btrfs-check(8)
==============

NAME
----
btrfs-rescue - Recover a damaged btrfs filesystem

SYNOPSIS
--------
*btrfs rescue* <subcommand> <args>

DESCRIPTION
-----------
*btrfs rescue* is used to try to recover a damaged btrfs filesystem.

SUBCOMMAND
----------
*chunk-recover* [options] <device>::
Recover the chunk tree by scanning the devices
+
`Options`
+
-y::::
assume an answer of 'yes' to all questions.
-v::::
verbose mode.
-h::::
help.

NOTE: Since *chunk-recover* will scan the whole device, it will be *VERY* slow
especially executed on a large device.

*super-recover* [options] <device>::
Recover bad superblocks from good copies.
+
`Options`
+
-y::::
assume an answer of 'yes' to all questions.
-v::::
verbose mode.

*zero-log* <device>::
clear out log tree

*btrfs rescue zero-log* will remove the log tree if log tree is corrupt, which
will allow you to mount the filesystem again.

The common case where this happens has been fixed a long time ago,
so it is unlikely that you will see this particular problem.

One can determine whether *btrfs-zero-log* is needed according to the kernel
backtrace:
----
? replay_one_dir_item+0xb5/0xb5 [btrfs]
? walk_log_tree+0x9c/0x19d [btrfs]
? btrfs_read_fs_root_no_radix+0x169/0x1a1 [btrfs]
? btrfs_recover_log_trees+0x195/0x29c [btrfs]
? replay_one_dir_item+0xb5/0xb5 [btrfs]
? btree_read_extent_buffer_pages+0x76/0xbc [btrfs]
? open_ctree+0xff6/0x132c [btrfs]
----

If the errors are like above, then *zero-log* could be used to clear
the log and the filesystem may be mounted normally again.

EXIT STATUS
-----------
*btrfs rescue* 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),
`btrfs-scrub`(8),
`btrfs-check`(8)
