ovl: do not try to reconnect a disconnected origin dentry
On lookup of non directory, we try to decode the origin file handle
stored in upper inode. The origin file handle is supposed to be decoded
to a disconnected non-dir dentry, which is fine, because we only need
the lower inode of a copy up origin.
However, if the origin file handle somehow turns out to be a directory
we pay the expensive cost of reconnecting the directory dentry, only to
get a mismatch file type and drop the dentry.
Optimize this case by explicitly opting out of reconnecting the dentry.
Opting-out of reconnect is done by passing a NULL acceptable callback
to exportfs_decode_fh().
While the case described above is a strange corner case that does not
really need to be optimized, the API added for this optimization will
be used by a following patch to optimize a more common case of decoding
an overlayfs file handle.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index dd6c10e..b51613b 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -266,8 +266,9 @@ static inline bool ovl_is_impuredir(struct dentry *dentry)
/* namei.c */
int ovl_check_fh_len(struct ovl_fh *fh, int fh_len);
-struct dentry *ovl_decode_real_fh(struct ovl_fh *fh, struct vfsmount *mnt);
-int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh,
+struct dentry *ovl_decode_real_fh(struct ovl_fh *fh, struct vfsmount *mnt,
+ bool connected);
+int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
struct dentry *upperdentry, struct ovl_path **stackp);
int ovl_verify_set_fh(struct dentry *dentry, const char *name,
struct dentry *real, bool is_upper, bool set);