From: Matthew Wilcox <willy@infradead.org>
To: David Howells <dhowells@redhat.com>
Cc: linux-cachefs@redhat.com,
Kent Overstreet <kent.overstreet@gmail.com>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
Trond Myklebust <trondmy@hammerspace.com>,
Anna Schumaker <anna.schumaker@netapp.com>,
Steve French <sfrench@samba.org>,
Dominique Martinet <asmadeus@codewreck.org>,
Jeff Layton <jlayton@redhat.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Omar Sandoval <osandov@osandov.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org,
linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org,
v9fs-developer@lists.sourceforge.net,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 01/67] mm: Stop filemap_read() from grabbing a superfluous page
Date: Tue, 19 Oct 2021 19:28:02 +0100 [thread overview]
Message-ID: <YW8OMsrEzrY8aSxo@casper.infradead.org> (raw)
In-Reply-To: <163456863216.2614702.6384850026368833133.stgit@warthog.procyon.org.uk>
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;
next prev parent reply other threads:[~2021-10-19 18:30 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-18 14:50 [PATCH 00/67] fscache: Rewrite index API and management system David Howells
2021-10-18 14:50 ` [PATCH 01/67] mm: Stop filemap_read() from grabbing a superfluous page David Howells
2021-10-19 17:13 ` Jeff Layton
2021-10-19 18:28 ` Matthew Wilcox [this message]
2021-10-19 18:48 ` David Howells
2021-10-19 20:04 ` Matthew Wilcox
2021-10-19 13:29 ` [Linux-cachefs] [PATCH 00/67] fscache: Rewrite index API and management system Marc Dionne
2021-10-19 18:08 ` Jeff Layton
2021-10-19 19:00 ` David Howells
2021-10-21 22:20 ` Omar Sandoval
2021-10-21 23:15 ` Steve French
2021-10-21 23:43 ` Jeff Layton
2021-10-22 18:52 ` David Howells
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