Re: Improve page refcount scalability

[Kiryl Shutsemau]

On Thu, Oct 15, 2026 at 02:12:19AM +0000, Jaegeuk Kim wrote:
> Indeed, it's a bug that user can see zeros between F2FS_IOC_START_ATOMIC_REPLACE
> and F2FS_IOC_COMMIT_ATOMIC_WRITE. I think we need to move the truncation path
> into the commit phase and use truncate_inode_pages() instead.

What about f2fs_abort_atomic_write(inode, true)?

It calls truncate_inode_pages_final() as well. As far as I can see, it
runs on the last writer's close (f2fs_release_file()), on flush when the
atomic writer exits (f2fs_file_flush()), from
F2FS_IOC_ABORT_ATOMIC_WRITE and when F2FS_IOC_COMMIT_ATOMIC_WRITE fails.

Can other processes still have the file open at those points?

AS_EXITING is never cleared. Does the inode then stay "exiting" until
it is evicted? If so, reclaim stops leaving shadow entries for the file,
and with the rcu-free series a hot folio of it could be freed without a
grace period while a reader still has the file open.

Would truncate_inode_pages() work for the abort path too?

-- 
  Kiryl Shutsemau / Kirill A. Shutemov