[PATCH 05/12] ovl: narrow locking in ovl_clear_empty()

[NeilBrown <neil@brown.name>]

Drop the locks immediately after rename, and use a separate lock for
cleanup.

This makes way for future changes where locks are taken on individual
dentries rather than the whole directory.

Note that ovl_cleanup_whiteouts() operates on "upper", a child of
"upperdir" and does not require upperdir or workdir to be locked.

Signed-off-by: NeilBrown <neil@brown.name>
---
 fs/overlayfs/dir.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 2d67704d641e..e3ea7d02219f 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -355,7 +355,6 @@ static struct dentry *ovl_clear_empty(struct dentry *dentry,
 {
 	struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
 	struct dentry *workdir = ovl_workdir(dentry);
-	struct inode *wdir = workdir->d_inode;
 	struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 	struct inode *udir = upperdir->d_inode;
 	struct path upperpath;
@@ -408,10 +407,10 @@ static struct dentry *ovl_clear_empty(struct dentry *dentry,
 	err = ovl_do_rename(ofs, workdir, opaquedir, upperdir, upper, RENAME_EXCHANGE);
 	if (err)
 		goto out_cleanup;
+	unlock_rename(workdir, upperdir);
 
 	ovl_cleanup_whiteouts(ofs, upper, list);
-	ovl_cleanup(ofs, wdir, upper);
-	unlock_rename(workdir, upperdir);
+	ovl_cleanup_unlocked(ofs, workdir, upper);
 
 	/* dentry's upper doesn't match now, get rid of it */
 	d_drop(dentry);
-- 
2.49.0