Received-SPF: pass (google.com: best guess record for domain of linux-ext4-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Wed, 26 Feb 2020 05:05:03 -0800
From:   Matthew Wilcox <willy@infradead.org>
To:     Ritesh Harjani <riteshh@linux.ibm.com>
Cc:     jack@suse.cz, tytso@mit.edu, linux-ext4@vger.kernel.org,
        adilger.kernel@dilger.ca, linux-fsdevel@vger.kernel.org,
        darrick.wong@oracle.com, hch@infradead.org, cmaiolino@redhat.com
Subject: Re: [PATCHv3 6/6] Documentation: Correct the description of
 FIEMAP_EXTENT_LAST
Message-ID: <20200226130503.GY24185@bombadil.infradead.org>
References: <cover.1582702693.git.riteshh@linux.ibm.com>
 <279638c6939b1f6ef3ab32912cb51da1a967cf8e.1582702694.git.riteshh@linux.ibm.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <279638c6939b1f6ef3ab32912cb51da1a967cf8e.1582702694.git.riteshh@linux.ibm.com>
Sender: linux-ext4-owner@vger.kernel.org
Precedence: bulk

On Wed, Feb 26, 2020 at 03:27:08PM +0530, Ritesh Harjani wrote:
> Currently FIEMAP_EXTENT_LAST is not working consistently across
> different filesystem's fiemap implementations and thus this feature
> may be broken. So fix the documentation about this flag to meet the
> right expectations.

Are you saying filesystems have both false positives and false negatives?
I can understand how a filesystem might fail to set FIEMAP_EXTENT_LAST,
but not how a filesystem might set it when there's actually another
extent beyond this one.

>  * FIEMAP_EXTENT_LAST
> -This is the last extent in the file. A mapping attempt past this
> -extent will return nothing.
> +This is generally the last extent in the file. A mapping attempt past this
> +extent may return nothing. But the user must still confirm by trying to map
> +past this extent, since different filesystems implement this differently.