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Subject: Re: [PATCH 0/5] ext4/overlayfs: fiemap related fixes
To:     Amir Goldstein <amir73il@gmail.com>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Ext4 <linux-ext4@vger.kernel.org>, Jan Kara <jack@suse.cz>,
        Theodore Tso <tytso@mit.edu>,
        Andreas Dilger <adilger@dilger.ca>,
        "Darrick J. Wong" <darrick.wong@oracle.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
        Murphy Zhou <jencce.kernel@gmail.com>,
        Miklos Szeredi <miklos@szeredi.hu>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        overlayfs <linux-unionfs@vger.kernel.org>
References: <cover.1587555962.git.riteshh@linux.ibm.com>
 <20200424101153.GC456@infradead.org>
 <20200424232024.A39974C046@d06av22.portsmouth.uk.ibm.com>
 <CAOQ4uxgiome-BnHDvDC=vHfidf4Ru3jqzOki0Z_YUkinEeYCRQ@mail.gmail.com>
From:   Ritesh Harjani <riteshh@linux.ibm.com>
Date:   Sat, 25 Apr 2020 15:14:32 +0530
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On 4/25/20 2:41 PM, Amir Goldstein wrote:
> On Sat, Apr 25, 2020 at 2:20 AM Ritesh Harjani <riteshh@linux.ibm.com> wrote:
>>
>> Hello Christoph,
>>
>> Thanks for your review comments.
>>
>> On 4/24/20 3:41 PM, Christoph Hellwig wrote:
>>> I think the right fix is to move fiemap_check_ranges into all the ->fiemap
>>
>> I do welcome your suggestion here. But I am not sure of what you are
>> suggesting should be done as a 1st round of changes for the immediate
>> reported problem.
>> So currently these patches take the same approach on overlayfs on how
>> VFS does it. So as a fix to the overlayfs over ext4 reported problems in
>> thread [1] & [2]. I think these patches are doing the right thing.
>>
>> Also maybe I am biased in some way because as I see these are the right
>> fixes with minimal changes only at places which does have a direct
>> problem.
>>
> 
> FWIW, I agree with you.
> And seems like Jan does as well, since he ACKed all your patches.
> Current patches would be easier to backport to stable kernels.
> 
> Plus, if we are going to cleanup the fiemap interface, need to look into
> FIEMAP_FLAG_SYNC handling.
> Does it makes sense to handle this flag in vfs ioctl code and other flags
> by filesystem code?
> See, iomap_fiemap() takes care of FIEMAP_FLAG_SYNC in addition
> to ioctl_fiemap(), so I would think that FIEMAP_FLAG_SYNC should
> probably be removed from ioctl_fiemap() and handled by
> generic_block_fiemap() and other filesystem specific implementation.

Yes, and that too. I too wanted to re-look on the above mentioned part.
Thanks for penning it down.

-ritesh