f2fs: do not skip dentry block writes

Previously, we skip dentry block writes when wbc is SYNC_NONE with no memory
pressure and the number of dirty pages is pretty small.

But, we didn't skip for normal data writes, which gives us not much big impact
on overall performance.
Moreover, by skipping some data writes, kworker falls into infinite loop to try
to write blocks, when many dir inodes have only one dentry block.

So, this patch removes skipping data writes.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index b6e4ed1..a294da7 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -697,9 +697,7 @@
 	if (sbi->sb->s_bdi->wb.dirty_exceeded)
 		return 0;
 
-	if (type == DATA)
-		return sbi->blocks_per_seg;
-	else if (type == NODE)
+	if (type == NODE)
 		return 3 * sbi->blocks_per_seg;
 	else if (type == META)
 		return MAX_BIO_BLOCKS(sbi);