Messages in this thread | | | Date | Thu, 12 Aug 2021 14:00:14 +0100 | From | Matthew Wilcox <> | Subject | Re: [PATCH 2/2] mm: Make swap_readpage() for SWP_FS_OPS use ->direct_IO() not ->readpage() |
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On Thu, Aug 12, 2021 at 12:57:58PM +0100, David Howells wrote:
I'm not quite sure why we need the refcount.
> + refcount_set(&ki->ki_refcnt, 2); > + init_sync_kiocb(&ki->iocb, swap_file); > + ki->page = page; > + ki->iocb.ki_flags = IOCB_DIRECT | IOCB_SWAP; > + ki->iocb.ki_pos = page_file_offset(page); > + ki->iocb.ki_filp = get_file(swap_file); > + if (!synchronous) > + ki->iocb.ki_complete = swapfile_read_complete; > + > + iov_iter_bvec(&to, READ, &bv, 1, PAGE_SIZE); > + ret = swap_file->f_mapping->a_ops->direct_IO(&ki->iocb, &to);
After submitting the IO here ...
> + if (ret != -EIOCBQUEUED) > + swapfile_read_complete(&ki->iocb, ret, 0);
We only touch the 'ki' here ... if the caller didn't call read_complete
> + swapfile_put_kiocb(ki);
Except for here, which is only touched in order to put the refcount.
So why can't swapfile_read_complete() do the work of freeing the ki?
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