From: Ross Zwisler <ross.zwisler@linux.intel.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>,
linux-kernel@vger.kernel.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Dan Williams <dan.j.williams@intel.com>,
Dave Chinner <david@fromorbit.com>, Jan Kara <jack@suse.com>,
Matthew Wilcox <willy@linux.intel.com>,
linux-fsdevel@vger.kernel.org, linux-nvdimm@ml01.01.org
Subject: Re: [PATCH 2/2] dax: fix bdev NULL pointer dereferences
Date: Fri, 29 Jan 2016 11:28:15 -0700 [thread overview]
Message-ID: <20160129182815.GB5224@linux.intel.com> (raw)
In-Reply-To: <20160128213858.GA29114@infradead.org>
On Thu, Jan 28, 2016 at 01:38:58PM -0800, Christoph Hellwig wrote:
> On Thu, Jan 28, 2016 at 12:35:04PM -0700, Ross Zwisler wrote:
> > There are a number of places in dax.c that look up the struct block_device
> > associated with an inode. Previously this was done by just using
> > inode->i_sb->s_bdev. This is correct for inodes that exist within the
> > filesystems supported by DAX (ext2, ext4 & XFS), but when running DAX
> > against raw block devices this value is NULL. This causes NULL pointer
> > dereferences when these block_device pointers are used.
>
> It's also wrong for an XFS file system with a RT device..
>
> > +#define DAX_BDEV(inode) (S_ISBLK(inode->i_mode) ? I_BDEV(inode) \
> > + : inode->i_sb->s_bdev)
>
> .. but this isn't going to fix it. You must use a bdev returned by
> get_blocks or a similar file system method.
I guess I need to go off and understand if we can have DAX mappings on such a
device. If we can, we may have a problem - we can get the block_device from
get_block() in I/O path and the various fault paths, but we don't have access
to get_block() when flushing via dax_writeback_mapping_range(). We avoid
needing it the normal case by storing the sector results from get_block() in
the radix tree.
/me is off to play with RT devices...
next prev parent reply other threads:[~2016-01-29 18:28 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-28 19:35 [PATCH 1/2] block: fix pfn_mkwrite() DAX fault handler Ross Zwisler
2016-01-28 19:35 ` Ross Zwisler
2016-01-28 19:35 ` [PATCH 2/2] dax: fix bdev NULL pointer dereferences Ross Zwisler
2016-01-28 19:35 ` Ross Zwisler
2016-01-28 20:21 ` Dan Williams
2016-01-28 20:21 ` Dan Williams
2016-01-28 21:38 ` Christoph Hellwig
2016-01-29 18:28 ` Ross Zwisler [this message]
2016-01-29 23:34 ` Ross Zwisler
2016-01-30 0:18 ` Dan Williams
2016-01-31 22:44 ` Dave Chinner
2016-01-30 5:28 ` Matthew Wilcox
2016-01-30 6:01 ` Dan Williams
2016-01-30 7:08 ` Jared Hulbert
2016-01-31 2:32 ` Matthew Wilcox
2016-01-31 6:12 ` Ross Zwisler
2016-01-31 10:55 ` Matthew Wilcox
2016-01-31 16:38 ` Dan Williams
2016-01-31 18:07 ` Matthew Wilcox
2016-01-31 18:18 ` Dan Williams
2016-01-31 18:27 ` Matthew Wilcox
2016-01-31 18:50 ` Dan Williams
2016-01-31 19:51 ` Dan Williams
2016-02-01 13:44 ` Matthew Wilcox
2016-02-01 14:51 ` Jan Kara
2016-02-01 20:49 ` Matthew Wilcox
2016-02-01 21:47 ` Dave Chinner
2016-02-02 6:06 ` Jared Hulbert
2016-02-02 6:46 ` Dan Williams
2016-02-02 8:05 ` Jared Hulbert
2016-02-02 16:51 ` Dan Williams
2016-02-02 21:46 ` Jared Hulbert
2016-02-03 0:34 ` Matthew Wilcox
2016-02-03 1:21 ` Jared Hulbert
2016-02-02 11:17 ` Jan Kara
2016-02-02 16:33 ` Dan Williams
2016-02-02 16:46 ` Jan Kara
2016-02-02 17:10 ` Dan Williams
2016-02-02 17:34 ` Ross Zwisler
2016-02-02 17:46 ` Dan Williams
2016-02-02 17:47 ` Dan Williams
2016-02-02 18:24 ` Ross Zwisler
2016-02-02 18:46 ` Matthew Wilcox
2016-02-02 18:59 ` Dan Williams
2016-02-02 20:14 ` Matthew Wilcox
2016-02-03 11:09 ` Jan Kara
2016-02-03 10:46 ` Jan Kara
2016-02-03 20:13 ` Ross Zwisler
2016-02-04 9:15 ` Jan Kara
2016-02-04 23:38 ` Ross Zwisler
2016-02-06 23:15 ` Dave Chinner
2016-02-07 5:27 ` Ross Zwisler
2016-02-04 19:56 ` Ross Zwisler
2016-02-04 20:29 ` Jan Kara
2016-02-04 22:19 ` Ross Zwisler
2016-02-05 22:25 ` Ross Zwisler
2016-02-06 23:40 ` Dave Chinner
2016-02-07 6:43 ` Ross Zwisler
2016-02-08 13:48 ` Jan Kara
2016-02-07 8:38 ` Christoph Hellwig
2016-02-08 15:55 ` Ross Zwisler
2016-02-02 18:41 ` Ross Zwisler
2016-02-02 18:53 ` Ross Zwisler
2016-02-02 0:02 ` Ross Zwisler
2016-02-02 7:10 ` Dave Chinner
2016-02-02 10:34 ` Jan Kara
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