VFS/nfsd/cachefiles/ovl: introduce start_removing() and end_removing()

start_removing() is similar to start_creating() but will only return a
positive dentry with the expectation that it will be removed.  This is
used by nfsd, cachefiles, and overlayfs.  They are changed to also use
end_removing() to terminate the action begun by start_removing().  This
is a simple alias for end_dirop().

Apart from changes to the error paths, as we no longer need to unlock on
a lookup error, an effect on callers is that they don't need to test if
the found dentry is positive or negative - they can be sure it is
positive.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://patch.msgid.link/20251113002050.676694-6-neilb@ownmail.net
Tested-by: syzbot@syzkaller.appspotmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

1 files changed, 5 insertions, 13 deletions

diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index c247a7c3291c..3eefaa2202e3 100644
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -324,20 +324,12 @@ nfsd4_unlink_clid_dir(char *name, struct nfsd_net *nn)
 	dprintk("NFSD: nfsd4_unlink_clid_dir. name %s\n", name);
 
 	dir = nn->rec_file->f_path.dentry;
-	inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
-	dentry = lookup_one(&nop_mnt_idmap, &QSTR(name), dir);
-	if (IS_ERR(dentry)) {
-		status = PTR_ERR(dentry);
-		goto out_unlock;
-	}
-	status = -ENOENT;
-	if (d_really_is_negative(dentry))
-		goto out;
+	dentry = start_removing(&nop_mnt_idmap, dir, &QSTR(name));
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
+
 	status = vfs_rmdir(&nop_mnt_idmap, d_inode(dir), dentry);
-out:
-	dput(dentry);
-out_unlock:
-	inode_unlock(d_inode(dir));
+	end_removing(dentry);
 	return status;
 }