On 25.07.19 г. 9:12 ч., Qu Wenruo wrote:
> Another wave of defence enhancment, including:
>
> - Enhanced eb accessors
> Not really needed for the fuzzed images, as 448de471cd4c
> ("btrfs: Check the first key and level for cached extent buffer")
> already fixed half of the reported images.
> Just add a final layer of safe net.
>
> Just to complain here, two experienced btrfs developer have got
> confused by @start, @len in functions like read_extent_buffer() with
> logical address.
> The best example to solve the confusion is to check the
> read_extent_buffer() call in btree_read_extent_buffer_pages().
>
> I'm not sure why this confusion happens or even get spread.
> My guess is the extent_buffer::start naming causing the problem.
>
> If so, I would definitely rename extent_buffer::start to
> extent_buffer::bytenr at any cost.
> Hopes the new commend will address the problem for now.
it should either be bytenr or disk_bytenr or disk_addr or address.
Looking at the code base though, it seems there is already a convention
that bytenr means the byte number in the logical address space. So
indeed, bytenr should be ok.
>
> - BUG_ON() hunt in __btrfs_free_extent()
> Kill BUG_ON()s in __btrfs_free_extent(), replace with error reporting
> and why it shouldn't happen.
>
> Also add comment on what __btrfs_free_extent() is designed to do, with
> two dump-tree examples for newcomers.
>
> - BUG_ON() hunt in __btrfs_inc_extent_ref()
> Just like __btrfs_free_extent(), but less comment as
> comment for __btrfs_free_extent() should also work for
> __btrfs_inc_extent_ref(), and __btrfs_inc_extent_ref() has a better
> structure than __btrfs_free_extent().
>
> - Defence against unbalanced empty leaf
>
> - Defence against bad key order across two tree blocks
>
> The last two cases can't be rejected by tree-checker and they are all
> cross-eb cases.
> Thankfully we can reuse existing first_key check against unbalanced
> empty leaf, but needs extra check deep into ctree.c for tree block
> merging time check.
>
> Reported-by: Jungyeon Yoon <jungyeon.yoon@xxxxxxxxx>
> [ Not to mail bombarding the report, thus only RB tag in cover letter ]
>
> Changelog:
> v2:
> - Remove duplicated error message in WARN() call.
> Changed to WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG))
> Also move WARN() after btrfs error message.
>
> - Fix a comment error in __btrfs_free_extent()
> It's not adding refs to a tree block, but adding the same refs
> to an existing tree block ref.
> It's impossible a btrfs tree owning the same tree block directly twice.
>
> - Add comment for eb accessors about @start and @len
> If anyone could tell me why such confusion between @start @len and
> logical address is here, I will definitely solve the root cause no
> matter how many codes need to be modified.
>
> - Use bool to replace int where only two values are returned
> Also rename to follow the bool type.
>
> - Remove one unrelated change for the error handler in
> btrfs_inc_extent_ref()
>
> - Add Reviewed-by tag
>
> Qu Wenruo (5):
> btrfs: extent_io: Do extra check for extent buffer read write
> functions
> btrfs: extent-tree: Kill BUG_ON() in __btrfs_free_extent() and do
> better comment
> btrfs: Detect unbalanced tree with empty leaf before crashing btree
> operations
> btrfs: extent-tree: Kill the BUG_ON() in
> insert_inline_extent_backref()
> btrfs: ctree: Checking key orders before merged tree blocks
>
> fs/btrfs/ctree.c | 68 +++++++++++++++++
> fs/btrfs/disk-io.c | 8 ++
> fs/btrfs/extent-tree.c | 164 ++++++++++++++++++++++++++++++++++++----
> fs/btrfs/extent_io.c | 76 ++++++++++---------
> fs/btrfs/tree-checker.c | 6 ++
> 5 files changed, 271 insertions(+), 51 deletions(-)
>
