CRED: Wrap task credential accesses in the OCFS2 filesystem

Wrap access to task credentials so that they can be separated more easily from
the task_struct during the introduction of COW creds.

Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id().

Change some task->e?[ug]id to task_e?[ug]id().  In some places it makes more
sense to use RCU directly rather than a convenient wrapper; these will be
addressed by later patches.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <joel.becker@oracle.com>
Cc: ocfs2-devel@oss.oracle.com
Signed-off-by: James Morris <jmorris@namei.org>

fs/ocfs2/dlm/dlmfs.c

@@ -339,8 +339,8 @@ static struct inode *dlmfs_get_root_inode(struct super_block *sb)
 		ip = DLMFS_I(inode);
 
 		inode->i_mode = mode;
-		inode->i_uid = current->fsuid;
-		inode->i_gid = current->fsgid;
+		inode->i_uid = current_fsuid();
+		inode->i_gid = current_fsgid();
 		inode->i_blocks = 0;
 		inode->i_mapping->backing_dev_info = &dlmfs_backing_dev_info;
 		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
@@ -365,8 +365,8 @@ static struct inode *dlmfs_get_inode(struct inode *parent,
 		return NULL;
 
 	inode->i_mode = mode;
-	inode->i_uid = current->fsuid;
-	inode->i_gid = current->fsgid;
+	inode->i_uid = current_fsuid();
+	inode->i_gid = current_fsgid();
 	inode->i_blocks = 0;
 	inode->i_mapping->backing_dev_info = &dlmfs_backing_dev_info;
 	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;

fs/ocfs2/namei.c

@@ -421,13 +421,13 @@ static int ocfs2_mknod_locked(struct ocfs2_super *osb,
 	fe->i_blkno = cpu_to_le64(fe_blkno);
 	fe->i_suballoc_bit = cpu_to_le16(suballoc_bit);
 	fe->i_suballoc_slot = cpu_to_le16(inode_ac->ac_alloc_slot);
-	fe->i_uid = cpu_to_le32(current->fsuid);
+	fe->i_uid = cpu_to_le32(current_fsuid());
 	if (dir->i_mode & S_ISGID) {
 		fe->i_gid = cpu_to_le32(dir->i_gid);
 		if (S_ISDIR(mode))
 			mode |= S_ISGID;
 	} else
-		fe->i_gid = cpu_to_le32(current->fsgid);
+		fe->i_gid = cpu_to_le32(current_fsgid());
 	fe->i_mode = cpu_to_le16(mode);
 	if (S_ISCHR(mode) || S_ISBLK(mode))
 		fe->id1.dev1.i_rdev = cpu_to_le64(huge_encode_dev(dev));