Messages in this thread | | | From | David Howells <> | Subject | Re: [PATCH 2/2] mm: Make swap_readpage() for SWP_FS_OPS use ->direct_IO() not ->readpage() | Date | Thu, 12 Aug 2021 14:37:59 +0100 |
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David Howells <dhowells@redhat.com> wrote:
> Matthew Wilcox <willy@infradead.org> wrote: > > > 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? > > When I was doing something similar for cachefiles, I couldn't get it to work > like that. I'll have another look at that.
Ah, yes. generic_file_direct_write() accesses in the kiocb *after* calling ->direct_IO(), so the kiocb *must not* go away until after generic_file_direct_write() has returned.
David
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