Ocfs2 devel - Mar 2020 - [PATCH v3] ocfs2: roll back the reference count modification of the parent directory if an error occurs

Under some conditions, the directory cannot be deleted.
The specific scenarios are as follows: (for example,
/mnt/ocfs2 is the mount point)

1. Create the /mnt/ocfs2/p_dir directory. At this time,
the i_nlink corresponding to the inode of
the /mnt/ocfs2/p_dir directory is equal to 2.

2. During the process of creating the
/mnt/ocfs2/p_dir/s_dir directory, if the call to the inc_nlink
function in ocfs2_mknod succeeds, the functions such as
ocfs2_init_acl, ocfs2_init_security_set, and ocfs2_dentry_attach_lock fail.
At this time, the i_nlink corresponding to the inode of the
/mnt/ocfs2/p_dir directory is equal to 3, but /mnt/ocfs2/p_dir/s_dir
is not added to the /mnt/ocfs2/p_dir directory entry.

3. Delete the /mnt/ocfs2/p_dir directory (rm -rf /mnt/ocfs2/p_dir).
At this time, it is found that the i_nlink corresponding to
the inode corresponding to the /mnt/ocfs2/p_dir directory is equal to 3.
Therefore, the /mnt/ocfs2/p_dir directory cannot be deleted.

Signed-off-by: Jian wang <wangjian161 at huawei.com>
---
  ocfs2/namei.c | 7 +++++++
  1 file changed, 7 insertions(+)

diff --git a/ocfs2/namei.c b/ocfs2/namei.c
index 8ea51cf..15f8ba1 100644
--- a/ocfs2/namei.c
+++ b/ocfs2/namei.c
@@ -247,6 +247,7 @@ static int ocfs2_mknod(struct inode *dir,
  	sigset_t oldset;
  	int did_block_signals = 0;
  	struct ocfs2_dentry_lock *dl = NULL;
+	int link_inc = 0;
  
  	trace_ocfs2_mknod(dir, dentry, dentry->d_name.len, dentry->d_name.name,
  			  (unsigned long long)OCFS2_I(dir)->ip_blkno,
@@ -399,6 +400,7 @@ static int ocfs2_mknod(struct inode *dir,
  		ocfs2_add_links_count(dirfe, 1);
  		ocfs2_journal_dirty(handle, parent_fe_bh);
  		inc_nlink(dir);
+		link_inc = 1;
  	}
  
  	status = ocfs2_init_acl(handle, inode, dir, new_fe_bh, parent_fe_bh,
@@ -444,6 +446,11 @@ static int ocfs2_mknod(struct inode *dir,
  	d_instantiate(dentry, inode);
  	status = 0;
  leave:
+	if (status < 0 && link_inc != 0) {
+		ocfs2_add_links_count(dirfe, -1);
+		drop_nlink(dir);
+	}
+
  	if (status < 0 && did_quota_inode)
  		dquot_free_inode(inode);
  	if (handle)
-- 
1.8.3.1

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