[PATCH] affs: implement ->drop_inode

affs wants to truncate the inode when the last user goes away, currently it
does that through a potentially racy i_count check in ->put_inode.  But we
already have a method that's called just after the we dropped the last
reference, ->drop_inode.  This patch implements affs_drop_inode to take
advantage of this.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/affs/affs.h

@@ -171,6 +171,7 @@ extern unsigned long		 affs_parent_ino(struct inode *dir);
 extern struct inode		*affs_new_inode(struct inode *dir);
 extern int			 affs_notify_change(struct dentry *dentry, struct iattr *attr);
 extern void			 affs_put_inode(struct inode *inode);
+extern void			 affs_drop_inode(struct inode *inode);
 extern void			 affs_delete_inode(struct inode *inode);
 extern void			 affs_clear_inode(struct inode *inode);
 extern void			 affs_read_inode(struct inode *inode);

fs/affs/inode.c

@@ -243,12 +243,17 @@ affs_put_inode(struct inode *inode)
 {
 	pr_debug("AFFS: put_inode(ino=%lu, nlink=%u)\n", inode->i_ino, inode->i_nlink);
 	affs_free_prealloc(inode);
-	if (atomic_read(&inode->i_count) == 1) {
-		mutex_lock(&inode->i_mutex);
-		if (inode->i_size != AFFS_I(inode)->mmu_private)
-			affs_truncate(inode);
-		mutex_unlock(&inode->i_mutex);
-	}
+}
+
+void
+affs_drop_inode(struct inode *inode)
+{
+	mutex_lock(&inode->i_mutex);
+	if (inode->i_size != AFFS_I(inode)->mmu_private)
+		affs_truncate(inode);
+	mutex_unlock(&inode->i_mutex);
+
+	generic_drop_inode(inode);
 }
 
 void

fs/affs/super.c

@@ -118,6 +118,7 @@ static const struct super_operations affs_sops = {
 	.read_inode	= affs_read_inode,
 	.write_inode	= affs_write_inode,
 	.put_inode	= affs_put_inode,
+	.drop_inode	= affs_drop_inode,
 	.delete_inode	= affs_delete_inode,
 	.clear_inode	= affs_clear_inode,
 	.put_super	= affs_put_super,