shmem: convert to ctime accessor functions

JIRA: https://issues.redhat.com/browse/RHEL-27743
Conflicts:
  * mm/shmem.c: minor context conflicts on the 2nd, 3rd, and 4th hunks
      due to RHEL missing commits 256c8ae ("fs: introduce dedicated
      idmap type for mounts") and its follow-up series, as well as
      due to out-of-order backport of commit  7a80e5b ("shmem: support
      idmapped mounts for tmpfs") which folds bits of commit 138060b
      ("fs: pass dentry to set acl method")

This patch is a backport of the following upstream commit:
commit 6528733
Author: Jeff Layton <[email protected]>
Date:   Wed Jul 5 15:01:52 2023 -0400

    shmem: convert to ctime accessor functions

    In later patches, we're going to change how the inode's ctime field is
    used. Switch to using accessor functions instead of raw accesses of
    inode->i_ctime.

    Signed-off-by: Jeff Layton <[email protected]>
    Reviewed-by: Jan Kara <[email protected]>
    Message-Id: <[email protected]>
    Signed-off-by: Christian Brauner <[email protected]>

Signed-off-by: Rafael Aquini <[email protected]>

Author: Rafael Aquini

mm/shmem.c

@@ -1136,7 +1136,7 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
 {
 	shmem_undo_range(inode, lstart, lend, false);
-	inode->i_ctime = inode->i_mtime = current_time(inode);
+	inode->i_mtime = inode_set_ctime_current(inode);
 	inode_inc_iversion(inode);
 }
 EXPORT_SYMBOL_GPL(shmem_truncate_range);
@@ -1245,9 +1245,9 @@ static int shmem_setattr(struct user_namespace *mnt_userns,
 	if (attr->ia_valid & ATTR_MODE)
 		error = posix_acl_chmod(mnt_userns, inode, inode->i_mode);
 	if (!error && update_ctime) {
-		inode->i_ctime = current_time(inode);
+		inode_set_ctime_current(inode);
 		if (update_mtime)
-			inode->i_mtime = inode->i_ctime;
+			inode->i_mtime = inode_get_ctime(inode);
 		inode_inc_iversion(inode);
 	}
 	return error;
@@ -2465,7 +2465,7 @@ static struct inode *__shmem_get_inode(struct user_namespace *mnt_userns,
 	inode->i_ino = ino;
 	inode_init_owner(mnt_userns, inode, dir, mode);
 	inode->i_blocks = 0;
-	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
+	inode->i_atime = inode->i_mtime = inode_set_ctime_current(inode);
 	inode->i_generation = get_random_u32();
 	info = SHMEM_I(inode);
 	memset(info, 0, (char *)inode - (char *)info);
@@ -3214,7 +3214,7 @@ shmem_mknod(struct user_namespace *mnt_userns, struct inode *dir,
 
 	error = 0;
 	dir->i_size += BOGO_DIRENT_SIZE;
-	dir->i_ctime = dir->i_mtime = current_time(dir);
+	dir->i_mtime = inode_set_ctime_current(dir);
 	inode_inc_iversion(dir);
 	d_instantiate(dentry, inode);
 	dget(dentry); /* Extra count - pin the dentry in core */
@@ -3296,7 +3296,8 @@ static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentr
 	}
 
 	dir->i_size += BOGO_DIRENT_SIZE;
-	inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
+	dir->i_mtime = inode_set_ctime_to_ts(dir,
+					     inode_set_ctime_current(inode));
 	inode_inc_iversion(dir);
 	inc_nlink(inode);
 	ihold(inode);	/* New dentry reference */
@@ -3314,7 +3315,8 @@ static int shmem_unlink(struct inode *dir, struct dentry *dentry)
 		shmem_free_inode(inode->i_sb);
 
 	dir->i_size -= BOGO_DIRENT_SIZE;
-	inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
+	dir->i_mtime = inode_set_ctime_to_ts(dir,
+					     inode_set_ctime_current(inode));
 	inode_inc_iversion(dir);
 	drop_nlink(inode);
 	dput(dentry);	/* Undo the count from "create" - this does all the work */
@@ -3457,7 +3459,7 @@ static int shmem_symlink(struct user_namespace *mnt_userns, struct inode *dir,
 		folio_put(folio);
 	}
 	dir->i_size += BOGO_DIRENT_SIZE;
-	dir->i_ctime = dir->i_mtime = current_time(dir);
+	dir->i_mtime = inode_set_ctime_current(dir);
 	inode_inc_iversion(dir);
 	d_instantiate(dentry, inode);
 	dget(dentry);
@@ -3529,7 +3531,7 @@ static int shmem_fileattr_set(struct user_namespace *mnt_userns,
 		(fa->flags & SHMEM_FL_USER_MODIFIABLE);
 
 	shmem_set_inode_flags(inode, info->fsflags);
-	inode->i_ctime = current_time(inode);
+	inode_set_ctime_current(inode);
 	inode_inc_iversion(inode);
 	return 0;
 }
@@ -3599,7 +3601,7 @@ static int shmem_xattr_handler_set(const struct xattr_handler *handler,
 	name = xattr_full_name(handler, name);
 	err = simple_xattr_set(&info->xattrs, name, value, size, flags, NULL);
 	if (!err) {
-		inode->i_ctime = current_time(inode);
+		inode_set_ctime_current(inode);
 		inode_inc_iversion(inode);
 	}
 	return err;