Re: [RFC PATCH] fuse: invalidate page cache pages before direct write

[Hao Xu <hao.xu@linux.dev>]

Ping...

On 5/9/23 16:01, Hao Xu wrote:
> From: Hao Xu <howeyxu@tencent.com>
> 
> In FOPEN_DIRECT_IO, page cache may still be there for a file, direct
> write should respect that and invalidate the corresponding pages so
> that page cache readers don't get stale data. Another thing this patch
> does is flush related pages to avoid its loss.
> 
> Signed-off-by: Hao Xu <howeyxu@tencent.com>
> ---
> 
> Reference:
> https://lore.kernel.org/linux-fsdevel/ee8380b3-683f-c526-5f10-1ce2ee6f79ad@linux.dev/#:~:text=I%20think%20this%20problem%20exists%20before%20this%20patchset
> 
>   fs/fuse/file.c | 14 +++++++++++++-
>   1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> index 89d97f6188e0..edc84c1dfc5c 100644
> --- a/fs/fuse/file.c
> +++ b/fs/fuse/file.c
> @@ -1490,7 +1490,8 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
>   	int write = flags & FUSE_DIO_WRITE;
>   	int cuse = flags & FUSE_DIO_CUSE;
>   	struct file *file = io->iocb->ki_filp;
> -	struct inode *inode = file->f_mapping->host;
> +	struct address_space *mapping = file->f_mapping;
> +	struct inode *inode = mapping->host;
>   	struct fuse_file *ff = file->private_data;
>   	struct fuse_conn *fc = ff->fm->fc;
>   	size_t nmax = write ? fc->max_write : fc->max_read;
> @@ -1516,6 +1517,17 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
>   			inode_unlock(inode);
>   	}
>   
> +	res = filemap_write_and_wait_range(mapping, pos, pos + count - 1);
> +	if (res)
> +		return res;
> +
> +	if (write) {
> +		if (invalidate_inode_pages2_range(mapping,
> +				idx_from, idx_to)) {
> +			return -ENOTBLK;
> +		}
> +	}
> +
>   	io->should_dirty = !write && user_backed_iter(iter);
>   	while (count) {
>   		ssize_t nres;