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From: Jan Kara <jack@suse.cz>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-fsdevel@vger.kernel.org, Jan Kara <jack@suse.cz>,
	linux-nvdimm@lists.01.org
Subject: Re: [PATCH 6/6] dax: Avoid page invalidation races and unnecessary radix tree traversals
Date: Mon, 3 Oct 2016 16:58:02 +0200	[thread overview]
Message-ID: <20161003145802.GD14183@quack2.suse.cz> (raw)
In-Reply-To: <20160928002034.GF9806@dastard>

On Wed 28-09-16 10:20:34, Dave Chinner wrote:
> On Tue, Sep 27, 2016 at 06:43:35PM +0200, Jan Kara wrote:
> > @@ -1410,6 +1422,17 @@ iomap_dax_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
> >  	if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED))
> >  		return -EIO;
> >  
> > +	/*
> > +	 * Write can allocate block for an area which has a hole page mapped
> > +	 * into page tables. We have to tear down these mappings so that data
> > +	 * written by write(2) is visible in mmap.
> > +	 */
> > +	if (iomap->flags & IOMAP_F_NEW && inode->i_mapping->nrpages) {
> 
> gcc should be throwing warnings about that:
> 
> 	if ((iomap->flags & IOMAP_F_NEW) && inode->i_mapping->nrpages) {

Actually the bitwise '&' takes precedense over the logical '&&' so the
evaluation order ends up being correct. But I agree it's better to be
explicit with parenthesis here. Fixed.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR
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WARNING: multiple messages have this Message-ID (diff)
From: Jan Kara <jack@suse.cz>
To: Dave Chinner <david@fromorbit.com>
Cc: Jan Kara <jack@suse.cz>,
	linux-fsdevel@vger.kernel.org, linux-nvdimm@lists.01.org,
	Dan Williams <dan.j.williams@intel.com>,
	Ross Zwisler <ross.zwisler@linux.intel.com>
Subject: Re: [PATCH 6/6] dax: Avoid page invalidation races and unnecessary radix tree traversals
Date: Mon, 3 Oct 2016 16:58:02 +0200	[thread overview]
Message-ID: <20161003145802.GD14183@quack2.suse.cz> (raw)
In-Reply-To: <20160928002034.GF9806@dastard>

On Wed 28-09-16 10:20:34, Dave Chinner wrote:
> On Tue, Sep 27, 2016 at 06:43:35PM +0200, Jan Kara wrote:
> > @@ -1410,6 +1422,17 @@ iomap_dax_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
> >  	if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED))
> >  		return -EIO;
> >  
> > +	/*
> > +	 * Write can allocate block for an area which has a hole page mapped
> > +	 * into page tables. We have to tear down these mappings so that data
> > +	 * written by write(2) is visible in mmap.
> > +	 */
> > +	if (iomap->flags & IOMAP_F_NEW && inode->i_mapping->nrpages) {
> 
> gcc should be throwing warnings about that:
> 
> 	if ((iomap->flags & IOMAP_F_NEW) && inode->i_mapping->nrpages) {

Actually the bitwise '&' takes precedense over the logical '&&' so the
evaluation order ends up being correct. But I agree it's better to be
explicit with parenthesis here. Fixed.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

  reply	other threads:[~2016-10-03 14:58 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-27 16:43 [PATCH 0/6] dax: Page invalidation fixes Jan Kara
2016-09-27 16:43 ` Jan Kara
2016-09-27 16:43 ` [PATCH 1/6] dax: Do not warn about BH_New buffers Jan Kara
2016-09-27 16:43   ` Jan Kara
     [not found]   ` <1474994615-29553-2-git-send-email-jack-AlSwsSmVLrQ@public.gmane.org>
2016-09-30  8:53     ` Christoph Hellwig
2016-09-30  8:53       ` Christoph Hellwig
2016-09-27 16:43 ` [PATCH 2/6] ext2: Return BH_New buffers for zeroed blocks Jan Kara
2016-09-27 16:43   ` Jan Kara
     [not found]   ` <1474994615-29553-3-git-send-email-jack-AlSwsSmVLrQ@public.gmane.org>
2016-09-30  8:53     ` Christoph Hellwig
2016-09-30  8:53       ` Christoph Hellwig
2016-09-27 16:43 ` [PATCH 3/6] ext4: Remove clearing of BH_New bit " Jan Kara
2016-09-27 16:43   ` Jan Kara
     [not found]   ` <1474994615-29553-4-git-send-email-jack-AlSwsSmVLrQ@public.gmane.org>
2016-09-30  8:53     ` Christoph Hellwig
2016-09-30  8:53       ` Christoph Hellwig
2016-09-27 16:43 ` [PATCH 4/6] xfs: Set BH_New for allocated DAX blocks in __xfs_get_blocks() Jan Kara
2016-09-27 16:43   ` Jan Kara
     [not found]   ` <1474994615-29553-5-git-send-email-jack-AlSwsSmVLrQ@public.gmane.org>
2016-09-27 17:01     ` Christoph Hellwig
2016-09-27 17:01       ` Christoph Hellwig
2016-09-27 17:17       ` Jan Kara
2016-09-28  0:22         ` Dave Chinner
2016-10-03 14:44           ` Jan Kara
2016-10-03 14:44             ` Jan Kara
     [not found]         ` <20160927171707.GA30327-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>
2016-09-28  2:13           ` Christoph Hellwig
2016-09-28  2:13             ` Christoph Hellwig
2016-10-03 14:42             ` Jan Kara
     [not found]               ` <20161003144246.GA14183-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>
2016-10-03 16:39                 ` Christoph Hellwig
2016-10-03 16:39                   ` Christoph Hellwig
2016-09-27 16:43 ` [PATCH 5/6] mm: Invalidate DAX radix tree entries only if appropriate Jan Kara
2016-09-27 16:43   ` Jan Kara
2016-09-28  0:18   ` Dave Chinner
2016-09-28  0:18     ` Dave Chinner
2016-10-03 14:52     ` Jan Kara
2016-10-03 14:52       ` Jan Kara
     [not found]   ` <1474994615-29553-6-git-send-email-jack-AlSwsSmVLrQ@public.gmane.org>
2016-09-30  8:57     ` Christoph Hellwig
2016-09-30  8:57       ` Christoph Hellwig
2016-10-03 12:56       ` Jan Kara
2016-09-27 16:43 ` [PATCH 6/6] dax: Avoid page invalidation races and unnecessary radix tree traversals Jan Kara
2016-09-27 16:43   ` Jan Kara
2016-09-28  0:20   ` Dave Chinner
2016-09-28  0:20     ` Dave Chinner
2016-10-03 14:58     ` Jan Kara [this message]
2016-10-03 14:58       ` Jan Kara
2016-10-03 23:40       ` Dave Chinner
2016-10-03 23:40         ` Dave Chinner
     [not found]   ` <1474994615-29553-7-git-send-email-jack-AlSwsSmVLrQ@public.gmane.org>
2016-09-30  8:55     ` Christoph Hellwig
2016-09-30  8:55       ` Christoph Hellwig
     [not found]       ` <20160930085544.GD22381-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2016-10-03 15:02         ` Jan Kara
2016-10-03 15:02           ` Jan Kara
     [not found] ` <1474994615-29553-1-git-send-email-jack-AlSwsSmVLrQ@public.gmane.org>
2016-09-30  8:59   ` [PATCH 0/6] dax: Page invalidation fixes Christoph Hellwig
2016-09-30  8:59     ` Christoph Hellwig
2016-10-03 13:01     ` Jan Kara

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