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Date: Tue, 27 Feb 2024 09:44:46 +0100
From: "Pankaj Raghav (Samsung)" <kernel@pankajraghav.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, 
	linux-kernel@vger.kernel.org, david@fromorbit.com, chandan.babu@oracle.com, 
	akpm@linux-foundation.org, mcgrof@kernel.org, ziy@nvidia.com, hare@suse.de, 
	djwong@kernel.org, gost.dev@samsung.com, linux-mm@kvack.org, 
	Pankaj Raghav <p.raghav@samsung.com>
Subject: Re: [PATCH 12/13] xfs: make the calculation generic in
 xfs_sb_validate_fsb_count()
Message-ID: <uw6wet56alvrcj6erv3fwn3hqjsyijhk4ke7f54yowt3mzkreh@hiov5ttykytu>
References: <20240226094936.2677493-1-kernel@pankajraghav.com>
 <20240226094936.2677493-13-kernel@pankajraghav.com>
 <ZdyQdGkSIw9OsSqc@casper.infradead.org>
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In-Reply-To: <ZdyQdGkSIw9OsSqc@casper.infradead.org>

On Mon, Feb 26, 2024 at 01:21:56PM +0000, Matthew Wilcox wrote:
> On Mon, Feb 26, 2024 at 10:49:35AM +0100, Pankaj Raghav (Samsung) wrote:
> > +	if (check_mul_overflow(nblocks, (1 << sbp->sb_blocklog), &bytes))
> 
> Why would you not use check_shl_overflow()?

This looks better than check_mul_overflow. I will use this in the next
version.
> 
> > +		return -EFBIG;
> > +
> > +	mapping_count = bytes >> PAGE_SHIFT;
> >  	/* Limited by ULONG_MAX of page cache index */
> > -	if (nblocks >> (PAGE_SHIFT - sbp->sb_blocklog) > ULONG_MAX)
> > +	if (mapping_count > ULONG_MAX)
> >  		return -EFBIG;
> >  	return 0;
> >  }
> > -- 
> > 2.43.0
> >