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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <d3ee362c-accf-4ad9-99a6-5834b1c0b438@bsbernd.com>
Date: Fri, 7 Feb 2025 15:29:13 +0100
From: Bernd Schubert <bernd@...ernd.com>
To: Luis Henriques <luis@...lia.com>, Miklos Szeredi <miklos@...redi.hu>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
 Matt Harvey <mharvey@...ptrading.com>, Dave Chinner <david@...morbit.com>
Subject: Re: [RFC PATCH] fuse: add new function to invalidate cache for all
 inodes



On 1/15/25 17:32, 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 superblock dcache.
> 
> Signed-off-by: Luis Henriques <luis@...lia.com>
> ---
> Just an additional note that this patch could eventually be simplified if
> Dave Chinner patch to iterate through the superblock inodes[1] is merged.
> 
> [1] https://lore.kernel.org/r/20241002014017.3801899-3-david@fromorbit.com
> 
>  fs/fuse/inode.c           | 53 +++++++++++++++++++++++++++++++++++++++
>  include/uapi/linux/fuse.h |  3 +++
>  2 files changed, 56 insertions(+)
> 
> diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> index 3ce4f4e81d09..1fd9a5f303da 100644
> --- a/fs/fuse/inode.c
> +++ b/fs/fuse/inode.c
> @@ -546,6 +546,56 @@ struct inode *fuse_ilookup(struct fuse_conn *fc, u64 nodeid,
>  	return NULL;
>  }
>  
> +static int fuse_reverse_inval_all(struct fuse_conn *fc)
> +{
> +	struct fuse_mount *fm;
> +	struct super_block *sb;
> +	struct inode *inode, *old_inode = NULL;
> +	struct fuse_inode *fi;
> +
> +	inode = fuse_ilookup(fc, FUSE_ROOT_ID, NULL);
> +	if (!inode)
> +		return -ENOENT;
> +
> +	fm = get_fuse_mount(inode);
> +	iput(inode);
> +	if (!fm)
> +		return -ENOENT;
> +	sb = fm->sb;
> +
> +	spin_lock(&sb->s_inode_list_lock);
> +	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
> +		spin_lock(&inode->i_lock);
> +		if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
> +		    !atomic_read(&inode->i_count)) {
> +			spin_unlock(&inode->i_lock);
> +			continue;
> +		}
> +
> +		__iget(inode);
> +		spin_unlock(&inode->i_lock);
> +		spin_unlock(&sb->s_inode_list_lock);
> +		iput(old_inode);
> +
> +		fi = get_fuse_inode(inode);
> +		spin_lock(&fi->lock);
> +		fi->attr_version = atomic64_inc_return(&fm->fc->attr_version);
> +		spin_unlock(&fi->lock);
> +		fuse_invalidate_attr(inode);
> +		forget_all_cached_acls(inode);
> +
> +		old_inode = inode;
> +		cond_resched();
> +		spin_lock(&sb->s_inode_list_lock);
> +	}
> +	spin_unlock(&sb->s_inode_list_lock);
> +	iput(old_inode);
> +
> +	shrink_dcache_sb(sb);
> +
> +	return 0;
> +}

Just a suggestion, assuming Daves patch gets merged, maybe you coud move
the actual action into into a sub function? Makes it better visible
what is actually does and would then make it easier to move the iteration
part to the generic approach?
Alternatively, maybe updates Daves patch and add fuse on top of it? Dave?


Thanks,
Bernd