fs: port ->set_acl() to pass const mnt_idmap

Convert to const struct mnt_idmap.

A mount's idmapping is immutable. The only thing that is allowed to be
modified afterwards is the reference count and that is hidden behind
mnt_idmap_get() and mnt_idmap_put(). Everything else only ever reads
from the idmapping. This is the same model that struct cred uses and the
idmapping is also rather sensitive.

So make the idmap argument const wherever we can. The conversion is done
from the bottom up so callers can continue to pass a non-const pointer
to a const parameter until the conversion is finished.

No functional changes.

Link: https://patch.msgid.link/20260901-work-idmap-const-v1-15-54ccd48e100b@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Seth Forshee <sforshee@kernel.org>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>

2 files changed, 9 insertions, 9 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 764ef2d97a5d..9186d9bb2697 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2028,7 +2028,7 @@ struct inode_operations {
 			struct file *, umode_t);
 	struct posix_acl *(*get_acl)(struct mnt_idmap *, struct dentry *,
 				     int);
-	int (*set_acl)(struct mnt_idmap *, struct dentry *,
+	int (*set_acl)(const struct mnt_idmap *, struct dentry *,
 		       struct posix_acl *, int);
 	int (*fileattr_set)(const struct mnt_idmap *idmap,
 			    struct dentry *dentry, struct file_kattr *fa);
diff --git a/include/linux/posix_acl.h b/include/linux/posix_acl.h
index 7c6cfcae0a9d..9220fe0c965d 100644
--- a/include/linux/posix_acl.h
+++ b/include/linux/posix_acl.h
@@ -74,20 +74,20 @@ extern int __posix_acl_create(struct posix_acl **, gfp_t, umode_t *);
 extern int __posix_acl_chmod(struct posix_acl **, gfp_t, umode_t);
 
 extern struct posix_acl *get_posix_acl(struct inode *, int);
-int set_posix_acl(struct mnt_idmap *, struct dentry *, int,
+int set_posix_acl(const struct mnt_idmap *, struct dentry *, int,
 		  struct posix_acl *);
 
 struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type);
 struct posix_acl *posix_acl_clone(const struct posix_acl *acl, gfp_t flags);
 
 #ifdef CONFIG_FS_POSIX_ACL
-int posix_acl_chmod(struct mnt_idmap *, struct dentry *, umode_t);
+int posix_acl_chmod(const struct mnt_idmap *, struct dentry *, umode_t);
 extern int posix_acl_create(struct inode *, umode_t *, struct posix_acl **,
 		struct posix_acl **);
 int posix_acl_update_mode(const struct mnt_idmap *, struct inode *, umode_t *,
 			  struct posix_acl **);
 
-int simple_set_acl(struct mnt_idmap *, struct dentry *,
+int simple_set_acl(const struct mnt_idmap *, struct dentry *,
 		   struct posix_acl *, int);
 extern int simple_acl_create(struct inode *, struct inode *);
 
@@ -105,16 +105,16 @@ static inline void cache_no_acl(struct inode *inode)
 	inode->i_default_acl = NULL;
 }
 
-int vfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
+int vfs_set_acl(const struct mnt_idmap *idmap, struct dentry *dentry,
 		const char *acl_name, struct posix_acl *kacl);
 struct posix_acl *vfs_get_acl(struct mnt_idmap *idmap,
 			      struct dentry *dentry, const char *acl_name);
-int vfs_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry,
+int vfs_remove_acl(const struct mnt_idmap *idmap, struct dentry *dentry,
 		   const char *acl_name);
 int posix_acl_listxattr(struct inode *inode, char **buffer,
 			ssize_t *remaining_size);
 #else
-static inline int posix_acl_chmod(struct mnt_idmap *idmap,
+static inline int posix_acl_chmod(const struct mnt_idmap *idmap,
 				  struct dentry *dentry, umode_t mode)
 {
 	return 0;
@@ -141,7 +141,7 @@ static inline void forget_all_cached_acls(struct inode *inode)
 {
 }
 
-static inline int vfs_set_acl(struct mnt_idmap *idmap,
+static inline int vfs_set_acl(const struct mnt_idmap *idmap,
 			      struct dentry *dentry, const char *name,
 			      struct posix_acl *acl)
 {
@@ -155,7 +155,7 @@ static inline struct posix_acl *vfs_get_acl(struct mnt_idmap *idmap,
 	return ERR_PTR(-EOPNOTSUPP);
 }
 
-static inline int vfs_remove_acl(struct mnt_idmap *idmap,
+static inline int vfs_remove_acl(const struct mnt_idmap *idmap,
 				 struct dentry *dentry, const char *acl_name)
 {
 	return -EOPNOTSUPP;