Provided by: nilfs-tools_2.1.0-1_amd64 bug


       mount.nilfs2 - mount a NILFS2 file system


       mount -t nilfs2 [-finrvw] [-o options [,...]] device dir
       mount -t nilfs2 [-finrvw] [-o options [,...]] device | dir

       mount.nilfs2 [-fnrvw] [-o options [,...]] device dir

       mount.nilfs2 [-V]


       mount.nilfs2  serves  to attach a NILFS2 file system on the specified directory dir. It is
       intended  to  be  executed  from  mount(8),  and  will  invoke   the   garbage   collector
       nilfs_cleanerd(8)   after   an  actual  mount  system  call  has  succeeded.   Conversely,
       umount.nilfs2(8) will shutdown the garbage collector before detaching the file system.

       The standard command line interface is the first form:
              mount -t nilfs2 [options] device dir
       This tells the kernel to attach the NILFS2 file system on device  at  the  directory  dir.
       With the second form, the mount program tries to find out a missing device or dir argument
       from the /etc/fstab table.

       The third form, which directly invokes mount.nilfs2, is  also  usable  since  mount.nilfs2
       maintains  by  itself  the  system  mount  state  such as the list of mounted file systems
       described in /etc/mtab. Howerver, the first or the  second  form  is  usually  recommended
       because some expansive options are not supported by the third form.


       The  full set of options used by an invocation of mount(8) is determined by extracting the
       options from the fstab table, then applying any options specified by the -o argument,  and
       finally applying a -r or -w option, when present.

       See mount(8) for the full set of options.  Commonly used options are as follows:

       -V     Output version.

       -f     Fakes  mounting  the  file  system,  meaning  that  the  actual system call will be
              skipped.  This option is used to add entries for devices that were mounted  earlier
              with  the  -n  option.  It  can also be used for invoking nilfs_cleanerd(8) skipped

       -i     Don't call mount.nilfs2.  This disables garbage collection and handling  of  pseudo
              mount options.

       -n     Mount  without writing in /etc/mtab.  This is necessary for example when /etc is on
              a read-only file system.  With this  option,  invocation  of  nilfs_cleanerd(8)  is
              skipped.   To  add  entries  to mtab and invoke the garbage collector later, the -f
              option is available.

       -r     Mount the file system read-only.  A synonym is "-o ro".

       -v     Verbose mode.

       -w     Mount the file system read/write. This is the default. A synonym is "-o rw".

       -o     Options are specified with a -o flag  followed  by  a  comma  separated  string  of
              options.   Some of these options are only useful when they appear in the /etc/fstab
              file.  For standard filesystem options, see mount(8).


       The following options apply only to the NILFS2 filesystem.  They all follow the -o flag.

              Disable barrier writes for the block I/O to a  lower  device.   The  barrier  write
              serves  an important role to ensure consistency of filesystems after a system crash
              or power failure.  NILFS2 uses this feature by default to assure  the  reliability.
              For devices not supporting the barrier write, it will be disabled automatically and
              a warning will be logged.

              Specify the checkpoint-number of the  snapshot  to  be  mounted.   Checkpoints  and
              snapshots  are  listed  by  lscp(1).   Only  the checkpoints marked as snapshot are
              mountable with this option.  Note that the read-only mount option must be specified

       errors=continue / errors=remount-ro / errors=panic
              Define  the behaviour when an error is encountered.  (Eigher ignore errors and just
              mark the file system erroneous and continue, or remount the file system  read-only,
              or panic and halt the system.)  The default is remount-ro.  In earlier kernels than
              Linux 2.6.35, continue was the default.

              Specify the protection-period for the cleaner daemon (in  seconds).  nilfs_cleanerd
              never  deletes  recent  checkpoints whose elapsed time from its creation is smaller
              than protection-period.

       nogc   Disable garbage collection. The cleaner daemon will not be started.  It can  be  be
              started  manually,  but  in  that  case  it  must  also  be stopped manually before

       order=relaxed / order=strict
              Specify order semantics for file data.  Metadata is always written  to  follow  the
              POSIX semantics about the order of filesystem operations.

                     Apply relaxed order semantics that allows modified data blocks to be written
                     to disk without making a checkpoint if no metadata update  is  going.   This
                     mode  is  equivalent  to the ordered data mode of the ext3 filesystem except
                     for the updates on data blocks still conserve atomicity.  This will  improve
                     synchronous write performance for overwriting.  This is the default mode.

              strict Apply  strict  in-order  semantics  that  preserves  sequence  of  all  file
                     operations  including  overwriting  of  data  blocks.   That  means,  it  is
                     guaranteed  that no overtaking of events occurs in the recovered file system
                     after a crash.  Unlike journaling filesystems, NILFS2 does not write a  same
                     block  twice to disk.  So there is no significant performance degradation in
                     comparison with the relaxed mode except for file overwriting.

              Disable recovery of the filesystem on mount.  This disables every write  access  on
              the device for read-only mounts or snapshots.  This option will fail for r/w mounts
              on an unclean volume.

              Enable the use of discard/TRIM commands.  The discard/TRIM commands are sent to the
              underlying  block device when blocks are freed.  This is useful for SSD devices and
              sparse/thinly-provisioned LUNs. (since 2.6.34)


       The return codes of mount.nilfs2 conform to those of mount(8); the following  codes  could
       be returned (the bits can be ORed):

       0      success

       1      incorrect invocation or permissions

       2      system error (out of memory, cannot fork, no more loop devices)

       4      internal bug

       8      user interrupt

       16     problems writing or locking /etc/mtab

       32     mount failure

       64     some mount succeeded


       mount.nilfs2  is  written  by  Ryusuke Konishi <> for NILFS2, based on the
       mount program included in the util-linux package.


       mount.nilfs2   is   part   of   the   nilfs-utils   package   and   is   available    from


       nilfs(8), mount(8), umount.nilfs2(8), nilfs_cleanerd(8), lscp(1).