| Date | Tue, 19 Oct 2021 19:28:02 +0100 | From | Matthew Wilcox <> | Subject | Re: [PATCH 01/67] mm: Stop filemap_read() from grabbing a superfluous page |
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On Mon, Oct 18, 2021 at 03:50:32PM +0100, David Howells wrote: > @@ -2625,6 +2625,10 @@ ssize_t filemap_read(struct kiocb *iocb, struct iov_iter *iter, > if ((iocb->ki_flags & IOCB_WAITQ) && already_read) > iocb->ki_flags |= IOCB_NOWAIT; > > + isize = i_size_read(inode); > + if (unlikely(iocb->ki_pos >= isize)) > + goto put_pages; > +
Is there a good reason to assign to isize here? I'd rather not, because it complicates analysis, and a later change might look at the isize read here, not realising it was a racy use. So I'd rather see:
if (unlikely(iocb->ki_pos >= i_size_read(inode))) goto put_pages;
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