btrfs-progs: doc: update btrfs-rescue page and drop btrfs-zero-log

- fix page title
- update zero-log text
- delete btrfs-zero-log.asciidoc as page is not shipped anymore

Signed-off-by: David Sterba <dsterba@suse.cz>
This commit is contained in:
David Sterba 2015-06-04 15:54:22 +02:00
parent 1d46539284
commit 4f43aaf4aa
2 changed files with 16 additions and 53 deletions

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@ -1,4 +1,4 @@
btrfs-check(8)
btrfs-rescue(8)
==============
NAME
@ -41,15 +41,21 @@ assume an answer of 'yes' to all questions.
verbose mode.
*zero-log* <device>::
clear out log tree
clear the filesystem 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.
This command will clear the filesystem log tree. This may fix a specific
set of problem when the filesystem mount fails due to the log replay. See below
for sample stacktraces that may show up in system log.
The common case where this happens has been fixed a long time ago,
so it is unlikely that you will see this particular problem.
so it is unlikely that you will see this particular problem, but the utility is
kept around.
One can determine whether *btrfs-zero-log* is needed according to the kernel
NOTE: clearing the log may lead to loss of changes that were made since the
last transaction commit. This may be up to 30 seconds (default commit period)
or less if the commit was implied by other filesystem activity.
One can determine whether *zero-log* is needed according to the kernel
backtrace:
----
? replay_one_dir_item+0xb5/0xb5 [btrfs]
@ -61,8 +67,10 @@ backtrace:
? 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.
If the errors are like above, then *zero-log* should be used to clear
the log and the filesystem may be mounted normally again. The keywords to look
for are 'open_ctree' which says that it's during mount and function names
that contain 'replay', 'recover' or 'log_tree'.
EXIT STATUS
-----------

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btrfs-zero-log(8)
=================
NAME
----
btrfs-zero-log - clear out log tree
SYNOPSIS
--------
*btrfs-zero-log* <dev>
DESCRIPTION
-----------
*btrfs-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 *btrfs-zero-log* should be used to clear
the log and the filesystem may be mounted normally again.
NOTE: If you use btrfs as the root filesystem, you may want to include
*btrfs-zero-log* into initramdisk if the log problems hits you often.
EXIT STATUS
-----------
*btrfs-zero-log* will return 0 if no error happened.
Other exit code means some problems happened.
SEE ALSO
--------
`mkfs.btrfs`(8)