1xfs_db(8) System Manager's Manual xfs_db(8)
2
6 xfs_db - debug an XFS filesystem
7
9 xfs_db [ -c cmd ] ... [ -i|r|x|F ] [ -f ] [ -l logdev ] [ -p progname ]
10 device
11 xfs_db -V
12
14 xfs_db is used to examine an XFS filesystem. Under rare circumstances
15 it can also be used to modify an XFS filesystem, but that task is nor‐
16 mally left to xfs_repair(8) or to scripts such as xfs_admin(8) that run
17 xfs_db.
18
20 -c cmd xfs_db commands may be run interactively (the default) or as ar‐
21 guments on the command line. Multiple -c arguments may be given.
22 The commands are run in the sequence given, then the program ex‐
23 its.
24 -f Specifies that the filesystem image to be processed is stored in
26 a regular file at device (see the mkfs.xfs(8) -d file option).
27 This might happen if an image copy of a filesystem has been made
28 into an ordinary file with xfs_copy(8).
29 -F Specifies that we want to continue even if the superblock magic
31 is not correct. For use in xfs_metadump.
32 -i Allows execution on a mounted filesystem, provided it is mounted
34 read-only. Useful for shell scripts which must only operate on
35 filesystems in a guaranteed consistent state (either unmounted
36 or mounted read-only). These semantics are slightly different to
37 that of the -r option.
38 -l logdev
40 Specifies the device where the filesystems external log resides.
41 Only for those filesystems which use an external log. See the
42 mkfs.xfs(8) -l option, and refer to xfs(5) for a detailed de‐
43 scription of the XFS log.
44 -p progname
46 Set the program name to progname for prompts and some error mes‐
47 sages, the default value is xfs_db.
48 -r Open device or filename read-only. This option is required if
50 the filesystem is mounted. It is only necessary to omit this
51 flag if a command that changes data (write, blocktrash, crc) is
52 to be used.
53 -x Specifies expert mode. This enables the (write, blocktrash, crc
55 invalidate/revalidate) commands.
56 -V Prints the version number and exits.
58
60 xfs_db commands can be broken up into two classes. Most commands are
61 for the navigation and display of data structures in the filesystem.
62 Other commands are for scanning the filesystem in some way.
63 Commands which are used to navigate the filesystem structure take argu‐
65 ments which reflect the names of filesystem structure fields. There
66 can be multiple field names separated by dots when the underlying
67 structures are nested, as in C. The field names can be indexed (as an
68 array index) if the underlying field is an array. The array indices
69 can be specified as a range, two numbers separated by a dash.
70 xfs_db maintains a current address in the filesystem. The granularity
72 of the address is a filesystem structure. This can be a filesystem
73 block, an inode or quota (smaller than a filesystem block), or a direc‐
74 tory block (could be larger than a filesystem block). There are a va‐
75 riety of commands to set the current address. Associated with the cur‐
76 rent address is the current data type, which is the structural type of
77 this data. Commands which follow the structure of the filesystem al‐
78 ways set the type as well as the address. Commands which examine
79 pieces of an individual file (inode) need the current inode to be set,
80 this is done with the inode command.
81 The current address/type information is actually maintained in a stack
83 that can be explicitly manipulated with the push, pop, and stack com‐
84 mands. This allows for easy examination of a nested filesystem struc‐
85 ture. Also, the last several locations visited are stored in a ring
86 buffer which can be manipulated with the forward, back, and ring com‐
87 mands.
88 XFS filesystems are divided into a small number of allocation groups.
90 xfs_db maintains a notion of the current allocation group which is ma‐
91 nipulated by some commands. The initial allocation group is 0.
92
94 Many commands have extensive online help. Use the help command for more
95 details on any command.
96 a See the addr command.
98 ablock filoff
100 Set current address to the offset filoff (a filesystem block
101 number) in the attribute area of the current inode.
102 addr [field-expression]
104 Set current address to the value of the field-expression. This
105 is used to "follow" a reference in one structure to the object
106 being referred to. If no argument is given, the current address
107 is printed.
108 agf [agno]
110 Set current address to the AGF block for allocation group agno.
111 If no argument is given, use the current allocation group.
112 agfl [agno]
114 Set current address to the AGFL block for allocation group agno.
115 If no argument is given, use the current allocation group.
116 agi [agno]
118 Set current address to the AGI block for allocation group agno.
119 If no argument is given, use the current allocation group.
120 agresv [agno]
122 Displays the length, free block count, per-AG reservation size,
123 and per-AG reservation usage for a given AG. If no argument is
124 given, display information for all AGs.
125 attr_remove [-r|-u|-s] [-n] name
127 Remove the specified extended attribute from the current file.
128 -r Sets the attribute in the root namespace. Only one name‐
130 space option can be specified.
131 -u Sets the attribute in the user namespace. Only one name‐
133 space option can be specified.
134 -s Sets the attribute in the secure namespace. Only one
136 namespace option can be specified.
137 -n Do not enable 'noattr2' mode on V4 filesystems.
139 attr_set [-r|-u|-s] [-n] [-R|-C] [-v namelen] name
141 Sets an extended attribute on the current file with the given
142 name.
143 -r Sets the attribute in the root namespace. Only one name‐
145 space option can be specified.
146 -u Sets the attribute in the user namespace. Only one name‐
148 space option can be specified.
149 -s Sets the attribute in the secure namespace. Only one
151 namespace option can be specified.
152 -n Do not enable 'noattr2' mode on V4 filesystems.
154 -R Replace the attribute. The command will fail if the at‐
156 tribute does not already exist.
157 -C Create the attribute. The command will fail if the at‐
159 tribute already exists.
160 -v Set the attribute value to a string of this length con‐
162 taining the letter 'v'.
163 b See the back command.
165 back Move to the previous location in the position ring.
167 blockfree
169 Free block usage information collected by the last execution of
170 the blockget command. This must be done before another blockget
171 command can be given, presumably with different arguments than
172 the previous one.
173 blockget [-npvs] [-b bno] ... [-i ino] ...
175 Get block usage and check filesystem consistency. The informa‐
176 tion is saved for use by a subsequent blockuse, ncheck, or
177 blocktrash command.
178 -b is used to specify filesystem block numbers about which
180 verbose information should be printed.
181 -i is used to specify inode numbers about which verbose in‐
183 formation should be printed.
184 -n is used to save pathnames for inodes visited, this is
186 used to support the xfs_ncheck(8) command. It also means
187 that pathnames will be printed for inodes that have prob‐
188 lems. This option uses a lot of memory so is not enabled
189 by default.
190 -p causes error messages to be prefixed with the filesystem
192 name being processed. This is useful if several copies of
193 xfs_db are run in parallel.
194 -s restricts output to severe errors only. This is useful if
196 the output is too long otherwise.
197 -v enables verbose output. Messages will be printed for ev‐
199 ery block and inode processed.
200 blocktrash [-z] [-o offset] [-n count] [-x min] [-y max] [-s seed]
202 [-0|1|2|3] [-t type] ...
203 Trash randomly selected filesystem metadata blocks. Trashing
204 occurs to randomly selected bits in the chosen blocks. This
205 command is available only in debugging versions of xfs_db. It
206 is useful for testing xfs_repair(8).
207 -0 | -1 | -2 | -3
209 These are used to set the operating mode for blocktrash.
210 Only one can be used: -0 changed bits are cleared; -1
211 changed bits are set; -2 changed bits are inverted; -3
212 changed bits are randomized.
213 -n supplies the count of block-trashings to perform (default
215 1).
216 -o supplies the bit offset at which to start trashing the
218 block. If the value is preceded by a '+', the trashing
219 will start at a randomly chosen offset that is larger
220 than the value supplied. The default is to randomly
221 choose an offset anywhere in the block.
222 -s supplies a seed to the random processing.
224 -t gives a type of blocks to be selected for trashing. Mul‐
226 tiple -t options may be given. If no -t options are given
227 then all metadata types can be trashed.
228 -x sets the minimum size of bit range to be trashed. The de‐
230 fault value is 1.
231 -y sets the maximum size of bit range to be trashed. The de‐
233 fault value is 1024.
234 -z trashes the block at the top of the stack. It is not
236 necessary to run blockget if this option is supplied.
237 blockuse [-n] [-c count]
239 Print usage for current filesystem block(s). For each block,
240 the type and (if any) inode are printed.
241 -c specifies a count of blocks to process. The default value
243 is 1 (the current block only).
244 -n specifies that file names should be printed. The prior
246 blockget command must have also specified the -n option.
247 bmap [-a] [-d] [block [len]]
249 Show the block map for the current inode. The map display can
250 be restricted to an area of the file with the block and len ar‐
251 guments. If block is given and len is omitted then 1 is assumed
252 for len.
253 The -a and -d options are used to select the attribute or data
255 area of the inode, if neither option is given then both areas
256 are shown.
257 btdump [-a] [-i]
259 If the cursor points to a btree node, dump the btree from that
260 block downward. If instead the cursor points to an inode, dump
261 the data fork block mapping btree if there is one. If the cur‐
262 sor points to a directory or extended attribute btree node, dump
263 that. By default, only records stored in the btree are dumped.
264 -a If the cursor points at an inode, dump the extended at‐
266 tribute block mapping btree, if present.
267 -i Dump all keys and pointers in intermediate btree nodes,
269 and all records in leaf btree nodes.
270 btheight [-b blksz] [-n recs] [-w max|min|absmax] btree types...
272 For a given number of btree records and a btree type, report the
273 number of records and blocks for each level of the btree, and
274 the total number of blocks. The btree type must be given after
275 the options.
276 A raw btree geometry can be provided in the format
278 "record_bytes:key_bytes:ptr_bytes:header_type", where
279 header_type is one of "short", "long", "shortcrc", or "longcrc".
280 The supported btree types are: bnobt, cntbt, inobt, finobt,
282 bmapbt, refcountbt, and rmapbt. The magic value all can be used
283 to walk through all btree types.
284 Options are as follows:
286 -b is used to override the btree block size. The default is
288 the filesystem block size.
289 -n is used to specify the number of records to store. This
291 argument is required.
292 -w absmax
294 shows the maximum possible height for the given btree
295 types.
296 -w max
298 shows only the best case scenario, which is when the
299 btree blocks are maximally loaded.
300 -w min
302 shows only the worst case scenario, which is when the
303 btree blocks are half full.
304 check See the blockget command.
306 convert type number [type number] ... type
308 Convert from one address form to another. The known types, with
309 alternate names, are:
310 agblock or agbno (filesystem block within an allocation
311 group)
312 agino or aginode (inode number within an allocation group)
313 agnumber or agno (allocation group number)
314 bboff or daddroff (byte offset in a daddr)
315 blkoff or fsboff or agboff (byte offset in a agblock or fs‐
316 block)
317 byte or fsbyte (byte address in filesystem)
318 daddr or bb (disk address, 512-byte blocks)
319 fsblock or fsb or fsbno (filesystem block, see the fsblock
320 command)
321 ino or inode (inode number)
322 inoidx or offset (index of inode in filesystem block)
323 inooff or inodeoff (byte offset in inode)
324 Only conversions that "make sense" are allowed. The compound
326 form (with more than three arguments) is useful for conversions
327 such as convert agno ag agbno agb fsblock.
328 crc [-i|-r|-v]
330 Invalidates, revalidates, or validates the CRC (checksum) field
331 of the current structure, if it has one. This command is avail‐
332 able only on CRC-enabled filesystems. With no argument, valida‐
333 tion is performed. Each command will display the resulting CRC
334 value and state.
335 -i Invalidate the structure's CRC value (incrementing it by
337 one), and write it to disk.
338 -r Recalculate the current structure's correct CRC value,
340 and write it to disk.
341 -v Validate and display the current value and state of the
343 structure's CRC.
344 daddr [d]
346 Set current address to the daddr (512 byte block) given by d.
347 If no value for d is given, the current address is printed, ex‐
348 pressed as a daddr. The type is set to data (uninterpreted).
349 dblock filoff
351 Set current address to the offset filoff (a filesystem block
352 number) in the data area of the current inode.
353 debug [flagbits]
355 Set debug option bits. These are used for debugging xfs_db. If
356 no value is given for flagbits, print the current debug option
357 bits. These are for the use of the implementor.
358 dquot [-g|-p|-u] id
360 Set current address to a group, project or user quota block for
361 the given ID. Defaults to user quota.
362 echo [arg] ...
364 Echo the arguments to the output.
365 f See the forward command.
367 forward
369 Move forward to the next entry in the position ring.
370 frag [-adflqRrv]
372 Get file fragmentation data. This prints information about frag‐
373 mentation of file data in the filesystem (as opposed to fragmen‐
374 tation of freespace, for which see the freesp command). Every
375 file in the filesystem is examined to see how far from ideal its
376 extent mappings are. A summary is printed giving the totals.
377 -v sets verbosity, every inode has information printed for
379 it. The remaining options select which inodes and ex‐
380 tents are examined. If no options are given then all are
381 assumed set, otherwise just those given are enabled.
382 -a enables processing of attribute data.
384 -d enables processing of directory data.
386 -f enables processing of regular file data.
388 -l enables processing of symbolic link data.
390 -q enables processing of quota file data.
392 -R enables processing of realtime control file data.
394 -r enables processing of realtime file data.
396 freesp [-bcds] [-A alignment] [-a ag] ... [-e i] [-h h1] ... [-m m]
398 Summarize free space for the filesystem. The free blocks are ex‐
399 amined and totalled, and displayed in the form of a histogram,
400 with a count of extents in each range of free extent sizes.
401 -A reports only free extents with starting blocks aligned to
403 alignment blocks.
404 -a adds ag to the list of allocation groups to be processed.
406 If no -a options are given then all allocation groups are
407 processed.
408 -b specifies that the histogram buckets are binary-sized,
410 with the starting sizes being the powers of 2.
411 -c specifies that freesp will search the by-size (cnt) space
413 Btree instead of the default by-block (bno) space Btree.
414 -d specifies that every free extent will be displayed.
416 -e specifies that the histogram buckets are equal-sized,
418 with the size specified as i.
419 -h specifies a starting block number for a histogram bucket
421 as h1. Multiple -h's are given to specify the complete
422 set of buckets.
423 -m specifies that the histogram starting block numbers are
425 powers of m. This is the general case of -b.
426 -s specifies that a final summary of total free extents,
428 free blocks, and the average free extent size is printed.
429 fsb See the fsblock command.
431 fsblock [fsb]
433 Set current address to the fsblock value given by fsb. If no
434 value for fsb is given the current address is printed, expressed
435 as an fsb. The type is set to data (uninterpreted). XFS
436 filesystem block numbers are computed ((agno << agshift) | ag‐
437 block) where agshift depends on the size of an allocation group.
438 Use the convert command to convert to and from this form. Block
439 numbers given for file blocks (for instance from the bmap com‐
440 mand) are in this form.
441 fsmap [ start ] [ end ]
443 Prints the mapping of disk blocks used by an XFS filesystem.
444 The map lists each extent used by files, allocation group meta‐
445 data, journalling logs, and static filesystem metadata, as well
446 as any regions that are unused. All blocks, offsets, and
447 lengths are specified in units of 512-byte blocks, no matter
448 what the filesystem's block size is. The optional start and end
449 arguments can be used to constrain the output to a particular
450 range of disk blocks.
451 fuzz [-c] [-d] field action
453 Write garbage into a specific structure field on disk. Expert
454 mode must be enabled to use this command. The operation happens
455 immediately; there is no buffering.
456 The fuzz command can take the following actions against a field:
458 zeroes
460 Clears all bits in the field.
461 ones
463 Sets all bits in the field.
464 firstbit
466 Flips the first bit in the field. For a scalar value,
467 this is the highest bit.
468 middlebit
470 Flips the middle bit in the field.
471 lastbit
473 Flips the last bit in the field. For a scalar value,
474 this is the lowest bit.
475 add Adds a small value to a scalar field.
477 sub Subtracts a small value from a scalar field.
479 random
481 Randomizes the contents of the field.
482 The following switches affect the write behavior:
484 -c Skip write verifiers and CRC recalculation; allows in‐
486 valid data to be written to disk.
487 -d Skip write verifiers but perform CRC recalculation; al‐
489 lows invalid data to be written to disk to test detection
490 of invalid data.
491 hash string
493 Prints the hash value of string using the hash function of the
494 XFS directory and attribute implementation.
495 help [command]
497 Print help for one or all commands.
498 info Displays selected geometry information about the filesystem.
500 The output will have the same format that mkfs.xfs(8) prints
501 when creating a filesystem or xfs_info(8) prints when querying a
502 filesystem.
503 inode [inode#]
505 Set the current inode number. If no inode# is given, print the
506 current inode number.
507 label [label]
509 Set the filesystem label. The filesystem label can be used by
510 mount(8) instead of using a device special file. The maximum
511 length of an XFS label is 12 characters - use of a longer label
512 will result in truncation and a warning will be issued. If no
513 label is given, the current filesystem label is printed.
514 log [stop | start filename]
516 Start logging output to filename, stop logging, or print the
517 current logging status.
518 logformat [-c cycle] [-s sunit]
520 Reformats the log to the specified log cycle and log stripe
521 unit. This has the effect of clearing the log destructively.
522 If the log cycle is not specified, the log is reformatted to the
523 current cycle. If the log stripe unit is not specified, the
524 stripe unit from the filesystem superblock is used.
525 logres Print transaction reservation size information for each transac‐
527 tion type. This makes it easier to find discrepancies in the
528 reservation calculations between xfsprogs and the kernel, which
529 will help when diagnosing minimum log size calculation errors.
530 ls [-i] [paths]...
532 List the contents of a directory. If a path resolves to a di‐
533 rectory, the directory will be listed. If no paths are supplied
534 and the IO cursor points at a directory inode, the contents of
535 that directory will be listed.
536 The output format is: directory cookie, inode number, file type,
538 hash, name length, name.
539 -i Resolve each of the given paths to an inode number and
541 print that number. If no paths are given and the IO cur‐
542 sor points to an inode, print the inode number.
543 metadump [-egow] filename
545 Dumps metadata to a file. See xfs_metadump(8) for more informa‐
546 tion.
547 ncheck [-s] [-i ino] ...
549 Print name-inode pairs. A blockget -n command must be run first
550 to gather the information.
551 -i specifies an inode number to be printed. If no -i options
553 are given then all inodes are printed.
554 -s specifies that only setuid and setgid files are printed.
556 p See the print command.
558 path dir_path
560 Walk the directory tree to an inode using the supplied path.
561 Absolute and relative paths are supported.
562 pop Pop location from the stack.
564 print [field-expression] ...
566 Print field values. If no argument is given, print all fields
567 in the current structure.
568 push [command]
570 Push location to the stack. If command is supplied, set the cur‐
571 rent location to the results of command after pushing the old
572 location.
573 q See the quit command.
575 quit Exit xfs_db.
577 ring [index]
579 Show position ring (if no index argument is given), or move to a
580 specific entry in the position ring given by index.
581 sb [agno]
583 Set current address to SB header in allocation group agno. If
584 no agno is given, use the current allocation group number.
585 source source-file
587 Process commands from source-file. source commands can be
588 nested.
589 stack View the location stack.
591 type [type]
593 Set the current data type to type. If no argument is given,
594 show the current data type. The possible data types are: agf,
595 agfl, agi, attr, bmapbta, bmapbtd, bnobt, cntbt, data, dir,
596 dir2, dqblk, inobt, inode, log, refcntbt, rmapbt, rtbitmap, rt‐
597 summary, sb, symlink and text. See the TYPES section below for
598 more information on these data types.
599 timelimit [OPTIONS]
601 Print the minimum and maximum supported values for inode time‐
602 stamps, quota expiration timers, and quota grace periods sup‐
603 ported by this filesystem. Options include:
604 --bigtime
606 Print the time limits of an XFS filesystem with the big‐
607 time feature enabled.
608 --classic
610 Print the time limits of a classic XFS filesystem.
611 --compact
613 Print all limits as raw values on a single line.
614 --pretty
616 Print the timestamps in the current locale's date and
617 time format instead of raw seconds since the Unix epoch.
618 uuid [uuid | generate | rewrite | restore]
620 Set the filesystem universally unique identifier (UUID). The
621 filesystem UUID can be used by mount(8) instead of using a de‐
622 vice special file. The uuid can be set directly to the desired
623 UUID, or it can be automatically generated using the generate
624 option. These options will both write the UUID into every copy
625 of the superblock in the filesystem. On a CRC-enabled filesys‐
626 tem, this will set an incompatible superblock flag, and the
627 filesystem will not be mountable with older kernels. This can
628 be reverted with the restore option, which will copy the origi‐
629 nal UUID back into place and clear the incompatible flag as
630 needed. rewrite copies the current UUID from the primary su‐
631 perblock to all secondary copies of the superblock. If no argu‐
632 ment is given, the current filesystem UUID is printed.
633 version [feature | versionnum features2]
635 Enable selected features for a filesystem (certain features can
636 be enabled on an unmounted filesystem, after mkfs.xfs(8) has
637 created the filesystem). Support for unwritten extents can be
638 enabled using the extflg option. Support for version 2 log for‐
639 mat can be enabled using the log2 option. Support for extended
640 attributes can be enabled using the attr1 or attr2 option. Once
641 enabled, extended attributes cannot be disabled, but the user
642 may toggle between attr1 and attr2 at will (older kernels may
643 not support the newer version).
644 If no argument is given, the current version and feature bits
646 are printed. With one argument, this command will write the up‐
647 dated version number into every copy of the superblock in the
648 filesystem. If two arguments are given, they will be used as
649 numeric values for the versionnum and features2 bits respec‐
650 tively, and their string equivalent reported (but no modifica‐
651 tions are made).
652 write [-c|-d] [field value] ...
654 Write a value to disk. Specific fields can be set in structures
655 (struct mode), or a block can be set to data values (data mode),
656 or a block can be set to string values (string mode, for symlink
657 blocks). The operation happens immediately: there is no buffer‐
658 ing.
659 Struct mode is in effect when the current type is structural,
661 i.e. not data. For struct mode, the syntax is "write field
662 value".
663 Data mode is in effect when the current type is data. In this
665 case the contents of the block can be shifted or rotated left or
666 right, or filled with a sequence, a constant value, or a random
667 value. In this mode write with no arguments gives more informa‐
668 tion on the allowed commands.
669 -c Skip write verifiers and CRC recalculation; allows in‐
671 valid data to be written to disk.
672 -d Skip write verifiers but perform CRC recalculation. This
674 allows invalid data to be written to disk to test detec‐
675 tion of invalid data. (This is not possible for some
676 types.)
677
679 This section gives the fields in each structure type and their mean‐
680 ings. Note that some types of block cover multiple actual structures,
681 for instance directory blocks.
682 agf The AGF block is the header for block allocation information;
684 it is in the second 512-byte block of each allocation group.
685 The following fields are defined:
686 magicnum AGF block magic number, 0x58414746 ('XAGF').
687 versionnum version number, currently 1.
688 seqno sequence number starting from 0.
689 length size in filesystem blocks of the allocation
690 group. All allocation groups except the last
691 one of the filesystem have the superblock's
692 agblocks value here.
693 bnoroot block number of the root of the Btree holding
694 free space information sorted by block num‐
695 ber.
696 cntroot block number of the root of the Btree holding
697 free space information sorted by block count.
698 bnolevel number of levels in the by-block-number
699 Btree.
700 cntlevel number of levels in the by-block-count Btree.
701 flfirst index into the AGFL block of the first active
702 entry.
703 fllast index into the AGFL block of the last active
704 entry.
705 flcount count of active entries in the AGFL block.
706 freeblks count of blocks represented in the freespace
707 Btrees.
708 longest longest free space represented in the
709 freespace Btrees.
710 btreeblks number of blocks held in the AGF Btrees.
711 agfl The AGFL block contains block numbers for use of the block
713 allocator; it is in the fourth 512-byte block of each alloca‐
714 tion group. Each entry in the active list is a block number
715 within the allocation group that can be used for any purpose
716 if space runs low. The AGF block fields flfirst, fllast, and
717 flcount designate which entries are currently active. Entry
718 space is allocated in a circular manner within the AGFL
719 block. Fields defined:
720 bno array of all block numbers. Even those which
721 are not active are printed.
722 agi The AGI block is the header for inode allocation information;
724 it is in the third 512-byte block of each allocation group.
725 Fields defined:
726 magicnum AGI block magic number, 0x58414749 ('XAGI').
727 versionnum version number, currently 1.
728 seqno sequence number starting from 0.
729 length size in filesystem blocks of the allocation
730 group.
731 count count of inodes allocated.
732 root block number of the root of the Btree holding
733 inode allocation information.
734 level number of levels in the inode allocation
735 Btree.
736 freecount count of allocated inodes that are not in
737 use.
738 newino last inode number allocated.
739 dirino unused.
740 unlinked an array of inode numbers within the alloca‐
741 tion group. The entries in the AGI block are
742 the heads of lists which run through the in‐
743 ode next_unlinked field. These inodes are to
744 be unlinked the next time the filesystem is
745 mounted.
746 attr An attribute fork is organized as a Btree with the actual
748 data embedded in the leaf blocks. The root of the Btree is
749 found in block 0 of the fork. The index (sort order) of the
750 Btree is the hash value of the attribute name. All the
751 blocks contain a blkinfo structure at the beginning, see type
752 dir for a description. Nonleaf blocks are identical in format
753 to those for version 1 and version 2 directories, see type
754 dir for a description. Leaf blocks can refer to "local" or
755 "remote" attribute values. Local values are stored directly
756 in the leaf block. Leaf blocks contain the following fields:
757 hdr header containing a blkinfo structure info
758 (magic number 0xfbee), a count of active en‐
759 tries, usedbytes total bytes of names and
760 values, the firstused byte in the name area,
761 holes set if the block needs compaction, and
762 array freemap as for dir leaf blocks.
763 entries array of structures containing a hashval,
764 nameidx (index into the block of the name),
765 and flags incomplete, root, and local.
766 nvlist array of structures describing the attribute
767 names and values. Fields always present: val‐
768 uelen (length of value in bytes), namelen,
769 and name. Fields present for local values:
770 value (value string). Fields present for re‐
771 mote values: valueblk (fork block number of
772 containing the value).
773 Remote values are stored in an independent block in the at‐
775 tribute fork. Prior to v5, value blocks had no structure,
776 but in v5 they acquired a header structure with the following
777 fields:
778 magic attr3 remote block magic number, 0x5841524d
779 ('XARM').
780 offset Byte offset of this data block within the
781 overall attribute value.
782 bytes Number of bytes stored in this block.
783 crc Checksum of the attribute block contents.
784 uuid Filesystem UUID.
785 owner Inode that owns this attribute value.
786 bno Block offset of this block within the inode's
787 attribute fork.
788 lsn Log serial number of the last time this block
789 was logged.
790 data The attribute value data.
791 bmapbt Files with many extents in their data or attribute fork will
793 have the extents described by the contents of a Btree for
794 that fork, instead of being stored directly in the inode.
795 Each bmap Btree starts with a root block contained within the
796 inode. The other levels of the Btree are stored in filesys‐
797 tem blocks. The blocks are linked to sibling left and right
798 blocks at each level, as well as by pointers from parent to
799 child blocks. Each block contains the following fields:
800 magic bmap Btree block magic number, 0x424d4150
801 ('BMAP').
802 level level of this block above the leaf level.
803 numrecs number of records or keys in the block.
804 leftsib left (logically lower) sibling block, 0 if
805 none.
806 rightsib right (logically higher) sibling block, 0 if
807 none.
808 recs [leaf blocks only] array of extent records.
809 Each record contains startoff, startblock,
810 blockcount, and extentflag (1 if the extent
811 is unwritten).
812 keys [non-leaf blocks only] array of key records.
813 These are the first key value of each block
814 in the level below this one. Each record con‐
815 tains startoff.
816 ptrs [non-leaf blocks only] array of child block
817 pointers. Each pointer is a filesystem block
818 number to the next level in the Btree.
819 bnobt There is one set of filesystem blocks forming the by-block-
821 number allocation Btree for each allocation group. The root
822 block of this Btree is designated by the bnoroot field in the
823 corresponding AGF block. The blocks are linked to sibling
824 left and right blocks at each level, as well as by pointers
825 from parent to child blocks. Each block has the following
826 fields:
827 magic BNOBT block magic number, 0x41425442
828 ('ABTB').
829 level level number of this block, 0 is a leaf.
830 numrecs number of data entries in the block.
831 leftsib left (logically lower) sibling block, 0 if
832 none.
833 rightsib right (logically higher) sibling block, 0 if
834 none.
835 recs [leaf blocks only] array of freespace
836 records. Each record contains startblock and
837 blockcount.
838 keys [non-leaf blocks only] array of key records.
839 These are the first value of each block in
840 the level below this one. Each record con‐
841 tains startblock and blockcount.
842 ptrs [non-leaf blocks only] array of child block
843 pointers. Each pointer is a block number
844 within the allocation group to the next level
845 in the Btree.
846 cntbt There is one set of filesystem blocks forming the by-block-
848 count allocation Btree for each allocation group. The root
849 block of this Btree is designated by the cntroot field in the
850 corresponding AGF block. The blocks are linked to sibling
851 left and right blocks at each level, as well as by pointers
852 from parent to child blocks. Each block has the following
853 fields:
854 magic CNTBT block magic number, 0x41425443
855 ('ABTC').
856 level level number of this block, 0 is a leaf.
857 numrecs number of data entries in the block.
858 leftsib left (logically lower) sibling block, 0 if
859 none.
860 rightsib right (logically higher) sibling block, 0 if
861 none.
862 recs [leaf blocks only] array of freespace
863 records. Each record contains startblock and
864 blockcount.
865 keys [non-leaf blocks only] array of key records.
866 These are the first value of each block in
867 the level below this one. Each record con‐
868 tains blockcount and startblock.
869 ptrs [non-leaf blocks only] array of child block
870 pointers. Each pointer is a block number
871 within the allocation group to the next level
872 in the Btree.
873 data User file blocks, and other blocks whose type is unknown,
875 have this type for display purposes in xfs_db. The block
876 data is displayed in hexadecimal format.
877 dir A version 1 directory is organized as a Btree with the direc‐
879 tory data embedded in the leaf blocks. The root of the Btree
880 is found in block 0 of the file. The index (sort order) of
881 the Btree is the hash value of the entry name. All the blocks
882 contain a blkinfo structure at the beginning with the follow‐
883 ing fields:
884 forw next sibling block.
885 back previous sibling block.
886 magic magic number for this block type.
887 The non-leaf (node) blocks have the following fields:
888 hdr header containing a blkinfo structure info
889 (magic number 0xfebe), the count of active
890 entries, and the level of this block above
891 the leaves.
892 btree array of entries containing hashval and be‐
893 fore fields. The before value is a block num‐
894 ber within the directory file to the child
895 block, the hashval is the last hash value in
896 that block.
897 The leaf blocks have the following fields:
898 hdr header containing a blkinfo structure info
899 (magic number 0xfeeb), the count of active
900 entries, namebytes (total name string bytes),
901 holes flag (block needs compaction), and
902 freemap (array of base, size entries for free
903 regions).
904 entries array of structures containing hashval,
905 nameidx (byte index into the block of the
906 name string), and namelen.
907 namelist array of structures containing inumber and
908 name.
909 dir2 A version 2 directory has four kinds of blocks. Data blocks
911 start at offset 0 in the file. There are two kinds of data
912 blocks: single-block directories have the leaf information
913 embedded at the end of the block, data blocks in multi-block
914 directories do not. Node and leaf blocks start at offset
915 32GiB (with either a single leaf block or the root node
916 block). Freespace blocks start at offset 64GiB. The node
917 and leaf blocks form a Btree, with references to the data in
918 the data blocks. The freespace blocks form an index of long‐
919 est free spaces within the data blocks.
920 A single-block directory block contains the following fields:
922 bhdr header containing magic number 0x58443242
923 ('XD2B') and an array bestfree of the longest
924 3 free spaces in the block (offset, length).
925 bu array of union structures. Each element is
926 either an entry or a freespace. For entries,
927 there are the following fields: inumber,
928 namelen, name, and tag. For freespace, there
929 are the following fields: freetag [22m(0xffff),
930 length, and tag. The tag value is the byte
931 offset in the block of the start of the entry
932 it is contained in.
933 bleaf array of leaf entries containing hashval and
934 address. The address is a 64-bit word offset
935 into the file.
936 btail tail structure containing the total count of
937 leaf entries and stale count of unused leaf
938 entries.
939 A data block contains the following fields:
940 dhdr header containing magic number 0x58443244
941 ('XD2D') and an array bestfree of the longest
942 3 free spaces in the block (offset, length).
943 du array of union structures as for bu.
944 Leaf blocks have two possible forms. If the Btree consists of
945 a single leaf then the freespace information is in the leaf
946 block, otherwise it is in separate blocks and the root of the
947 Btree is a node block. A leaf block contains the following
948 fields:
949 lhdr header containing a blkinfo structure info
950 (magic number 0xd2f1 for the single leaf
951 case, 0xd2ff for the true Btree case), the
952 total count of leaf entries, and stale count
953 of unused leaf entries.
954 lents leaf entries, as for bleaf.
955 lbests [single leaf only] array of values which rep‐
956 resent the longest freespace in each data
957 block in the directory.
958 ltail [single leaf only] tail structure containing
959 bestcount count of lbests.
960 A node block is identical to that for types attr and dir.
961 A freespace block contains the following fields:
963 fhdr header containing magic number 0x58443246
964 ('XD2F'), firstdb first data block number
965 covered by this freespace block, nvalid num‐
966 ber of valid entries, and nused number of en‐
967 tries representing real data blocks.
968 fbests array of values as for lbests.
969 dqblk The quota information is stored in files referred to by the
971 superblock uquotino and pquotino fields. Each filesystem
972 block in a quota file contains a constant number of quota en‐
973 tries. The quota entry size is currently 136 bytes, so with a
974 4KiB filesystem block size there are 30 quota entries per
975 block. The dquot command is used to locate these entries in
976 the filesystem. The file entries are indexed by the user or
977 project identifier to determine the block and offset. Each
978 quota entry has the following fields:
979 magic magic number, 0x4451 ('DQ').
980 version version number, currently 1.
981 flags flags, values include 0x01 for user quota,
982 0x02 for project quota.
983 id user or project identifier.
984 blk_hardlimit absolute limit on blocks in use.
985 blk_softlimit preferred limit on blocks in use.
986 ino_hardlimit absolute limit on inodes in use.
987 ino_softlimit preferred limit on inodes in use.
988 bcount blocks actually in use.
989 icount inodes actually in use.
990 itimer time when service will be refused if soft
991 limit is violated for inodes.
992 btimer time when service will be refused if soft
993 limit is violated for blocks.
994 iwarns number of warnings issued about inode
995 limit violations.
996 bwarns number of warnings issued about block
997 limit violations.
998 rtb_hardlimit absolute limit on realtime blocks in use.
999 rtb_softlimit preferred limit on realtime blocks in use.
1000 rtbcount realtime blocks actually in use.
1001 rtbtimer time when service will be refused if soft
1002 limit is violated for realtime blocks.
1003 rtbwarns number of warnings issued about realtime
1004 block limit violations.
1005 inobt There is one set of filesystem blocks forming the inode allo‐
1007 cation Btree for each allocation group. The root block of
1008 this Btree is designated by the root field in the correspond‐
1009 ing AGI block. The blocks are linked to sibling left and
1010 right blocks at each level, as well as by pointers from par‐
1011 ent to child blocks. Each block has the following fields:
1012 magic INOBT block magic number, 0x49414254
1013 ('IABT').
1014 level level number of this block, 0 is a leaf.
1015 numrecs number of data entries in the block.
1016 leftsib left (logically lower) sibling block, 0 if
1017 none.
1018 rightsib right (logically higher) sibling block, 0 if
1019 none.
1020 recs [leaf blocks only] array of inode records.
1021 Each record contains startino allocation-
1022 group relative inode number, freecount count
1023 of free inodes in this chunk, and free bit‐
1024 map, LSB corresponds to inode 0.
1025 keys [non-leaf blocks only] array of key records.
1026 These are the first value of each block in
1027 the level below this one. Each record con‐
1028 tains startino.
1029 ptrs [non-leaf blocks only] array of child block
1030 pointers. Each pointer is a block number
1031 within the allocation group to the next level
1032 in the Btree.
1033 inode Inodes are allocated in "chunks" of 64 inodes each. Usually a
1035 chunk is multiple filesystem blocks, although there are cases
1036 with large filesystem blocks where a chunk is less than one
1037 block. The inode Btree (see inobt above) refers to the inode
1038 numbers per allocation group. The inode numbers directly re‐
1039 flect the location of the inode block on disk. Use the inode
1040 command to point xfs_db to a specific inode. Each inode con‐
1041 tains four regions: core, next_unlinked, u, and a. core con‐
1042 tains the fixed information. next_unlinked is separated from
1043 the core due to journaling considerations, see type agi field
1044 unlinked. u is a union structure that is different in size
1045 and format depending on the type and representation of the
1046 file data ("data fork"). a is an optional union structure to
1047 describe attribute data, that is different in size, format,
1048 and location depending on the presence and representation of
1049 attribute data, and the size of the u data ("attribute
1050 fork"). xfs_db automatically selects the proper union mem‐
1051 bers based on information in the inode.
1052 The following are fields in the inode core:
1054 magic inode magic number, 0x494e ('IN').
1055 mode mode and type of file, as described in
1056 chmod(2), mknod(2), and stat(2).
1057 version inode version, 1 or 2.
1058 format format of u union data (0: xfs_dev_t, 1: lo‐
1059 cal file - in-inode directory or symlink, 2:
1060 extent list, 3: Btree root, 4: unique id [un‐
1061 used]).
1062 nlinkv1 number of links to the file in a version 1
1063 inode.
1064 nlinkv2 number of links to the file in a version 2
1065 inode.
1066 projid_lo owner's project id (low word; version 2 inode
1067 only). projid_hi owner's project id (high
1068 word; version 2 inode only).
1069 uid owner's user id.
1070 gid owner's group id.
1071 atime time last accessed (seconds and nanoseconds).
1072 mtime time last modified.
1073 ctime time created or inode last modified.
1074 size number of bytes in the file.
1075 nblocks total number of blocks in the file including
1076 indirect and attribute.
1077 extsize basic/minimum extent size for the file.
1078 nextents number of extents in the data fork.
1079 naextents number of extents in the attribute fork.
1080 forkoff attribute fork offset in the inode, in 64-bit
1081 words from the start of u.
1082 aformat format of a data (1: local attribute data, 2:
1083 extent list, 3: Btree root).
1084 dmevmask DMAPI event mask.
1085 dmstate DMAPI state information.
1086 newrtbm file is the realtime bitmap and is "new" for‐
1087 mat.
1088 prealloc file has preallocated data space after EOF.
1089 realtime file data is in the realtime subvolume.
1090 gen inode generation number.
1091 The following fields are in the u data fork union:
1092 bmbt bmap Btree root. This looks like a bmapbtd
1093 block with redundant information removed.
1094 bmx array of extent descriptors.
1095 dev dev_t for the block or character device.
1096 sfdir shortform (in-inode) version 1 directory.
1097 This consists of a hdr containing the parent
1098 inode number and a count of active entries in
1099 the directory, followed by an array list of
1100 hdr.count entries. Each such entry contains
1101 inumber, namelen, and name string.
1102 sfdir2 shortform (in-inode) version 2 directory.
1103 This consists of a hdr containing a count of
1104 active entries in the directory, an i8count
1105 of entries with inumbers that don't fit in a
1106 32-bit value, and the parent inode number,
1107 followed by an array list of hdr.count en‐
1108 tries. Each such entry contains namelen, a
1109 saved offset used when the directory is con‐
1110 verted to a larger form, a name string, and
1111 the inumber.
1112 symlink symbolic link string value.
1113 The following fields are in the a attribute fork union if it
1114 exists:
1115 bmbt bmap Btree root, as above.
1116 bmx array of extent descriptors.
1117 sfattr shortform (in-inode) attribute values. This
1118 consists of a hdr containing a totsize (total
1119 size in bytes) and a count of active entries,
1120 followed by an array list of hdr.count en‐
1121 tries. Each such entry contains namelen, val‐
1122 uelen, root flag, name, and value.
1123 log Log blocks contain the journal entries for XFS. It's not
1125 useful to examine these with xfs_db, use xfs_logprint(8) in‐
1126 stead.
1127 refcntbt There is one set of filesystem blocks forming the reference
1129 count Btree for each allocation group. The root block of this
1130 Btree is designated by the refcntroot field in the corre‐
1131 sponding AGF block. The blocks are linked to sibling left
1132 and right blocks at each level, as well as by pointers from
1133 parent to child blocks. Each block has the following fields:
1134 magic REFC block magic number, 0x52334643 ('R3FC').
1135 level level number of this block, 0 is a leaf.
1136 numrecs number of data entries in the block.
1137 leftsib left (logically lower) sibling block, 0 if
1138 none.
1139 rightsib right (logically higher) sibling block, 0 if
1140 none.
1141 recs [leaf blocks only] array of reference count
1142 records. Each record contains startblock,
1143 blockcount, and refcount.
1144 keys [non-leaf blocks only] array of key records.
1145 These are the first value of each block in
1146 the level below this one. Each record con‐
1147 tains startblock.
1148 ptrs [non-leaf blocks only] array of child block
1149 pointers. Each pointer is a block number
1150 within the allocation group to the next level
1151 in the Btree.
1152 rmapbt There is one set of filesystem blocks forming the reverse
1154 mapping Btree for each allocation group. The root block of
1155 this Btree is designated by the rmaproot field in the corre‐
1156 sponding AGF block. The blocks are linked to sibling left
1157 and right blocks at each level, as well as by pointers from
1158 parent to child blocks. Each block has the following fields:
1159 magic RMAP block magic number, 0x524d4233 ('RMB3').
1160 level level number of this block, 0 is a leaf.
1161 numrecs number of data entries in the block.
1162 leftsib left (logically lower) sibling block, 0 if
1163 none.
1164 rightsib right (logically higher) sibling block, 0 if
1165 none.
1166 recs [leaf blocks only] array of reference count
1167 records. Each record contains startblock,
1168 blockcount, owner, offset, attr_fork,
1169 bmbt_block, and unwritten.
1170 keys [non-leaf blocks only] array of double-key
1171 records. The first ("low") key contains the
1172 first value of each block in the level below
1173 this one. The second ("high") key contains
1174 the largest key that can be used to identify
1175 any record in the subtree. Each record con‐
1176 tains startblock, owner, offset, attr_fork,
1177 and bmbt_block.
1178 ptrs [non-leaf blocks only] array of child block
1179 pointers. Each pointer is a block number
1180 within the allocation group to the next level
1181 in the Btree.
1182 rtbitmap If the filesystem has a realtime subvolume, then the rbmino
1184 field in the superblock refers to a file that contains the
1185 realtime bitmap. Each bit in the bitmap file controls the
1186 allocation of a single realtime extent (set == free). The
1187 bitmap is processed in 32-bit words, the LSB of a word is
1188 used for the first extent controlled by that bitmap word. The
1189 atime field of the realtime bitmap inode contains a counter
1190 that is used to control where the next new realtime file will
1191 start.
1192 rtsummary If the filesystem has a realtime subvolume, then the rsumino
1194 field in the superblock refers to a file that contains the
1195 realtime summary data. The summary file contains a two-dimen‐
1196 sional array of 16-bit values. Each value counts the number
1197 of free extent runs (consecutive free realtime extents) of a
1198 given range of sizes that starts in a given bitmap block.
1199 The size ranges are binary buckets (low size in the bucket is
1200 a power of 2). There are as many size ranges as are neces‐
1201 sary given the size of the realtime subvolume. The first di‐
1202 mension is the size range, the second dimension is the start‐
1203 ing bitmap block number (adjacent entries are for the same
1204 size, adjacent bitmap blocks).
1205 sb There is one sb (superblock) structure per allocation group.
1207 It is the first disk block in the allocation group. Only the
1208 first one (block 0 of the filesystem) is actually used; the
1209 other blocks are redundant information for xfs_repair(8) to
1210 use if the first superblock is damaged. Fields defined:
1211 magicnum superblock magic number, 0x58465342 ('XFSB').
1212 blocksize filesystem block size in bytes.
1213 dblocks number of filesystem blocks present in the
1214 data subvolume.
1215 rblocks number of filesystem blocks present in the
1216 realtime subvolume.
1217 rextents number of realtime extents that rblocks con‐
1218 tain.
1219 uuid unique identifier of the filesystem.
1220 logstart starting filesystem block number of the log
1221 (journal). If this value is 0 the log is
1222 "external".
1223 rootino root inode number.
1224 rbmino realtime bitmap inode number.
1225 rsumino realtime summary data inode number.
1226 rextsize realtime extent size in filesystem blocks.
1227 agblocks size of an allocation group in filesystem
1228 blocks.
1229 agcount number of allocation groups.
1230 rbmblocks number of realtime bitmap blocks.
1231 logblocks number of log blocks (filesystem blocks).
1232 versionnum filesystem version information. This value
1233 is currently 1, 2, 3, or 4 in the low 4 bits.
1234 If the low bits are 4 then the other bits
1235 have additional meanings. 1 is the original
1236 value. 2 means that attributes were used. 3
1237 means that version 2 inodes (large link
1238 counts) were used. 4 is the bitmask version
1239 of the version number. In this case, the
1240 other bits are used as flags (0x0010: at‐
1241 tributes were used, 0x0020: version 2 inodes
1242 were used, 0x0040: quotas were used, 0x0080:
1243 inode cluster alignment is in force, 0x0100:
1244 data stripe alignment is in force, 0x0200:
1245 the shared_vn field is used, 0x1000: unwrit‐
1246 ten extent tracking is on, 0x2000: version 2
1247 directories are in use).
1248 sectsize sector size in bytes, currently always 512.
1249 This is the size of the superblock and the
1250 other header blocks.
1251 inodesize inode size in bytes.
1252 inopblock number of inodes per filesystem block.
1253 fname obsolete, filesystem name.
1254 fpack obsolete, filesystem pack name.
1255 blocklog log2 of blocksize.
1256 sectlog log2 of sectsize.
1257 inodelog log2 of inodesize.
1258 inopblog log2 of inopblock.
1259 agblklog log2 of agblocks (rounded up).
1260 rextslog log2 of rextents.
1261 inprogress mkfs.xfs(8) or xfs_copy(8) aborted before
1262 completing this filesystem.
1263 imax_pct maximum percentage of filesystem space used
1264 for inode blocks.
1265 icount number of allocated inodes.
1266 ifree number of allocated inodes that are not in
1267 use.
1268 fdblocks number of free data blocks.
1269 frextents number of free realtime extents.
1270 uquotino user quota inode number.
1271 pquotino project quota inode number; this is currently
1272 unused.
1273 qflags quota status flags (0x01: user quota account‐
1274 ing is on, 0x02: user quota limits are en‐
1275 forced, 0x04: quotacheck has been run on user
1276 quotas, 0x08: project quota accounting is on,
1277 0x10: project quota limits are enforced,
1278 0x20: quotacheck has been run on project quo‐
1279 tas).
1280 flags random flags. 0x01: only read-only mounts are
1281 allowed.
1282 shared_vn shared version number (shared readonly
1283 filesystems).
1284 inoalignmt inode chunk alignment in filesystem blocks.
1285 unit stripe or RAID unit.
1286 width stripe or RAID width.
1287 dirblklog log2 of directory block size (filesystem
1288 blocks).
1289 symlink Symbolic link blocks are used only when the symbolic link
1291 value does not fit inside the inode. The block content is
1292 just the string value. Bytes past the logical end of the
1293 symbolic link value have arbitrary values.
1294 text User file blocks, and other blocks whose type is unknown,
1296 have this type for display purposes in xfs_db. The block
1297 data is displayed in two columns: Hexadecimal format and
1298 printable ASCII chars.
1299
1301 Many messages can come from the check (blockget) command. If the
1302 filesystem is completely corrupt, a core dump might be produced instead
1303 of the message
1304 device is not a valid filesystem
1305 If the filesystem is very large (has many files) then check might run
1307 out of memory. In this case the message
1308 out of memory
1309 is printed.
1310 The following is a description of the most likely problems and the as‐
1312 sociated messages. Most of the diagnostics produced are only meaning‐
1313 ful with an understanding of the structure of the filesystem.
1314 agf_freeblks n, counted m in ag a
1316 The freeblocks count in the allocation group header for alloca‐
1317 tion group a doesn't match the number of blocks counted free.
1318 agf_longest n, counted m in ag a
1320 The longest free extent in the allocation group header for allo‐
1321 cation group a doesn't match the longest free extent found in
1322 the allocation group.
1323 agi_count n, counted m in ag a
1325 The allocated inode count in the allocation group header for al‐
1326 location group a doesn't match the number of inodes counted in
1327 the allocation group.
1328 agi_freecount n, counted m in ag a
1330 The free inode count in the allocation group header for alloca‐
1331 tion group a doesn't match the number of inodes counted free in
1332 the allocation group.
1333 block a/b expected inum 0 got i
1335 The block number is specified as a pair (allocation group num‐
1336 ber, block in the allocation group). The block is used multiple
1337 times (shared), between multiple inodes. This message usually
1338 follows a message of the next type.
1339 block a/b expected type unknown got y
1341 The block is used multiple times (shared).
1342 block a/b type unknown not expected
1344
1346 mkfs.xfs(8), xfs_admin(8), xfs_copy(8), xfs_logprint(8), xfs_metad‐
1347 ump(8), xfs_ncheck(8), xfs_repair(8), mount(8), chmod(2), mknod(2),
1348 stat(2), xfs(5).
1349 xfs_db(8)