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From: "Darrick J. Wong" <djwong@kernel.org>
To: Jan Kara <jack@suse.cz>
Cc: 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: Tue, 25 May 2021 13:48:05 -0700	[thread overview]
Message-ID: <20210525204805.GM202121@locust> (raw)
In-Reply-To: <20210525135100.11221-4-jack@suse.cz>

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);

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
> 

  reply	other threads:[~2021-05-25 20:48 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 [this message]
2021-05-26 10:07     ` Jan Kara
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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