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From: Jan Kara <jack@suse.cz>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: Jan Kara <jack@suse.cz>,
	linux-fsdevel@vger.kernel.org,
	Christoph Hellwig <hch@infradead.org>,
	Dave Chinner <david@fromorbit.com>,
	ceph-devel@vger.kernel.org, Chao Yu <yuchao0@huawei.com>,
	Damien Le Moal <damien.lemoal@wdc.com>,
	"Darrick J. Wong" <darrick.wong@oracle.com>,
	Jaegeuk Kim <jaegeuk@kernel.org>,
	Jeff Layton <jlayton@kernel.org>,
	Johannes Thumshirn <jth@kernel.org>,
	linux-cifs@vger.kernel.org, linux-ext4@vger.kernel.org,
	linux-f2fs-devel@lists.sourceforge.net, linux-mm@kvack.org,
	linux-xfs@vger.kernel.org, Miklos Szeredi <miklos@szeredi.hu>,
	Steve French <sfrench@samba.org>, Ted Tso <tytso@mit.edu>,
	Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH 04/13] mm: Add functions to lock invalidate_lock for two mappings
Date: Wed, 26 May 2021 12:07:02 +0200	[thread overview]
Message-ID: <20210526100702.GB30369@quack2.suse.cz> (raw)
In-Reply-To: <20210525204805.GM202121@locust>

On Tue 25-05-21 13:48:05, Darrick J. Wong wrote:
> On Tue, May 25, 2021 at 03:50:41PM +0200, Jan Kara wrote:
> > Some operations such as reflinking blocks among files will need to lock
> > invalidate_lock for two mappings. Add helper functions to do that.
> > 
> > Signed-off-by: Jan Kara <jack@suse.cz>
> > ---
> >  include/linux/fs.h |  6 ++++++
> >  mm/filemap.c       | 38 ++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 44 insertions(+)
> > 
> > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > index 897238d9f1e0..e6f7447505f5 100644
> > --- a/include/linux/fs.h
> > +++ b/include/linux/fs.h
> > @@ -822,6 +822,12 @@ static inline void inode_lock_shared_nested(struct inode *inode, unsigned subcla
> >  void lock_two_nondirectories(struct inode *, struct inode*);
> >  void unlock_two_nondirectories(struct inode *, struct inode*);
> >  
> > +void filemap_invalidate_down_write_two(struct address_space *mapping1,
> > +				       struct address_space *mapping2);
> > +void filemap_invalidate_up_write_two(struct address_space *mapping1,
> 
> TBH I find myself wishing that the invalidate_lock used the same
> lock/unlock style wrappers that we use for i_rwsem.
> 
> filemap_invalidate_lock(inode1->mapping);
> filemap_invalidate_lock_two(inode1->i_mapping, inode2->i_mapping);

OK, and filemap_invalidate_lock_shared() for down_read()? I guess that
works for me.

								Honza

 
> To be fair, I've never been able to keep straight that down means lock
> and up means unlock.  Ah well, at least you didn't use "p" and "v".
> 
> Mechanically, the changes look ok to me.
> Acked-by: Darrick J. Wong <djwong@kernel.org>
> 
> --D
> 
> > +				     struct address_space *mapping2);
> > +
> > +
> >  /*
> >   * NOTE: in a 32bit arch with a preemptable kernel and
> >   * an UP compile the i_size_read/write must be atomic
> > diff --git a/mm/filemap.c b/mm/filemap.c
> > index 4d9ec4c6cc34..d3801a9739aa 100644
> > --- a/mm/filemap.c
> > +++ b/mm/filemap.c
> > @@ -1009,6 +1009,44 @@ struct page *__page_cache_alloc(gfp_t gfp)
> >  EXPORT_SYMBOL(__page_cache_alloc);
> >  #endif
> >  
> > +/*
> > + * filemap_invalidate_down_write_two - lock invalidate_lock for two mappings
> > + *
> > + * Lock exclusively invalidate_lock of any passed mapping that is not NULL.
> > + *
> > + * @mapping1: the first mapping to lock
> > + * @mapping2: the second mapping to lock
> > + */
> > +void filemap_invalidate_down_write_two(struct address_space *mapping1,
> > +				       struct address_space *mapping2)
> > +{
> > +	if (mapping1 > mapping2)
> > +		swap(mapping1, mapping2);
> > +	if (mapping1)
> > +		down_write(&mapping1->invalidate_lock);
> > +	if (mapping2 && mapping1 != mapping2)
> > +		down_write_nested(&mapping2->invalidate_lock, 1);
> > +}
> > +EXPORT_SYMBOL(filemap_invalidate_down_write_two);
> > +
> > +/*
> > + * filemap_invalidate_up_write_two - unlock invalidate_lock for two mappings
> > + *
> > + * Unlock exclusive invalidate_lock of any passed mapping that is not NULL.
> > + *
> > + * @mapping1: the first mapping to unlock
> > + * @mapping2: the second mapping to unlock
> > + */
> > +void filemap_invalidate_up_write_two(struct address_space *mapping1,
> > +				     struct address_space *mapping2)
> > +{
> > +	if (mapping1)
> > +		up_write(&mapping1->invalidate_lock);
> > +	if (mapping2 && mapping1 != mapping2)
> > +		up_write(&mapping2->invalidate_lock);
> > +}
> > +EXPORT_SYMBOL(filemap_invalidate_up_write_two);
> > +
> >  /*
> >   * In order to wait for pages to become available there must be
> >   * waitqueues associated with pages. By using a hash table of
> > -- 
> > 2.26.2
> > 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

  reply	other threads:[~2021-05-26 10:07 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-25 13:50 [PATCH 0/13 v6] fs: Hole punch vs page cache filling races Jan Kara
2021-05-25 13:50 ` [PATCH 01/13] mm: Fix comments mentioning i_mutex Jan Kara
2021-05-25 13:50 ` [PATCH 02/13] documentation: Sync file_operations members with reality Jan Kara
2021-05-25 20:43   ` Darrick J. Wong
2021-05-25 13:50 ` [PATCH 03/13] mm: Protect operations adding pages to page cache with invalidate_lock Jan Kara
2021-05-25 21:01   ` Darrick J. Wong
2021-05-26 10:00     ` Jan Kara
2021-05-25 13:50 ` [PATCH 04/13] mm: Add functions to lock invalidate_lock for two mappings Jan Kara
2021-05-25 20:48   ` Darrick J. Wong
2021-05-26 10:07     ` Jan Kara [this message]
2021-05-26 12:11       ` Damien Le Moal
2021-05-26 13:45         ` Jan Kara
2021-05-26 15:25           ` Darrick J. Wong
2021-05-25 13:50 ` [PATCH 05/13] ext4: Convert to use mapping->invalidate_lock Jan Kara
2021-05-25 13:50 ` [PATCH 06/13] ext2: Convert to using invalidate_lock Jan Kara
2021-05-25 13:50 ` [PATCH 07/13] xfs: Convert to use invalidate_lock Jan Kara
2021-05-25 21:37   ` Darrick J. Wong
2021-05-26 10:18     ` Jan Kara
2021-05-26 15:32       ` Darrick J. Wong
2021-05-27 12:01         ` Jan Kara
2021-05-25 21:40   ` Dave Chinner
2021-05-26 10:20     ` Jan Kara
2021-05-26 13:42       ` Jan Kara
2021-05-25 13:50 ` [PATCH 08/13] xfs: Convert double locking of MMAPLOCK to use VFS helpers Jan Kara
2021-05-25 21:41   ` Darrick J. Wong
2021-05-25 13:50 ` [PATCH 09/13] zonefs: Convert to using invalidate_lock Jan Kara
2021-05-25 13:50 ` [PATCH 10/13] f2fs: " Jan Kara
2021-05-26  9:55   ` Chao Yu
2021-05-25 13:50 ` [PATCH 11/13] fuse: " Jan Kara
2021-05-25 13:50 ` [PATCH 12/13] ceph: Fix race between hole punch and page fault Jan Kara
2021-05-25 13:50 ` [PATCH 13/13] cifs: " Jan Kara

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