Re: [PATCH 0/5] New rescue mount options

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

[-- Attachment #1.1: Type: text/plain, Size: 2592 bytes --]



On 2020/9/24 下午11:32, Josef Bacik wrote:
> Hello,
> 
> This is the next version of my rescue=all patches, this time broken up in to a
> few discrete patches, with some cleanups as well.  I have a PR for the xfstest
> that exercises these options, it can be found here
> 
>   https://github.com/btrfs/fstests/pull/35
> 
> This is the same idea as the previous versions, except I've made a mechanical
> change.  Instead we have rescue=ignorebadroots, which ignores any global roots
> that we may not be able to read.  We will still fail to mount if thinks like the
> chunk root or the tree root are corrupt, but this will allow us to mount read
> only if the extent root or csum root are completely hosed.
> 
> I've added a new patch this go around, rescue=ignoredatacsums.  Somebody had
> indicated that they would prefer that the original rescue=all allowed us to
> continue to read csums if the root was still intact.  In order to handle that
> usecase that's what you get with rescue=ignorebadroots, however if your csum
> tree is corrupt in the middle of the tree you could still end up with problems.
> Thus we have rescue=ignoredatacsums which will completely disable the csum tree
> as well.

The extra hard ignore for data csum is really good.

> 
> And finally we have rescue=all, which simply enables ignoredatacsums,
> ignorebadroots, and notreelogreplay.  We need an easy catch-all option for
> distros to fallback on to get users the highest probability of being able to
> recover their data, so we will use rescue=all to turn on all the fanciest rescue
> options that we have, and then use the discrete options for more fine grained
> recovery.  Thanks,

Now rescue=all makes more sense. It's just an alias for one to salvage
as much data as possible.

Thanks,
Qu
> 
> Josef
> 
> Josef Bacik (5):
>   btrfs: unify the ro checking for mount options
>   btrfs: push the NODATASUM check into btrfs_lookup_bio_sums
>   btrfs: introduce rescue=ignorebadroots
>   btrfs: introduce rescue=ignoredatacsums
>   btrfs: introduce rescue=all
> 
>  fs/btrfs/block-group.c | 48 +++++++++++++++++++++++++++
>  fs/btrfs/block-rsv.c   |  8 +++++
>  fs/btrfs/compression.c | 17 ++++------
>  fs/btrfs/ctree.h       |  2 ++
>  fs/btrfs/disk-io.c     | 74 +++++++++++++++++++++++++++---------------
>  fs/btrfs/file-item.c   |  4 +++
>  fs/btrfs/inode.c       | 18 +++++++---
>  fs/btrfs/super.c       | 49 ++++++++++++++++++++++++----
>  fs/btrfs/volumes.c     |  7 ++++
>  9 files changed, 179 insertions(+), 48 deletions(-)
> 


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 488 bytes --]