>From b32511dbd58c8d9111001a33d253a283943bbf7a Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Tue, 4 Aug 2009 00:17:35 +0200
Subject: [PATCH] ext3: Debug unlinking of inodes

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext3/inode.c    |   28 ++++++++++++++++++++++++++++
 fs/ext3/namei.c    |    2 +-
 include/linux/fs.h |    6 ++++++
 3 files changed, 35 insertions(+), 1 deletions(-)

diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
index b49908a..dca30a2 100644
--- a/fs/ext3/inode.c
+++ b/fs/ext3/inode.c
@@ -2876,6 +2876,9 @@ bad_inode:
 	return ERR_PTR(ret);
 }
 
+struct buffer_head *ext3_find_entry(struct inode *dir,
+                                        struct qstr *entry,
+                                        struct ext3_dir_entry_2 **res_dir);
 /*
  * Post the struct inode info into an on-disk inode location in the
  * buffer-cache.  This gobbles the caller's reference to the
@@ -2892,6 +2895,31 @@ static int ext3_do_update_inode(handle_t *handle,
 	struct buffer_head *bh = iloc->bh;
 	int err = 0, rc, block;
 
+	if (!inode->i_nlink && !inode->i_checked_drop) {
+		struct dentry *dentry;
+		struct ext3_dir_entry_2 *de;
+		struct buffer_head *bh;
+
+		inode->i_checked_drop = 1;
+		if (list_empty(&inode->i_dentry)) {
+			printk("No dentry for unlinked inode %lu\nNlink dropped at 0x%lx\n", inode->i_ino, inode->i_dropped);
+			dump_stack();
+			goto next;
+		}
+		dentry = list_entry(inode->i_dentry.next, struct dentry, d_alias);
+		if (!dentry->d_parent) {
+			printk("Dentry %s for unlinked inode %lu has no parent\nNlink dropped at 0x%lx\n", dentry->d_name.name, inode->i_ino, inode->i_dropped);
+			dump_stack();
+			goto next;
+		}
+		bh = ext3_find_entry(dentry->d_parent->d_inode, &dentry->d_name, &de);
+		if (bh && le32_to_cpu(de->inode) == inode->i_ino) {
+			printk("Found directory entry %s for unlinked inode %lu\nNlink dropped at 0x%lx\n", dentry->d_name.name, inode->i_ino, inode->i_dropped);
+			brelse(bh);
+			dump_stack();
+		}
+	}
+next:
 	/* For fields not not tracking in the in-memory inode,
 	 * initialise them to zero for new inodes. */
 	if (ei->i_state & EXT3_STATE_NEW)
diff --git a/fs/ext3/namei.c b/fs/ext3/namei.c
index 6ff7b97..e66b6c0 100644
--- a/fs/ext3/namei.c
+++ b/fs/ext3/namei.c
@@ -850,7 +850,7 @@ static inline int search_dirblock(struct buffer_head * bh,
  * The returned buffer_head has ->b_count elevated.  The caller is expected
  * to brelse() it when appropriate.
  */
-static struct buffer_head *ext3_find_entry(struct inode *dir,
+struct buffer_head *ext3_find_entry(struct inode *dir,
 					struct qstr *entry,
 					struct ext3_dir_entry_2 **res_dir)
 {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index a36ffa5..271c51c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -780,6 +780,8 @@ struct inode {
 	struct posix_acl	*i_acl;
 	struct posix_acl	*i_default_acl;
 #endif
+	unsigned long		i_dropped;
+	int			i_checked_drop;
 	void			*i_private; /* fs or device private pointer */
 };
 
@@ -1693,6 +1695,8 @@ static inline void inode_inc_link_count(struct inode *inode)
 static inline void drop_nlink(struct inode *inode)
 {
 	inode->i_nlink--;
+	inode->i_dropped = _THIS_IP_;
+	inode->i_checked_drop = 0;
 }
 
 /**
@@ -1706,6 +1710,8 @@ static inline void drop_nlink(struct inode *inode)
 static inline void clear_nlink(struct inode *inode)
 {
 	inode->i_nlink = 0;
+	inode->i_dropped = _THIS_IP_;
+	inode->i_checked_drop = 0;
 }
 
 static inline void inode_dec_link_count(struct inode *inode)
-- 
1.6.0.2