Commit e6a74dcf authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

xfs: refactor aligning bestlen to prod 



There are two places in xfs_rtalloc.c where we want to make sure that a
count of rt extents is aligned with a particular prod(uct) factor.  In
one spot, we actually use rounddown(), albeit unnecessarily if prod < 2.
In the other case, we open-code this rounding inefficiently by promoting
the 32-bit length value to a 64-bit value and then performing a 64-bit
division to figure out the subtraction.

Refactor this into a single helper that uses the correct types and
division method for the type, and skips the division entirely unless
prod is large enough to make a difference.

Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent e99aa040

fs/xfs/xfs_rtalloc.c

+15 −11
Original line number Diff line number Diff line
@@ -194,6 +194,17 @@ xfs_rtallocate_range( 
	return xfs_rtmodify_range(args, start, len, 0);

}



/* Reduce @rtxlen until it is a multiple of @prod. */

static inline xfs_rtxlen_t

xfs_rtalloc_align_len(

	xfs_rtxlen_t	rtxlen,

	xfs_rtxlen_t	prod)

{

	if (unlikely(prod > 1))

		return rounddown(rtxlen, prod);

	return rtxlen;

}



/*

 * Make sure we don't run off the end of the rt volume.  Be careful that

 * adjusting maxlen downwards doesn't cause us to fail the alignment checks.
@@ -208,7 +219,7 @@ xfs_rtallocate_clamp_len( 
	xfs_rtxlen_t		ret;



	ret = min(mp->m_sb.sb_rextents, startrtx + rtxlen) - startrtx;

	return rounddown(ret, prod);

	return xfs_rtalloc_align_len(ret, prod);

}



/*
@@ -292,17 +303,10 @@ xfs_rtallocate_extent_block( 
		goto nospace;



	/*

	 * If size should be a multiple of prod, make that so.

	 * Ensure bestlen is a multiple of prod, but don't return a too-short

	 * extent.

	 */

	if (prod > 1) {

		xfs_rtxlen_t	p;	/* amount to trim length by */



		div_u64_rem(bestlen, prod, &p);

		if (p)

			bestlen -= p;

	}



	/* Don't return a too-short extent. */

	bestlen = xfs_rtalloc_align_len(bestlen, prod);

	if (bestlen < minlen)

		goto nospace;