BTRFS-INSPECT-INTERNAL(8) BTRFS BTRFS-INSPECT-INTERNAL(8)
NAME
btrfs-inspect-internal - query various internal information
SYNOPSIS
btrfs inspect-internal <subcommand> <args>
DESCRIPTION
This command group provides an interface to query internal information.
The functionality ranges from a simple UI to an ioctl or a more complex
query that assembles the result from several internal structures. The
latter usually requires calls to privileged ioctls.
SUBCOMMAND
dump-super [options] <device> [device...]
Show btrfs superblock information stored on given devices in
textual form. By default the first superblock is printed, more
details about all copies or additional backup data can be
printed.
Besides verification of the filesystem signature, there are no
other sanity checks. The superblock checksum status is reported,
the device item and filesystem UUIDs are checked and reported.
NOTE:
The meaning of option -s has changed in version 4.8 to be
consistent with other tools to specify superblock copy rather
the offset. The old way still works, but prints a warning.
Please update your scripts to use --bytenr instead. The
option -i has been deprecated.
Options
-f|--full
print full superblock information, including the system
chunk array and backup roots
-a|--all
print information about all present superblock copies
(cannot be used together with -s option)
-i <super>
(deprecated since 4.8, same behaviour as --super)
--bytenr <bytenr>
specify offset to a superblock in a non-standard location
at bytenr, useful for debugging (disables the -f option)
If there are multiple options specified, only the last
one applies.
-F|--force
attempt to print the superblock even if a valid BTRFS
signature is not found; the result may be completely
wrong if the data does not resemble a superblock
-s|--super <bytenr>
(see compatibility note above)
specify which mirror to print, valid values are 0, 1 and
2 and the superblock must be present on the device with a
valid signature, can be used together with --force
dump-tree [options] <device> [device...]
Dump tree structures from a given device in textual form, expand
keys to human readable equivalents where possible. This is
useful for analyzing filesystem state or inconsistencies and has
a positive educational effect on understanding the internal
filesystem structure.
NOTE:
By default contains file names, consider that if you're asked
to send the dump for analysis and use --hide-names
eventually. Does not contain file data.
Special characters in file names, xattr names and values are
escaped, in the C style like \n and octal encoding \NNN.
Options
-e|--extents
print only extent-related information: extent and device
trees
-d|--device
print only device-related information: tree root, chunk
and device trees
-r|--roots
print only short root node information, i.e. the root
tree keys
-R|--backups
same as --roots plus print backup root info, i.e. the
backup root keys and the respective tree root block
offset
-u|--uuid
print only the uuid tree information, empty output if the
tree does not exist
-b <block_num>
print info of the specified block only, can be specified
multiple times
--follow
use with -b, print all children tree blocks of
<block_num>
--dfs (default up to 5.2)
use depth-first search to print trees, the nodes and
leaves are intermixed in the output
--bfs (default since 5.3)
use breadth-first search to print trees, the nodes are
printed before all leaves
--hide-names
print a placeholder HIDDEN instead of various names,
useful for developers to inspect the dump while keeping
potentially sensitive information hidden
This is:
• directory entries (files, directories, subvolumes)
• default subvolume
• extended attributes (name, value)
• hardlink names (if stored inside another item or as
extended references in standalone items)
NOTE:
Lengths are not hidden because they can be calculated
from the item size anyway.
--csum-headers
print b-tree node checksums stored in headers (metadata)
--csum-items
print checksums stored in checksum items (data)
--noscan
do not automatically scan the system for other devices
from the same filesystem, only use the devices provided
as the arguments
-t <tree_id>
print only the tree with the specified ID, where the ID
can be numerical or common name in a flexible human
readable form
The tree id name recognition rules:
• case does not matter
• the C source definition, e.g. BTRFS_ROOT_TREE_OBJECTID
• short forms without BTRFS_ prefix, without _TREE and
_OBJECTID suffix, e.g. ROOT_TREE, ROOT
• convenience aliases, e.g. DEVICE for the DEV tree,
CHECKSUM for CSUM
• unrecognized ID is an error
inode-resolve [-v] <ino> <path>
(needs root privileges)
resolve paths to all files with given inode number ino in a
given subvolume at path, i.e. all hardlinks
Options
-v (deprecated) alias for global -v option
logical-resolve [-Pvo] [-s <bufsize>] <logical> <path>
(needs root privileges)
resolve paths to all files at given logical address in the
linear filesystem space
Options
-P skip the path resolving and print the inodes instead
-o ignore offsets, find all references to an extent instead
of a single block. Requires kernel support for the V2
ioctl (added in 4.15). The results might need further
processing to filter out unwanted extents by the offset
that is supposed to be obtained by other means.
-s <bufsize>
set internal buffer for storing the file names to
bufsize, default is 64KiB, maximum 16MiB. Buffer sizes
over 64KiB require kernel support for the V2 ioctl (added
in 4.15).
-v (deprecated) alias for global -v option
list-chunks [options] <path>
(needs root privileges)
Enumerate chunks on all devices. The chunks represent the
physical range on devices (not to be confused with block groups
that represent the logical ranges, but the terms are often used
interchangeably).
Example output:
Devid PNumber Type/profile PStart Length PEnd LNumber LStart Usage%
----- ------- ----------------- --------- --------- --------- ------- --------- ------
1 1 Data/single 1.00MiB 84.00MiB 85.00MiB 68 191.60GiB 62.77
1 2 System/DUP 85.00MiB 32.00MiB 117.00MiB 39 140.17GiB 0.05
1 3 System/DUP 117.00MiB 32.00MiB 149.00MiB 40 140.17GiB 0.05
1 4 Metadata/DUP 149.00MiB 192.00MiB 341.00MiB 59 188.41GiB 45.00
1 5 Metadata/DUP 341.00MiB 192.00MiB 533.00MiB 60 188.41GiB 45.00
1 6 Data/single 533.00MiB 1.00GiB 1.52GiB 49 169.91GiB 72.23
1 7 Data/single 1.52GiB 16.00MiB 1.54GiB 69 191.68GiB 79.83
1 8 Data/single 1.54GiB 1.00GiB 2.54GiB 17 100.90GiB 46.39
1 9 Data/single 2.54GiB 1.00GiB 3.54GiB 16 99.90GiB 40.68
1 10 Data/single 3.54GiB 1.00GiB 4.54GiB 1 71.40GiB 62.97
1 11 Data/single 4.54GiB 1.00GiB 5.54GiB 33 125.04GiB 26.00
1 12 Data/single 5.54GiB 1.00GiB 6.54GiB 50 170.91GiB 60.44
1 13 Data/single 6.54GiB 512.00MiB 7.04GiB 63 189.16GiB 67.34
1 14 Data/single 7.04GiB 1.00GiB 8.04GiB 51 171.91GiB 70.94
• Devid -- the device id
• PNumber -- the number of the chunk on the device (in order)
• Type/profile -- the chunk type and profile
• PStart -- the chunk start on the device
• Length -- the chunk length (same for physical and logical
address space)
• PEnd -- the chunk end, effectively PStart + Length
• LNumber -- the number of the chunk, in the logical address
space of the whole filesystem
• LStart -- the chunk start in the logical address space of the
whole filesystem, as it's a single space it's also called
offset
• Usage -- chunk usage, percentage of used data/metadata of the
chunk length
The chunks in the output can be sorted by one or more sorting
criteria, evaluated as specified, in the ascending order. By
default the chunks are sorted by devid and pstart, this is most
convenient for single device filesystems.
On multi-device filesystems it's up to the user what is
preferred as the layout of chunks on e.g. striped profiles
(RAID0 etc) cannot be easily represented. A logical view with
corresponding underlying structure would be better, but sorting
by lstart,devid at least groups devices of the given logical
range. Can be also combined with usage.
This output can provide information for balance filters.
Options
--sort MODE
sort by a column (ascending):
MODE is a comma separated list of:
devid - by device id (default, with pstart)
pstart - physical start (relative to the beginning of
the device)
lstart - logical offset (in the logical address space)
usage - by chunk usage (percentage)
length - by chunk length
--raw raw numbers in bytes, without the B suffix
--human-readable
print human friendly numbers, base 1024, this is the
default
--iec select the 1024 base for the following options, according
to the IEC standard
--si select the 1000 base for the following options, according
to the SI standard
--kbytes
show sizes in KiB, or kB with --si
--mbytes
show sizes in MiB, or MB with --si
--gbytes
show sizes in GiB, or GB with --si
--tbytes
show sizes in TiB, or TB with --si
map-swapfile [options] <file>
(needs root privileges)
Find device-specific physical offset of file that can be used
for hibernation. Also verify that the file is suitable as a
swapfile. See also command btrfs filesystem mkswapfile and the
Swapfile feature description.
NOTE:
Do not use filefrag or FIEMAP ioctl values reported as
physical, this is different due to internal filesystem
mappings. The hibernation expects offset relative to the
physical block device.
Options
-r|--resume-offset
print only the value suitable as resume offset for file
/sys/power/resume_offset
min-dev-size [options] <path>
(needs root privileges)
return the minimum size the device can be shrunk to, without
performing any resize operation, this may be useful before
executing the actual resize operation
Options
--id <id>
specify the device id to query, default is 1 if this
option is not used
rootid <path>
for a given file or directory, return the containing tree root
id, but for a subvolume itself return its own tree id (i.e.
subvol id)
NOTE:
The result is undefined for the so-called empty subvolumes
(identified by inode number 2), but such a subvolume does not
contain any files anyway
subvolid-resolve <subvolid> <path>
(needs root privileges)
resolve the absolute path of the subvolume id subvolid
tree-stats [options] <device>
(needs root privileges)
Print sizes and statistics of trees. This takes a device as an
argument and not a mount point unlike other commands.
NOTE:
In case the the filesystem is still mounted it's possible to
run the command but the results may be inaccurate or various
errors may be printed in case there are ongoing writes to the
filesystem. A warning is printed in such case.
Options
-b|--raw
raw numbers in bytes, without the B suffix
-t <tree_id>
print only the tree with the specified ID, where the ID
can be numerical or common name in a flexible human
readable form
The tree id name recognition rules:
• case does not matter
• the C source definition, e.g. BTRFS_ROOT_TREE_OBJECTID
• short forms without BTRFS_ prefix, without _TREE and
_OBJECTID suffix, e.g. ROOT_TREE, ROOT
• convenience aliases, e.g. DEVICE for the DEV tree,
CHECKSUM for CSUM
• unrecognized ID is an error
--human-readable
print human friendly numbers, base 1024, this is the
default
--iec select the 1024 base for the following options, according
to the IEC standard
--si select the 1000 base for the following options, according
to the SI standard
--kbytes
show sizes in KiB, or kB with --si
--mbytes
show sizes in MiB, or MB with --si
--gbytes
show sizes in GiB, or GB with --si
--tbytes
show sizes in TiB, or TB with --si
EXIT STATUS
btrfs inspect-internal returns a zero exit status if it succeeds. Non
zero is returned in case of failure.
AVAILABILITY
btrfs is part of btrfs-progs. Please refer to the documentation at
https://btrfs.readthedocs.io.
SEE ALSO
mkfs.btrfs(8)
6.16.1 September 10, 2025 BTRFS-INSPECT-INTERNAL(8)
btrfs inspect internal \- query various internal information