linux-kernel - Re: [RFC PATCH v2] fuse: add new function to invalidate cache for all inodes

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Message-ID: <b5db41a7-1b26-4d12-b99f-c630f3054585@ddn.com>
Date: Mon, 10 Feb 2025 09:58:21 +0000
From: Bernd Schubert <bschubert@....com>
To: Luis Henriques <luis@...lia.com>, Miklos Szeredi <miklos@...redi.hu>
CC: "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH v2] fuse: add new function to invalidate cache for all
 inodes

On 2/10/25 10:48, Luis Henriques wrote:
> Currently userspace is able to notify the kernel to invalidate the cache for
> an inode.  This means that, if all the inodes in a filesystem need to be
> invalidated, then userspace needs to iterate through all of them and do this
> kernel notification separately.
> 
> This patch adds a new option that allows userspace to invalidate all the
> inodes with a single notification operation.  In addition to invalidate all
> the inodes, it also shrinks the sb dcache.
> 
> Signed-off-by: Luis Henriques <luis@...lia.com>
> ---
> Hi!
> 
> As suggested by Bernd, this patch v2 simply adds an helper function that
> will make it easier to replace most of it's code by a call to function
> super_iter_inodes() when Dave Chinner's patch[1] eventually gets merged.
> 
> [1] https://lore.kernel.org/r/20241002014017.3801899-3-david@fromorbit.com
> 
>  fs/fuse/inode.c           | 59 +++++++++++++++++++++++++++++++++++++++
>  include/uapi/linux/fuse.h |  3 ++
>  2 files changed, 62 insertions(+)
> 
> diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> index e9db2cb8c150..be51b53006d8 100644
> --- a/fs/fuse/inode.c
> +++ b/fs/fuse/inode.c
> @@ -547,6 +547,62 @@ struct inode *fuse_ilookup(struct fuse_conn *fc, u64 nodeid,
>  	return NULL;
>  }
>  
> +static void inval_single_inode(struct inode *inode, struct fuse_conn *fc)
> +{
> +	struct fuse_inode *fi;
> +
> +	fi = get_fuse_inode(inode);
> +	spin_lock(&fi->lock);
> +	fi->attr_version = atomic64_inc_return(&fc->attr_version);
> +	spin_unlock(&fi->lock);
> +	fuse_invalidate_attr(inode);
> +	forget_all_cached_acls(inode);


Thank you, much easier to read.

Could fuse_reverse_inval_inode() call into this? What are the semantics 
for  invalidate_inode_pages2_range() in this case? Totally invalidate?
No page cache invalidation at all as right now? If so, why?



Thanks,
Bernd