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>

3 files changed, 18 insertions, 12 deletions

diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index b8f0e829ecbd..d905bb9cd2ca 100644
--- a/fs/exfat/exfat_fs.h
+++ b/fs/exfat/exfat_fs.h
@@ -416,9 +416,11 @@ int exfat_count_used_clusters(struct super_block *sb, unsigned int *ret_count);
 extern const struct file_operations exfat_file_operations;
 int __exfat_truncate(struct inode *inode, loff_t new_size);
 void exfat_truncate(struct inode *inode, loff_t size);
-int exfat_setattr(struct dentry *dentry, struct iattr *attr);
-int exfat_getattr(const struct path *path, struct kstat *stat,
-		unsigned int request_mask, unsigned int query_flags);
+int exfat_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+		  struct iattr *attr);
+int exfat_getattr(struct user_namespace *mnt_userns, const struct path *path,
+		  struct kstat *stat, unsigned int request_mask,
+		  unsigned int query_flags);
 int exfat_file_fsync(struct file *file, loff_t start, loff_t end, int datasync);
 
 /* namei.c */
diff --git a/fs/exfat/file.c b/fs/exfat/file.c
index e9705b3295d3..3aa6eb4de5e3 100644
--- a/fs/exfat/file.c
+++ b/fs/exfat/file.c
@@ -267,8 +267,9 @@ write_size:
 	mutex_unlock(&sbi->s_lock);
 }
 
-int exfat_getattr(const struct path *path, struct kstat *stat,
-		unsigned int request_mask, unsigned int query_flags)
+int exfat_getattr(struct user_namespace *mnt_uerns, const struct path *path,
+		  struct kstat *stat, unsigned int request_mask,
+		  unsigned int query_flags)
 {
 	struct inode *inode = d_backing_inode(path->dentry);
 	struct exfat_inode_info *ei = EXFAT_I(inode);
@@ -282,7 +283,8 @@ int exfat_getattr(const struct path *path, struct kstat *stat,
 	return 0;
 }
 
-int exfat_setattr(struct dentry *dentry, struct iattr *attr)
+int exfat_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+		  struct iattr *attr)
 {
 	struct exfat_sb_info *sbi = EXFAT_SB(dentry->d_sb);
 	struct inode *inode = dentry->d_inode;
diff --git a/fs/exfat/namei.c b/fs/exfat/namei.c
index 2932b23a3b6c..d9e8ec689c55 100644
--- a/fs/exfat/namei.c
+++ b/fs/exfat/namei.c
@@ -541,8 +541,8 @@ out:
 	return ret;
 }
 
-static int exfat_create(struct inode *dir, struct dentry *dentry, umode_t mode,
-		bool excl)
+static int exfat_create(struct user_namespace *mnt_userns, struct inode *dir,
+			struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct super_block *sb = dir->i_sb;
 	struct inode *inode;
@@ -827,7 +827,8 @@ unlock:
 	return err;
 }
 
-static int exfat_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+static int exfat_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+		       struct dentry *dentry, umode_t mode)
 {
 	struct super_block *sb = dir->i_sb;
 	struct inode *inode;
@@ -1318,9 +1319,10 @@ out:
 	return ret;
 }
 
-static int exfat_rename(struct inode *old_dir, struct dentry *old_dentry,
-		struct inode *new_dir, struct dentry *new_dentry,
-		unsigned int flags)
+static int exfat_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)
 {
 	struct inode *old_inode, *new_inode;
 	struct super_block *sb = old_dir->i_sb;