Re: [PATCH v6 3/3] writeback: switch a replaced cgwb's inodes to its successor

[Liz Fong-Jones]

Tejun,

Thanks, confirmed. On mainline, with a debug delay holding a sync's
work between its cutoff and queue_io(), v6 left 378 of 400 files empty
after a crash and v7 none. v7 holds wb_switch_rwsem across the scan and
takes your other three points:
https://lore.kernel.org/all/20261015-wb-dying-cgwb-flush-v7-0-9278d9ebaf5d@xxxxxxxxxxxx/

Since f6988c90671e, mainline's own cleanup_offline_cgwb() rotates
b_dirty_time the same way, so a racing syncfs can drop lazytime
timestamps. Separate fix:
https://lore.kernel.org/all/20261015114307.1041273-1-lizf@xxxxxxxxxxxx/

Liz