[PATCH -V26 04/16] fs: Don't allow to create hardlink for deleted file

From: Aneesh Kumar K.V
Date: Sat Jan 29 2011 - 14:11:29 EST

Add inode->i_nlink == 0 check in VFS. Some of the file systems
do this internally. A followup patch will remove those instance.
This is needed to ensure that with link by handle we don't allow
to create hardlink of an unlinked file. The check also prevent a race
between unlink and link

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
fs/namei.c | 6 +++++-
1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 6b0536f..a8346fa 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3318,7 +3318,11 @@ int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_de
return error;

- error = dir->i_op->link(old_dentry, dir, new_dentry);
+ /* Make sure we don't allow creating hardlink to an unlinked file */
+ if (inode->i_nlink == 0)
+ error = -ENOENT;
+ else
+ error = dir->i_op->link(old_dentry, dir, new_dentry);
if (!error)
fsnotify_link(dir, inode, new_dentry);

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