simplify checks for I_CLEAR/I_FREEING

add I_CLEAR instead of replacing I_FREEING with it.  I_CLEAR is
equivalent to I_FREEING for almost all code looking at either;
it's there to keep track of having called clear_inode() exactly
once per inode lifetime, at some point after having set I_FREEING.
I_CLEAR and I_FREEING never get set at the same time with the
current code, so we can switch to setting i_flags to I_FREEING | I_CLEAR
instead of I_CLEAR without loss of information.  As the result of
such change, checks become simpler and the amount of code that needs
to know about I_CLEAR shrinks a lot.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/notify/inode_mark.c

@@ -369,11 +369,11 @@ void fsnotify_unmount_inodes(struct list_head *list)
 		struct inode *need_iput_tmp;
 
 		/*
-		 * We cannot __iget() an inode in state I_CLEAR, I_FREEING,
+		 * We cannot __iget() an inode in state I_FREEING,
 		 * I_WILL_FREE, or I_NEW which is fine because by that point
 		 * the inode cannot have any associated watches.
 		 */
-		if (inode->i_state & (I_CLEAR|I_FREEING|I_WILL_FREE|I_NEW))
+		if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW))
 			continue;
 
 		/*
@@ -397,7 +397,7 @@ void fsnotify_unmount_inodes(struct list_head *list)
 		/* In case the dropping of a reference would nuke next_i. */
 		if ((&next_i->i_sb_list != list) &&
 		    atomic_read(&next_i->i_count) &&
-		    !(next_i->i_state & (I_CLEAR | I_FREEING | I_WILL_FREE))) {
+		    !(next_i->i_state & (I_FREEING | I_WILL_FREE))) {
 			__iget(next_i);
 			need_iput = next_i;
 		}

fs/notify/inotify/inotify.c

@@ -377,11 +377,11 @@ void inotify_unmount_inodes(struct list_head *list)
 		struct list_head *watches;
 
 		/*
-		 * We cannot __iget() an inode in state I_CLEAR, I_FREEING,
+		 * We cannot __iget() an inode in state I_FREEING,
 		 * I_WILL_FREE, or I_NEW which is fine because by that point
 		 * the inode cannot have any associated watches.
 		 */
-		if (inode->i_state & (I_CLEAR|I_FREEING|I_WILL_FREE|I_NEW))
+		if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW))
 			continue;
 
 		/*
@@ -403,8 +403,7 @@ void inotify_unmount_inodes(struct list_head *list)
 		/* In case the dropping of a reference would nuke next_i. */
 		if ((&next_i->i_sb_list != list) &&
 				atomic_read(&next_i->i_count) &&
-				!(next_i->i_state & (I_CLEAR | I_FREEING |
-					I_WILL_FREE))) {
+				!(next_i->i_state & (I_FREEING|I_WILL_FREE))) {
 			__iget(next_i);
 			need_iput = next_i;
 		}