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/btrfs/inode.c

@@ -3860,7 +3860,7 @@ static void inode_tree_add(struct inode *inode)
 			p = &parent->rb_right;
 		else {
 			WARN_ON(!(entry->vfs_inode.i_state &
-				  (I_WILL_FREE | I_FREEING | I_CLEAR)));
+				  (I_WILL_FREE | I_FREEING)));
 			rb_erase(parent, &root->inode_tree);
 			RB_CLEAR_NODE(parent);
 			spin_unlock(&root->inode_lock);

fs/drop_caches.c

@@ -18,7 +18,7 @@ static void drop_pagecache_sb(struct super_block *sb, void *unused)
 
 	spin_lock(&inode_lock);
 	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
-		if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW))
+		if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW))
 			continue;
 		if (inode->i_mapping->nrpages == 0)
 			continue;

fs/fs-writeback.c

@@ -352,7 +352,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
 
 	spin_lock(&inode_lock);
 	inode->i_state &= ~I_SYNC;
-	if (!(inode->i_state & (I_FREEING | I_CLEAR))) {
+	if (!(inode->i_state & I_FREEING)) {
 		if ((inode->i_state & I_DIRTY_PAGES) && wbc->for_kupdate) {
 			/*
 			 * More pages get dirtied by a fast dirtier.
@@ -499,7 +499,7 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb,
 		if (inode_dirtied_after(inode, wbc->wb_start))
 			return 1;
 
-		BUG_ON(inode->i_state & (I_FREEING | I_CLEAR));
+		BUG_ON(inode->i_state & I_FREEING);
 		__iget(inode);
 		pages_skipped = wbc->pages_skipped;
 		writeback_single_inode(inode, wbc);
@@ -935,7 +935,7 @@ void __mark_inode_dirty(struct inode *inode, int flags)
 			if (hlist_unhashed(&inode->i_hash))
 				goto out;
 		}
-		if (inode->i_state & (I_FREEING|I_CLEAR))
+		if (inode->i_state & I_FREEING)
 			goto out;
 
 		/*
@@ -1001,7 +1001,7 @@ static void wait_sb_inodes(struct super_block *sb)
 	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
 		struct address_space *mapping;
 
-		if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW))
+		if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW))
 			continue;
 		mapping = inode->i_mapping;
 		if (mapping->nrpages == 0)

fs/gfs2/inode.c

@@ -84,7 +84,7 @@ static int iget_skip_test(struct inode *inode, void *opaque)
 	struct gfs2_skip_data *data = opaque;
 
 	if (ip->i_no_addr == data->no_addr) {
-		if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)){
+		if (inode->i_state & (I_FREEING|I_WILL_FREE)){
 			data->skipped = 1;
 			return 0;
 		}

fs/inode.c

@@ -317,7 +317,7 @@ void clear_inode(struct inode *inode)
 		bd_forget(inode);
 	if (S_ISCHR(inode->i_mode) && inode->i_cdev)
 		cd_forget(inode);
-	inode->i_state = I_CLEAR;
+	inode->i_state = I_FREEING | I_CLEAR;
 }
 EXPORT_SYMBOL(clear_inode);
 
@@ -553,7 +553,7 @@ static struct inode *find_inode(struct super_block *sb,
 			continue;
 		if (!test(inode, data))
 			continue;
-		if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)) {
+		if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
 			__wait_on_freeing_inode(inode);
 			goto repeat;
 		}
@@ -578,7 +578,7 @@ static struct inode *find_inode_fast(struct super_block *sb,
 			continue;
 		if (inode->i_sb != sb)
 			continue;
-		if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)) {
+		if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
 			__wait_on_freeing_inode(inode);
 			goto repeat;
 		}
@@ -840,7 +840,7 @@ EXPORT_SYMBOL(iunique);
 struct inode *igrab(struct inode *inode)
 {
 	spin_lock(&inode_lock);
-	if (!(inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)))
+	if (!(inode->i_state & (I_FREEING|I_WILL_FREE)))
 		__iget(inode);
 	else
 		/*
@@ -1089,7 +1089,7 @@ int insert_inode_locked(struct inode *inode)
 				continue;
 			if (old->i_sb != sb)
 				continue;
-			if (old->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE))
+			if (old->i_state & (I_FREEING|I_WILL_FREE))
 				continue;
 			break;
 		}
@@ -1128,7 +1128,7 @@ int insert_inode_locked4(struct inode *inode, unsigned long hashval,
 				continue;
 			if (!test(old, data))
 				continue;
-			if (old->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE))
+			if (old->i_state & (I_FREEING|I_WILL_FREE))
 				continue;
 			break;
 		}
@@ -1218,7 +1218,7 @@ void generic_delete_inode(struct inode *inode)
 	hlist_del_init(&inode->i_hash);
 	spin_unlock(&inode_lock);
 	wake_up_inode(inode);
-	BUG_ON(inode->i_state != I_CLEAR);
+	BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
 	destroy_inode(inode);
 }
 EXPORT_SYMBOL(generic_delete_inode);
@@ -1322,7 +1322,7 @@ static inline void iput_final(struct inode *inode)
 void iput(struct inode *inode)
 {
 	if (inode) {
-		BUG_ON(inode->i_state == I_CLEAR);
+		BUG_ON(inode->i_state & I_CLEAR);
 
 		if (atomic_dec_and_lock(&inode->i_count, &inode_lock))
 			iput_final(inode);

fs/nilfs2/gcdat.c

@@ -78,7 +78,7 @@ void nilfs_clear_gcdat_inode(struct the_nilfs *nilfs)
 	struct inode *gcdat = nilfs->ns_gc_dat;
 	struct nilfs_inode_info *gii = NILFS_I(gcdat);
 
-	gcdat->i_state = I_CLEAR;
+	gcdat->i_state = I_FREEING | I_CLEAR;
 	gii->i_flags = 0;
 
 	nilfs_palloc_clear_cache(gcdat);

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;
 		}

fs/quota/dquot.c

@@ -885,7 +885,7 @@ static void add_dquot_ref(struct super_block *sb, int type)
 
 	spin_lock(&inode_lock);
 	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
-		if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW))
+		if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW))
 			continue;
 #ifdef CONFIG_QUOTA_DEBUG
 		if (unlikely(inode_get_rsv_space(inode) > 0))

fs/xfs/linux-2.6/xfs_iops.c

@@ -80,7 +80,7 @@ xfs_mark_inode_dirty_sync(
 {
 	struct inode	*inode = VFS_I(ip);
 
-	if (!(inode->i_state & (I_WILL_FREE|I_FREEING|I_CLEAR)))
+	if (!(inode->i_state & (I_WILL_FREE|I_FREEING)))
 		mark_inode_dirty_sync(inode);
 }
 
@@ -90,7 +90,7 @@ xfs_mark_inode_dirty(
 {
 	struct inode	*inode = VFS_I(ip);
 
-	if (!(inode->i_state & (I_WILL_FREE|I_FREEING|I_CLEAR)))
+	if (!(inode->i_state & (I_WILL_FREE|I_FREEING)))
 		mark_inode_dirty(inode);
 }
 

include/linux/fs.h

@@ -1616,8 +1616,8 @@ struct super_operations {
  * I_FREEING		Set when inode is about to be freed but still has dirty
  *			pages or buffers attached or the inode itself is still
  *			dirty.
- * I_CLEAR		Set by clear_inode().  In this state the inode is clean
- *			and can be destroyed.
+ * I_CLEAR		Added by clear_inode().  In this state the inode is clean
+ *			and can be destroyed.  Inode keeps I_FREEING.
  *
  *			Inodes that are I_WILL_FREE, I_FREEING or I_CLEAR are
  *			prohibited for many purposes.  iget() must wait for