btrfs-progs/Documentation/btrfs-inspect-internal.asciidoc

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...]::
(replaces the standalone tool *btrfs-show-super*)
+
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...]::
(replaces the standalone tool *btrfs-debug-tree*)
+
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: 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, ie. the root tree keys
-R|--backups::::
same as --roots plus print backup root info, ie. 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:
[options="compact"]
* 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.
+
--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:
[options="compact"]
* case does not matter
* the C source definition, eg. BTRFS_ROOT_TREE_OBJECTID
* short forms without BTRFS_ prefix, without _TREE and _OBJECTID suffix, eg. ROOT_TREE, ROOT
* convenience aliases, eg. 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', ie. 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 64k,
maximum 16m.  Buffer sizes over 64K require kernel support for the V2 ioctl
(added in 4.15).
-v::::
(deprecated) alias for global '-v' option

*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 (ie. 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.
+
`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 btrfs wiki http://btrfs.wiki.kernel.org for
further details.

SEE ALSO
--------
`mkfs.btrfs`(8)