The fs:all for rank option description was confusing. It seemd like the fs was optional, but it is mandatory. This change modifies the help message to reflect the correct way to use all in the --rank option.

→ ./bin/cephfs-journal-tool -h                                                                                                                                                                                                                                                                                                                                                         
Usage:                                                                                                                                                                                                                                                                                                                                                                                 
  cephfs-journal-tool [options] journal <command>                                                                                                                                                                                                                                                                                                                                      
    <command>:                                                                                                                                                                                                                                                                                                                                                                         
      inspect                                                                                                                                                                                                                                                                                                                                                                          
      import <path> [--force]                                                                                                                                                                                                                                                                                                                                                          
      export <path>                                                                                                                                                                                                                                                                                                                                                                    
      reset [--force]                                                                                                                                                                                                                                                                                                                                                                  
  cephfs-journal-tool [options] header <get|set> <field> <value>
    <field>: [trimmed_pos|expire_pos|write_pos|pool_id]
  cephfs-journal-tool [options] event <effect> <selector> <output> [special options]
    <selector>:
      --range=<start>..<end>
      --path=<substring>
      --inode=<integer>
      --type=<UPDATE|OPEN|SESSION...><
      --frag=<ino>.<frag> [--dname=<dentry string>]
      --client=<session id integer>
    <effect>: [get|recover_dentries|splice]
    <output>: [summary|list|binary|json] [--path <path>]

General options:
  --rank=filesystem:{mds-rank|all} Journal rank or all (mandatory)
  --journal=<mdlog|purge_queue>  Journal type (purge_queue means
                                 this journal is used to queue for purge operation,
                                 default is mdlog, and only mdlog support event mode)

Special options
  --alternate-pool <name>     Alternative metadata pool to target
                              when using recover_dentries.
  --conf/-c FILE    read configuration from the given configuration file
  --id ID           set ID portion of my name
  --name/-n TYPE.ID set name
  --cluster NAME    set cluster name (default: ceph)
  --setuser USER    set uid to user or uid (and gid to user's gid)
  --setgroup GROUP  set gid to group or gid
  --version         show version and quit