ext4: simplify i_state checks in __ext4_update_other_inode_time()

Since I_DIRTY_TIME and I_DIRTY_INODE are mutually exclusive in i_state,
there's no need to check for I_DIRTY_TIME && !I_DIRTY_INODE.  Just check
for I_DIRTY_TIME.

Also introduce a helper function in include/linux/fs.h to do this check.

Link: https://lore.kernel.org/r/20210112190253.64307-12-ebiggers@kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 4cc6c78..d809a06 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4961,15 +4961,11 @@ static void __ext4_update_other_inode_time(struct super_block *sb,
 	if (!inode)
 		return;
 
-	if ((inode->i_state & (I_FREEING | I_WILL_FREE | I_NEW |
-			       I_DIRTY_INODE)) ||
-	    ((inode->i_state & I_DIRTY_TIME) == 0))
+	if (!inode_is_dirtytime_only(inode))
 		return;
 
 	spin_lock(&inode->i_lock);
-	if (((inode->i_state & (I_FREEING | I_WILL_FREE | I_NEW |
-				I_DIRTY_INODE)) == 0) &&
-	    (inode->i_state & I_DIRTY_TIME)) {
+	if (inode_is_dirtytime_only(inode)) {
 		struct ext4_inode_info	*ei = EXT4_I(inode);
 
 		inode->i_state &= ~I_DIRTY_TIME;