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Date: Tue, 28 Nov 2023 06:04:26 -0800
From: Christoph Hellwig <hch@infradead.org>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH 1/6] xfs: check rt bitmap file geometry more thoroughly
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References: <170086928333.2771542.10506226721850199807.stgit@frogsfrogsfrogs>
 <170086928361.2771542.12276270495680939208.stgit@frogsfrogsfrogs>
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> +	/*
> +	 * Now that we've locked the rtbitmap, we can't race with growfsrt
> +	 * trying to expand the bitmap or change the size of the rt volume.
> +	 * Hence it is safe to compute and check the geometry values.
> +	 */
> +	rtb->rextents = xfs_rtb_to_rtx(mp, mp->m_sb.sb_rblocks);
> +	rtb->rextslog = rtb->rextents ? xfs_highbit32(rtb->rextents) : 0;
> +	rtb->rbmblocks = xfs_rtbitmap_blockcount(mp, rtb->rextents);

All these will be 0 if mp->m_sb.sb_rblocks, and rtb is zeroed allocation
right above, so calculating the values seems a bit odd.  Why not simply:

	if (mp->m_sb.sb_rblocks) {
		rtb->rextents = xfs_rtb_to_rtx(mp, mp->m_sb.sb_rblocks);
		rtb->rextslog = xfs_highbit32(rtb->rextents);
		rtb->rbmblocks = xfs_rtbitmap_blockcount(mp, rtb->rextents);
	}

?

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>