linux-kernel - Re: [PATCH v9 2/3] fs: move drop_pagecache

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Message-ID: <Y9+YUWUdMPKnJpyq@casper.infradead.org>
Date:   Sun, 5 Feb 2023 11:51:45 +0000
From:   Matthew Wilcox <willy@...radead.org>
To:     Shiyang Ruan <ruansy.fnst@...itsu.com>
Cc:     linux-kernel@...r.kernel.org, linux-xfs@...r.kernel.org,
        nvdimm@...ts.linux.dev, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org, djwong@...nel.org,
        dan.j.williams@...el.com, david@...morbit.com, hch@...radead.org,
        jane.chu@...cle.com
Subject: Re: [PATCH v9 2/3] fs: move drop_pagecache_sb() for others to use

On Sat, Feb 04, 2023 at 02:58:37PM +0000, Shiyang Ruan wrote:
> @@ -678,6 +679,48 @@ void drop_super_exclusive(struct super_block *sb)
>  }
>  EXPORT_SYMBOL(drop_super_exclusive);
>  
> +/*

You've gone to the trouble of writing kernel-doc, just add the extra '*'
and make it actually part of the documentation!

> + *	super_drop_pagecache - drop all page caches of a filesystem
> + *	@sb: superblock to invalidate
> + *	@arg: invalidate method, such as invalidate_inode_pages(),
> + *	        invalidate_inode_pages2()
> + *
> + *	Scans the inodes of a filesystem, drop all page caches.
> + */

> +++ b/include/linux/fs.h
> @@ -3308,6 +3308,7 @@ extern struct super_block *get_super(struct block_device *);
>  extern struct super_block *get_active_super(struct block_device *bdev);
>  extern void drop_super(struct super_block *sb);
>  extern void drop_super_exclusive(struct super_block *sb);
> +void super_drop_pagecache(struct super_block *sb, void *unused);

But the arg isn't unused.  Call it 'invalidator' here.

> +/**
> + * invalidate_inode_pages - Invalidate all clean, unlocked cache of one inode
> + * @mapping: the address_space which holds the cache to invalidate
> + *
> + * This function removes all pages that are clean, unmapped and unlocked,
> + * as well as shadow entries. It will not block on IO activity.
> + */
> +int invalidate_inode_pages(struct address_space *mapping)
> +{
> +	invalidate_mapping_pages(mapping, 0, -1);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(invalidate_inode_pages);

I might make this a static function in super.c but maybe you need it
in the next patch.