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From: Andreas Gruenbacher <agruenba@redhat.com>
Date: Thu, 24 May 2018 20:25:55 +0200
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Subject: Re: gfs2 iomap: BUG_ON(buffer_unmapped) in submit_bh_wbc
To: Christoph Hellwig <hch@lst.de>
Cc: "K.V, Aneesh" <aneesh.kumar@linux.vnet.ibm.com>,
        cluster-devel <cluster-devel@redhat.com>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>
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On 24 May 2018 at 20:13, Christoph Hellwig <hch@lst.de> wrote:
> On Thu, May 24, 2018 at 08:05:03PM +0200, Andreas Gruenbacher wrote:
>> Approach (1) is quite trivial:
>>
>> --- a/fs/buffer.c
>> +++ b/fs/buffer.c
>> @@ -1908,7 +1908,7 @@ iomap_to_bh(struct inode *inode, sector_t,
>> struct buffer_head *bh,
>>                 set_buffer_unwritten(bh);
>>                 /* FALLTHRU */
>>         case IOMAP_MAPPED:
>> -               if (offset >= i_size_read(inode))
>> +               if ((iomap->flags & IOMAP_F_NEW) || offset >=
>> i_size_read(inode))
>>                         set_buffer_new(bh);
>>                 bh->b_blocknr = (iomap->addr + offset - iomap->offset) >>
>>                                 inode->i_blkbits;
>>
>
> This is the right thing to do.  We just didn't need to do it for XFS
> as we'll never allocate normal blocks in write_begin.

Okay, that's easy.

> You'll probably need similar tweaks in my new iomap write code, which
> you're hopefully looking into as well.

Didn't get very far with your bh removal patches so far.

Thanks,
Andreas