This is needed to maintain Unix semantics.
Signed-off-by: Erez Zadok <ezk@xxxxxxxxxxxxx>
---
fs/unionfs/inode.c | 17 +++++++++++++++++
1 files changed, 17 insertions(+), 0 deletions(-)
diff --git a/fs/unionfs/inode.c b/fs/unionfs/inode.c
index 6ca52f4..f4facf4 100644
--- a/fs/unionfs/inode.c
+++ b/fs/unionfs/inode.c
@@ -90,6 +90,23 @@ static int unionfs_create(struct inode *parent, struct dentry *dentry,
err = vfs_unlink(lower_dir_dentry->d_inode, wh_dentry);
unlock_dir(lower_dir_dentry);
+ /*
+ * Whiteouts are special files and should be deleted
+ * no matter what (as if they never existed), in
+ * order to allow this create operation to succeed.
+ * This is especially important in sticky
+ * directories: a whiteout may have been created by
+ * one user, but the newly created file may be
+ * created by another user. Therefore, in order to
+ * maintain Unix semantics, if the vfs_unlink above
+ * ailed, then we have to try to directly unlink the
+ * whiteout. Note: in the ODF version of unionfs,
+ * whiteout are handled much more cleanly.
+ */
+ if (err == -EPERM) {
+ struct inode *inode = lower_dir_dentry->d_inode;
+ err = inode->i_op->unlink(inode, wh_dentry);
+ }
if (err) {
printk(KERN_ERR "unionfs: create: could not "
"unlink whiteout, err = %d\n", err);
--
1.5.2.2
-
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