[PATCH 3.4 15/92] eCryptfs: Invalidate dcache entries when lower i_nlink is zero

lizf
2016-04-18T11:17:42Z

From: Tyler Hicks <tyhicks@canonical.com>

3.4.112-rc1 review patch. If anyone has any objections, please let me know.

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

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>
[bwh: Backported to 3.2:
- Test d_revalidate pointer directly rather than a DCACHE_OP flag
- Open-code d_inode()
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Zefan Li <lizefan@huawei.com>
---
fs/ecryptfs/dentry.c | 32 ++++++++++++++++----------------
1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/fs/ecryptfs/dentry.c b/fs/ecryptfs/dentry.c
index 534c1d4..eba8f1d 100644
--- a/fs/ecryptfs/dentry.c
+++ b/fs/ecryptfs/dentry.c
@@ -55,26 +55,26 @@ static int ecryptfs_d_revalidate(struct dentry *dentry, struct nameidata *nd)

lower_dentry = ecryptfs_dentry_to_lower(dentry);
lower_mnt = ecryptfs_dentry_to_lower_mnt(dentry);
- if (!lower_dentry->d_op || !lower_dentry->d_op->d_revalidate)
- goto out;
- if (nd) {
- dentry_save = nd->path.dentry;
- vfsmount_save = nd->path.mnt;
- nd->path.dentry = lower_dentry;
- nd->path.mnt = lower_mnt;
- }
- rc = lower_dentry->d_op->d_revalidate(lower_dentry, nd);
- if (nd) {
- nd->path.dentry = dentry_save;
- nd->path.mnt = vfsmount_save;
+ if (lower_dentry->d_op && lower_dentry->d_op->d_revalidate) {
+ if (nd) {
+ dentry_save = nd->path.dentry;
+ vfsmount_save = nd->path.mnt;
+ nd->path.dentry = lower_dentry;
+ nd->path.mnt = lower_mnt;
+ }
+ rc = lower_dentry->d_op->d_revalidate(lower_dentry, nd);
+ if (nd) {
+ nd->path.dentry = dentry_save;
+ nd->path.mnt = vfsmount_save;
+ }
}
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;
}
-out:
return rc;
}

--
1.9.1