ext4: prepare to drop EXT4_STATE_DELALLOC_RESERVED

The EXT4_STATE_DELALLOC_RESERVED flag was originally implemented
because it was too hard to make sure the mballoc and get_block flags
could be reliably passed down through all of the codepaths that end up
calling ext4_mb_new_blocks().

Since then, we have mb_flags passed down through most of the code
paths, so getting rid of EXT4_STATE_DELALLOC_RESERVED isn't as tricky
as it used to.

This commit plumbs in the last of what is required, and then adds a
WARN_ON check to make sure we haven't missed anything.  If this passes
a full regression test run, we can then drop
EXT4_STATE_DELALLOC_RESERVED.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 3ac1686..8170b32 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -1933,6 +1933,8 @@
 	ext4_lblk_t next;
 	int mb_flags = 0, unwritten;
 
+	if (gb_flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
+		mb_flags |= EXT4_MB_DELALLOC_RESERVED;
 	if (unlikely(ext4_ext_get_actual_len(newext) == 0)) {
 		EXT4_ERROR_INODE(inode, "ext4_ext_get_actual_len(newext) == 0");
 		return -EIO;
@@ -2054,7 +2056,7 @@
 	 * We're gonna add a new leaf in the tree.
 	 */
 	if (gb_flags & EXT4_GET_BLOCKS_METADATA_NOFAIL)
-		mb_flags = EXT4_MB_USE_RESERVED;
+		mb_flags |= EXT4_MB_USE_RESERVED;
 	err = ext4_ext_create_new_leaf(handle, inode, mb_flags, gb_flags,
 				       ppath, newext);
 	if (err)
@@ -4438,6 +4440,8 @@
 		ar.flags = 0;
 	if (flags & EXT4_GET_BLOCKS_NO_NORMALIZE)
 		ar.flags |= EXT4_MB_HINT_NOPREALLOC;
+	if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
+		ar.flags |= EXT4_MB_DELALLOC_RESERVED;
 	newblock = ext4_mb_new_blocks(handle, &ar, &err);
 	if (!newblock)
 		goto out2;