On Tue, 29 Apr 2025 19:55:36 +0200, Jan Kara wrote:
> Luis and David are reporting that after running generic/750 test for 90+
> hours on 2k ext4 filesystem, they are able to trigger a warning in
> jbd2_journal_dirty_metadata() complaining that there are not enough
> credits in the running transaction started in ext4_do_writepages().
>
> Indeed the code in ext4_do_writepages() is racy and the extent tree can
> change between the time we compute credits necessary for extent tree
> computation and the time we actually modify the extent tree. Thus it may
> happen that the number of credits actually needed is higher. Modify
> ext4_ext_index_trans_blocks() to count with the worst case of maximum
> tree depth. This can reduce the possible number of writers that can
> operate in the system in parallel (because the credit estimates now won't
> fit in one transaction) but for reasonably sized journals this shouldn't
> really be an issue. So just go with a safe and simple fix.
>
> [...]
Applied, thanks!
[1/1] ext4: Fix calculation of credits for extent tree modification
commit: 32a93f5bc9b9812fc710f43a4d8a6830f91e4988
Best regards,
--
Theodore Ts'o <tytso@xxxxxxx>
