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Message-ID: <x49skdoslfn.fsf@segfault.boston.devel.redhat.com>
Date: Mon, 12 Oct 2009 11:04:28 -0400
From: Jeff Moyer <jmoyer@...hat.com>
To: Christoph Hellwig <hch@....de>
Cc: linux-kernel@...r.kernel.org, Jens Axboe <jens.axboe@...cle.com>
Subject: Re: [PATCH] blkdev: flush disk cache on ->fsync
Christoph Hellwig <hch@....de> writes:
> Is anyone going to pick up this patch?
>
> On Thu, Aug 20, 2009 at 08:24:32PM +0200, Christoph Hellwig wrote:
>> Currently there is no barrier support in the block device code. That
>> means we cannot guarantee any sort of data integerity when using the
>> block device node with dis kwrite caches enabled. Using the raw block
>> device node is a typical use case for virtualization (and I assume
>> databases, too). This patch changes block_fsync to issue a cache flush
>> and thus make fsync on block device nodes actually useful.
>>
>> Note that in mainline we would also need to add such code to the
>> ->aio_write method for O_SYNC handling, but assuming that Jan's patch
>> series for the O_SYNC rewrite goes in it will also call into ->fsync
>> for 2.6.32.
>>
>>
>> Signed-off-by: Christoph Hellwig <hch@....de>
>>
>>
>> diff --git a/fs/block_dev.c b/fs/block_dev.c
>> index 94dfda2..298ad75 100644
>> --- a/fs/block_dev.c
>> +++ b/fs/block_dev.c
>> @@ -398,7 +398,17 @@ static loff_t block_llseek(struct file *file, loff_t offset, int origin)
>>
>> static int block_fsync(struct file *filp, struct dentry *dentry, int datasync)
>> {
>> - return sync_blockdev(I_BDEV(filp->f_mapping->host));
>> + struct block_device *bdev = I_BDEV(filp->f_mapping->host);
>> + int error;
>> +
>> + error = sync_blockdev(bdev);
>> + if (error)
>> + return error;
>> +
>> + error = blkdev_issue_flush(bdev, NULL);
>> + if (error == -EOPNOTSUPP)
>> + error = 0;
>> + return error;
>> }
>>
>> /*
> ---end quoted text---
Looks ok to me. Jens?
Acked-by: Jeff Moyer <jmoyer@...hat.com>
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