[PATCH] ext2_new_block cleanups and fixes

The general error logic handling in there is:

	*errp = -EFOO;
	<lots of code>
	if (some_error)
		goto out;

this is fragile and unmaintainable, because the setting of the error code is
"far away" from the site where the error was detected.

And the code was actually wrong - we're returning ENOSPC in places where fs
metadata inconsistency was detected.  We traditionally return -EIO in this
case.

So change it all to do, effectively:

	if (some_error) {
		*errp = -EFOO;
		goto out;
	}

fs/ext2/balloc.c

@@ -334,22 +334,23 @@ int ext2_new_block (struct inode * inode, unsigned long goal,
 	if (!prealloc_count || *prealloc_count)
 		prealloc_goal = 0;
 
-	*err = -EDQUOT;
-	if (DQUOT_ALLOC_BLOCK(inode, 1))
+	if (DQUOT_ALLOC_BLOCK(inode, 1)) {
+		*err = -EDQUOT;
 		goto out;
+	}
 
 	while (prealloc_goal && DQUOT_PREALLOC_BLOCK(inode, prealloc_goal))
 		prealloc_goal--;
 
 	dq_alloc = prealloc_goal + 1;
 
-	*err = -ENOSPC;
-
 	lock_super (sb);
 
 	es_alloc = reserve_blocks(sb, dq_alloc);
-	if (!es_alloc)
+	if (!es_alloc) {
+		*err = -ENOSPC;
 		goto out_unlock;
+	}
 
 	ext2_debug ("goal=%lu.\n", goal);
 
@@ -396,8 +397,10 @@ int ext2_new_block (struct inode * inode, unsigned long goal,
 			goto io_error;
 		group_alloc = group_reserve_blocks(desc, gdp_bh, es_alloc);
 	}
-	if (bit >= sbi->s_groups_count)
+	if (bit >= sbi->s_groups_count) {
+		*err = -ENOSPC;
 		goto out_release;
+	}
 	brelse(bitmap_bh);
 	bitmap_bh = read_block_bitmap(sb, group_no);
 	if (!bitmap_bh)
@@ -409,7 +412,7 @@ int ext2_new_block (struct inode * inode, unsigned long goal,
 			"Free blocks count corrupted for block group %d",
 				group_no);
 		group_alloc = 0;
-		goto out_release;
+		goto io_error;
 	}
 
 got_block:
@@ -432,7 +435,7 @@ int ext2_new_block (struct inode * inode, unsigned long goal,
 			    "block(%d) >= blocks count(%d) - "
 			    "block_group = %d, es == %p ", ret_block,
 			le32_to_cpu(es->s_blocks_count), group_no, es);
-		goto out_release;
+		goto io_error;
 	}
 	block = target_block;