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    Command:

    xfs_db

    
    
    

    SYNOPSIS

           xfs_db [ -c cmd ] ... [ -i|r|x|F ] [ -f ] [ -l logdev ] [ -p progname ]
           device
           xfs_db -V
    
    
    

    DESCRIPTION

           xfs_db is used to examine an XFS filesystem. Under  rare  circumstances
           it  can also be used to modify an XFS filesystem, but that task is nor-
           mally left to xfs_repair(8) or to scripts such as xfs_admin(8) that run
           xfs_db.
    
    
    

    OPTIONS

           -c cmd xfs_db  commands  may  be  run interactively (the default) or as
                  arguments on the command line.  Multiple  -c  arguments  may  be
                  given. The commands are run in the sequence given, then the pro-
                  gram  exits.  This  is   the   mechanism   used   to   implement
                  xfs_check(8).
    
           -f     Specifies that the filesystem image to be processed is stored in
                  a regular file at device (see the mkfs.xfs(8) -d  file  option).
                  This might happen if an image copy of a filesystem has been made
                  into an ordinary file with xfs_copy(8).
    
           -F     Specifies that we want to continue even if the superblock  magic
                  is not correct.  For use in xfs_check and xfs_metadump.
    
           -i     Allows execution on a mounted filesystem, provided it is mounted
                  read-only.  Useful for shell scripts such as xfs_check(8), which
                  must  only  operate  on  filesystems  in a guarenteed consistent
                  state (either unmounted or mounted read-only).  These  semantics
                  are slightly different to that of the -r option.
    
           -l logdev
                  Specifies the device where the filesystems external log resides.
                  Only for those filesystems which use an external  log.  See  the
                  mkfs.xfs(8)  -l  option,  and  refer  to  xfs(5)  for a detailed
                  description of the XFS log.
    
           -p progname
                  Set the program name to progname for prompts and some error mes-
                  sages, the default value is xfs_db.
    
           -r     Open  device  or  filename read-only. This option is required if
                  the filesystem is mounted.  It is only necessary  to  omit  this
                  flag if a command that changes data (write, blocktrash) is to be
                  used.
    
           -x     Specifies expert mode.  This enables the  write  and  blocktrash
                  commands.
    
           -V     Prints out the current version number and exits.
           of  the  address  is  a filesystem structure.  This can be a filesystem
           block, an inode or quota (smaller than a filesystem block), or a direc-
           tory  block  (could  be  larger  than a filesystem block).  There are a
           variety of commands to set the current address.   Associated  with  the
           current  address is the current data type, which is the structural type
           of this data.  Commands which follow the structure  of  the  filesystem
           always  set  the  type  as well as the address.  Commands which examine
           pieces of an individual file (inode) need the current inode to be  set,
           this is done with the inode command.
    
           The  current address/type information is actually maintained in a stack
           that can be explicitly manipulated with the push, pop, and  stack  com-
           mands.   This allows for easy examination of a nested filesystem struc-
           ture.  Also, the last several locations visited are stored  in  a  ring
           buffer  which  can be manipulated with the forward, back, and ring com-
           mands.
    
           XFS filesystems are divided into a small number of  allocation  groups.
           xfs_db  maintains  a  notion  of  the current allocation group which is
           manipulated by some commands. The initial allocation group is 0.
    
    
    

    COMMANDS

           Many commands have extensive online help. Use the help command for more
           details on any command.
    
           a      See the addr command.
    
           ablock filoff
                  Set  current  address  to  the offset filoff (a filesystem block
                  number) in the attribute area of the current inode.
    
           addr [field-expression]
                  Set current address to the value of the field-expression.   This
                  is  used  to "follow" a reference in one structure to the object
                  being referred to. If no argument is given, the current  address
                  is printed.
    
           agf [agno]
                  Set  current address to the AGF block for allocation group agno.
                  If no argument is given, use the current allocation group.
    
           agfl [agno]
                  Set current address to the AGFL block for allocation group agno.
                  If no argument is given, use the current allocation group.
    
           agi [agno]
                  Set  current address to the AGI block for allocation group agno.
                  If no argument is given, use the current allocation group.
    
           b      See the back command.
    
           back   Move to the previous location in the position ring.
    
                     -i  is used to specify  inode  numbers  about  which  verbose
                         information should be printed.
    
                     -n  is  used  to  save  pathnames for inodes visited, this is
                         used to support the xfs_ncheck(8) command. It also  means
                         that pathnames will be printed for inodes that have prob-
                         lems. This option uses a lot of memory so is not  enabled
                         by default.
    
                     -p  causes  error messages to be prefixed with the filesystem
                         name being processed. This is useful if several copies of
                         xfs_db are run in parallel.
    
                     -s  restricts output to severe errors only. This is useful if
                         the output is too long otherwise.
    
                     -v  enables verbose output.  Messages  will  be  printed  for
                         every block and inode processed.
    
           blocktrash  [-n count] [-x min] [-y max] [-s seed] [-0|1|2|3] [-t type]
           ...
                  Trash  randomly  selected  filesystem metadata blocks.  Trashing
                  occurs to randomly selected bits in  the  chosen  blocks.   This
                  command  is  available only in debugging versions of xfs_db.  It
                  is useful for testing xfs_repair(8) and xfs_check(8).
    
                     -0 | -1 | -2 | -3
                         These are used to set the operating mode for  blocktrash.
                         Only  one  can  be  used: -0 changed bits are cleared; -1
                         changed bits are set; -2 changed bits  are  inverted;  -3
                         changed bits are randomized.
    
                     -n  supplies the count of block-trashings to perform (default
                         1).
    
                     -s  supplies a seed to the random processing.
    
                     -t  gives a type of blocks to be selected for trashing.  Mul-
                         tiple -t options may be given. If no -t options are given
                         then all metadata types can be trashed.
    
                     -x  sets the minimum size of bit range  to  be  trashed.  The
                         default value is 1.
    
                     -y  sets  the  maximum  size  of bit range to be trashed. The
                         default value is 1024.
    
           blockuse [-n] [-c count]
                  Print usage for current filesystem block(s).   For  each  block,
                  the type and (if any) inode are printed.
    
                  are shown.
    
           check  See the blockget command.
    
           convert type number [type number] ... type
                  Convert from one address form to another.  The known types, with
                  alternate names, are:
                     agblock or  agbno  (filesystem  block  within  an  allocation
                            group)
                     agino or aginode (inode number within an allocation group)
                     agnumber or agno (allocation group number)
                     bboff or daddroff (byte offset in a daddr)
                     blkoff  or  fsboff  or  agboff  (byte  offset in a agblock or
                            fsblock)
                     byte or fsbyte (byte address in filesystem)
                     daddr or bb (disk address, 512-byte blocks)
                     fsblock or fsb or fsbno (filesystem block,  see  the  fsblock
                            command)
                     ino or inode (inode number)
                     inoidx or offset (index of inode in filesystem block)
                     inooff or inodeoff (byte offset in inode)
    
                  Only  conversions  that  "make sense" are allowed.  The compound
                  form (with more than three arguments) is useful for  conversions
                  such as convert agno ag agbno agb fsblock.
    
           daddr [d]
                  Set  current  address  to the daddr (512 byte block) given by d.
                  If no value for d is given,  the  current  address  is  printed,
                  expressed  as a daddr.  The type is set to data (uninterpreted).
    
           dblock filoff
                  Set current address to the offset  filoff  (a  filesystem  block
                  number) in the data area of the current inode.
    
           debug [flagbits]
                  Set  debug option bits. These are used for debugging xfs_db.  If
                  no value is given for flagbits, print the current  debug  option
                  bits. These are for the use of the implementor.
    
           dquot [projectid_or_userid]
                  Set current address to a project or user quota block.
    
           echo [arg] ...
                  Echo the arguments to the output.
    
           f      See the forward command.
    
           forward
                  Move forward to the next entry in the position ring.
    
           frag [-adflqRrv]
    
                     -f  enables processing of regular file data.
    
                     -l  enables processing of symbolic link data.
    
                     -q  enables processing of quota file data.
    
                     -R  enables processing of realtime control file data.
    
                     -r  enables processing of realtime file data.
    
           freesp [-bcds] [-a ag] ... [-e i] [-h h1] ... [-m m]
                  Summarize  free  space  for  the filesystem. The free blocks are
                  examined and totalled, and displayed in the form of a histogram,
                  with a count of extents in each range of free extent sizes.
    
                     -a  adds ag to the list of allocation groups to be processed.
                         If no -a options are given then all allocation groups are
                         processed.
    
                     -b  specifies  that  the  histogram buckets are binary-sized,
                         with the starting sizes being the powers of 2.
    
                     -c  specifies that freesp will search the by-size (cnt) space
                         Btree  instead of the default by-block (bno) space Btree.
    
                     -d  specifies that every free extent will be displayed.
    
                     -e  specifies that the  histogram  buckets  are  equal-sized,
                         with the size specified as i.
    
                     -h  specifies  a starting block number for a histogram bucket
                         as h1.  Multiple -h's are given to specify  the  complete
                         set of buckets.
    
                     -m  specifies  that  the histogram starting block numbers are
                         powers of m.  This is the general case of -b.
    
                     -s  specifies that a final summary  of  total  free  extents,
                         free blocks, and the average free extent size is printed.
    
           fsb    See the fsblock command.
    
           fsblock [fsb]
                  Set current address to the fsblock value given by  fsb.   If  no
                  value for fsb is given the current address is printed, expressed
                  as an fsb.   The  type  is  set  to  data  (uninterpreted).  XFS
                  filesystem  block  numbers  are  computed  ((agno  << agshift) |
                  agblock) where agshift depends on  the  size  of  an  allocation
                  group. Use the convert command to convert to and from this form.
                  Block numbers given for file blocks (for instance from the  bmap
                  command) are in this form.
                  mount(8) instead of using a device special  file.   The  maximum
                  length  of an XFS label is 12 characters - use of a longer label
                  will result in truncation and a warning will be  issued.  If  no
                  label is given, the current filesystem label is printed.
    
           log [stop | start filename]
                  Start  logging  output  to  filename, stop logging, or print the
                  current logging status.
    
           metadump [-egow] filename
                  Dumps metadata to a file. See xfs_metadump(8) for more  informa-
                  tion.
    
           ncheck [-s] [-i ino] ...
                  Print  name-inode pairs. A blockget -n command must be run first
                  to gather the information.
    
                     -i  specifies an inode number to be printed. If no -i options
                         are given then all inodes are printed.
    
                     -s  specifies  that only setuid and setgid files are printed.
    
           p      See the print command.
    
           pop    Pop location from the stack.
    
           print [field-expression] ...
                  Print field values.  If no argument is given, print  all  fields
                  in the current structure.
    
           push [command]
                  Push location to the stack. If command is supplied, set the cur-
                  rent location to the results of command after  pushing  the  old
                  location.
    
           q      See the quit command.
    
           quit   Exit xfs_db.
    
           ring [index]
                  Show position ring (if no index argument is given), or move to a
                  specific entry in the position ring given by index.
    
           sb [agno]
                  Set current address to SB header in allocation group  agno.   If
                  no agno is given, use the current allocation group number.
    
           source source-file
                  Process  commands  from  source-file.   source  commands  can be
                  nested.
    
           stack  View the location stack.
                  generate  option.  These  options  will both write the UUID into
                  every copy of the superblock in the filesystem.  rewrite  copies
                  the  current  UUID  from the primary superblock to all secondary
                  copies of the superblock.  If no argument is given, the  current
                  filesystem UUID is printed.
    
           version [feature | versionnum features2]
                  Enable  selected features for a filesystem (certain features can
                  be enabled on an unmounted  filesystem,  after  mkfs.xfs(8)  has
                  created  the  filesystem).  Support for unwritten extents can be
                  enabled using the extflg option. Support for version 2 log  for-
                  mat  can  be enabled using the log2 option. Support for extended
                  attributes can be enabled using the attr1 or attr2 option.  Once
                  enabled,  extended  attributes  cannot be disabled, but the user
                  may toggle between attr1 and attr2 at will  (older  kernels  may
                  not support the newer version).
    
                  If  no  argument  is given, the current version and feature bits
                  are printed.  With one argument, this  command  will  write  the
                  updated  version number into every copy of the superblock in the
                  filesystem.  If two arguments are given, they will  be  used  as
                  numeric  values  for  the  versionnum and features2 bits respec-
                  tively, and their string equivalent reported (but  no  modifica-
                  tions are made).
    
           write [field value] ...
                  Write a value to disk.  Specific fields can be set in structures
                  (struct mode), or a block can be set to data values (data mode),
                  or a block can be set to string values (string mode, for symlink
                  blocks).  The operation happens immediately: there is no buffer-
                  ing.
    
                  Struct  mode  is  in effect when the current type is structural,
                  i.e. not data. For struct  mode,  the  syntax  is  "write  field
                  value".
    
                  Data  mode  is  in effect when the current type is data. In this
                  case the contents of the block can be shifted or rotated left or
                  right,  or filled with a sequence, a constant value, or a random
                  value. In this mode write with no arguments gives more  informa-
                  tion on the allowed commands.
    
    
    

    TYPES

           This  section  gives  the fields in each structure type and their mean-
           ings.  Note that some types of block cover multiple actual  structures,
           for instance directory blocks.
    
           agf       The AGF block is the header for block allocation information;
                     it is in the second 512-byte block of each allocation  group.
                     The following fields are defined:
                         magicnum    AGF  block magic number, 0x58414746 ('XAGF').
                         versionnum  version number, currently 1.
                                     entry.
                         fllast      index into the AGFL block of the last  active
                                     entry.
                         flcount     count of active entries in the AGFL block.
                         freeblks    count  of blocks represented in the freespace
                                     Btrees.
                         longest     longest  free  space   represented   in   the
                                     freespace Btrees.
                         btreeblks   number of blocks held in the AGF Btrees.
    
           agfl      The  AGFL  block  contains block numbers for use of the block
                     allocator; it is in the fourth 512-byte block of each alloca-
                     tion  group.  Each entry in the active list is a block number
                     within the allocation group that can be used for any  purpose
                     if space runs low.  The AGF block fields flfirst, fllast, and
                     flcount designate which entries are currently active.   Entry
                     space  is  allocated  in  a  circular  manner within the AGFL
                     block.  Fields defined:
                         bno         array of all block numbers. Even those  which
                                     are not active are printed.
    
           agi       The AGI block is the header for inode allocation information;
                     it is in the third 512-byte block of each  allocation  group.
                     Fields defined:
                         magicnum    AGI  block magic number, 0x58414749 ('XAGI').
                         versionnum  version number, currently 1.
                         seqno       sequence number starting from 0.
                         length      size in filesystem blocks of  the  allocation
                                     group.
                         count       count of inodes allocated.
                         root        block number of the root of the Btree holding
                                     inode allocation information.
                         level       number of  levels  in  the  inode  allocation
                                     Btree.
                         freecount   count  of  allocated  inodes  that are not in
                                     use.
                         newino      last inode number allocated.
                         dirino      unused.
                         unlinked    an array of inode numbers within the  alloca-
                                     tion  group. The entries in the AGI block are
                                     the heads of  lists  which  run  through  the
                                     inode  next_unlinked  field. These inodes are
                                     to be unlinked the next time  the  filesystem
                                     is mounted.
    
           attr      An  attribute  fork  is  organized as a Btree with the actual
                     data embedded in the leaf blocks. The root of  the  Btree  is
                     found  in block 0 of the fork.  The index (sort order) of the
                     Btree is the hash value  of  the  attribute  name.   All  the
                     blocks contain a blkinfo structure at the beginning, see type
                     dir for a description. Nonleaf blocks are identical in format
                     to  those  for  version 1 and version 2 directories, see type
                         nvlist      array  of structures describing the attribute
                                     names and values. Fields always present: val-
                                     uelen  (length  of  value in bytes), namelen,
                                     and name.  Fields present for  local  values:
                                     value  (value  string).  Fields  present  for
                                     remote values: valueblk (fork block number of
                                     containing the value).
    
           bmapbt    Files  with many extents in their data or attribute fork will
                     have the extents described by the contents  of  a  Btree  for
                     that  fork,  instead  of  being stored directly in the inode.
                     Each bmap Btree starts with a root block contained within the
                     inode.   The other levels of the Btree are stored in filesys-
                     tem blocks.  The blocks are linked to sibling left and  right
                     blocks  at  each level, as well as by pointers from parent to
                     child blocks.  Each block contains the following fields:
                         magic       bmap Btree  block  magic  number,  0x424d4150
                                     ('BMAP').
                         level       level of this block above the leaf level.
                         numrecs     number of records or keys in the block.
                         leftsib     left  (logically  lower)  sibling block, 0 if
                                     none.
                         rightsib    right (logically higher) sibling block, 0  if
                                     none.
                         recs        [leaf  blocks  only] array of extent records.
                                     Each record  contains  startoff,  startblock,
                                     blockcount,  and  extentflag (1 if the extent
                                     is unwritten).
                         keys        [nonleaf blocks only] array of  key  records.
                                     These  are  the first key value of each block
                                     in the level below this one. Each record con-
                                     tains startoff.
                         ptrs        [nonleaf  blocks  only]  array of child block
                                     pointers.  Each pointer is a filesystem block
                                     number to the next level in the Btree.
    
           bnobt     There  is  one set of filesystem blocks forming the by-block-
                     number allocation Btree for each allocation group.  The  root
                     block of this Btree is designated by the bnoroot field in the
                     coresponding AGF block.  The blocks  are  linked  to  sibling
                     left  and  right blocks at each level, as well as by pointers
                     from parent to child blocks.  Each block  has  the  following
                     fields:
                         magic       BNOBT    block   magic   number,   0x41425442
                                     ('ABTB').
                         level       level number of this block, 0 is a leaf.
                         numrecs     number of data entries in the block.
                         leftsib     left (logically lower) sibling  block,  0  if
                                     none.
                         rightsib    right  (logically higher) sibling block, 0 if
                                     none.
                         recs        [leaf  blocks  only]   array   of   freespace
    
                     coresponding AGF block. The blocks are linked to sibling left
                     and right blocks at each level, as well as by  pointers  from
                     parent to child blocks. Each block has the following fields:
                         magic       CNTBT    block   magic   number,   0x41425443
                                     ('ABTC').
                         level       level number of this block, 0 is a leaf.
                         numrecs     number of data entries in the block.
                         leftsib     left (logically lower) sibling  block,  0  if
                                     none.
                         rightsib    right  (logically higher) sibling block, 0 if
                                     none.
                         recs        [leaf  blocks  only]   array   of   freespace
                                     records.  Each record contains startblock and
                                     blockcount.
                         keys        [nonleaf blocks only] array of  key  records.
                                     These  are  the  first value of each block in
                                     the level below this one.  Each  record  con-
                                     tains blockcount and startblock.
                         ptrs        [nonleaf  blocks  only]  array of child block
                                     pointers. Each  pointer  is  a  block  number
                                     within the allocation group to the next level
                                     in the Btree.
    
           data      User file blocks, and other blocks  whose  type  is  unknown,
                     have  this  type  for  display purposes in xfs_db.  The block
                     data is displayed in hexadecimal format.
    
           dir       A version 1 directory is organized as a Btree with the direc-
                     tory  data embedded in the leaf blocks. The root of the Btree
                     is found in block 0 of the file. The index  (sort  order)  of
                     the Btree is the hash value of the entry name. All the blocks
                     contain a blkinfo structure at the beginning with the follow-
                     ing fields:
                         forw        next sibling block.
                         back        previous sibling block.
                         magic       magic number for this block type.
    
                     The non-leaf (node) blocks have the following fields:
                         hdr         header  containing  a  blkinfo structure info
                                     (magic number 0xfebe), the  count  of  active
                                     entries,  and  the  level of this block above
                                     the leaves.
                         btree       array  of  entries  containing  hashval   and
                                     before  fields.  The  before value is a block
                                     number within the directory file to the child
                                     block,  the hashval is the last hash value in
                                     that block.
    
                     The leaf blocks have the following fields:
                         hdr         header containing a  blkinfo  structure  info
                                     (magic  number  0xfeeb),  the count of active
                                     entries, namebytes (total name string bytes),
    
                     32GiB  (with  either  a  single  leaf  block or the root node
                     block).  Freespace blocks start at offset  64GiB.   The  node
                     and  leaf blocks form a Btree, with references to the data in
                     the data blocks.  The  freespace  blocks  form  an  index  of
                     longest free spaces within the data blocks.
    
                     A single-block directory block contains the following fields:
                         bhdr        header  containing  magic  number  0x58443242
                                     ('XD2B') and an array bestfree of the longest
                                     3 free spaces in the block (offset,  length).
                         bu          array  of  union  structures. Each element is
                                     either an entry or a freespace.  For entries,
                                     there  are  the  following  fields:  inumber,
                                     namelen, name, and tag.  For freespace, there
                                     are  the  following fields: freetag (0xffff),
                                     length, and tag.  The tag value is  the  byte
                                     offset in the block of the start of the entry
                                     it is contained in.
                         bleaf       array of leaf entries containing hashval  and
                                     address.  The address is a 64-bit word offset
                                     into the file.
                         btail       tail structure containing the total count  of
                                     leaf  entries  and stale count of unused leaf
                                     entries.
    
                     A data block contains the following fields:
                         dhdr        header  containing  magic  number  0x58443244
                                     ('XD2D') and an array bestfree of the longest
                                     3 free spaces in the block (offset,  length).
                         du          array of union structures as for bu.
    
                     Leaf blocks have two possible forms. If the Btree consists of
                     a single leaf then the freespace information is in  the  leaf
                     block, otherwise it is in separate blocks and the root of the
                     Btree is a node block. A leaf block  contains  the  following
                     fields:
                         lhdr        header  containing  a  blkinfo structure info
                                     (magic number  0xd2f1  for  the  single  leaf
                                     case,  0xd2ff  for  the true Btree case), the
                                     total count of leaf entries, and stale  count
                                     of unused leaf entries.
                         lents       leaf entries, as for bleaf.
                         lbests      [single leaf only] array of values which rep-
                                     resent the longest  freespace  in  each  data
                                     block in the directory.
                         ltail       [single  leaf only] tail structure containing
                                     bestcount count of lbests.
    
                     A node block is identical to that for types attr and dir.
    
                     A freespace block contains the following fields:
                         fhdr        header  containing  magic  number  0x58443246
    
                     quota entry has the following fields:
                         magic          magic number, 0x4451 ('DQ').
                         version        version number, currently 1.
                         flags          flags, values include 0x01 for user quota,
                                        0x02 for project quota.
                         id             user or project identifier.
                         blk_hardlimit  absolute limit on blocks in use.
                         blk_softlimit  preferred limit on blocks in use.
                         ino_hardlimit  absolute limit on inodes in use.
                         ino_softlimit  preferred limit on inodes in use.
                         bcount         blocks actually in use.
                         icount         inodes actually in use.
                         itimer         time  when service will be refused if soft
                                        limit is violated for inodes.
                         btimer         time when service will be refused if  soft
                                        limit is violated for blocks.
                         iwarns         number  of  warnings  issued  about  inode
                                        limit violations.
                         bwarns         number  of  warnings  issued  about  block
                                        limit violations.
                         rtb_hardlimit  absolute  limit on realtime blocks in use.
                         rtb_softlimit  preferred limit on realtime blocks in use.
                         rtbcount       realtime blocks actually in use.
                         rtbtimer       time  when service will be refused if soft
                                        limit is violated for realtime blocks.
                         rtbwarns       number of warnings issued  about  realtime
                                        block limit violations.
    
           inobt     There is one set of filesystem blocks forming the inode allo-
                     cation Btree for each allocation group.  The  root  block  of
                     this  Btree is designated by the root field in the corespond-
                     ing AGI block.  The blocks are linked  to  sibling  left  and
                     right  blocks at each level, as well as by pointers from par-
                     ent to child blocks.  Each block has the following fields:
                         magic       INOBT   block   magic   number,    0x49414254
                                     ('IABT').
                         level       level number of this block, 0 is a leaf.
                         numrecs     number of data entries in the block.
                         leftsib     left  (logically  lower)  sibling block, 0 if
                                     none.
                         rightsib    right (logically higher) sibling block, 0  if
                                     none.
                         recs        [leaf  blocks  only]  array of inode records.
                                     Each  record  contains  startino  allocation-
                                     group  relative inode number, freecount count
                                     of  free  inodes  in  this  chunk,  and  free
                                     bitmap, LSB corresponds to inode 0.
                         keys        [nonleaf  blocks  only] array of key records.
                                     These are the first value of  each  block  in
                                     the  level  below  this one. Each record con-
                                     tains startino.
                         ptrs        [nonleaf blocks only] array  of  child  block
    
                     field  unlinked.  u is a union structure that is different in
                     size and format depending on the type and  representation  of
                     the  file  data ("data fork").  a is an optional union struc-
                     ture to describe attribute data, that is different  in  size,
                     format,  and location depending on the presence and represen-
                     tation of  attribute  data,  and  the  size  of  the  u  data
                     ("attribute  fork").  xfs_db automatically selects the proper
                     union members based on information in the inode.
    
                     The following are fields in the inode core:
                         magic       inode magic number, 0x494e ('IN').
                         mode        mode  and  type  of  file,  as  described  in
                                     chmod(2), mknod(2), and stat(2).
                         version     inode version, 1 or 2.
                         format      format  of  u  union  data  (0: xfs_dev_t, 1:
                                     local file - in-inode directory  or  symlink,
                                     2:  extent  list, 3: Btree root, 4: unique id
                                     [unused]).
                         nlinkv1     number of links to the file in  a  version  1
                                     inode.
                         nlinkv2     number  of  links  to the file in a version 2
                                     inode.
                         projid_lo   owner's project id (low word; version 2 inode
                                     only).   projid_hi  owner's  project id (high
                                     word; version 2 inode only).
                         uid         owner's user id.
                         gid         owner's group id.
                         atime       time last accessed (seconds and nanoseconds).
                         mtime       time last modified.
                         ctime       time created or inode last modified.
                         size        number of bytes in the file.
                         nblocks     total  number of blocks in the file including
                                     indirect and attribute.
                         extsize     basic/minimum extent size for the file.
                         nextents    number of extents in the data fork.
                         naextents   number of extents in the attribute fork.
                         forkoff     attribute fork offset in the inode, in 64-bit
                                     words from the start of u.
                         aformat     format of a data (1: local attribute data, 2:
                                     extent list, 3: Btree root).
                         dmevmask    DMAPI event mask.
                         dmstate     DMAPI state information.
                         newrtbm     file is the realtime bitmap and is "new" for-
                                     mat.
                         prealloc    file has preallocated data space after EOF.
                         realtime    file data is in the realtime subvolume.
                         gen         inode generation number.
    
                     The following fields are in the u data fork union:
                         bmbt        bmap  Btree  root.  This looks like a bmapbtd
                                     block with redundant information removed.
                         bmx         array of extent descriptors.
                                     saved offset used when the directory is  con-
                                     verted  to  a larger form, a name string, and
                                     the inumber.
                         symlink     symbolic link string value.
    
                     The following fields are in the a attribute fork union if  it
                     exists:
                         bmbt        bmap Btree root, as above.
                         bmx         array of extent descriptors.
                         sfattr      shortform  (in-inode)  attribute values. This
                                     consists of a hdr containing a totsize (total
                                     size in bytes) and a count of active entries,
                                     followed  by  an  array  list  of   hdr.count
                                     entries.  Each  such  entry contains namelen,
                                     valuelen, root flag, name, and value.
    
           log       Log blocks contain the journal entries  for  XFS.   It's  not
                     useful  to  examine  these  with  xfs_db, use xfs_logprint(8)
                     instead.
    
           rtbitmap  If the filesystem has a realtime subvolume, then  the  rbmino
                     field  in  the  superblock refers to a file that contains the
                     realtime bitmap.  Each bit in the bitmap  file  controls  the
                     allocation  of  a  single  realtime extent (set == free). The
                     bitmap is processed in 32-bit words, the LSB  of  a  word  is
                     used for the first extent controlled by that bitmap word. The
                     atime field of the realtime bitmap inode contains  a  counter
                     that is used to control where the next new realtime file will
                     start.
    
           rtsummary If the filesystem has a realtime subvolume, then the  rsumino
                     field  in  the  superblock refers to a file that contains the
                     realtime summary data. The summary file contains a two-dimen-
                     sional  array of 16-bit values.  Each value counts the number
                     of free extent runs (consecutive free realtime extents) of  a
                     given  range  of  sizes  that starts in a given bitmap block.
                     The size ranges are binary buckets (low size in the bucket is
                     a  power  of 2).  There are as many size ranges as are neces-
                     sary given the size of the  realtime  subvolume.   The  first
                     dimension  is  the  size  range,  the second dimension is the
                     starting bitmap block number (adjacent entries  are  for  the
                     same size, adjacent bitmap blocks).
    
           sb        There  is one sb (superblock) structure per allocation group.
                     It is the first disk block in the allocation group.  Only the
                     first  one  (block 0 of the filesystem) is actually used; the
                     other blocks are redundant information for  xfs_repair(8)  to
                     use if the first superblock is damaged. Fields defined:
                         magicnum    superblock magic number, 0x58465342 ('XFSB').
                         blocksize   filesystem block size in bytes.
                         dblocks     number of filesystem blocks  present  in  the
                                     data subvolume.
    
                         agcount     number of allocation groups.
                         rbmblocks   number of realtime bitmap blocks.
                         logblocks   number of log blocks (filesystem blocks).
                         versionnum  filesystem version information.   This  value
                                     is currently 1, 2, 3, or 4 in the low 4 bits.
                                     If the low bits are 4  then  the  other  bits
                                     have  additional meanings.  1 is the original
                                     value.  2 means that attributes were used.  3
                                     means  that  version  2  inodes  (large  link
                                     counts) were used.  4 is the bitmask  version
                                     of  the  version  number.   In this case, the
                                     other  bits  are  used  as   flags   (0x0010:
                                     attributes   were  used,  0x0020:  version  2
                                     inodes were used, 0x0040: quotas  were  used,
                                     0x0080:  inode cluster alignment is in force,
                                     0x0100: data stripe alignment  is  in  force,
                                     0x0200:  the shared_vn field is used, 0x1000:
                                     unwritten extent tracking is on, 0x2000: ver-
                                     sion 2 directories are in use).
                         sectsize    sector  size  in bytes, currently always 512.
                                     This is the size of the  superblock  and  the
                                     other header blocks.
                         inodesize   inode size in bytes.
                         inopblock   number of inodes per filesystem block.
                         fname       obsolete, filesystem name.
                         fpack       obsolete, filesystem pack name.
                         blocklog    log2 of blocksize.
                         sectlog     log2 of sectsize.
                         inodelog    log2 of inodesize.
                         inopblog    log2 of inopblock.
                         agblklog    log2 of agblocks (rounded up).
                         rextslog    log2 of rextents.
                         inprogress  mkfs.xfs(8)  or  xfs_copy(8)  aborted  before
                                     completing this filesystem.
                         imax_pct    maximum percentage of filesystem  space  used
                                     for inode blocks.
                         icount      number of allocated inodes.
                         ifree       number  of  allocated  inodes that are not in
                                     use.
                         fdblocks    number of free data blocks.
                         frextents   number of free realtime extents.
                         uquotino    user quota inode number.
                         pquotino    project quota inode number; this is currently
                                     unused.
                         qflags      quota status flags (0x01: user quota account-
                                     ing  is  on,  0x02:  user  quota  limits  are
                                     enforced,  0x04:  quotacheck  has been run on
                                     user quotas, 0x08: project  quota  accounting
                                     is   on,   0x10:  project  quota  limits  are
                                     enforced, 0x20: quotacheck has  been  run  on
                                     project quotas).
                         flags       random flags. 0x01: only read-only mounts are
    
           text      User  file  blocks,  and  other blocks whose type is unknown,
                     have this type for display purposes  in  xfs_db.   The  block
                     data  is  displayed  in  two  columns: Hexadecimal format and
                     printable ASCII chars.
    
    
    

    DIAGNOSTICS

           Many messages can come from the check  (blockget)  command;  these  are
           documented in xfs_check(8).
    
    
    

    SEE ALSO

           mkfs.xfs(8),  xfs_admin(8), xfs_check(8), xfs_copy(8), xfs_logprint(8),
           xfs_metadump(8),  xfs_ncheck(8),  xfs_repair(8),  mount(8),   chmod(2),
           mknod(2), stat(2), xfs(5).
    
                                                                         xfs_db(8)
    
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