Provided by: xfsprogs_3.1.9ubuntu2_amd64 bug

NAME

       xfs_repair - repair an XFS filesystem

SYNOPSIS

       xfs_repair  [  -dfLnPv  ]  [  -m  maxmem  ] [ -c subopt=value ] [ -o subopt[=value] ] [ -t
       interval ] [ -l logdev ] [ -r rtdev ] device
       xfs_repair -V

DESCRIPTION

       xfs_repair repairs corrupt or damaged XFS filesystems (see  xfs(5)).   The  filesystem  is
       specified  using the device argument which should be the device name of the disk partition
       or volume containing the filesystem. If given the name of a block device, xfs_repair  will
       attempt to find the raw device associated with the specified block device and will use the
       raw device instead.

       Regardless, the filesystem to be repaired must  be  unmounted,  otherwise,  the  resulting
       filesystem may be inconsistent or corrupt.

OPTIONS

       -f     Specifies  that the filesystem image to be processed is stored in a regular file at
              device (see the mkfs.xfs -d file option). This might happen if an image copy  of  a
              filesystem  has  been copied or written into an ordinary file.  This option implies
              that any external log or realtime section is also in an ordinary file.

       -L     Force Log Zeroing.  Forces xfs_repair to zero the log even if it is dirty (contains
              metadata  changes).  When using this option the filesystem will likely appear to be
              corrupt, and can cause the loss of user files and/or data.

       -l logdev
              Specifies the device special file where the filesystem's external log resides. Only
              for  those  filesystems which use an external log.  See the mkfs.xfs -l option, and
              refer to xfs(5) for a detailed description of the XFS log.

       -r rtdev
              Specifies the device special file where the filesystem's realtime section  resides.
              Only  for  those  filesystems  which  use  a realtime section.  See the mkfs.xfs -r
              option, and refer to xfs(5) for a detailed description of the XFS realtime section.

       -n     No modify mode. Specifies that xfs_repair should  not  modify  the  filesystem  but
              should only scan the filesystem and indicate what repairs would have been made.

       -P     Disable  prefetching  of  inode  and  directory blocks. Use this option if you find
              xfs_repair gets stuck and stops proceeding.  Interrupting  a  stuck  xfs_repair  is
              safe.

       -m maxmem
              Specifies  the  approximate  maximum  amount  of  memory,  in megabytes, to use for
              xfs_repair.  xfs_repair has its own internal block cache which will scale out up to
              the  lesser  of  the  process's  virtual address limit or about 75% of the system's
              physical RAM.  This option overrides these limits.

              NOTE: These memory limits are only approximate and may use more than the  specified
              limit.

       -c subopt=value
              Change  filesystem  parameters.  Refer  to xfs_admin(8) for information on changing
              filesystem parameters.

       -o subopt[=value]
              Override what the program might conclude about the filesystem if left  to  its  own
              devices.

              The suboptions supported are:

                 ihash=ihashsize
                        overrides  the  default  inode cache hash size. The total number of inode
                        cache entries are limited to 8 times this amount. The  default  ihashsize
                        is 1024 (for a total of 8192 entries).

                 bhash=bhashsize
                        overrides  the default buffer cache hash size. The total number of buffer
                        cache entries are limited to 8 times this amount. The default size is set
                        to use up the remainder of 75% of the system's physical RAM size.

                 ag_stride=ags_per_concat_unit
                        This  creates  additional processing threads to parallel process AGs that
                        span multiple concat units. This can significantly reduce repair times on
                        concat based filesystems.

                 force_geometry
                        Check the filesystem even if geometry information could not be validated.
                        Geometry information can not be validated if  only  a  single  allocation
                        group and exist and thus we do not have a backup superblock available, or
                        if there are two allocation groups and the two superblocks do  not  agree
                        on  the  filesystem  geometry.  Only use this option if you validated the
                        geometry yourself and know what you are doing.  If In  doubt  run  in  no
                        modify mode first.

       -t  interval
              Modify  reporting  interval. During long runs xfs_repair outputs its progress every
              15 minutes. Reporting is only activated when ag_stride is enabled.

       -v     Verbose output.

       -d     Repair dangerously. Allow xfs_repair to repair an XFS filesystem mounted read only.
              This  is  typically  done  on  a  root fileystem from single user mode, immediately
              followed by a reboot.

       -V     Prints out the current version number and exits.

   Checks Performed
       Inconsistencies corrected include the following:

       1.     Inode and inode blockmap (addressing) checks: bad magic number in inode, bad  magic
              numbers in inode blockmap blocks, extents out of order, incorrect number of records
              in inode blockmap blocks, blocks claimed that are not in a legal data area  of  the
              filesystem, blocks that are claimed by more than one inode.

       2.     Inode  allocation  map checks: bad magic number in inode map blocks, inode state as
              indicated by map (free or in-use) inconsistent with state indicated by  the  inode,
              inodes referenced by the filesystem that do not appear in the inode allocation map,
              inode allocation map referencing blocks that do not appear to contain inodes.

       3.     Size checks: number of blocks  claimed  by  inode  inconsistent  with  inode  size,
              directory size not block aligned, inode size not consistent with inode format.

       4.     Directory  checks:  bad  magic  numbers  in  directory  blocks, incorrect number of
              entries in a directory block, bad freespace information in a directory leaf  block,
              entry pointing to an unallocated (free) or out of range inode, overlapping entries,
              missing or incorrect dot and  dotdot  entries,  entries  out  of  hashvalue  order,
              incorrect  internal  directory  pointers,  directory type not consistent with inode
              format and size.

       5.     Pathname checks: files or directories not referenced by a  pathname  starting  from
              the filesystem root, illegal pathname components.

       6.     Link  count  checks:  link  counts  that  do not agree with the number of directory
              references to the inode.

       7.     Freemap checks: blocks claimed free by the freemap but also claimed  by  an  inode,
              blocks unclaimed by any inode but not appearing in the freemap.

       8.     Super Block checks: total free block and/or free i-node count incorrect, filesystem
              geometry inconsistent, secondary and primary superblocks contradictory.

       Orphaned files and directories (allocated, in-use but  unreferenced)  are  reconnected  by
       placing them in the lost+found directory.  The name assigned is the inode number.

   Disk Errors
       xfs_repair  aborts  on  most  disk  I/O  errors.  Therefore, if you are trying to repair a
       filesystem that was damaged due to a disk drive failure, steps should be taken  to  ensure
       that  all  blocks  in  the  filesystem are readable and writeable before attempting to use
       xfs_repair to repair the filesystem. A possible method is using dd(8)  to  copy  the  data
       onto a good disk.

   lost+found
       The  directory lost+found does not have to already exist in the filesystem being repaired.
       If the directory does not exist, it is automatically created if required.  If  it  already
       exists,  it  will  be  checked  for  consistency  and if valid will be used for additional
       orphaned files. Invalid lost+found directories are removed and recreated.  Existing  files
       in a valid lost+found are not removed or renamed.

   Corrupted Superblocks
       XFS  has  both  primary  and  secondary  superblocks.   xfs_repair uses information in the
       primary superblock to automatically find and validate the primary superblock  against  the
       secondary superblocks before proceeding.  Should the primary be too corrupted to be useful
       in locating the secondary superblocks, the program scans the filesystem until it finds and
       validates some secondary superblocks.  At that point, it generates a primary superblock.

   Quotas
       If  quotas  are  in  use,  it  is  possible  that xfs_repair will clear some or all of the
       filesystem quota information.  If  so,  the  program  issues  a  warning  just  before  it
       terminates.   If all quota information is lost, quotas are disabled and the program issues
       a warning to that effect.

       Note that xfs_repair does not check the validity of quota limits. It is  recommended  that
       you  check  the  quota  limit  information  manually  after xfs_repair.  Also, space usage
       information is automatically regenerated the next time  the  filesystem  is  mounted  with
       quotas turned on, so the next quota mount of the filesystem may take some time.

DIAGNOSTICS

       xfs_repair issues informative messages as it proceeds indicating what it has found that is
       abnormal or any corrective action that it has taken.  Most of the messages are  completely
       understandable  only to those who are knowledgeable about the structure of the filesystem.
       Some of the more common messages are explained  here.   Note  that  the  language  of  the
       messages  is slightly different if xfs_repair is run in no-modify mode because the program
       is not changing anything on disk.  No-modify mode indicates what it would do to repair the
       filesystem if run without the no-modify flag.

       disconnected inode ino, moving to lost+found

              An  inode  numbered  ino was not connected to the filesystem directory tree and was
              reconnected to the lost+found directory. The inode is  assigned  the  name  of  its
              inode  number (ino).  If a lost+found directory does not exist, it is automatically
              created.

       disconnected dir inode ino, moving to lost+found

              As above only the inode is a directory inode.  If a directory inode is attached  to
              lost+found,  all  of  its  children  (if  any)  stay  attached to the directory and
              therefore get automatically reconnected when the directory is reconnected.

       imap claims in-use inode ino is free, correcting imap

              The inode allocation map thinks that inode ino is free whereas examination  of  the
              inode  indicates  that  the  inode may be in use (although it may be disconnected).
              The program updates the inode allocation map.

       imap claims free inode ino is in use, correcting imap

              The inode allocation map thinks that inode ino is in use whereas examination of the
              inode  indicates  that  the inode is not in use and therefore is free.  The program
              updates the inode allocation map.

       resetting inode ino nlinks from x to y

              The program detected a mismatch between  the  number  of  valid  directory  entries
              referencing  inode  ino  and  the  number  of  references recorded in the inode and
              corrected the the number in the inode.

       fork-type fork in ino ino claims used block bno

              Inode ino claims a block bno that is used (claimed) by either another inode or  the
              filesystem  itself  for  metadata  storage.  The  fork-type  is either data or attr
              indicating whether the problem lies in the portion of the inode that tracks regular
              data  or  the  portion  of the inode that stores XFS attributes.  If the inode is a
              real-time (rt) inode, the message says so.  Any inode that claims  blocks  used  by
              the  filesystem  is  deleted.  If two or more inodes claim the same block, they are
              both deleted.

       fork-type fork in ino ino claims dup extent ...

              Inode ino claims a block in an extent known to be  claimed  more  than  once.   The
              offset  in  the  inode,  start  and  length of the extent is given.  The message is
              slightly different if the inode is  a  real-time  (rt)  inode  and  the  extent  is
              therefore a real-time (rt) extent.

       inode ino - bad extent ...

              An  extent  record  in  the blockmap of inode ino claims blocks that are out of the
              legal range of the filesystem.  The message  supplies  the  start,  end,  and  file
              offset  of  the extent.  The message is slightly different if the extent is a real-
              time (rt) extent.

       bad fork-type fork in inode ino

              There was something structurally wrong or inconsistent  with  the  data  structures
              that map offsets to filesystem blocks.

       cleared inode ino

              There  was  something  wrong  with  the inode that was uncorrectable so the program
              freed the inode.  This usually happens because the inode  claims  blocks  that  are
              used  by  something  else  or  the inode itself is badly corrupted. Typically, this
              message is preceded by one or more messages indicating why the inode needed  to  be
              cleared.

       bad attribute fork in inode ino, clearing attr fork

              There  was something wrong with the portion of the inode that stores XFS attributes
              (the attribute fork) so the program reset the attribute fork.  As a result of this,
              all attributes on that inode are lost.

       correcting nextents for inode ino, was x - counted y

              The program found that the number of extents used to store the data in the inode is
              wrong and corrected the number.  The message refers to nextents  if  the  count  is
              wrong on the number of extents used to store attribute information.

       entry  name  in  dir  dir_ino  not consistent with .. value (xxxx) in dir ino ino, junking
       entry name in directory inode dir_ino

              The entry name in  directory  inode  dir_ino  references  a  directory  inode  ino.
              However, the .. entry in directory ino does not point back to directory dir_ino, so
              the program deletes the entry name in directory inode dir_ino.   If  the  directory
              inode  ino  winds up becoming a disconnected inode as a result of this, it is moved
              to lost+found later.

       entry name in dir dir_ino references already connected dir ino ino, junking entry name  in
       directory inode dir_ino

              The  entry  name in directory inode dir_ino points to a directory inode ino that is
              known to be a child of another directory.  Therefore, the entry is invalid  and  is
              deleted.   This  message  refers  to an entry in a small directory.  If this were a
              large directory, the last phrase would read "will clear entry".

       entry references free inode ino in directory dir_ino, will clear entry

              An entry in directory inode dir_ino references an inode ino that  is  known  to  be
              free.  The  entry  is  therefore  invalid and is deleted.  This message refers to a
              large directory.  If the directory were small,  the  message  would  read  "junking
              entry ...".

EXIT STATUS

       xfs_repair  -n  (no  modify  node)  will return a status of 1 if filesystem corruption was
       detected and 0 if no filesystem corruption was detected.  xfs_repair run  without  the  -n
       option will always return a status code of 0.

BUGS

       The  filesystem  to  be checked and repaired must have been unmounted cleanly using normal
       system administration procedures (the umount(8) command or  system  shutdown),  not  as  a
       result  of  a  crash  or  system reset.  If the filesystem has not been unmounted cleanly,
       mount it and unmount it cleanly before running xfs_repair.

       xfs_repair does not do a thorough job on XFS extended attributes.  The  structure  of  the
       attribute  fork will be consistent, but only the contents of attribute forks that will fit
       into an inode are checked.  This limitation will be fixed in the future.

       The  no-modify  mode  (-n  option)  is  not  completely  accurate.   It  does  not   catch
       inconsistencies  in  the  freespace  and  inode  maps,  particularly lost blocks or subtly
       corrupted maps (trees).

       The no-modify mode can generate repeated warnings  about  the  same  problems  because  it
       cannot fix the problems as they are encountered.

       If   a  filesystem  fails  to  be  repaired,  a  metadump  image  can  be  generated  with
       xfs_metadump(8) and be sent to an XFS maintainer  to  be  analysed  and  xfs_repair  fixed
       and/or improved.

SEE ALSO

       dd(1), mkfs.xfs(8), umount(8), xfs_admin(8), xfs_check(8), xfs_metadump(8), xfs(5).

                                                                                    xfs_repair(8)