[PATCH 4.1 093/159] eCryptfs: Invalidate dcache entries when lower i_nlink is zero

Greg Kroah-Hartman
2015-09-26T21:39:02Z

From: Tyler Hicks <tyhicks@canonical.com>

commit 5556e7e6d30e8e9b5ee51b0e5edd526ee80e5e36 upstream.

Consider eCryptfs dcache entries to be stale when the corresponding
lower inode's i_nlink count is zero. This solves a problem caused by the
lower inode being directly modified, without going through the eCryptfs
mount, leaving stale eCryptfs dentries cached and the eCryptfs inode's
i_nlink count not being cleared.

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Reported-by: Richard Weinberger <richard@nod.at>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/ecryptfs/dentry.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)

--- a/fs/ecryptfs/dentry.c
+++ b/fs/ecryptfs/dentry.c
@@ -45,20 +45,20 @@
static int ecryptfs_d_revalidate(struct dentry *dentry, unsigned int flags)
{
struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
- int rc;
-
- if (!(lower_dentry->d_flags & DCACHE_OP_REVALIDATE))
- return 1;
+ int rc = 1;

if (flags & LOOKUP_RCU)
return -ECHILD;

- rc = lower_dentry->d_op->d_revalidate(lower_dentry, flags);
+ if (lower_dentry->d_flags & DCACHE_OP_REVALIDATE)
+ rc = lower_dentry->d_op->d_revalidate(lower_dentry, flags);
+
if (d_really_is_positive(dentry)) {
- struct inode *lower_inode =
- ecryptfs_inode_to_lower(d_inode(dentry));
+ struct inode *inode = d_inode(dentry);

- fsstack_copy_attr_all(d_inode(dentry), lower_inode);
+ fsstack_copy_attr_all(inode, ecryptfs_inode_to_lower(inode));
+ if (!inode->i_nlink)
+ return 0;
}
return rc;
}