Re: [PATCH 01/67] mm: Stop filemap_read() from grabbing a superfluous page
From: Matthew Wilcox <willy@infradead.org>
Date: 2021-10-19 18:30:04
Also in:
ceph-devel, linux-cifs, linux-fsdevel, linux-nfs, lkml
On Mon, Oct 18, 2021 at 03:50:32PM +0100, David Howells wrote:
quoted hunk ↗ jump to hunk
@@ -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;