btrfs: use a flag to control when to clear the file extent range

We only care about updating the file extent range when we are doing a
normal truncation.  We skip this for tree logging currently, but we can
also skip this for eviction as well.  Using a flag makes it more
explicit when we want to do this work.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/free-space-cache.c

@@ -294,6 +294,7 @@ int btrfs_truncate_free_space_cache(struct btrfs_trans_handle *trans,
 	struct btrfs_truncate_control control = {
 		.new_size = 0,
 		.min_type = BTRFS_EXTENT_DATA_KEY,
+		.clear_extent_range = true,
 	};
 	struct btrfs_inode *inode = BTRFS_I(vfs_inode);
 	struct btrfs_root *root = inode->root;

fs/btrfs/inode-item.c

@@ -624,11 +624,11 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
 		}
 delete:
 		/*
-		 * We use btrfs_truncate_inode_items() to clean up log trees for
-		 * multiple fsyncs, and in this case we don't want to clear the
-		 * file extent range because it's just the log.
+		 * We only want to clear the file extent range if we're
+		 * modifying the actual inode's mapping, which is just the
+		 * normal truncate path.
 		 */
-		if (root == inode->root) {
+		if (control->clear_extent_range) {
 			ret = btrfs_inode_clear_file_extent_range(inode,
 						  clear_start, clear_len);
 			if (ret) {

fs/btrfs/inode-item.h

@@ -43,6 +43,12 @@ struct btrfs_truncate_control {
 	 * extents we drop.
 	 */
 	bool skip_ref_updates;
+
+	/*
+	 * IN: true if we need to clear the file extent range for the inode as
+	 * we drop the file extent items.
+	 */
+	bool clear_extent_range;
 };
 
 int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,

fs/btrfs/inode.c

@@ -8534,6 +8534,7 @@ static int btrfs_truncate(struct inode *inode, bool skip_writeback)
 {
 	struct btrfs_truncate_control control = {
 		.min_type = BTRFS_EXTENT_DATA_KEY,
+		.clear_extent_range = true,
 	};
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 	struct btrfs_root *root = BTRFS_I(inode)->root;