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

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Message-ID: <87k0c17x6f.fsf@brahms.olymp>
Date:   Thu, 07 Apr 2022 16:03:36 +0100
From:   Luís Henriques <lhenriques@...e.de>
To:     Jeff Layton <jlayton@...nel.org>
Cc:     Xiubo Li <xiubli@...hat.com>, 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

Jeff Layton <jlayton@...nel.org> writes:

> On Thu, 2022-04-07 at 15:38 +0100, 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);
>
> Looks good. I suspect we can also remove the
> invalidate_indode_pages2_range call earlier in this function too. I may
> roll that into this patch.

Right, that occurred to me as well but I wasn't really sure that would be
safe.

> I'll give this an xfstests run with fscrypt enabled and see how it does.

I'll do the same here, I just run a few tests on a vstart cluster.  But
I'll definitely give it some more testing.

Cheers,
-- 
Luís