xfs_db

xfs_db(8) System Manager's Manual xfs_db(8)

NAME

   xfs_db - debug an XFS filesystem

SYNOPSIS

   xfs_db [ -c cmd ] ... [ -i|r|x|F ] [ -f ] [ -l logdev ] [ -R rtdev ] [ -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 normally 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 program exits.

   -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_metadump.

   -i     Allows  execution  on  a mounted filesystem, provided it is mounted read-only.  Useful for shell scripts which must only operate on filesystems in a guaranteed 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 messages, the default value is xfs_db.

   -R     rtdev Specifies the device where the realtime data resides.  This is only relevant for filesystems that have a realtime section.  See the mkfs.xfs(8) -r option,  and  refer  to
          xfs(5) for a detailed description of the XFS realtime section.

   -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, block
          trash, crc) is to be used.

   -x     Specifies expert mode.  This enables the (write, blocktrash, crc invalidate/revalidate) commands.

   -V     Prints the version number and exits.

CONCEPTS

   xfs_db commands can be broken up into two classes. Most commands are for the navigation and display of data structures in the filesystem.  Other commands are for scanning the filesys
   tem in some way.

   Commands which are used to navigate the filesystem structure take arguments which reflect the names of filesystem structure fields.  There can be multiple  field  names  separated  by
   dots  when  the underlying structures are nested, as in C.  The field names can be indexed (as an array index) if the underlying field is an array.  The array indices can be specified
   as a range, two numbers separated by a dash.

   xfs_db maintains a current address in the filesystem.  The granularity of the address is a filesystem structure.  This can be a filesystem block, an inode or  quota  (smaller  than  a
   filesystem block), or a directory 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 commands.  This allows for easy examination  of
   a nested filesystem structure.  Also, the last several locations visited are stored in a ring buffer which can be manipulated with the forward, back, and ring commands.

   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 al
   location 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.

   agresv [agno]
          Displays the length, free block count, per-AG reservation size, and per-AG reservation usage for a given AG.  If no argument is given, display information for all AGs.

   attr_get [-p|-r|-u|-s|-Z] [-N namefile|name]
          Print the value of the specified extended attribute from the current file.

             -p  Sets the attribute in the parent namespace.  Only one namespace option can be specified.

             -r  Sets the attribute in the root namespace.  Only one namespace option can be specified.

             -u  Sets the attribute in the user namespace.  Only one namespace option can be specified.

             -s  Sets the attribute in the secure namespace.  Only one namespace option can be specified.

             -Z  Sets a filesystem property in the root namespace.  Only one namespace option can be specified.

             -N  Read the name from this file.

   attr_list [-p|-r|-u|-s|-Z] [-v]
          Lists the extended attributes of the current file.

             -p  Sets the attribute in the parent namespace.  Only one namespace option can be specified.

             -r  Sets the attribute in the root namespace.  Only one namespace option can be specified.

             -u  Sets the attribute in the user namespace.  Only one namespace option can be specified.

             -s  Sets the attribute in the secure namespace.  Only one namespace option can be specified.

             -Z  Sets a filesystem property in the root namespace.  Only one namespace option can be specified.

             -v  Print the extended attribute values too.

   attr_remove [-p|-r|-u|-s|-Z] [-n] [-N namefile|name]
          Remove the specified extended attribute from the current file.

             -p  Sets the attribute in the parent namespace.  Only one namespace option can be specified.

             -r  Sets the attribute in the root namespace.  Only one namespace option can be specified.

             -u  Sets the attribute in the user namespace.  Only one namespace option can be specified.

             -s  Sets the attribute in the secure namespace.  Only one namespace option can be specified.

             -Z  Sets a filesystem property in the root namespace.  Only one namespace option can be specified.

             -N  Read the name from this file.

             -n  Do not enable 'noattr2' mode on V4 filesystems.

   attr_set [-p-r|-u|-s|-Z] [-n] [-R|-C] [-v valuelen|-V valuefile] [-N namefile|name] [value]
          Sets an extended attribute on the current file with the given name.

             -p  Sets the attribute in the parent namespace.  Only one namespace option can be specified.

             -r  Sets the attribute in the root namespace.  Only one namespace option can be specified.

             -u  Sets the attribute in the user namespace.  Only one namespace option can be specified.

             -s  Sets the attribute in the secure namespace.  Only one namespace option can be specified.

             -Z  Sets a filesystem property in the root namespace.  Only one namespace option can be specified.

             -N  Read the name from this file.

             -n  Do not enable 'noattr2' mode on V4 filesystems.

             -R  Replace the attribute.  The command will fail if the attribute does not already exist.

             -C  Create the attribute.  The command will fail if the attribute already exists.

             -V  Read the value from this file.

             -v  Set the attribute value to a string of this length containing the letter 'v'.

   b      See the back command.

   back   Move to the previous location in the position ring.

   blockfree
          Free block usage information collected by the last execution of the blockget command. This must be done before another blockget command can be given, presumably with  different
          arguments than the previous one.

   blockget [-npvs] [-b bno] ... [-i ino] ...
          Get block usage.  The information is saved for use by a subsequent blockuse, ncheck, or blocktrash command.

             -b  is used to specify filesystem block numbers about which verbose information should be printed.

             -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 [-z] [-o offset] [-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).

             -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).

             -o  supplies the bit offset at which to start trashing the block.  If the value is preceded by a '+', the trashing will start at a randomly chosen offset that is larger than
                 the value supplied.  The default is to randomly choose an offset anywhere in the block.

             -s  supplies a seed to the random processing.

             -t  gives a type of blocks to be selected for trashing. Multiple -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.

             -z  trashes the block at the top of the stack.  It is not necessary to run blockget if this option is supplied.

   blockuse [-n] [-c count]
          Print usage for current filesystem block(s).  For each block, the type and (if any) inode are printed.

             -c  specifies a count of blocks to process. The default value is 1 (the current block only).

             -n  specifies that file names should be printed. The prior blockget command must have also specified the -n option.

   bmap [-a] [-d] [block [len]]
          Show the block map for the current inode.  The map display can be restricted to an area of the file with the block and len arguments. If block is given and len is omitted  then
          1 is assumed for len.

          The -a and -d options are used to select the attribute or data area of the inode, if neither option is given then both areas are shown.

   bmapinflate [-d dirty_bytes] [-e] [-n nr]
          Duplicates  the  first data fork mapping this many times, as if the mapping had been repeatedly reflinked.  This is an expert-mode command for exercising high-refcount filesys
          tems only.  Existing data fork mappings will be forgotten and the refcount btree will not be updated.  This command leaves at least the refcount btree and the  inode  inconsis
          tent; xfs_repair must be run afterwards.

             -d  Constrain the memory consumption of new dirty btree blocks to this quantity.  Defaults to 60MiB.

             -e  Estimate the number of blocks and height of the new data fork mapping structure and exit without changing anything.

             -n  Create this many copies of the first mapping.

   btdump [-a] [-i]
          If  the  cursor  points  to a btree node, dump the btree from that block downward.  If instead the cursor points to an inode, dump the data fork block mapping btree if there is
          one.  If the cursor points to a directory or extended attribute btree node, dump that.  By default, only records stored in the btree are dumped.

             -a  If the cursor points at an inode, dump the extended attribute block mapping btree, if present.

             -i  Dump all keys and pointers in intermediate btree nodes, and all records in leaf btree nodes.

   btheight [-b blksz] [-n recs] [-w max|min|absmax] btree types...
          For a given number of btree records and a btree type, report the number of records and blocks for each level of the btree, and the total number of blocks.  The btree type  must
          be given after the options.

          A raw btree geometry can be provided in the format "record_bytes:key_bytes:ptr_bytes:header_type", where header_type is one of "short", "long", "shortcrc", or "longcrc".

          The supported btree types are: bnobt, cntbt, inobt, finobt, bmapbt, refcountbt, and rmapbt.  The magic value all can be used to walk through all btree types.

          Options are as follows:

             -b  is used to override the btree block size.  The default is the filesystem block size.

             -n  is used to specify the number of records to store.  This argument is required.

             -w absmax
                 shows the maximum possible height for the given btree types.

             -w max
                 shows only the best case scenario, which is when the btree blocks are maximally loaded.

             -w min
                 shows only the worst case scenario, which is when the btree blocks are half full.

   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.

   crc [-i|-r|-v]
          Invalidates,  revalidates,  or  validates the CRC (checksum) field of the current structure, if it has one.  This command is available only on CRC-enabled filesystems.  With no
          argument, validation is performed.  Each command will display the resulting CRC value and state.

             -i  Invalidate the structure's CRC value (incrementing it by one), and write it to disk.

             -r  Recalculate the current structure's correct CRC value, and write it to disk.

             -v  Validate and display the current value and state of the structure's CRC.

   daddr [-r] [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 (unin‐
          terpreted).

          If an address and the -l option are specified, the current address is set to the external log device.  If an address and the -r option are specified, the current address is set
          to the realtime device.

   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 [-g|-p|-u] id
          Set current address to a group, project or user quota block for the given ID. Defaults to user quota.

   dump_iunlinked [-a agno ] [-b bucket ] [-q] [-v]
          Dump the contents of unlinked buckets.

          Options include:

             -a  Print only this AG's unlinked buckets.

             -b  Print only this bucket within each AGI.

             -q  Only print the essentials.

             -v  Print resource usage of each file on the unlinked lists.

   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]
          Get file fragmentation data. This prints information about fragmentation of file data in the filesystem (as opposed to fragmentation of freespace, for which see the freesp com
          mand). Every file in the filesystem is examined to see how far from ideal its extent mappings are. A summary is printed giving the totals.

             -v  sets verbosity, every inode has information printed for it.  The remaining options select which inodes and extents are examined.  If no options are given  then  all  are
                 assumed set, otherwise just those given are enabled.

             -a  enables processing of attribute data.

             -d  enables processing of directory data.

             -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 alignment] [-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 ex
          tent sizes.

             -A  reports only free extents with starting blocks aligned to alignment blocks.

             -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  (uninter‐
          preted). 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.

   fsmap [ start ] [ end ]
          Prints  the mapping of disk blocks used by an XFS filesystem.  The map lists each extent used by files, allocation group metadata, journalling logs, and static filesystem meta‐
          data, as well as any regions that are unused.  All blocks, offsets, and lengths are specified in units of 512-byte blocks, no matter what the filesystem's block size  is.   The
          optional start and end arguments can be used to constrain the output to a particular range of disk blocks.

   fuzz [-c] [-d] field action
          Write garbage into a specific structure field on disk.  Expert mode must be enabled to use this command.  The operation happens immediately; there is no buffering.

          The fuzz command can take the following actions against a field:

             zeroes
                 Clears all bits in the field.

             ones
                 Sets all bits in the field.

             firstbit
                 Flips the first bit in the field.  For a scalar value, this is the highest bit.

             middlebit
                 Flips the middle bit in the field.

             lastbit
                 Flips the last bit in the field.  For a scalar value, this is the lowest bit.

             add Adds a small value to a scalar field.

             sub Subtracts a small value from a scalar field.

             random
                 Randomizes the contents of the field.

          The following switches affect the write behavior:

             -c  Skip write verifiers and CRC recalculation; allows invalid data to be written to disk.

             -d  Skip write verifiers but perform CRC recalculation; allows invalid data to be written to disk to test detection of invalid data.

   hash[-d|-pparent_ino]"strings
          Prints the hash value of string using the hash function of the XFS directory and attribute implementation.

          If the -d option is specified, the directory-specific hash function is used.  This only makes a difference on filesystems with ascii case-insensitive lookups enabled.

          If  the -p option is specified, the parent pointer-specific hash function is used.  The parent directory inumber must be specified as an argument.  This only makes a difference
          on filesystems with ascii case-insensitive lookups enabled.

   hashcoll [-a] [-s seed] [-n nr] [-p path] -i | names...
          Create directory entries or extended attributes names that all have the same hash value.  The metadump name obfuscation algorithm is used here.  Names are written  to  standard
          output, with a NULL between each name for use with xargs -0.
             -a  Create extended attribute names.
             -i  Read the first name to create from standard input.  Up to 255 bytes are read.  If this option is not specified, first names are taken from the command line.
             -n nr
                 Create this many duplicated names.  The default is to create one name.
             -p path
                 Create directory entries or extended attributes in this file instead of writing the names to standard output.
             -s seed
                 Seed the random number generator with this value.

   help [command]
          Print help for one or all commands.

   info   Displays selected geometry information about the filesystem.  The output will have the same format that mkfs.xfs(8) prints when creating a filesystem or xfs_info(8) prints when
          querying a filesystem.

   inode [inode#]
          Set the current inode number. If no inode# is given, print the current inode number.

   iunlink [-n nr ]
          Allocate inodes and put them on the unlinked list.

          Options include:

             -n  Create this number of unlinked inodes.  If not specified, 1 inode will be created.

   label [label]
          Set  the  filesystem label. The filesystem label can be used by 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.

   link [-i ino] [-m] [-p path] [-t ftype] name
          In the current directory, create a directory entry with the given name pointing to a file.  The file must be specified either as a directory tree path as given by the path  op‐
          tion;  or  directly as an inode number as given by the ino option.  The file type in the directory entry will be determined from the mode of the child file unless the ftype op‐
          tion is given.  The -m option specifies that the path lookup should be done in the metadata directory tree.  The file being targetted must not be on the iunlink list.

   log [stop | start filename]
          Start logging output to filename, stop logging, or print the current logging status.

   logblock [logbno]
          Set current address to the log block value given by logbno.  If no value for logbno is given the current address is printed, expressed as an fsb.  The type is set to data  (un‐
          interpreted).   If  the  filesystem has an external log, then the address will be within the log device.  If the filesystem has an internal log, then the address will be within
          the internal log.

   logformat [-c cycle] [-s sunit]
          Reformats the log to the specified log cycle and log stripe unit.  This has the effect of clearing the log destructively.  If the log cycle is not specified, the log is  refor‐
          matted to the current cycle.  If the log stripe unit is not specified, the stripe unit from the filesystem superblock is used.

   logres Print  transaction  reservation size information for each transaction type.  This makes it easier to find discrepancies in the reservation calculations between xfsprogs and the
          kernel, which will help when diagnosing minimum log size calculation errors.

   ls [-im] [paths]...
          List the contents of a directory.  If a path resolves to a directory, the directory will be listed.  If no paths are supplied and the IO cursor points at a directory inode, the
          contents of that directory will be listed.

          The output format is: directory cookie, inode number, file type, hash, name length, name.

             -i  Resolve each of the given paths to an inode number and print that number.  If no paths are given and the IO cursor points to an inode, print the inode number.

             -m  Absolute paths should be walked from the root of the metadata directory tree.

   metadump [-egow] filename
          Dumps metadata to a file. See xfs_metadump(8) for more information.

   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.

   parent [-m] [paths]...
          List the parents of a file.  If a path resolves to a file, the parents of that file will be listed.  If no paths are supplied and the IO cursor points at an inode, the  parents
          of that file will be listed.  The -m option causes absolute paths to be walked from the root of the metadata directory tree.

          The output format is: inode number, inode generation, ondisk namehash, namehash, name length, name.

   path [-m] dir_path
          Walk  the directory tree to an inode using the supplied path.  Absolute and relative paths are supported.  The -m option causes absolute paths to be walked from the root of the
          metadata directory tree.

   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 current location to the results of command after pushing the old location.

   q      See the quit command.

   quit   Exit xfs_db.

   rtblock [rtbno]
          Set current address to the location on the realtime device given by rtbno.  This value must be a realtime block number.  If no value for rtbno is given the current  address  is
          printed, expressed as an rtbno.  The type is set to data (uninterpreted).

   rtextent [rtxno]
          Set  current  address  to the location on the realtime device given by rtextent.  This value must be a linear address in units of realtime extents.  If no value for rtextent is
          given the current address is printed, expressed as an rtextent.  The type is set to data (uninterpreted).

   ring [index]
          Show position ring (if no index argument is given), or move to a specific entry in the position ring given by index.

   rtconvert type number [type number] ... type
          Convert from one address form to another for realtime section addresses.  The known types, with alternate names, are:

             rgblock or rgbno (realtime block within a realtime group)
             rgnumber or rgno (realtime group number)
             bboff or daddroff (byte offset in a daddr)
             blkoff or fsboff or rtboff (byte offset in a rtblock or rtextent)
             byte or fsbyte (byte address in filesystem)
             daddr or bb (disk address, 512-byte blocks)
             rtblock or rtb or rtbno (realtime filesystem block, see the fsblock command)
             rtx or rtextent (realtime extent)
             rbmblock or rbmb (realtime bitmap block)
             rbmword or rbmw (32-bit word within a realtime bitmap block)
             rsumblock or rsmb (realtime summary file block)
             rsuminfo or rsmi (32-bit counter within a realtime summary block)
             rsumlog or rsml (log2len parameter used for summary file offset computations)

          Only conversions that "make sense" are allowed.  The compound form (with more than three arguments) is useful for conversions such as convert rgno rg rgbno rgb rtblock.

          Realtime summary file location conversions have the following rules: Each info word in the rt summary file counts the number of free extents of a given log2(length) that  start
          in a given rt bitmap block.

          To  compute  summary file location information for a given rt bitmap block, a log2(extent length) must be specified as the last type/number pair before the conversion type, and
          the type must be rsumlog.

          For example, these commands tell us where to look in the rt summary file for the number of free rtextents of length 2^21 starting in rt bitmap block 30:

          rtconvert rbmblock 30 rsumlog 21 rsumblock

          rtconvert rbmblock 30 rsumlog 21 rsuminfo

          To compute the rt bitmap block from summary file location, the type/number pairs must be specified exactly in the order rsumlog, rsuminfo, rsumblock.

          For example, this command tells us which block in the rt bitmap file is summarized by info word 809 in rt summary block 10 assuming that the maximum free extent length is  2^21
          rtextents:

          rtconvert rsumlog 21 rsuminfo 809 rsumblock 10 rbmblock

   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.

   type [type]
          Set  the  current  data  type to type.  If no argument is given, show the current data type.  The possible data types are: agf, agfl, agi, attr, bmapbta, bmapbtd, bnobt, cntbt,
          data, dir, dir2, dqblk, inobt, inode, log, refcntbt, rmapbt, rtbitmap, rtsummary, sb, symlink and text.  See the TYPES section below for more information on these data types.

   timelimit [OPTIONS]
          Print the minimum and maximum supported values for inode timestamps, quota expiration timers, and quota grace periods supported by this filesystem.  Options include:

             --bigtime
                 Print the time limits of an XFS filesystem with the bigtime feature enabled.

             --classic
                 Print the time limits of a classic XFS filesystem.

             --compact
                 Print all limits as raw values on a single line.

             --pretty
                 Print the timestamps in the current locale's date and time format instead of raw seconds since the Unix epoch.

   unlink name
          In the current directory, remove a directory entry with the given name.  The file being targetted will not be put on the iunlink list.

   uuid [uuid | generate | rewrite | restore]
          Set the filesystem universally unique identifier (UUID).  The filesystem UUID can be used by mount(8) instead of using a device special file.  The uuid can be set  directly  to
          the  desired  UUID,  or it can be automatically generated using the generate option. These options will both write the UUID into every copy of the superblock in the filesystem.
          On a CRC-enabled filesystem, this will set an incompatible superblock flag, and the filesystem will not be mountable with older kernels.  This can be reverted with the  restore
          option,  which  will  copy the original UUID back into place and clear the incompatible flag as needed.  rewrite copies the current UUID from the primary superblock to all sec‐
          ondary 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 ex‐
          tents can be enabled using the extflg option. Support for version 2 log format 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  su‐
          perblock in the filesystem.  If two arguments are given, they will be used as numeric values for the versionnum and features2 bits respectively, and their string equivalent re‐
          ported (but no modifications are made).

   write [-c|-d] [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 buffering.

          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 information on the allowed commands.

             -c  Skip write verifiers and CRC recalculation; allows invalid data to be written to disk.

             -d  Skip write verifiers but perform CRC recalculation.  This allows invalid data to be written to disk to test detection of invalid data.  (This is not  possible  for  some
                 types.)

TYPES

   This section gives the fields in each structure type and their meanings.  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.
                 seqno       sequence number starting from 0.
                 length      size in filesystem blocks of the allocation group. All allocation groups except the last one of the filesystem have the superblock's agblocks value here.
                 bnoroot     block number of the root of the Btree holding free space information sorted by block number.
                 cntroot     block number of the root of the Btree holding free space information sorted by block count.
                 bnolevel    number of levels in the by-block-number Btree.
                 cntlevel    number of levels in the by-block-count Btree.
                 flfirst     index into the AGFL block of the first active 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 allocation 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  cur‐
             rently 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 allocation 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 dir for a description. Leaf blocks can refer to "local" or "remote" attribute values. Local  values  are
             stored directly in the leaf block.  Leaf blocks contain the following fields:
                 hdr         header containing a blkinfo structure info (magic number 0xfbee), a count of active entries, usedbytes total bytes of names and values, the firstused byte in
                             the name area, holes set if the block needs compaction, and array freemap as for dir leaf blocks.
                 entries     array of structures containing a hashval, nameidx (index into the block of the name), and flags incomplete, root, and local.
                 nvlist      array of structures describing the attribute names and values. Fields always present: valuelen (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).

             Remote values are stored in an independent block in the attribute fork.  Prior to v5, value blocks had no structure, but in v5 they acquired a header structure with the fol‐
             lowing fields:
                 magic       attr3 remote block magic number, 0x5841524d ('XARM').
                 offset      Byte offset of this data block within the overall attribute value.
                 bytes       Number of bytes stored in this block.
                 crc         Checksum of the attribute block contents.
                 uuid        Filesystem UUID.
                 owner       Inode that owns this attribute value.
                 bno         Block offset of this block within the inode's attribute fork.
                 lsn         Log serial number of the last time this block was logged.
                 data        The attribute value data.

   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 in
             ode.   Each bmap Btree starts with a root block contained within the inode.  The other levels of the Btree are stored in filesystem 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        [non-leaf blocks only] array of key records. These are the first key value of each block in the level below this one. Each record contains startoff.
                 ptrs        [non-leaf 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 corresponding 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 records. Each record contains startblock and blockcount.
                 keys        [non-leaf  blocks only] array of key records. These are the first value of each block in the level below this one. Each record contains startblock and block
                             count.
                 ptrs        [non-leaf blocks only] array of child block pointers. Each pointer is a block number within the allocation group to the next level in the Btree.

   cntbt     There is one set of filesystem blocks forming the by-block-count allocation Btree for each allocation group. The root block of this Btree is designated by the cntroot  field
             in  the corresponding 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        [non-leaf blocks only] array of key records. These are the first value of each block in the level below this one. Each record contains blockcount and  start
                             block.
                 ptrs        [non-leaf 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 directory data embedded in the leaf blocks. The root of the Btree is found in block 0 of the file. The index (sort or
             der) of the Btree is the hash value of the entry name. All the blocks contain a blkinfo structure at the beginning with the following 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), holes flag  (block  needs
                             compaction), and freemap (array of base, size entries for free regions).
                 entries     array of structures containing hashval, nameidx (byte index into the block of the name string), and namelen.
                 namelist    array of structures containing inumber and name.

   dir2      A  version  2 directory has four kinds of blocks.  Data blocks start at offset 0 in the file.  There are two kinds of data blocks: single-block directories have the leaf in
             formation embedded at the end of the block, data blocks in multi-block directories do not.  Node and leaf blocks start at offset 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 represent 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  ('XD2F'), firstdb first data block number covered by this freespace block, nvalid number of valid entries, and
                             nused number of entries representing real data blocks.
                 fbests      array of values as for lbests.

   dqblk     The quota information is stored in files referred to by the superblock uquotino and pquotino fields. Each filesystem block in a quota file  contains  a  constant  number  of
             quota  entries.  The  quota entry size is currently 136 bytes, so with a 4KiB filesystem block size there are 30 quota entries per block. The dquot command is used to locate
             these entries in the filesystem.  The file entries are indexed by the user or project identifier to determine the block and offset.   Each  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 allocation Btree for each allocation group. The root block of this Btree is designated by the root field in the cor
             responding AGI 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  follow
             ing 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        [non-leaf blocks only] array of key records. These are the first value of each block in the level below this one. Each record contains startino.
                 ptrs        [non-leaf blocks only] array of child block pointers. Each pointer is a block number within the allocation group to the next level in the Btree.

   inode     Inodes are allocated in "chunks" of 64 inodes each. Usually a chunk is multiple filesystem blocks, although there are cases with large filesystem blocks  where  a  chunk  is
             less  than  one block. The inode Btree (see inobt above) refers to the inode numbers per allocation group. The inode numbers directly reflect the location of the inode block
             on disk. Use the inode command to point xfs_db to a specific inode. Each inode contains four regions: core, next_unlinked, u, and a.  core contains  the  fixed  information.
             next_unlinked  is separated from the core due to journaling considerations, see type agi field unlinked.  u is a union structure that is different in size and format depend
             ing on the type and representation of the file data ("data fork").  a is an optional union structure to describe attribute data, that is different in size, format, and loca
             tion depending on the presence and representation 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" format.
                 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.
                 dev         dev_t for the block or character device.
                 sfdir       shortform  (in-inode) version 1 directory. This consists of a hdr containing the parent inode number and a count of active entries in the directory, followed
                             by an array list of hdr.count entries. Each such entry contains inumber, namelen, and name string.
                 sfdir2      shortform (in-inode) version 2 directory. This consists of a hdr containing a count of active entries in the directory, an i8count of entries  with  inumbers
                             that don't fit in a 32-bit value, and the parent inode number, followed by an array list of hdr.count entries. Each such entry contains namelen, a saved off‐
                             set used when the directory is converted 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.

   refcntbt  There is one set of filesystem blocks forming the reference count Btree for each allocation group. The root block of this Btree is designated by the refcntroot field in  the
             corresponding  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 fol
             lowing fields:
                 magic       REFC block magic number, 0x52334643 ('R3FC').
                 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 reference count records. Each record contains startblock, blockcount, and refcount.
                 keys        [non-leaf blocks only] array of key records. These are the first value of each block in the level below this one. Each record contains startblock.
                 ptrs        [non-leaf blocks only] array of child block pointers. Each pointer is a block number within the allocation group to the next level in the Btree.

   rmapbt    There is one set of filesystem blocks forming the reverse mapping Btree for each allocation group. The root block of this Btree is designated by the rmaproot  field  in  the
             corresponding  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 fol
             lowing fields:
                 magic       RMAP block magic number, 0x524d4233 ('RMB3').
                 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 reference count records. Each record contains startblock, blockcount, owner, offset, attr_fork, bmbt_block, and unwritten.
                 keys        [non-leaf blocks only] array of double-key records. The first ("low") key contains the first value of each block in the level  below  this  one.  The  second
                             ("high")  key contains the largest key that can be used to identify any record in the subtree. Each record contains startblock, owner, offset, attr_fork, and
                             bmbt_block.
                 ptrs        [non-leaf blocks only] array of child block pointers. Each pointer is a block number within the allocation group to the next level in the Btree.

   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-dimensional 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 necessary given the size of the real
             time  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.
                 rblocks     number of filesystem blocks present in the realtime subvolume.
                 rextents    number of realtime extents that rblocks contain.
                 uuid        unique identifier of the filesystem.
                 logstart    starting filesystem block number of the log (journal).  If this value is 0 the log is "external".
                 rootino     root inode number.
                 rbmino      realtime bitmap inode number.
                 rsumino     realtime summary data inode number.
                 rextsize    realtime extent size in filesystem blocks.
                 agblocks    size of an allocation group in filesystem blocks.
                 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  mean
                             ings.   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: version 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 accounting 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 allowed.
                 shared_vn   shared version number (shared readonly filesystems).
                 inoalignmt  inode chunk alignment in filesystem blocks.
                 unit        stripe or RAID unit.
                 width       stripe or RAID width.
                 dirblklog   log2 of directory block size (filesystem blocks).

   symlink   Symbolic link blocks are used only when the symbolic link value does not fit inside the inode. The block content is just the string value.  Bytes past the logical end of the
             symbolic link value have arbitrary values.

   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 blockget command.  If the filesystem is completely corrupt, a core dump might be produced instead of the message
          device is not a valid filesystem

   If the filesystem is very large (has many files) then blockget might run out of memory. In this case the message
          out of memory
   is printed.

   The following is a description of the most likely problems and the associated messages.  Most of the diagnostics produced are only meaningful with an understanding of the structure of
   the filesystem.

   agf_freeblks n, counted m in ag a
          The freeblocks count in the allocation group header for allocation group a doesn't match the number of blocks counted free.

   agf_longest n, counted m in ag a
          The longest free extent in the allocation group header for allocation group a doesn't match the longest free extent found in the allocation group.

   agi_count n, counted m in ag a
          The allocated inode count in the allocation group header for allocation group a doesn't match the number of inodes counted in the allocation group.

   agi_freecount n, counted m in ag a
          The free inode count in the allocation group header for allocation group a doesn't match the number of inodes counted free in the allocation group.

   block a/b expected inum 0 got i
          The  block  number  is  specified as a pair (allocation group number, block in the allocation group).  The block is used multiple times (shared), between multiple inodes.  This
          message usually follows a message of the next type.

   block a/b expected type unknown got y
          The block is used multiple times (shared).

   block a/b type unknown not expected

SEE ALSO

   mkfs.xfs(8), xfs_admin(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)