GIT: unionfs2-2.6.27.y: Unionfs: create opaque directories' whiteouts unconditionally

[Erez Zadok]

commit 0716ce836b3fdc23418abd4e9d19ecc39fda7384
Author: Erez Zadok <ezk at cs.sunysb.edu>
Date:   Sun Nov 25 23:01:28 2007 -0500

    Unionfs: create opaque directories' whiteouts unconditionally
    
    Needed to maintain Unix semantics (LTP testing).
    
    Signed-off-by: Erez Zadok <ezk at cs.sunysb.edu>

diff --git a/fs/unionfs/subr.c b/fs/unionfs/subr.c
index 968ee8c..1a26c57 100644
--- a/fs/unionfs/subr.c
+++ b/fs/unionfs/subr.c
@@ -162,6 +162,19 @@ int make_dir_opaque(struct dentry *dentry, int bindex)
 	struct dentry *lower_dentry, *diropq;
 	struct inode *lower_dir;
 	struct nameidata nd;
+	kernel_cap_t orig_cap;
+
+	/*
+	 * Opaque directory whiteout markers are special files (like regular
+	 * whiteouts), and should appear to the users as if they don't
+	 * exist.  They should be created/deleted regardless of directory
+	 * search/create permissions, but only for the duration of this
+	 * creation of the .wh.__dir_opaque: file.  Note, this does not
+	 * circumvent normal ->permission).
+	 */
+	orig_cap = current->cap_effective;
+	cap_raise(current->cap_effective, CAP_DAC_READ_SEARCH);
+	cap_raise(current->cap_effective, CAP_DAC_OVERRIDE);
 
 	lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
 	lower_dir = lower_dentry->d_inode;
@@ -189,6 +202,7 @@ int make_dir_opaque(struct dentry *dentry, int bindex)
 
 out:
 	mutex_unlock(&lower_dir->i_mutex);
+	current->cap_effective = orig_cap;
 	return err;
 }