[PATCH 55/58][v2] Make ->drop_inode() just return whether inode needs to be dropped

[Al Viro <viro@ZenIV.linux.org.uk>]

[v2:clean btrfs part of that a bit]
... and let iput_final() do the actual eviction or retention

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

diff --git a/drivers/staging/pohmelfs/inode.c b/drivers/staging/pohmelfs/inode.c
index e818f53..d32726d 100644
--- a/drivers/staging/pohmelfs/inode.c
+++ b/drivers/staging/pohmelfs/inode.c
@@ -1232,7 +1232,7 @@ static void pohmelfs_drop_inode(struct inode *inode)
 	list_del_init(&pi->inode_entry);
 	spin_unlock(&psb->ino_lock);
 
-	generic_drop_inode(inode);
+	return generic_drop_inode(inode);
 }
 
 static struct pohmelfs_inode *pohmelfs_get_inode_from_list(struct pohmelfs_sb *psb,
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 394d542..eaf286a 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2395,7 +2395,7 @@ int btrfs_write_inode(struct inode *inode, struct writeback_control *wbc);
 void btrfs_dirty_inode(struct inode *inode);
 struct inode *btrfs_alloc_inode(struct super_block *sb);
 void btrfs_destroy_inode(struct inode *inode);
-void btrfs_drop_inode(struct inode *inode);
+int btrfs_drop_inode(struct inode *inode);
 int btrfs_init_cachep(void);
 void btrfs_destroy_cachep(void);
 long btrfs_ioctl_trans_end(struct file *file);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 21ea393..08c9299 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3943,7 +3943,7 @@ again:
 			if (atomic_read(&inode->i_count) > 1)
 				d_prune_aliases(inode);
 			/*
-			 * btrfs_drop_inode will remove it from
+			 * btrfs_drop_inode will have it removed from
 			 * the inode cache when its usage count
 			 * hits zero.
 			 */
@@ -6337,13 +6337,14 @@ free:
 	kmem_cache_free(btrfs_inode_cachep, BTRFS_I(inode));
 }
 
-void btrfs_drop_inode(struct inode *inode)
+int btrfs_drop_inode(struct inode *inode)
 {
 	struct btrfs_root *root = BTRFS_I(inode)->root;
-	if (inode->i_nlink > 0 && btrfs_root_refs(&root->root_item) == 0)
-		generic_delete_inode(inode);
+
+	if (btrfs_root_refs(&root->root_item) == 0)
+		return 1;
 	else
-		generic_drop_inode(inode);
+		return generic_drop_inode(inode);
 }
 
 static void init_once(void *foo)
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 555f5a4..fa865ab 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -1191,7 +1191,7 @@ static int gfs2_remount_fs(struct super_block *sb, int *flags, char *data)
  * node for later deallocation.
  */
 
-static void gfs2_drop_inode(struct inode *inode)
+static int gfs2_drop_inode(struct inode *inode)
 {
 	struct gfs2_inode *ip = GFS2_I(inode);
 
@@ -1200,7 +1200,7 @@ static void gfs2_drop_inode(struct inode *inode)
 		if (gl && test_bit(GLF_DEMOTE, &gl->gl_flags))
 			clear_nlink(inode);
 	}
-	generic_drop_inode(inode);
+	return generic_drop_inode(inode);
 }
 
 static int is_ancestor(const struct dentry *d1, const struct dentry *d2)
diff --git a/fs/inode.c b/fs/inode.c
index 0d8aa56..1b9504e 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1183,58 +1183,51 @@ void remove_inode_hash(struct inode *inode)
 }
 EXPORT_SYMBOL(remove_inode_hash);
 
+int generic_delete_inode(struct inode *inode)
+{
+	return 1;
+}
+EXPORT_SYMBOL(generic_delete_inode);
+
 /*
- * Tell the filesystem that this inode is no longer of any interest and should
- * be completely destroyed.
- *
- * We leave the inode in the inode hash table until *after* the filesystem's
- * ->delete_inode completes.  This ensures that an iget (such as nfsd might
- * instigate) will always find up-to-date information either in the hash or on
- * disk.
- *
- * I_FREEING is set so that no-one will take a new reference to the inode while
- * it is being deleted.
+ * Normal UNIX filesystem behaviour: delete the
+ * inode when the usage count drops to zero, and
+ * i_nlink is zero.
  */
-void generic_delete_inode(struct inode *inode)
+int generic_drop_inode(struct inode *inode)
 {
-	list_del_init(&inode->i_list);
-	list_del_init(&inode->i_sb_list);
-	WARN_ON(inode->i_state & I_NEW);
-	inode->i_state |= I_FREEING;
-	inodes_stat.nr_inodes--;
-	spin_unlock(&inode_lock);
-
-	evict(inode);
-
-	spin_lock(&inode_lock);
-	hlist_del_init(&inode->i_hash);
-	spin_unlock(&inode_lock);
-	wake_up_inode(inode);
-	BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
-	destroy_inode(inode);
+	return !inode->i_nlink || hlist_unhashed(&inode->i_hash);
 }
-EXPORT_SYMBOL(generic_delete_inode);
+EXPORT_SYMBOL_GPL(generic_drop_inode);
 
-/**
- *	generic_detach_inode - remove inode from inode lists
- *	@inode: inode to remove
- *
- *	Remove inode from inode lists, write it if it's dirty. This is just an
- *	internal VFS helper exported for hugetlbfs. Do not use!
+/*
+ * Called when we're dropping the last reference
+ * to an inode.
  *
- *	Returns 1 if inode should be completely destroyed.
+ * Call the FS "drop_inode()" function, defaulting to
+ * the legacy UNIX filesystem behaviour.  If it tells
+ * us to evict inode, do so.  Otherwise, retain inode
+ * in cache if fs is alive, sync and evict if fs is
+ * shutting down.
  */
-static int generic_detach_inode(struct inode *inode)
+static void iput_final(struct inode *inode)
 {
 	struct super_block *sb = inode->i_sb;
+	const struct super_operations *op = inode->i_sb->s_op;
+	int drop;
+
+	if (op && op->drop_inode)
+		drop = op->drop_inode(inode);
+	else
+		drop = generic_drop_inode(inode);
 
-	if (!hlist_unhashed(&inode->i_hash)) {
+	if (!drop) {
 		if (!(inode->i_state & (I_DIRTY|I_SYNC)))
 			list_move(&inode->i_list, &inode_unused);
 		inodes_stat.nr_unused++;
 		if (sb->s_flags & MS_ACTIVE) {
 			spin_unlock(&inode_lock);
-			return 0;
+			return;
 		}
 		WARN_ON(inode->i_state & I_NEW);
 		inode->i_state |= I_WILL_FREE;
@@ -1252,53 +1245,15 @@ static int generic_detach_inode(struct inode *inode)
 	inode->i_state |= I_FREEING;
 	inodes_stat.nr_inodes--;
 	spin_unlock(&inode_lock);
-	return 1;
-}
-
-static void generic_forget_inode(struct inode *inode)
-{
-	if (!generic_detach_inode(inode))
-		return;
 	evict(inode);
+	spin_lock(&inode_lock);
+	hlist_del_init(&inode->i_hash);
+	spin_unlock(&inode_lock);
 	wake_up_inode(inode);
+	BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
 	destroy_inode(inode);
 }
 
-/*
- * Normal UNIX filesystem behaviour: delete the
- * inode when the usage count drops to zero, and
- * i_nlink is zero.
- */
-void generic_drop_inode(struct inode *inode)
-{
-	if (!inode->i_nlink)
-		generic_delete_inode(inode);
-	else
-		generic_forget_inode(inode);
-}
-EXPORT_SYMBOL_GPL(generic_drop_inode);
-
-/*
- * Called when we're dropping the last reference
- * to an inode.
- *
- * Call the FS "drop()" function, defaulting to
- * the legacy UNIX filesystem behaviour..
- *
- * NOTE! NOTE! NOTE! We're called with the inode lock
- * held, and the drop function is supposed to release
- * the lock!
- */
-static inline void iput_final(struct inode *inode)
-{
-	const struct super_operations *op = inode->i_sb->s_op;
-	void (*drop)(struct inode *) = generic_drop_inode;
-
-	if (op && op->drop_inode)
-		drop = op->drop_inode;
-	drop(inode);
-}
-
 /**
  *	iput	- put an inode
  *	@inode: inode to put
diff --git a/fs/logfs/inode.c b/fs/logfs/inode.c
index 78be674..d8c71ec 100644
--- a/fs/logfs/inode.c
+++ b/fs/logfs/inode.c
@@ -287,7 +287,7 @@ static int logfs_write_inode(struct inode *inode, struct writeback_control *wbc)
 }
 
 /* called with inode_lock held */
-static void logfs_drop_inode(struct inode *inode)
+static int logfs_drop_inode(struct inode *inode)
 {
 	struct logfs_super *super = logfs_super(inode->i_sb);
 	struct logfs_inode *li = logfs_inode(inode);
@@ -295,7 +295,7 @@ static void logfs_drop_inode(struct inode *inode)
 	spin_lock(&logfs_inode_lock);
 	list_move(&li->li_freeing_list, &super->s_freeing_list);
 	spin_unlock(&logfs_inode_lock);
-	generic_drop_inode(inode);
+	return generic_drop_inode(inode);
 }
 
 static void logfs_set_ino_generation(struct super_block *sb,
diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index eb7fd07..0492464 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -1194,9 +1194,10 @@ void ocfs2_evict_inode(struct inode *inode)
 /* Called under inode_lock, with no more references on the
  * struct inode, so it's safe here to check the flags field
  * and to manipulate i_nlink without any other locks. */
-void ocfs2_drop_inode(struct inode *inode)
+int ocfs2_drop_inode(struct inode *inode)
 {
 	struct ocfs2_inode_info *oi = OCFS2_I(inode);
+	int res;
 
 	mlog_entry_void();
 
@@ -1204,11 +1205,12 @@ void ocfs2_drop_inode(struct inode *inode)
 	     (unsigned long long)oi->ip_blkno, inode->i_nlink, oi->ip_flags);
 
 	if (oi->ip_flags & OCFS2_INODE_MAYBE_ORPHANED)
-		generic_delete_inode(inode);
+		res = 1;
 	else
-		generic_drop_inode(inode);
+		res = generic_drop_inode(inode);
 
 	mlog_exit_void();
+	return res;
 }
 
 /*
diff --git a/fs/ocfs2/inode.h b/fs/ocfs2/inode.h
index 975eedd..6de5a86 100644
--- a/fs/ocfs2/inode.h
+++ b/fs/ocfs2/inode.h
@@ -124,7 +124,7 @@ static inline struct ocfs2_caching_info *INODE_CACHE(struct inode *inode)
 }
 
 void ocfs2_evict_inode(struct inode *inode);
-void ocfs2_drop_inode(struct inode *inode);
+int ocfs2_drop_inode(struct inode *inode);
 
 /* Flags for ocfs2_iget() */
 #define OCFS2_FI_FLAG_SYSFILE		0x1
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 801b0f2..183188b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1561,7 +1561,7 @@ struct super_operations {
 
    	void (*dirty_inode) (struct inode *);
 	int (*write_inode) (struct inode *, struct writeback_control *wbc);
-	void (*drop_inode) (struct inode *);
+	int (*drop_inode) (struct inode *);
 	void (*evict_inode) (struct inode *);
 	void (*put_super) (struct super_block *);
 	void (*write_super) (struct super_block *);
@@ -2150,8 +2150,8 @@ extern void iput(struct inode *);
 extern struct inode * igrab(struct inode *);
 extern ino_t iunique(struct super_block *, ino_t);
 extern int inode_needs_sync(struct inode *inode);
-extern void generic_delete_inode(struct inode *inode);
-extern void generic_drop_inode(struct inode *inode);
+extern int generic_delete_inode(struct inode *inode);
+extern int generic_drop_inode(struct inode *inode);
 
 extern struct inode *ilookup5_nowait(struct super_block *sb,
 		unsigned long hashval, int (*test)(struct inode *, void *),