On Sat, Apr 05, 2014 at 04:00:27PM -0600, cwillu wrote:
> On Fri, Apr 4, 2014 at 12:46 PM, Marc MERLIN <marc@merlins.org> wrote:
> > On Wed, Apr 02, 2014 at 04:29:35PM +0800, Qu Wenruo wrote:
> >> Convert man page for btrfs-zero-log
> >>
> >> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
> >> ---
> >>  Documentation/Makefile           |  2 +-
> >>  Documentation/btrfs-zero-log.txt | 39 +++++++++++++++++++++++++++++++++++++++
> >>  2 files changed, 40 insertions(+), 1 deletion(-)
> >>  create mode 100644 Documentation/btrfs-zero-log.txt
> >>
> >> diff --git a/Documentation/Makefile b/Documentation/Makefile
> >> index e002d53..de06629 100644
> >> --- a/Documentation/Makefile
> >> +++ b/Documentation/Makefile
> >> @@ -11,7 +11,7 @@ MAN8_TXT += btrfs-image.txt
> >>  MAN8_TXT += btrfs-map-logical.txt
> >>  MAN8_TXT += btrfs-show-super.txt
> >>  MAN8_TXT += btrfstune.txt
> >> -#MAN8_TXT += btrfs-zero-log.txt
> >> +MAN8_TXT += btrfs-zero-log.txt
> >>  #MAN8_TXT += fsck.btrfs.txt
> >>  #MAN8_TXT += mkfs.btrfs.txt
> >>
> >> diff --git a/Documentation/btrfs-zero-log.txt b/Documentation/btrfs-zero-log.txt
> >> new file mode 100644
> >> index 0000000..e3041fa
> >> --- /dev/null
> >> +++ b/Documentation/btrfs-zero-log.txt
> >> @@ -0,0 +1,39 @@
> >> +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.
> >
> > A note on this one: this can happen if your SSD rites things in the
> > wrong order or potentially writes garbage when power is lost, or before
> > locking up.
> > I hit this problem about 10 times and it wasn't a btrfs bug, just the
> > drive doing bad things.
> 
> And -o recovery didn't work around it?  My understanding is that -o
> recovery will skip reading the log.

   No, I'm pretty sure we've had people with problems with the log
where -orecovery didn't help, but -oro,recovery allowed it to be
mounted, because -ro didn't try to replay the log.

   Hugo.

-- 
=== Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk ===
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     --- If the first-ever performance is the première,  is the ---     
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