linux-kernel - Re: [PATCH v3] ceph: invalidate pages when doing direct/sync writes

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Message-ID: <87fsmp7x3z.fsf@brahms.olymp>
Date:   Thu, 07 Apr 2022 16:05:04 +0100
From:   Luís Henriques <lhenriques@...e.de>
To:     Xiubo Li <xiubli@...hat.com>
Cc:     Jeff Layton <jlayton@...nel.org>,
        Ilya Dryomov <idryomov@...il.com>, ceph-devel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] ceph: invalidate pages when doing direct/sync writes

Xiubo Li <xiubli@...hat.com> writes:

> 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@...e.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@...hat.com>
>

Sure, I'll send out v4 with an extra comment.  Thanks.

Cheers,
-- 
Luís