From: NeilBrown <neil@brown.name>
Date: Wed, 16 Jul 2025 00:44:17 +0000 (+1000)
Subject: ovl: narrow locking in ovl_clear_empty()
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4f622bd9f3e5dd1e882ee8f4194ea1d95dcf752f;p=thirdparty%2Flinux.git

ovl: narrow locking in ovl_clear_empty()

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.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://lore.kernel.org/20250716004725.1206467-7-neil@brown.name
Signed-off-by: Christian Brauner <brauner@kernel.org>
---

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 1a146a71993a6..540b67f5cdf5d 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -353,7 +353,6 @@ 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 path upperpath;
 	struct dentry *upper;
@@ -399,12 +398,12 @@ static struct dentry *ovl_clear_empty(struct dentry *dentry,
 		goto out_cleanup;
 
 	err = ovl_do_rename(ofs, workdir, opaquedir, upperdir, upper, RENAME_EXCHANGE);
+	unlock_rename(workdir, upperdir);
 	if (err)
-		goto out_cleanup;
+		goto out_cleanup_unlocked;
 
 	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);