From: Matthew Wilcox <willy@infradead.org>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Andreas Gruenbacher <agruenba@redhat.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Christoph Hellwig <hch@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org, Jeff Layton <jlayton@kernel.org>,
Sage Weil <sage@redhat.com>, Ilya Dryomov <idryomov@gmail.com>,
Theodore Ts'o <tytso@mit.edu>,
Andreas Dilger <adilger.kernel@dilger.ca>,
Jaegeuk Kim <jaegeuk@kernel.org>, Chao Yu <chao@kernel.org>,
linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Richard Weinberger <richard@nod.at>,
Artem Bityutskiy <dedekind1@gmail.com>,
Adrian Hunter <adrian.hunter@intel.com>,
ceph-devel@vger.kernel.org, linux-ext4@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net,
linux-mtd@lists.infradead.org, Chris Mason <clm@fb.com>,
Josef Bacik <josef@toxicpanda.com>,
David Sterba <dsterba@suse.com>,
linux-btrfs@vger.kernel.org, Jan Kara <jack@suse.cz>
Subject: Re: [PATCH v3] fs: Fix page_mkwrite off-by-one errors
Date: Wed, 18 Dec 2019 11:21:44 -0800 [thread overview]
Message-ID: <20191218192144.GF32169@bombadil.infradead.org> (raw)
In-Reply-To: <20191218185216.GA7497@magnolia>
On Wed, Dec 18, 2019 at 10:52:16AM -0800, Darrick J. Wong wrote:
> > @@ -9016,13 +9016,11 @@ vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf)
> > ret = VM_FAULT_NOPAGE; /* make the VM retry the fault */
> > again:
> > lock_page(page);
> > - size = i_size_read(inode);
> >
> > - if ((page->mapping != inode->i_mapping) ||
> > - (page_start >= size)) {
> > - /* page got truncated out from underneath us */
> > + ret2 = page_mkwrite_check_truncate(page, inode);
> > + if (ret2 < 0)
> > goto out_unlock;
>
> ...here we try to return -EFAULT as vm_fault_t. Notice how btrfs returns
> VM_FAULT_* values directly and never calls block_page_mkwrite_return? I
> know dsterba acked this, but I cannot see how this is correct?
I think you misread it. 'ret2' is never returned; we'll end up returning
VM_FAULT_NOPAGE here. Arguably it should be SIGBUS or something, but
I think retrying the fault will also end up giving a SIGBUS.
next prev parent reply other threads:[~2019-12-18 19:21 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-18 13:09 [PATCH v3] fs: Fix page_mkwrite off-by-one errors Andreas Gruenbacher
2019-12-18 14:10 ` Jan Kara
2019-12-18 18:52 ` Darrick J. Wong
2019-12-18 19:15 ` Andreas Gruenbacher
2019-12-18 19:23 ` Darrick J. Wong
2019-12-22 1:59 ` Theodore Y. Ts'o
2019-12-18 19:21 ` Matthew Wilcox [this message]
2020-01-07 23:20 ` Darrick J. Wong
2020-01-08 9:09 ` Chao Yu
2020-01-08 11:51 ` Jaegeuk Kim
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