Provided by: xfsprogs_5.10.0-2ubuntu3_amd64 bug

NAME

       xfs_repair - repair an XFS filesystem

SYNOPSIS

       xfs_repair  [ -dfLPv ] [ -n | -e ] [ -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.   See  the  DIRTY  LOGS
              section for more information.

       -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.
              This option cannot be used together with -e.

       -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:

                 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 exists 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.

                 noquota
                        Don't  validate quota counters at all.  Quotacheck will be run during the
                        next mount to recalculate all values.

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

       -v     Verbose output.  May be specified multiple times to increase verbosity.

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

       -e     If any metadata corruption was repaired, the status returned is 4  instead  of  the
              usual 0. This option cannot be used together with -n.

       -V     Prints the 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  writable  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 mode) 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 if it completes without problems, unless  the
       flag  -e  is  used.  If  it  is  used,  then  status 4 is reported when any issue with the
       filesystem was found, but could be  fixed.  If  a  runtime  error  is  encountered  during
       operation, it will return a status of 1. In this case, xfs_repair should be restarted.  If
       xfs_repair is unable to proceed due to a dirty log, it will return a  status  of  2.   See
       below.

DIRTY LOGS

       Due  to  the  design  of the XFS log, a dirty log can only be replayed by the kernel, on a
       machine having the same CPU architecture as the machine which  was  writing  to  the  log.
       xfs_repair cannot replay a dirty log and will exit with a status code of 2 when it detects
       a dirty log.

       In this situation, the log can be replayed by  mounting  and  immediately  unmounting  the
       filesystem on the same class of machine that crashed.  Please make sure that the machine's
       hardware is reliable before replaying to avoid compounding the problems.

       If mounting fails, the log can be erased by running xfs_repair with the  -L  option.   All
       metadata  updates  in  progress  at  the  time  of the crash will be lost, which may cause
       significant filesystem damage.  This should only be used as a last resort.

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_metadump(8), xfs(5).

                                                                                    xfs_repair(8)