Re: [PATCH 07/11] fs: add a ->sync_lazytime method

[Jan Kara <jack@suse.cz>]

On Thu 08-01-26 15:19:07, Christoph Hellwig wrote:
> Allow the file system to explicitly implement lazytime syncing instead
> of pigging back on generic inode dirtying.  This allows to simplify
> the XFS implementation and prepares for non-blocking lazytime timestamp
> updates.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
> Reviewed-by: Jeff Layton <jlayton@kernel.org>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  Documentation/filesystems/locking.rst |  2 ++
>  Documentation/filesystems/vfs.rst     |  6 ++++++
>  fs/fs-writeback.c                     | 13 +++++++++++--
>  include/linux/fs.h                    |  1 +
>  4 files changed, 20 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst
> index 37a4a7fa8094..0312fba6d73b 100644
> --- a/Documentation/filesystems/locking.rst
> +++ b/Documentation/filesystems/locking.rst
> @@ -82,6 +82,7 @@ prototypes::
>  	int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start, u64 len);
>  	void (*update_time)(struct inode *inode, enum fs_update_time type,
>  			    int flags);
> +	void (*sync_lazytime)(struct inode *inode);
>  	int (*atomic_open)(struct inode *, struct dentry *,
>  				struct file *, unsigned open_flag,
>  				umode_t create_mode);
> @@ -118,6 +119,7 @@ getattr:	no
>  listxattr:	no
>  fiemap:		no
>  update_time:	no
> +sync_lazytime:	no
>  atomic_open:	shared (exclusive if O_CREAT is set in open flags)
>  tmpfile:	no
>  fileattr_get:	no or exclusive
> diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst
> index 51aa9db64784..d8cb181f69f8 100644
> --- a/Documentation/filesystems/vfs.rst
> +++ b/Documentation/filesystems/vfs.rst
> @@ -487,6 +487,7 @@ As of kernel 2.6.22, the following members are defined:
>  		ssize_t (*listxattr) (struct dentry *, char *, size_t);
>  		void (*update_time)(struct inode *inode, enum fs_update_time type,
>  				    int flags);
> +		void (*sync_lazytime)(struct inode *inode);
>  		int (*atomic_open)(struct inode *, struct dentry *, struct file *,
>  				   unsigned open_flag, umode_t create_mode);
>  		int (*tmpfile) (struct mnt_idmap *, struct inode *, struct file *, umode_t);
> @@ -643,6 +644,11 @@ otherwise noted.
>  	an inode.  If this is not defined the VFS will update the inode
>  	itself and call mark_inode_dirty_sync.
>  
> +``sync_lazytime``:
> +	called by the writeback code to update the lazy time stamps to
> +	regular time stamp updates that get syncing into the on-disk
> +	inode.
> +
>  ``atomic_open``
>  	called on the last component of an open.  Using this optional
>  	method the filesystem can look up, possibly create and open the
> diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> index 3d68b757136c..62658be2578b 100644
> --- a/fs/fs-writeback.c
> +++ b/fs/fs-writeback.c
> @@ -1717,7 +1717,10 @@ bool sync_lazytime(struct inode *inode)
>  		return false;
>  
>  	trace_writeback_lazytime(inode);
> -	mark_inode_dirty_sync(inode);
> +	if (inode->i_op->sync_lazytime)
> +		inode->i_op->sync_lazytime(inode);
> +	else
> +		mark_inode_dirty_sync(inode);
>  	return true;
>  }
>  
> @@ -2569,6 +2572,8 @@ void __mark_inode_dirty(struct inode *inode, int flags)
>  	trace_writeback_mark_inode_dirty(inode, flags);
>  
>  	if (flags & I_DIRTY_INODE) {
> +		bool was_dirty_time = false;
> +
>  		/*
>  		 * Inode timestamp update will piggback on this dirtying.
>  		 * We tell ->dirty_inode callback that timestamps need to
> @@ -2579,6 +2584,7 @@ void __mark_inode_dirty(struct inode *inode, int flags)
>  			if (inode_state_read(inode) & I_DIRTY_TIME) {
>  				inode_state_clear(inode, I_DIRTY_TIME);
>  				flags |= I_DIRTY_TIME;
> +				was_dirty_time = true;
>  			}
>  			spin_unlock(&inode->i_lock);
>  		}
> @@ -2591,9 +2597,12 @@ void __mark_inode_dirty(struct inode *inode, int flags)
>  		 * for just I_DIRTY_PAGES or I_DIRTY_TIME.
>  		 */
>  		trace_writeback_dirty_inode_start(inode, flags);
> -		if (sb->s_op->dirty_inode)
> +		if (sb->s_op->dirty_inode) {
>  			sb->s_op->dirty_inode(inode,
>  				flags & (I_DIRTY_INODE | I_DIRTY_TIME));
> +		} else if (was_dirty_time && inode->i_op->sync_lazytime) {
> +			inode->i_op->sync_lazytime(inode);
> +		}
>  		trace_writeback_dirty_inode(inode, flags);
>  
>  		/* I_DIRTY_INODE supersedes I_DIRTY_TIME. */
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 35b3e6c6b084..7837db1ba1d2 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2024,6 +2024,7 @@ struct inode_operations {
>  		      u64 len);
>  	int (*update_time)(struct inode *inode, enum fs_update_time type,
>  			   unsigned int flags);
> +	void (*sync_lazytime)(struct inode *inode);
>  	int (*atomic_open)(struct inode *, struct dentry *,
>  			   struct file *, unsigned open_flag,
>  			   umode_t create_mode);
> -- 
> 2.47.3
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR