[PATCH v3 12/16] ovl: constant st_ino/st_dev across copy up

Amir Goldstein
2017-04-26T21:35:35Z

When getting attributes for overlay inode of path type COPYUP,
get the inode and dev numbers from the copy up origin inode.

This results in constant and persistent st_ino/st_dev representation
of files in overlay mount before and after copy up as well as after
mount cycle.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
fs/overlayfs/inode.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 17b8418..3615a52 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -60,15 +60,25 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr)
static int ovl_getattr(const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int flags)
{
- struct dentry *dentry = path->dentry;
+ struct dentry *lower, *dentry = path->dentry;
struct path realpath;
const struct cred *old_cred;
+ enum ovl_path_type type;
int err;

- ovl_path_real(dentry, &realpath);
+ type = ovl_path_real(dentry, &realpath);
old_cred = ovl_override_creds(dentry->d_sb);
err = vfs_getattr(&realpath, stat, request_mask, flags);
revert_creds(old_cred);
+ if (err)
+ return err;
+
+ lower = ovl_dentry_lower(dentry);
+ if (OVL_TYPE_COPYUP(type) && lower) {
+ stat->dev = lower->d_sb->s_dev;
+ stat->ino = lower->d_inode->i_ino;
+ }
+
return err;
}

--
2.7.4