Commit e23aaf45 authored by Omar Sandoval's avatar Omar Sandoval Committed by Darrick J. Wong
Browse files

xfs: invert the realtime summary cache 



In commit 355e3532 ("xfs: cache minimum realtime summary level"), I
added a cache of the minimum level of the realtime summary that has any
free extents. However, it turns out that the _maximum_ level is more
useful for upcoming optimizations, and basically equivalent for the
existing usage. So, let's change the meaning of the cache to be the
maximum level + 1, or 0 if there are no free extents.

For example, if the cache contains:

{0, 4}

then there are no free extents starting in realtime bitmap block 0, and
there are no free extents larger than or equal to 2^4 blocks starting in
realtime bitmap block 1. The cache is a loose upper bound, so there may
or may not be free extents smaller than 2^4 blocks in realtime bitmap
block 1.

Signed-off-by: default avatarOmar Sandoval <osandov@fb.com>
Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent e2cf427c

fs/xfs/libxfs/xfs_rtbitmap.c

+3 −3
Original line number Diff line number Diff line
@@ -495,10 +495,10 @@ xfs_rtmodify_summary_int( 
		xfs_suminfo_t	val = xfs_suminfo_add(args, infoword, delta);



		if (mp->m_rsum_cache) {

			if (val == 0 && log == mp->m_rsum_cache[bbno])

				mp->m_rsum_cache[bbno]++;

			if (val != 0 && log < mp->m_rsum_cache[bbno])

			if (val == 0 && log + 1 == mp->m_rsum_cache[bbno])

				mp->m_rsum_cache[bbno] = log;

			if (val != 0 && log >= mp->m_rsum_cache[bbno])

				mp->m_rsum_cache[bbno] = log + 1;

		}

		xfs_trans_log_rtsummary(args, infoword);

		if (sum)

fs/xfs/xfs_mount.h

+3 −3
Original line number Diff line number Diff line
@@ -101,9 +101,9 @@ typedef struct xfs_mount { 


	/*

	 * Optional cache of rt summary level per bitmap block with the

	 * invariant that m_rsum_cache[bbno] <= the minimum i for which

	 * rsum[i][bbno] != 0. Reads and writes are serialized by the rsumip

	 * inode lock.

	 * invariant that m_rsum_cache[bbno] > the maximum i for which

	 * rsum[i][bbno] != 0, or 0 if rsum[i][bbno] == 0 for all i.

	 * Reads and writes are serialized by the rsumip inode lock.

	 */

	uint8_t			*m_rsum_cache;

	struct xfs_mru_cache	*m_filestream;  /* per-mount filestream data */

fs/xfs/xfs_rtalloc.c

+19 −12
Original line number Diff line number Diff line
@@ -54,14 +54,19 @@ xfs_rtany_summary( 
	int			log;	/* loop counter, log2 of ext. size */

	xfs_suminfo_t		sum;	/* summary data */



	/* There are no extents at levels < m_rsum_cache[bbno]. */

	if (mp->m_rsum_cache && low < mp->m_rsum_cache[bbno])

		low = mp->m_rsum_cache[bbno];

	/* There are no extents at levels >= m_rsum_cache[bbno]. */

	if (mp->m_rsum_cache) {

		high = min(high, mp->m_rsum_cache[bbno] - 1);

		if (low > high) {

			*stat = 0;

			return 0;

		}

	}



	/*

	 * Loop over logs of extent sizes.

	 */

	for (log = low; log <= high; log++) {

	for (log = high; log >= low; log--) {

		/*

		 * Get one summary datum.

		 */
@@ -82,9 +87,9 @@ xfs_rtany_summary( 
	 */

	*stat = 0;

out:

	/* There were no extents at levels < log. */

	if (mp->m_rsum_cache && log > mp->m_rsum_cache[bbno])

		mp->m_rsum_cache[bbno] = log;

	/* There were no extents at levels > log. */

	if (mp->m_rsum_cache && log + 1 < mp->m_rsum_cache[bbno])

		mp->m_rsum_cache[bbno] = log + 1;

	return 0;

}
@@ -887,12 +892,14 @@ xfs_alloc_rsum_cache( 
	xfs_extlen_t	rbmblocks)	/* number of rt bitmap blocks */

{

	/*

	 * The rsum cache is initialized to all zeroes, which is trivially a

	 * lower bound on the minimum level with any free extents. We can

	 * continue without the cache if it couldn't be allocated.

	 * The rsum cache is initialized to the maximum value, which is

	 * trivially an upper bound on the maximum level with any free extents.

	 * We can continue without the cache if it couldn't be allocated.

	 */

	mp->m_rsum_cache = kvzalloc(rbmblocks, GFP_KERNEL);

	if (!mp->m_rsum_cache)

	mp->m_rsum_cache = kvmalloc(rbmblocks, GFP_KERNEL);

	if (mp->m_rsum_cache)

		memset(mp->m_rsum_cache, -1, rbmblocks);

	else

		xfs_warn(mp, "could not allocate realtime summary cache");

}