fs: make helpers idmap mount aware

Extend some inode methods with an additional user namespace argument. A
filesystem that is aware of idmapped mounts will receive the user
namespace the mount has been marked with. This can be used for
additional permission checking and also to enable filesystems to
translate between uids and gids if they need to. We have implemented all
relevant helpers in earlier patches.

As requested we simply extend the exisiting inode method instead of
introducing new ones. This is a little more code churn but it's mostly
mechanical and doesnt't leave us with additional inode methods.

Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
diff --git a/fs/hpfs/namei.c b/fs/hpfs/namei.c
index 1aee391..d73f8a67 100644
--- a/fs/hpfs/namei.c
+++ b/fs/hpfs/namei.c
@@ -20,7 +20,8 @@ static void hpfs_update_directory_times(struct inode *dir)
 	hpfs_write_inode_nolock(dir);
 }
 
-static int hpfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+static int hpfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+		      struct dentry *dentry, umode_t mode)
 {
 	const unsigned char *name = dentry->d_name.name;
 	unsigned len = dentry->d_name.len;
@@ -128,7 +129,8 @@ static int hpfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 	return err;
 }
 
-static int hpfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool excl)
+static int hpfs_create(struct user_namespace *mnt_userns, struct inode *dir,
+		       struct dentry *dentry, umode_t mode, bool excl)
 {
 	const unsigned char *name = dentry->d_name.name;
 	unsigned len = dentry->d_name.len;
@@ -215,7 +217,8 @@ static int hpfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, b
 	return err;
 }
 
-static int hpfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t rdev)
+static int hpfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
+		      struct dentry *dentry, umode_t mode, dev_t rdev)
 {
 	const unsigned char *name = dentry->d_name.name;
 	unsigned len = dentry->d_name.len;
@@ -289,7 +292,8 @@ static int hpfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, de
 	return err;
 }
 
-static int hpfs_symlink(struct inode *dir, struct dentry *dentry, const char *symlink)
+static int hpfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
+			struct dentry *dentry, const char *symlink)
 {
 	const unsigned char *name = dentry->d_name.name;
 	unsigned len = dentry->d_name.len;
@@ -506,10 +510,10 @@ static int hpfs_symlink_readpage(struct file *file, struct page *page)
 const struct address_space_operations hpfs_symlink_aops = {
 	.readpage	= hpfs_symlink_readpage
 };
-	
-static int hpfs_rename(struct inode *old_dir, struct dentry *old_dentry,
-		       struct inode *new_dir, struct dentry *new_dentry,
-		       unsigned int flags)
+
+static int hpfs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
+		       struct dentry *old_dentry, struct inode *new_dir,
+		       struct dentry *new_dentry, unsigned int flags)
 {
 	const unsigned char *old_name = old_dentry->d_name.name;
 	unsigned old_len = old_dentry->d_name.len;