[02/10] fs: move mapping helpers

Commit Message

Christian Brauner Nov. 23, 2021, 11:42 a.m. UTC

From: Christian Brauner <[e-mail]>

The low-level mapping helpers were so far crammed into fs.h. They are
out of place there. The fs.h header should just contain the higher-level
mapping helpers that interact directly with vfs objects such as struct
super_block or struct inode and not the bare mapping helpers. Similarly,
only vfs and specific fs code shall interact with low-level mapping
helpers. And so they won't be made accessible automatically through
regular {g,u}id helpers.

Cc: Seth Forshee <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: Al Viro <[e-mail]>
CC: [e-mail]
Signed-off-by: Christian Brauner <[e-mail]>
---
 include/linux/fs.h          |  91 +-------------------------------
 include/linux/mnt_mapping.h | 101 ++++++++++++++++++++++++++++++++++++
 2 files changed, 102 insertions(+), 90 deletions(-)
 create mode 100644 include/linux/mnt_mapping.h

Comments

Amir Goldstein Nov. 30, 2021, 6:35 a.m. UTC | #1

On Tue, Nov 23, 2021 at 3:29 PM Christian Brauner <[e-mail]> wrote:
>
> From: Christian Brauner <[e-mail]>
>
> The low-level mapping helpers were so far crammed into fs.h. They are
> out of place there. The fs.h header should just contain the higher-level
> mapping helpers that interact directly with vfs objects such as struct
> super_block or struct inode and not the bare mapping helpers. Similarly,
> only vfs and specific fs code shall interact with low-level mapping
> helpers. And so they won't be made accessible automatically through
> regular {g,u}id helpers.
>
> Cc: Seth Forshee <[e-mail]>
> Cc: Christoph Hellwig <[e-mail]>
> Cc: Al Viro <[e-mail]>
> CC: [e-mail]
> Signed-off-by: Christian Brauner <[e-mail]>
> ---
>  include/linux/fs.h          |  91 +-------------------------------
>  include/linux/mnt_mapping.h | 101 ++++++++++++++++++++++++++++++++++++
>  2 files changed, 102 insertions(+), 90 deletions(-)
>  create mode 100644 include/linux/mnt_mapping.h
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 192242476b2b..eb69e8b035fa 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -41,6 +41,7 @@
>  #include <linux/stddef.h>
>  #include <linux/mount.h>
>  #include <linux/cred.h>
> +#include <linux/mnt_mapping.h>

If I grepped correctly, there are ~20 files that use these helpers.
Please put the include in those files, so changes to this header
will not compile the world.

And how about mnt_idmapping.h or idmapped_mnt.h?
Not sure if this naming issue was discussed already.

Thanks,
Amir.

Christian Brauner Nov. 30, 2021, 8:53 a.m. UTC | #2

On Tue, Nov 30, 2021 at 08:35:56AM +0200, Amir Goldstein wrote:
> On Tue, Nov 23, 2021 at 3:29 PM Christian Brauner <[e-mail]> wrote:
> >
> > From: Christian Brauner <[e-mail]>
> >
> > The low-level mapping helpers were so far crammed into fs.h. They are
> > out of place there. The fs.h header should just contain the higher-level
> > mapping helpers that interact directly with vfs objects such as struct
> > super_block or struct inode and not the bare mapping helpers. Similarly,
> > only vfs and specific fs code shall interact with low-level mapping
> > helpers. And so they won't be made accessible automatically through
> > regular {g,u}id helpers.
> >
> > Cc: Seth Forshee <[e-mail]>
> > Cc: Christoph Hellwig <[e-mail]>
> > Cc: Al Viro <[e-mail]>
> > CC: [e-mail]
> > Signed-off-by: Christian Brauner <[e-mail]>
> > ---
> >  include/linux/fs.h          |  91 +-------------------------------
> >  include/linux/mnt_mapping.h | 101 ++++++++++++++++++++++++++++++++++++
> >  2 files changed, 102 insertions(+), 90 deletions(-)
> >  create mode 100644 include/linux/mnt_mapping.h
> >
> > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > index 192242476b2b..eb69e8b035fa 100644
> > --- a/include/linux/fs.h
> > +++ b/include/linux/fs.h
> > @@ -41,6 +41,7 @@
> >  #include <linux/stddef.h>
> >  #include <linux/mount.h>
> >  #include <linux/cred.h>
> > +#include <linux/mnt_mapping.h>
> 
> If I grepped correctly, there are ~20 files that use these helpers.
> Please put the include in those files, so changes to this header
> will not compile the world.

Ok, happy to.

> 
> And how about mnt_idmapping.h or idmapped_mnt.h?

I think then I'll opt for mnt_idmapping.h.

> Not sure if this naming issue was discussed already.

Nope!

Thanks!
Christian

Patch

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 192242476b2b..eb69e8b035fa 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -41,6 +41,7 @@ 
 #include <linux/stddef.h>
 #include <linux/mount.h>
 #include <linux/cred.h>
+#include <linux/mnt_mapping.h>
 
 #include <asm/byteorder.h>
 #include <uapi/linux/fs.h>
@@ -1624,34 +1625,6 @@  static inline void i_gid_write(struct inode *inode, gid_t gid)
 	inode->i_gid = make_kgid(inode->i_sb->s_user_ns, gid);
 }
 
-/**
- * kuid_into_mnt - map a kuid down into a mnt_userns
- * @mnt_userns: user namespace of the relevant mount
- * @kuid: kuid to be mapped
- *
- * Return: @kuid mapped according to @mnt_userns.
- * If @kuid has no mapping INVALID_UID is returned.
- */
-static inline kuid_t kuid_into_mnt(struct user_namespace *mnt_userns,
-				   kuid_t kuid)
-{
-	return make_kuid(mnt_userns, __kuid_val(kuid));
-}
-
-/**
- * kgid_into_mnt - map a kgid down into a mnt_userns
- * @mnt_userns: user namespace of the relevant mount
- * @kgid: kgid to be mapped
- *
- * Return: @kgid mapped according to @mnt_userns.
- * If @kgid has no mapping INVALID_GID is returned.
- */
-static inline kgid_t kgid_into_mnt(struct user_namespace *mnt_userns,
-				   kgid_t kgid)
-{
-	return make_kgid(mnt_userns, __kgid_val(kgid));
-}
-
 /**
  * i_uid_into_mnt - map an inode's i_uid down into a mnt_userns
  * @mnt_userns: user namespace of the mount the inode was found from
@@ -1680,68 +1653,6 @@  static inline kgid_t i_gid_into_mnt(struct user_namespace *mnt_userns,
 	return kgid_into_mnt(mnt_userns, inode->i_gid);
 }
 
-/**
- * kuid_from_mnt - map a kuid up into a mnt_userns
- * @mnt_userns: user namespace of the relevant mount
- * @kuid: kuid to be mapped
- *
- * Return: @kuid mapped up according to @mnt_userns.
- * If @kuid has no mapping INVALID_UID is returned.
- */
-static inline kuid_t kuid_from_mnt(struct user_namespace *mnt_userns,
-				   kuid_t kuid)
-{
-	return KUIDT_INIT(from_kuid(mnt_userns, kuid));
-}
-
-/**
- * kgid_from_mnt - map a kgid up into a mnt_userns
- * @mnt_userns: user namespace of the relevant mount
- * @kgid: kgid to be mapped
- *
- * Return: @kgid mapped up according to @mnt_userns.
- * If @kgid has no mapping INVALID_GID is returned.
- */
-static inline kgid_t kgid_from_mnt(struct user_namespace *mnt_userns,
-				   kgid_t kgid)
-{
-	return KGIDT_INIT(from_kgid(mnt_userns, kgid));
-}
-
-/**
- * mapped_fsuid - return caller's fsuid mapped up into a mnt_userns
- * @mnt_userns: user namespace of the relevant mount
- *
- * Use this helper to initialize a new vfs or filesystem object based on
- * the caller's fsuid. A common example is initializing the i_uid field of
- * a newly allocated inode triggered by a creation event such as mkdir or
- * O_CREAT. Other examples include the allocation of quotas for a specific
- * user.
- *
- * Return: the caller's current fsuid mapped up according to @mnt_userns.
- */
-static inline kuid_t mapped_fsuid(struct user_namespace *mnt_userns)
-{
-	return kuid_from_mnt(mnt_userns, current_fsuid());
-}
-
-/**
- * mapped_fsgid - return caller's fsgid mapped up into a mnt_userns
- * @mnt_userns: user namespace of the relevant mount
- *
- * Use this helper to initialize a new vfs or filesystem object based on
- * the caller's fsgid. A common example is initializing the i_gid field of
- * a newly allocated inode triggered by a creation event such as mkdir or
- * O_CREAT. Other examples include the allocation of quotas for a specific
- * user.
- *
- * Return: the caller's current fsgid mapped up according to @mnt_userns.
- */
-static inline kgid_t mapped_fsgid(struct user_namespace *mnt_userns)
-{
-	return kgid_from_mnt(mnt_userns, current_fsgid());
-}
-
 /**
  * inode_fsuid_set - initialize inode's i_uid field with callers fsuid
  * @inode: inode to initialize
diff --git a/include/linux/mnt_mapping.h b/include/linux/mnt_mapping.h
new file mode 100644
index 000000000000..7ff8b66b80cb
--- /dev/null
+++ b/include/linux/mnt_mapping.h
@@ -0,0 +1,101 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_MNT_MAPPING_H
+#define _LINUX_MNT_MAPPING_H
+
+#include <linux/types.h>
+#include <linux/uidgid.h>
+
+struct user_namespace;
+extern struct user_namespace init_user_ns;
+
+/**
+ * kuid_into_mnt - map a kuid down into a mnt_userns
+ * @mnt_userns: user namespace of the relevant mount
+ * @kuid: kuid to be mapped
+ *
+ * Return: @kuid mapped according to @mnt_userns.
+ * If @kuid has no mapping INVALID_UID is returned.
+ */
+static inline kuid_t kuid_into_mnt(struct user_namespace *mnt_userns,
+				   kuid_t kuid)
+{
+	return make_kuid(mnt_userns, __kuid_val(kuid));
+}
+
+/**
+ * kgid_into_mnt - map a kgid down into a mnt_userns
+ * @mnt_userns: user namespace of the relevant mount
+ * @kgid: kgid to be mapped
+ *
+ * Return: @kgid mapped according to @mnt_userns.
+ * If @kgid has no mapping INVALID_GID is returned.
+ */
+static inline kgid_t kgid_into_mnt(struct user_namespace *mnt_userns,
+				   kgid_t kgid)
+{
+	return make_kgid(mnt_userns, __kgid_val(kgid));
+}
+
+/**
+ * kuid_from_mnt - map a kuid up into a mnt_userns
+ * @mnt_userns: user namespace of the relevant mount
+ * @kuid: kuid to be mapped
+ *
+ * Return: @kuid mapped up according to @mnt_userns.
+ * If @kuid has no mapping INVALID_UID is returned.
+ */
+static inline kuid_t kuid_from_mnt(struct user_namespace *mnt_userns,
+				   kuid_t kuid)
+{
+	return KUIDT_INIT(from_kuid(mnt_userns, kuid));
+}
+
+/**
+ * kgid_from_mnt - map a kgid up into a mnt_userns
+ * @mnt_userns: user namespace of the relevant mount
+ * @kgid: kgid to be mapped
+ *
+ * Return: @kgid mapped up according to @mnt_userns.
+ * If @kgid has no mapping INVALID_GID is returned.
+ */
+static inline kgid_t kgid_from_mnt(struct user_namespace *mnt_userns,
+				   kgid_t kgid)
+{
+	return KGIDT_INIT(from_kgid(mnt_userns, kgid));
+}
+
+/**
+ * mapped_fsuid - return caller's fsuid mapped up into a mnt_userns
+ * @mnt_userns: user namespace of the relevant mount
+ *
+ * Use this helper to initialize a new vfs or filesystem object based on
+ * the caller's fsuid. A common example is initializing the i_uid field of
+ * a newly allocated inode triggered by a creation event such as mkdir or
+ * O_CREAT. Other examples include the allocation of quotas for a specific
+ * user.
+ *
+ * Return: the caller's current fsuid mapped up according to @mnt_userns.
+ */
+static inline kuid_t mapped_fsuid(struct user_namespace *mnt_userns)
+{
+	return kuid_from_mnt(mnt_userns, current_fsuid());
+}
+
+/**
+ * mapped_fsgid - return caller's fsgid mapped up into a mnt_userns
+ * @mnt_userns: user namespace of the relevant mount
+ *
+ * Use this helper to initialize a new vfs or filesystem object based on
+ * the caller's fsgid. A common example is initializing the i_gid field of
+ * a newly allocated inode triggered by a creation event such as mkdir or
+ * O_CREAT. Other examples include the allocation of quotas for a specific
+ * user.
+ *
+ * Return: the caller's current fsgid mapped up according to @mnt_userns.
+ */
+static inline kgid_t mapped_fsgid(struct user_namespace *mnt_userns)
+{
+	return kgid_from_mnt(mnt_userns, current_fsgid());
+}
+
+#endif /* _LINUX_MNT_MAPPING_H */