Re: [PATCH] btrfs: make sure that WRITTEN is set on all metadata blocks

[David Sterba <dsterba@suse.cz>]

On Mon, Apr 29, 2024 at 09:03:35AM -0400, Josef Bacik wrote:
> We previously would call btrfs_check_leaf() if we had the check
> integrity code enabled, which meant that we could only run the extended
> leaf checks if we had WRITTEN set on the header flags.
> 
> This leaves a gap in our checking, because we could end up with
> corruption on disk where WRITTEN isn't set on the leaf, and then the
> extended leaf checks don't get run which we rely on to validate all of
> the item pointers to make sure we don't access memory outside of the
> extent buffer.
> 
> However, since 732fab95abe2 ("btrfs: check-integrity: remove
> CONFIG_BTRFS_FS_CHECK_INTEGRITY option") we no longer call
> btrfs_check_leaf() from btrfs_mark_buffer_dirty(), which means we only
> ever call it on blocks that are being written out, and thus have WRITTEN
> set, or that are being read in, which should have WRITTEN set.
> 
> Add checks to make sure we have WRITTEN set appropriately, and then make
> sure __btrfs_check_leaf() always does the item checking.  This will
> protect us from file systems that have been corrupted and no longer have
> WRITTEN set on some of the blocks.
> 
> Reported-by: lei lu <llfamsec@gmail.com>
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>

Reviewed-by: David Sterba <dsterba@suse.com>