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       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  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

       -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  previously.

       -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 together.

       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 continue.

              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-

       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 unmounting.

       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


       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).