[PATCH 3.16.y-ckt 048/133] eCryptfs: Invalidate dcache entries when lower i_nlink is zero

From: Luis Henriques
Date: Wed Sep 30 2015 - 06:23:38 EST


3.16.7-ckt18 -stable review patch. If anyone has any objections, please let me know.

------------------

From: Tyler Hicks <tyhicks@xxxxxxxxxxxxx>

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@xxxxxxxxxxxxx>
Reported-by: Richard Weinberger <richard@xxxxxx>
[ luis: backported to 3.16:
- use dentry->d_inode instead of d_inode(dentry)
- adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
fs/ecryptfs/dentry.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/ecryptfs/dentry.c b/fs/ecryptfs/dentry.c
index 4000f6b3a750..c7703c056e06 100644
--- 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 (dentry->d_inode) {
- struct inode *lower_inode =
- ecryptfs_inode_to_lower(dentry->d_inode);
+ struct inode *inode = dentry->d_inode;

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