Re: [PATCH 07/11] zonefs: Convert to using invalidate_lock

[Damien Le Moal <Damien.LeMoal@wdc.com>]

On 2021/05/12 22:46, Jan Kara wrote:
> Use invalidate_lock instead of zonefs' private i_mmap_sem. The intended
> purpose is exactly the same.
> 
> CC: Damien Le Moal <damien.lemoal@wdc.com>
> CC: Johannes Thumshirn <jth@kernel.org>
> CC: <linux-fsdevel@vger.kernel.org>
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
>  fs/zonefs/super.c  | 23 +++++------------------
>  fs/zonefs/zonefs.h |  7 +++----
>  2 files changed, 8 insertions(+), 22 deletions(-)
> 
> diff --git a/fs/zonefs/super.c b/fs/zonefs/super.c
> index cd145d318b17..da2e95d98677 100644
> --- a/fs/zonefs/super.c
> +++ b/fs/zonefs/super.c
> @@ -462,7 +462,7 @@ static int zonefs_file_truncate(struct inode *inode, loff_t isize)
>  	inode_dio_wait(inode);
>  
>  	/* Serialize against page faults */
> -	down_write(&zi->i_mmap_sem);
> +	down_write(&inode->i_mapping->invalidate_lock);
>  
>  	/* Serialize against zonefs_iomap_begin() */
>  	mutex_lock(&zi->i_truncate_mutex);
> @@ -500,7 +500,7 @@ static int zonefs_file_truncate(struct inode *inode, loff_t isize)
>  
>  unlock:
>  	mutex_unlock(&zi->i_truncate_mutex);
> -	up_write(&zi->i_mmap_sem);
> +	up_write(&inode->i_mapping->invalidate_lock);
>  
>  	return ret;
>  }
> @@ -575,18 +575,6 @@ static int zonefs_file_fsync(struct file *file, loff_t start, loff_t end,
>  	return ret;
>  }
>  
> -static vm_fault_t zonefs_filemap_fault(struct vm_fault *vmf)
> -{
> -	struct zonefs_inode_info *zi = ZONEFS_I(file_inode(vmf->vma->vm_file));
> -	vm_fault_t ret;
> -
> -	down_read(&zi->i_mmap_sem);
> -	ret = filemap_fault(vmf);
> -	up_read(&zi->i_mmap_sem);
> -
> -	return ret;
> -}
> -
>  static vm_fault_t zonefs_filemap_page_mkwrite(struct vm_fault *vmf)
>  {
>  	struct inode *inode = file_inode(vmf->vma->vm_file);
> @@ -607,16 +595,16 @@ static vm_fault_t zonefs_filemap_page_mkwrite(struct vm_fault *vmf)
>  	file_update_time(vmf->vma->vm_file);
>  
>  	/* Serialize against truncates */
> -	down_read(&zi->i_mmap_sem);
> +	down_read(&inode->i_mapping->invalidate_lock);
>  	ret = iomap_page_mkwrite(vmf, &zonefs_iomap_ops);
> -	up_read(&zi->i_mmap_sem);
> +	up_read(&inode->i_mapping->invalidate_lock);
>  
>  	sb_end_pagefault(inode->i_sb);
>  	return ret;
>  }
>  
>  static const struct vm_operations_struct zonefs_file_vm_ops = {
> -	.fault		= zonefs_filemap_fault,
> +	.fault		= filemap_fault,
>  	.map_pages	= filemap_map_pages,
>  	.page_mkwrite	= zonefs_filemap_page_mkwrite,
>  };
> @@ -1158,7 +1146,6 @@ static struct inode *zonefs_alloc_inode(struct super_block *sb)
>  
>  	inode_init_once(&zi->i_vnode);
>  	mutex_init(&zi->i_truncate_mutex);
> -	init_rwsem(&zi->i_mmap_sem);
>  	zi->i_wr_refcnt = 0;
>  
>  	return &zi->i_vnode;
> diff --git a/fs/zonefs/zonefs.h b/fs/zonefs/zonefs.h
> index 51141907097c..7b147907c328 100644
> --- a/fs/zonefs/zonefs.h
> +++ b/fs/zonefs/zonefs.h
> @@ -70,12 +70,11 @@ struct zonefs_inode_info {
>  	 * and changes to the inode private data, and in particular changes to
>  	 * a sequential file size on completion of direct IO writes.
>  	 * Serialization of mmap read IOs with truncate and syscall IO
> -	 * operations is done with i_mmap_sem in addition to i_truncate_mutex.
> -	 * Only zonefs_seq_file_truncate() takes both lock (i_mmap_sem first,
> -	 * i_truncate_mutex second).
> +	 * operations is done with invalidate_lock in addition to
> +	 * i_truncate_mutex.  Only zonefs_seq_file_truncate() takes both lock
> +	 * (invalidate_lock first, i_truncate_mutex second).
>  	 */
>  	struct mutex		i_truncate_mutex;
> -	struct rw_semaphore	i_mmap_sem;
>  
>  	/* guarded by i_truncate_mutex */
>  	unsigned int		i_wr_refcnt;
> 

Looks OK to me for zonefs. This is a nice cleanup.

Acked-by: Damien Le Moal <damien.lemoal@wdc.com>

-- 
Damien Le Moal
Western Digital Research