[PATCH RFC v2 05/28] vfs: allow rmdir to wait for delegation break on parent

Jeff Layton
2025-06-02T14:02:32Z

In order to add directory delegation support, we need to break
delegations on the parent whenever there is going to be a change in the
directory.

Rename vfs_rmdir as __vfs_rmdir, make it static and add a new
delegated_inode parameter. Add a vfs_rmdir wrapper that passes in a NULL
pointer for it. Add the necessary try_break_deleg calls to
__vfs_rmdir(). Convert do_rmdir to use __vfs_rmdir and wait for the
delegation break to complete before proceeding.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
fs/namei.c | 51 ++++++++++++++++++++++++++++++++++-----------------
1 file changed, 34 insertions(+), 17 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 7c9e237ed1b1a535934ffe5e523424bb035e7ae0..2211ed9f427cc97391d068b1a33ce388266a3e02 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4438,22 +4438,8 @@ SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode)
return do_mkdirat(AT_FDCWD, getname(pathname), mode);
}

-/**
- * vfs_rmdir - remove directory
- * @idmap: idmap of the mount the inode was found from
- * @dir: inode of the parent directory
- * @dentry: dentry of the child directory
- *
- * Remove a directory.
- *
- * If the inode has been found through an idmapped mount the idmap of
- * the vfsmount must be passed through @idmap. This function will then take
- * care to map the inode according to @idmap before checking permissions.
- * On non-idmapped mounts or if permission checking is to be performed on the
- * raw inode simply pass @nop_mnt_idmap.
- */
-int vfs_rmdir(struct mnt_idmap *idmap, struct inode *dir,
- struct dentry *dentry)
+static int __vfs_rmdir(struct mnt_idmap *idmap, struct inode *dir,
+ struct dentry *dentry, struct inode **delegated_inode)
{
int error = may_delete(idmap, dir, dentry, 1);

@@ -4475,6 +4461,10 @@ int vfs_rmdir(struct mnt_idmap *idmap, struct inode *dir,
if (error)
goto out;

+ error = try_break_deleg(dir, delegated_inode);
+ if (error)
+ goto out;
+
error = dir->i_op->rmdir(dir, dentry);
if (error)
goto out;
@@ -4491,6 +4481,26 @@ int vfs_rmdir(struct mnt_idmap *idmap, struct inode *dir,
d_delete_notify(dir, dentry);
return error;
}
+
+/**
+ * vfs_rmdir - remove directory
+ * @idmap: idmap of the mount the inode was found from
+ * @dir: inode of the parent directory
+ * @dentry: dentry of the child directory
+ *
+ * Remove a directory.
+ *
+ * If the inode has been found through an idmapped mount the idmap of
+ * the vfsmount must be passed through @idmap. This function will then take
+ * care to map the inode according to @idmap before checking permissions.
+ * On non-idmapped mounts or if permission checking is to be performed on the
+ * raw inode simply pass @nop_mnt_idmap.
+ */
+int vfs_rmdir(struct mnt_idmap *idmap, struct inode *dir,
+ struct dentry *dentry)
+{
+ return __vfs_rmdir(idmap, dir, dentry, NULL);
+}
EXPORT_SYMBOL(vfs_rmdir);

int do_rmdir(int dfd, struct filename *name)
@@ -4501,6 +4511,7 @@ int do_rmdir(int dfd, struct filename *name)
struct qstr last;
int type;
unsigned int lookup_flags = 0;
+ struct inode *delegated_inode = NULL;
retry:
error = filename_parentat(dfd, name, lookup_flags, &path, &last, &type);
if (error)
@@ -4530,7 +4541,8 @@ int do_rmdir(int dfd, struct filename *name)
error = security_path_rmdir(&path, dentry);
if (error)
goto exit4;
- error = vfs_rmdir(mnt_idmap(path.mnt), path.dentry->d_inode, dentry);
+ error = __vfs_rmdir(mnt_idmap(path.mnt), path.dentry->d_inode,
+ dentry, &delegated_inode);
exit4:
dput(dentry);
exit3:
@@ -4538,6 +4550,11 @@ int do_rmdir(int dfd, struct filename *name)
mnt_drop_write(path.mnt);
exit2:
path_put(&path);
+ if (delegated_inode) {
+ error = break_deleg_wait(&delegated_inode);
+ if (!error)
+ goto retry;
+ }
if (retry_estale(error, lookup_flags)) {
lookup_flags |= LOOKUP_REVAL;
goto retry;

--
2.49.0