fs: port ->setattr() to pass mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

101 files changed, 257 insertions, 245 deletions

diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst
index 36fa2a83d714..04ad02dcd269 100644
--- a/Documentation/filesystems/locking.rst
+++ b/Documentation/filesystems/locking.rst
@@ -71,7 +71,7 @@ prototypes::
 	void (*truncate) (struct inode *);
 	int (*permission) (struct inode *, int, unsigned int);
 	struct posix_acl * (*get_inode_acl)(struct inode *, int, bool);
-	int (*setattr) (struct dentry *, struct iattr *);
+	int (*setattr) (struct mnt_idmap *, struct dentry *, struct iattr *);
 	int (*getattr) (const struct path *, struct kstat *, u32, unsigned int);
 	ssize_t (*listxattr) (struct dentry *, char *, size_t);
 	int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start, u64 len);
diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst
index 2c15e7053113..894e2a5c3603 100644
--- a/Documentation/filesystems/vfs.rst
+++ b/Documentation/filesystems/vfs.rst
@@ -436,7 +436,7 @@ As of kernel 2.6.22, the following members are defined:
 					 struct delayed_call *);
 		int (*permission) (struct user_namespace *, struct inode *, int);
 		struct posix_acl * (*get_inode_acl)(struct inode *, int, bool);
-		int (*setattr) (struct user_namespace *, struct dentry *, struct iattr *);
+		int (*setattr) (struct mnt_idmap *, struct dentry *, struct iattr *);
 		int (*getattr) (struct user_namespace *, const struct path *, struct kstat *, u32, unsigned int);
 		ssize_t (*listxattr) (struct dentry *, char *, size_t);
 		void (*update_time)(struct inode *, struct timespec *, int);
diff --git a/arch/powerpc/platforms/cell/spufs/inode.c b/arch/powerpc/platforms/cell/spufs/inode.c
index dbcfe361831a..19fec984fdb0 100644
--- a/arch/powerpc/platforms/cell/spufs/inode.c
+++ b/arch/powerpc/platforms/cell/spufs/inode.c
@@ -92,7 +92,7 @@ out:
 }
 
 static int
-spufs_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+spufs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	      struct iattr *attr)
 {
 	struct inode *inode = d_inode(dentry);
@@ -100,7 +100,7 @@ spufs_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 	if ((attr->ia_valid & ATTR_SIZE) &&
 	    (attr->ia_size != inode->i_size))
 		return -EINVAL;
-	setattr_copy(&init_user_ns, inode, attr);
+	setattr_copy(&nop_mnt_idmap, inode, attr);
 	mark_inode_dirty(inode);
 	return 0;
 }
diff --git a/fs/9p/acl.c b/fs/9p/acl.c
index c397c51f80d9..9848a245fa6f 100644
--- a/fs/9p/acl.c
+++ b/fs/9p/acl.c
@@ -225,7 +225,7 @@ int v9fs_iop_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry,
 			 * FIXME should we update ctime ?
 			 * What is the following setxattr update the mode ?
 			 */
-			v9fs_vfs_setattr_dotl(&init_user_ns, dentry, &iattr);
+			v9fs_vfs_setattr_dotl(&nop_mnt_idmap, dentry, &iattr);
 		}
 		break;
 	case ACL_TYPE_DEFAULT:
diff --git a/fs/9p/v9fs_vfs.h b/fs/9p/v9fs_vfs.h
index bc417da7e9c1..75106b9f293d 100644
--- a/fs/9p/v9fs_vfs.h
+++ b/fs/9p/v9fs_vfs.h
@@ -60,7 +60,7 @@ void v9fs_inode2stat(struct inode *inode, struct p9_wstat *stat);
 int v9fs_uflags2omode(int uflags, int extended);
 
 void v9fs_blank_wstat(struct p9_wstat *wstat);
-int v9fs_vfs_setattr_dotl(struct user_namespace *mnt_userns,
+int v9fs_vfs_setattr_dotl(struct mnt_idmap *idmap,
 			  struct dentry *dentry, struct iattr *iattr);
 int v9fs_file_fsync_dotl(struct file *filp, loff_t start, loff_t end,
 			 int datasync);
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 27a04a226d97..d8cd3f17bbf3 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -1060,13 +1060,13 @@ v9fs_vfs_getattr(struct user_namespace *mnt_userns, const struct path *path,
 
 /**
  * v9fs_vfs_setattr - set file metadata
- * @mnt_userns: The user namespace of the mount
+ * @idmap: idmap of the mount
  * @dentry: file whose metadata to set
  * @iattr: metadata assignment structure
  *
  */
 
-static int v9fs_vfs_setattr(struct user_namespace *mnt_userns,
+static int v9fs_vfs_setattr(struct mnt_idmap *idmap,
 			    struct dentry *dentry, struct iattr *iattr)
 {
 	int retval, use_dentry = 0;
@@ -1077,7 +1077,7 @@ static int v9fs_vfs_setattr(struct user_namespace *mnt_userns,
 	struct p9_wstat wstat;
 
 	p9_debug(P9_DEBUG_VFS, "\n");
-	retval = setattr_prepare(&init_user_ns, dentry, iattr);
+	retval = setattr_prepare(&nop_mnt_idmap, dentry, iattr);
 	if (retval)
 		return retval;
 
@@ -1135,7 +1135,7 @@ static int v9fs_vfs_setattr(struct user_namespace *mnt_userns,
 
 	v9fs_invalidate_inode_attr(inode);
 
-	setattr_copy(&init_user_ns, inode, iattr);
+	setattr_copy(&nop_mnt_idmap, inode, iattr);
 	mark_inode_dirty(inode);
 	return 0;
 }
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index f806b3f11649..dfe6b4017bd0 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -529,13 +529,13 @@ static int v9fs_mapped_iattr_valid(int iattr_valid)
 
 /**
  * v9fs_vfs_setattr_dotl - set file metadata
- * @mnt_userns: The user namespace of the mount
+ * @idmap: idmap of the mount
  * @dentry: file whose metadata to set
  * @iattr: metadata assignment structure
  *
  */
 
-int v9fs_vfs_setattr_dotl(struct user_namespace *mnt_userns,
+int v9fs_vfs_setattr_dotl(struct mnt_idmap *idmap,
 			  struct dentry *dentry, struct iattr *iattr)
 {
 	int retval, use_dentry = 0;
@@ -548,7 +548,7 @@ int v9fs_vfs_setattr_dotl(struct user_namespace *mnt_userns,
 
 	p9_debug(P9_DEBUG_VFS, "\n");
 
-	retval = setattr_prepare(&init_user_ns, dentry, iattr);
+	retval = setattr_prepare(&nop_mnt_idmap, dentry, iattr);
 	if (retval)
 		return retval;
 
@@ -597,7 +597,7 @@ int v9fs_vfs_setattr_dotl(struct user_namespace *mnt_userns,
 		truncate_setsize(inode, iattr->ia_size);
 
 	v9fs_invalidate_inode_attr(inode);
-	setattr_copy(&init_user_ns, inode, iattr);
+	setattr_copy(&nop_mnt_idmap, inode, iattr);
 	mark_inode_dirty(inode);
 	if (iattr->ia_valid & ATTR_MODE) {
 		/* We also want to update ACL when we update mode bits */
diff --git a/fs/adfs/adfs.h b/fs/adfs/adfs.h
index 06b7c92343ad..223f0283d20f 100644
--- a/fs/adfs/adfs.h
+++ b/fs/adfs/adfs.h
@@ -144,7 +144,7 @@ struct adfs_discmap {
 /* Inode stuff */
 struct inode *adfs_iget(struct super_block *sb, struct object_info *obj);
 int adfs_write_inode(struct inode *inode, struct writeback_control *wbc);
-int adfs_notify_change(struct user_namespace *mnt_userns, struct dentry *dentry,
+int adfs_notify_change(struct mnt_idmap *idmap, struct dentry *dentry,
 		       struct iattr *attr);
 
 /* map.c */
diff --git a/fs/adfs/inode.c b/fs/adfs/inode.c
index ee22278b0cfc..c3ac613d0975 100644
--- a/fs/adfs/inode.c
+++ b/fs/adfs/inode.c
@@ -294,7 +294,7 @@ out:
  * later.
  */
 int
-adfs_notify_change(struct user_namespace *mnt_userns, struct dentry *dentry,
+adfs_notify_change(struct mnt_idmap *idmap, struct dentry *dentry,
 		   struct iattr *attr)
 {
 	struct inode *inode = d_inode(dentry);
@@ -302,7 +302,7 @@ adfs_notify_change(struct user_namespace *mnt_userns, struct dentry *dentry,
 	unsigned int ia_valid = attr->ia_valid;
 	int error;
 	
-	error = setattr_prepare(&init_user_ns, dentry, attr);
+	error = setattr_prepare(&nop_mnt_idmap, dentry, attr);
 
 	/*
 	 * we can't change the UID or GID of any file -
diff --git a/fs/affs/affs.h b/fs/affs/affs.h
index bfa89e131ead..8c98e2644a5e 100644
--- a/fs/affs/affs.h
+++ b/fs/affs/affs.h
@@ -185,7 +185,7 @@ extern int	affs_rename2(struct user_namespace *mnt_userns,
 /* inode.c */
 
 extern struct inode		*affs_new_inode(struct inode *dir);
-extern int			 affs_notify_change(struct user_namespace *mnt_userns,
+extern int			 affs_notify_change(struct mnt_idmap *idmap,
 					struct dentry *dentry, struct iattr *attr);
 extern void			 affs_evict_inode(struct inode *inode);
 extern struct inode		*affs_iget(struct super_block *sb,
diff --git a/fs/affs/inode.c b/fs/affs/inode.c
index 2352a75bd9d6..27f77a52c5c8 100644
--- a/fs/affs/inode.c
+++ b/fs/affs/inode.c
@@ -216,7 +216,7 @@ affs_write_inode(struct inode *inode, struct writeback_control *wbc)
 }
 
 int
-affs_notify_change(struct user_namespace *mnt_userns, struct dentry *dentry,
+affs_notify_change(struct mnt_idmap *idmap, struct dentry *dentry,
 		   struct iattr *attr)
 {
 	struct inode *inode = d_inode(dentry);
@@ -224,7 +224,7 @@ affs_notify_change(struct user_namespace *mnt_userns, struct dentry *dentry,
 
 	pr_debug("notify_change(%lu,0x%x)\n", inode->i_ino, attr->ia_valid);
 
-	error = setattr_prepare(&init_user_ns, dentry, attr);
+	error = setattr_prepare(&nop_mnt_idmap, dentry, attr);
 	if (error)
 		goto out;
 
@@ -250,7 +250,7 @@ affs_notify_change(struct user_namespace *mnt_userns, struct dentry *dentry,
 		affs_truncate(inode);
 	}
 
-	setattr_copy(&init_user_ns, inode, attr);
+	setattr_copy(&nop_mnt_idmap, inode, attr);
 	mark_inode_dirty(inode);
 
 	if (attr->ia_valid & ATTR_MODE)
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 6d3a3dbe4928..f001cf1750ec 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -870,7 +870,7 @@ static const struct afs_operation_ops afs_setattr_operation = {
 /*
  * set the attributes of an inode
  */
-int afs_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+int afs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		struct iattr *attr)
 {
 	const unsigned int supported =
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index fd8567b98e2b..e2a23efc91b6 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -1172,7 +1172,7 @@ extern bool afs_check_validity(struct afs_vnode *);
 extern int afs_validate(struct afs_vnode *, struct key *);
 extern int afs_getattr(struct user_namespace *mnt_userns, const struct path *,
 		       struct kstat *, u32, unsigned int);
-extern int afs_setattr(struct user_namespace *mnt_userns, struct dentry *, struct iattr *);
+extern int afs_setattr(struct mnt_idmap *idmap, struct dentry *, struct iattr *);
 extern void afs_evict_inode(struct inode *);
 extern int afs_drop_inode(struct inode *);
 
diff --git a/fs/attr.c b/fs/attr.c
index 023a3860568a..39d35621e57b 100644
--- a/fs/attr.c
+++ b/