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 op-
tion -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 use-
ful for analyzing filesystem state or inconsistencies and has a
positive educational effect on understanding the internal
filesystem structure.
NOTE:
Contains file names, consider that if you're asked to send
the dump for analysis. Does not contain file data.
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 off-
set
-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, use-
ful for developers to inspect the dump while keeping po-
tentially 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 ex-
tended 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 read-
able 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 lin-
ear 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 buf-
size, 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
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 physi-
cal, 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 exe-
cuting the actual resize operation
Options
--id <id>
specify the device id to query, default is 1 if this op-
tion 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. sub-
vol 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 Print raw numbers in bytes.
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 or wiki http://btrfs.wiki.kernel.org for
further information.
SEE ALSO
mkfs.btrfs(8)
6.2 Feb 28, 2023 BTRFS-INSPECT-INTERNAL(8)
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