Directory file handles must be connectable. With current implementation
directories are copied up on encode, so directory file handles are
guarantied to be upper.
Implement get_parent() operation to reconnect a non pure upper overlay dir
dentry. fh_to_parent() operation is not implemented for non pure upper, so
connectable non-dir non pure upper file handles are not supported.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/export.c | 58 ++++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 51 insertions(+), 7 deletions(-)
diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
index f97f68e92eba..7c04ae99c18b 100644
--- a/fs/overlayfs/export.c
+++ b/fs/overlayfs/export.c
@@ -357,11 +357,14 @@ static struct dentry *ovl_fh_to_parent(struct super_block *sb, struct fid *fid,
static struct dentry *ovl_get_parent(struct dentry *dentry)
{
+ struct dentry *root = dentry->d_sb->s_root;
+ struct ovl_entry *roe = root->d_fsdata;
+ struct dentry *parent;
struct dentry *upper;
-
- /* TODO: handle connecting of non pure upper */
- if (ovl_dentry_lower(dentry))
- return ERR_PTR(-EACCES);
+ struct dentry *origin = NULL;
+ struct path *stack = NULL;
+ unsigned int ctr = 0;
+ int err;
/*
* When ovl_fh_to_d() returns an overlay dentry, its real upper
@@ -369,16 +372,57 @@ static struct dentry *ovl_get_parent(struct dentry *dentry)
* the upper dentry is done by ovl_decode_fh() when decoding the
* real upper file handle, so here we have the upper dentry parent
* and we need to instantiate an overlay dentry with upper dentry
- * parent.
+ * parent and the lower dir pointed to by origin xattr.
+ *
+ * TODO: handle reconnecting of non upper overlay dentry.
*/
upper = ovl_dentry_upper(dentry);
if (!upper || (upper->d_flags & DCACHE_DISCONNECTED))
return ERR_PTR(-ESTALE);
upper = dget_parent(upper);
+ if (upper == ovl_dentry_upper(root)) {
+ dput(upper);
+ return dget(root);
+ }
- /* Find or instantiate a pure upper dentry */
- return ovl_obtain_alias(dentry->d_sb, upper, NULL);
+ /* Check if parent is merge dir or pure upper */
+ err = ovl_check_origin(upper, roe->lowerstack, roe->numlower,
+ &stack, &ctr);
+ if (err)
+ goto out_err;
+
+ if (ctr) {
+ struct dentry *index;
+
+ /*
+ * Lookup index by decoded origin to verify dir is indexed.
+ * We only decode upper with origin if it is indexed, so NFS
+ * export will work only if overlay was mounted with index=all
+ * from the start.
+ */
+ origin = stack[0].dentry;
+ index = ovl_lookup_index(ovl_indexdir(dentry->d_sb), upper,
+ origin);
+ err = index ? PTR_ERR(index) : -ESTALE;
+ if (IS_ERR_OR_NULL(index))
+ goto out_err;
+
+ dput(index);
+ }
+
+ /* Find or instantiate an upper dentry */
+ parent = ovl_obtain_alias(dentry->d_sb, upper, origin);
+
+out:
+ dput(origin);
+ kfree(stack);
+ return parent;
+
+out_err:
+ dput(upper);
+ parent = ERR_PTR(err);
+ goto out;
}
const struct export_operations ovl_export_operations = {
--
2.7.4
