Re: [PATCH v2 0/3] btrfs: handle missing block group and raid stripe tree roots

在 2026/7/13 18:20, Dongjiang Zhu 写道:
> The rescue=ignorebadroots mount option allows mounting to continue when
> some tree roots cannot be loaded. For the block group tree and raid stripe
> tree, this leaves the corresponding root pointer NULL while the on-disk
> feature bit remains set.
> 
> btrfs_update_global_block_rsv() accounts both trees based only on their
> feature bits, so it dereferences the missing root while mounting. Rescue
> mounts are fully read-only and cannot start transactions, so they do not
> need a real global block reserve.
> 
> This series moves the full read-only helper to fs.h and uses it to skip
> global reserve accounting for rescue mounts. It also reports a missing
> raid stripe tree root explicitly if a later data read requires a raid
> stripe lookup.
> 
> Changes in v2:
> - Replace the per-root NULL checks with a dummy global block reserve for
>    full read-only mounts, as suggested by Qu Wenruo.
> - Move and rename fs_is_full_ro() so the global reserve code can use it.
> 
> v1:
> https://lore.kernel.org/linux-btrfs/[email protected]/

Looks good to me overall.

Reviewed-by: Qu Wenruo <[email protected]>

> 
> Dongjiang Zhu (3):
>    btrfs: move the full read-only helper to fs.h
>    btrfs: skip global block reserve accounting for rescue mounts

I'll squash the btrfs_is_full_ro() commit into this one, as that is the 
only commit utilizing it.

I can do this at merge time so no need to refresh the series.

Thanks,
Qu

>    btrfs: report missing raid stripe tree root during lookup
> 
>   fs/btrfs/block-rsv.c        | 19 +++++++++++++++++--
>   fs/btrfs/disk-io.c          | 11 +----------
>   fs/btrfs/fs.h               |  9 +++++++++
>   fs/btrfs/raid-stripe-tree.c |  7 +++++++
>   4 files changed, 34 insertions(+), 12 deletions(-)
>