Linux-XFS Archive on lore.kernel.org
 help / color / Atom feed
From: Ira Weiny <ira.weiny@intel.com>
To: Jan Kara <jack@suse.cz>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>,
	linux-kernel@vger.kernel.org,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Dan Williams <dan.j.williams@intel.com>,
	Dave Chinner <david@fromorbit.com>,
	Christoph Hellwig <hch@lst.de>,
	"Theodore Y. Ts'o" <tytso@mit.edu>,
	linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org
Subject: Re: [RFC PATCH V2 09/12] fs: Prevent mode change if file is mmap'ed
Date: Wed, 15 Jan 2020 10:24:46 -0800
Message-ID: <20200115182446.GD23311@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <20200115113455.GA2595@quack2.suse.cz>

On Wed, Jan 15, 2020 at 12:34:55PM +0100, Jan Kara wrote:
> On Tue 14-01-20 09:53:54, Ira Weiny wrote:
> > On Mon, Jan 13, 2020 at 05:30:04PM -0800, Darrick J. Wong wrote:
> > > > > > +		error = -EBUSY;
> > > > > > +		goto out_unlock;
> > > > > > +	}
> > > > > > +
> > > > > >  	error = filemap_write_and_wait(inode->i_mapping);
> > > > > >  	if (error)
> > > > > >  		goto out_unlock;
> > > > > > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > > > > > index 631f11d6246e..6e7dc626b657 100644
> > > > > > --- a/include/linux/fs.h
> > > > > > +++ b/include/linux/fs.h
> > > > > > @@ -740,6 +740,7 @@ struct inode {
> > > > > >  #endif
> > > > > >  
> > > > > >  	void			*i_private; /* fs or device private pointer */
> > > > > > +	atomic64_t               i_mapped;
> > > > > 
> > > > > I would have expected to find this in struct address_space since the
> > > > > mapping count is a function of the address space, right?
> > > > 
> > > > I suppose but the only external call (above) would be passing an inode.  So to
> > > > me it seemed better here.
> > > 
> > > But the number of memory mappings reflects the state of the address
> > > space, not the inode.  Or maybe put another way, if I were an mm
> > > developer I would not expect to look in struct inode for mm state.
> > 
> > This is a good point...
> > 
> > > 
> > > static inline bool inode_has_mappings(struct inode *inode)
> > > {
> > > 	return atomic64_read(&inode->i_mapping->mapcount) > 0;
> > > }
> > > 
> > > OTOH if there exist other mm developers who /do/ find that storing the
> > > mmap count in struct inode is more logical, please let me know. :)
> > 
> > ...  My thinking was that the number of mappings does not matters to the mm
> > system...  However, I'm starting to think you are correct...  ;-)
> > 
> > I've made a note of it and we will see what others think.
> 
> Well, more importantly mapping != inode. There can be multiple inodes
> pointing to the same mapping (struct address_space) as is the case for
> example for block devices. So this counter definitely belongs into struct
> address_space.

Ah Yes, great point.  Done.

Ira


  reply index

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-10 19:29 [RFC PATCH V2 00/12] Enable per-file/directory DAX operations V2 ira.weiny
2020-01-10 19:29 ` [RFC PATCH V2 01/12] fs/stat: Define DAX statx attribute ira.weiny
2020-01-15 11:37   ` Jan Kara
2020-01-15 17:38     ` Darrick J. Wong
2020-01-15 19:45       ` Ira Weiny
2020-01-15 20:10         ` Dan Williams
2020-01-15 22:38           ` Ira Weiny
2020-01-16  5:39             ` Darrick J. Wong
2020-01-16  6:05               ` Dan Williams
2020-01-16  6:18                 ` Darrick J. Wong
2020-01-16  6:25                   ` Dan Williams
2020-01-18  9:11                 ` Dave Chinner
2020-01-16 17:55               ` Ira Weiny
2020-01-16 18:04                 ` Darrick J. Wong
2020-01-16 18:52                   ` Ira Weiny
2020-01-16 22:19                     ` Darrick J. Wong
2020-01-17 11:58                     ` Jan Kara
2020-01-10 19:29 ` [RFC PATCH V2 02/12] fs/xfs: Isolate the physical DAX flag from effective ira.weiny
2020-01-10 19:29 ` [RFC PATCH V2 03/12] fs/xfs: Separate functionality of xfs_inode_supports_dax() ira.weiny
2020-01-10 19:29 ` [RFC PATCH V2 04/12] fs/xfs: Clean up DAX support check ira.weiny
2020-01-10 19:29 ` [RFC PATCH V2 05/12] fs: remove unneeded IS_DAX() check ira.weiny
2020-01-16  9:38   ` Jan Kara
2020-01-16 18:47     ` Ira Weiny
2020-01-10 19:29 ` [RFC PATCH V2 06/12] fs/xfs: Check if the inode supports DAX under lock ira.weiny
2020-01-10 19:29 ` [RFC PATCH V2 07/12] fs: Add locking for a dynamic inode 'mode' ira.weiny
2020-01-13 22:12   ` Darrick J. Wong
2020-01-14  0:20     ` Ira Weiny
2020-01-14  1:03       ` Darrick J. Wong
2020-01-15 19:08         ` Ira Weiny
2020-01-16  5:40           ` Darrick J. Wong
2020-01-16 18:54             ` Ira Weiny
2020-01-10 19:29 ` [RFC PATCH V2 08/12] fs/xfs: Add lock/unlock mode to xfs ira.weiny
2020-01-13 22:19   ` Darrick J. Wong
2020-01-14  0:35     ` Ira Weiny
2020-01-15  0:57       ` Ira Weiny
2020-01-15 23:52     ` Ira Weiny
2020-01-16  9:24   ` Jan Kara
2020-01-16 19:12     ` Ira Weiny
2020-01-10 19:29 ` [RFC PATCH V2 09/12] fs: Prevent mode change if file is mmap'ed ira.weiny
2020-01-13 22:22   ` Darrick J. Wong
2020-01-14  0:46     ` Ira Weiny
2020-01-14  1:30       ` Darrick J. Wong
2020-01-14 17:53         ` Ira Weiny
2020-01-15 11:34           ` Jan Kara
2020-01-15 18:24             ` Ira Weiny [this message]
2020-01-15 10:21   ` David Laight
2020-01-15 17:53     ` Ira Weiny
2020-01-10 19:29 ` [RFC PATCH V2 10/12] fs/xfs: Fix truncate up ira.weiny
2020-01-13 22:27   ` Darrick J. Wong
2020-01-14  0:40     ` Ira Weiny
2020-01-14  1:14       ` Darrick J. Wong
2020-01-14 19:00         ` Ira Weiny
2020-01-14 19:39           ` Ira Weiny
2020-01-10 19:29 ` [RFC PATCH V2 11/12] fs/xfs: Clean up locking in dax invalidate ira.weiny
2020-01-10 19:29 ` [RFC PATCH V2 12/12] fs/xfs: Allow toggle of effective DAX flag ira.weiny

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200115182446.GD23311@iweiny-DESK2.sc.intel.com \
    --to=ira.weiny@intel.com \
    --cc=dan.j.williams@intel.com \
    --cc=darrick.wong@oracle.com \
    --cc=david@fromorbit.com \
    --cc=hch@lst.de \
    --cc=jack@suse.cz \
    --cc=linux-ext4@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-xfs@vger.kernel.org \
    --cc=tytso@mit.edu \
    --cc=viro@zeniv.linux.org.uk \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-XFS Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-xfs/0 linux-xfs/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-xfs linux-xfs/ https://lore.kernel.org/linux-xfs \
		linux-xfs@vger.kernel.org
	public-inbox-index linux-xfs

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-xfs


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git