From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Jens Axboe <axboe@fb.com>, Jens Axboe <axboe@kernel.dk>,
Jan Kara <jack@suse.cz>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@ml01.01.org>,
Dave Chinner <david@fromorbit.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Jeff Moyer <jmoyer@redhat.com>, Jan Kara <jack@suse.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v3 03/15] block, dax: fix lifetime of in-kernel dax mappings with dax_map_atomic()
Date: Mon, 18 Jan 2016 11:42:43 +0100 [thread overview]
Message-ID: <CAMuHMdVTXDJ_KF95u+uNCJcs6pT2eJmVSg6at_vfAfp2ovctnQ@mail.gmail.com> (raw)
In-Reply-To: <20151102042958.6610.65193.stgit@dwillia2-desk3.amr.corp.intel.com>
Hi Dan,
On Mon, Nov 2, 2015 at 5:29 AM, Dan Williams <dan.j.williams@intel.com> wrote:
> The DAX implementation needs to protect new calls to ->direct_access()
> and usage of its return value against unbind of the underlying block
> device. Use blk_queue_enter()/blk_queue_exit() to either prevent
> blk_cleanup_queue() from proceeding, or fail the dax_map_atomic() if the
> request_queue is being torn down.
> index f8e543839e5c..a480729c00ec 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
> loff_t start, loff_t end, get_block_t get_block,
> struct buffer_head *bh)
> {
> - ssize_t retval = 0;
> - loff_t pos = start;
> - loff_t max = start;
> - loff_t bh_max = start;
> - void __pmem *addr;
> + loff_t pos = start, max = start, bh_max = start;
> + struct block_device *bdev = NULL;
> + int rw = iov_iter_rw(iter), rc;
fs/dax.c:138: warning: ‘rc’ may be used uninitialized in this function
rc will be uninitialized if start == end, and the while loop below is never
executed. I don't know whether it's 100% guaranteed this isn't the case.
Note that the old retval was preinitialized to 0.
> + long map_len = 0;
> + unsigned long pfn;
> + void __pmem *addr = NULL;
> + void __pmem *kmap = (void __pmem *) ERR_PTR(-EIO);
> bool hole = false;
> bool need_wmb = false;
>
> - if (iov_iter_rw(iter) != WRITE)
> + if (rw == READ)
> end = min(end, i_size_read(inode));
>
> while (pos < end) {
> @@ -175,8 +219,9 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
>
> if (need_wmb)
> wmb_pmem();
> + dax_unmap_atomic(bdev, kmap);
>
> - return (pos == start) ? retval : pos - start;
> + return (pos == start) ? rc : pos - start;
> }
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2016-01-18 10:42 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-02 4:29 [PATCH v3 00/15] block, dax updates for 4.4 Dan Williams
2015-11-02 4:29 ` [PATCH v3 01/15] pmem, dax: clean up clear_pmem() Dan Williams
2015-11-02 4:29 ` [PATCH v3 02/15] dax: increase granularity of dax_clear_blocks() operations Dan Williams
2015-11-03 0:51 ` Dave Chinner
2015-11-03 3:27 ` Dan Williams
2015-11-03 4:48 ` Dave Chinner
2015-11-03 5:31 ` Dan Williams
2015-11-03 5:52 ` Dave Chinner
2015-11-03 7:24 ` Dan Williams
2015-11-03 16:21 ` Jan Kara
2015-11-03 17:57 ` Ross Zwisler
2015-11-03 20:59 ` Dave Chinner
2015-11-02 4:29 ` [PATCH v3 03/15] block, dax: fix lifetime of in-kernel dax mappings with dax_map_atomic() Dan Williams
2015-11-03 19:01 ` Ross Zwisler
2015-11-03 19:09 ` Jeff Moyer
2015-11-03 22:50 ` Dan Williams
2016-01-18 10:42 ` Geert Uytterhoeven [this message]
2015-11-02 4:30 ` [PATCH v3 04/15] libnvdimm, pmem: move request_queue allocation earlier in probe Dan Williams
2015-11-03 19:15 ` Ross Zwisler
2015-11-02 4:30 ` [PATCH v3 05/15] libnvdimm, pmem: fix size trim in pmem_direct_access() Dan Williams
2015-11-03 19:32 ` Ross Zwisler
2015-11-03 21:39 ` Dan Williams
2015-11-02 4:30 ` [PATCH v3 06/15] um: kill pfn_t Dan Williams
2015-11-02 4:30 ` [PATCH v3 07/15] kvm: rename pfn_t to kvm_pfn_t Dan Williams
2015-11-02 4:30 ` [PATCH v3 08/15] mm, dax, pmem: introduce pfn_t Dan Williams
2015-11-02 16:30 ` Joe Perches
2015-11-02 4:30 ` [PATCH v3 09/15] block: notify queue death confirmation Dan Williams
2015-11-02 4:30 ` [PATCH v3 10/15] dax, pmem: introduce zone_device_revoke() and devm_memunmap_pages() Dan Williams
2015-11-02 4:30 ` [PATCH v3 11/15] block: introduce bdev_file_inode() Dan Williams
2015-11-02 4:30 ` [PATCH v3 12/15] block: enable dax for raw block devices Dan Williams
2015-11-02 4:30 ` [PATCH v3 13/15] block, dax: make dax mappings opt-in by default Dan Williams
2015-11-03 0:32 ` Dave Chinner
2015-11-03 7:35 ` Dan Williams
2015-11-03 20:20 ` Dave Chinner
2015-11-03 23:04 ` Dan Williams
2015-11-04 19:23 ` Dan Williams
2015-11-02 4:30 ` [PATCH v3 14/15] dax: dirty extent notification Dan Williams
2015-11-03 1:16 ` Dave Chinner
2015-11-03 4:56 ` Dan Williams
2015-11-03 5:40 ` Dave Chinner
2015-11-03 7:20 ` Dan Williams
2015-11-03 20:51 ` Dave Chinner
2015-11-03 21:19 ` Dan Williams
2015-11-03 21:37 ` Ross Zwisler
2015-11-03 21:43 ` Dan Williams
2015-11-03 21:18 ` Ross Zwisler
2015-11-03 21:34 ` Dan Williams
2015-11-02 4:31 ` [PATCH v3 15/15] pmem: blkdev_issue_flush support Dan Williams
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