From a65e58e791a1690da8de731c8391816a22f5555c Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Sat, 20 Mar 2021 13:26:22 +0100 Subject: fs: document and rename fsid helpers Vivek pointed out that the fs{g,u}id_into_mnt() naming scheme can be misleading as it could be understood as implying they do the exact same thing as i_{g,u}id_into_mnt(). The original motivation for this naming scheme was to signal to callers that the helpers will always take care to map the k{g,u}id such that the ownership is expressed in terms of the mnt_users. Get rid of the confusion by renaming those helpers to something more sensible. Al suggested mapped_fs{g,u}id() which seems a really good fit. Usually filesystems don't need to bother with these helpers directly only in some cases where they allocate objects that carry {g,u}ids which are either filesystem specific (e.g. xfs quota objects) or don't have a clean set of helpers as inodes have. Link: https://lore.kernel.org/r/20210320122623.599086-3-christian.brauner@ubuntu.com Inspired-by: Vivek Goyal Cc: Christoph Hellwig Cc: Darrick J. Wong Cc: Al Viro Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig Signed-off-by: Christian Brauner --- include/linux/fs.h | 28 ++++++++++++++++++++++++++-- 1 file changed, 26 insertions(+), 2 deletions(-) (limited to 'include/linux/fs.h') diff --git a/include/linux/fs.h b/include/linux/fs.h index 33873531ffa6..e34967829183 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1658,12 +1658,36 @@ static inline kgid_t kgid_from_mnt(struct user_namespace *mnt_userns, return KGIDT_INIT(from_kgid(mnt_userns, kgid)); } -static inline kuid_t fsuid_into_mnt(struct user_namespace *mnt_userns) +/** + * 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()); } -static inline kgid_t fsgid_into_mnt(struct user_namespace *mnt_userns) +/** + * 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()); } -- cgit v1.2.3