATOMIC);
+		prealloc = alloc_extent_state_atomic(prealloc);
+		BUG_ON(!prealloc);
 		err = split_state(tree, state, prealloc, start);
 		BUG_ON(err == -EEXIST);
 		prealloc = NULL;
@@ -551,8 +559,8 @@ int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 	 * on the first half
 	 */
 	if (state->start <= end && state->end > end) {
-		if (!prealloc)
-			prealloc = alloc_extent_state(GFP_ATOMIC);
+		prealloc = alloc_extent_state_atomic(prealloc);
+		BUG_ON(!prealloc);
 		err = split_state(tree, state, prealloc, end + 1);
 		BUG_ON(err == -EEXIST);
 		if (wake)
@@ -725,8 +733,7 @@ int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 again:
 	if (!prealloc && (mask & __GFP_WAIT)) {
 		prealloc = alloc_extent_state(mask);
-		if (!prealloc)
-			return -ENOMEM;
+		BUG_ON(!prealloc);
 	}
 
 	spin_lock(&tree->lock);
@@ -743,6 +750,8 @@ int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 	 */
 	node = tree_search(tree, start);
 	if (!node) {
+		prealloc = alloc_extent_state_atomic(prealloc);
+		BUG_ON(!prealloc);
 		err = insert_state(tree, prealloc, start, end, &bits);
 		prealloc = NULL;
 		BUG_ON(err == -EEXIST);
@@ -811,6 +820,9 @@ int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 			err = -EEXIST;
 			goto out;
 		}
+
+		prealloc = alloc_extent_state_atomic(prealloc);
+		BUG_ON(!prealloc);
 		err = split_state(tree, state, prealloc, start);
 		BUG_ON(err == -EEXIST);
 		prealloc = NULL;
@@ -841,6 +853,9 @@ int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 			this_end = end;
 		else
 			this_end = last_start - 1;
+
+		prealloc = alloc_extent_state_atomic(prealloc);
+		BUG_ON(!prealloc);
 		err = insert_state(tree, prealloc, start, this_end,
 				   &bits);
 		BUG_ON(err == -EEXIST);
@@ -865,6 +880,9 @@ int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 			err = -EEXIST;
 			goto out;
 		}
+
+		prealloc = alloc_extent_state_atomic(prealloc);
+		BUG_ON(!prealloc);
 		err = split_state(tree, state, prealloc, end + 1);
 		BUG_ON(err == -EEXIST);