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Subject: Re: [PATCH v3] ceph: invalidate pages when doing direct/sync writes
To:     =?UTF-8?Q?Lu=c3=ads_Henriques?= <lhenriques@suse.de>,
        Jeff Layton <jlayton@kernel.org>,
        Ilya Dryomov <idryomov@gmail.com>
Cc:     ceph-devel@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20220407143834.7516-1-lhenriques@suse.de>
From:   Xiubo Li <xiubli@redhat.com>
Message-ID: <253c9edf-01c5-40a3-3a11-738f29df8142@redhat.com>
Date:   Thu, 7 Apr 2022 22:48:20 +0800
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On 4/7/22 10:38 PM, Luís Henriques wrote:
> When doing a direct/sync write, we need to invalidate the page cache in
> the range being written to.  If we don't do this, the cache will include
> invalid data as we just did a write that avoided the page cache.
>
> Signed-off-by: Luís Henriques <lhenriques@suse.de>
> ---
>   fs/ceph/file.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
>
> Ok, here's a new attempt.  After discussion in this thread and on IRC, I
> think this is the right fix.  generic/647 now passes with and without
> encryption.  Thanks!
>
> Changes since v2:
> - Invalidation needs to be done after a write
>
> Changes since v1:
> - Replaced truncate_inode_pages_range() by invalidate_inode_pages2_range
> - Call fscache_invalidate with FSCACHE_INVAL_DIO_WRITE if we're doing DIO
>
> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> index 5072570c2203..63e67eb60310 100644
> --- a/fs/ceph/file.c
> +++ b/fs/ceph/file.c
> @@ -1938,6 +1938,15 @@ ceph_sync_write(struct kiocb *iocb, struct iov_iter *from, loff_t pos,
>   			break;
>   		}
>   		ceph_clear_error_write(ci);
> +		ret = invalidate_inode_pages2_range(
> +				inode->i_mapping,
> +				pos >> PAGE_SHIFT,
> +				(pos + len - 1) >> PAGE_SHIFT);
> +		if (ret < 0) {
> +			dout("invalidate_inode_pages2_range returned %d\n",
> +			     ret);
> +			ret = 0;
> +		}
>   		pos += len;
>   		written += len;
>   		dout("sync_write written %d\n", written);
>
LGTM.

Maybe it worth adding a comment to explain why we need this and where 
the mapping come from ?

Reviewed-by: Xiubo Li <xiubli@redhat.com>