ext4: replace i_delalloc_reserved_flag with EXT4_STATE_DELALLOC_RESERVED

Remove the short element i_delalloc_reserved_flag from the
ext4_inode_info structure and replace it a new bit in i_state_flags.
Since we have an ext4_inode_info for every ext4 inode cached in the
inode cache, any savings we can produce here is a very good thing from
a memory utilization perspective.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 12b604a..d47a80e 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4283,7 +4283,7 @@
 	 * EDQUOT check, as blocks and quotas have been already
 	 * reserved when data being copied into pagecache.
 	 */
-	if (EXT4_I(ar->inode)->i_delalloc_reserved_flag)
+	if (ext4_test_inode_state(ar->inode, EXT4_STATE_DELALLOC_RESERVED))
 		ar->flags |= EXT4_MB_DELALLOC_RESERVED;
 	else {
 		/* Without delayed allocation we need to verify
@@ -4380,7 +4380,8 @@
 	if (inquota && ar->len < inquota)
 		dquot_free_block(ar->inode, inquota - ar->len);
 	if (!ar->len) {
-		if (!EXT4_I(ar->inode)->i_delalloc_reserved_flag)
+		if (!ext4_test_inode_state(ar->inode,
+					   EXT4_STATE_DELALLOC_RESERVED))
 			/* release all the reserved blocks if non delalloc */
 			percpu_counter_sub(&sbi->s_dirtyblocks_counter,
 						reserv_blks);