[PATCH v2 0/5] xfs: rework online repair incore bitmap

[PATCH v2 0/5] xfs: rework online repair incore bitmap

[Darrick J. Wong]

Hi all,

In this series, we make some changes to the incore bitmap code: First,
we shorten the prefix to 'xbitmap'.  Then, we rework some utility
functions for later use by online repair and clarify how the walk
functions are supposed to be used.

Finally, we use all these new pieces to convert the incore bitmap to use
an interval tree instead of linked lists.  This lifts the limitation
that callers had to be careful not to set a range that was already set;
and gets us ready for the btree rebuilder functions needing to be able
to set bits in a bitmap and generate maximal contiguous extents for the
set ranges.

If you're going to start using this mess, you probably ought to just
pull from my git trees, which are linked below.

This is an extraordinary way to destroy everything.  Enjoy!
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=repair-bitmap-rework

[PATCH 1/5] xfs: rename xfs_bitmap to xbitmap

[Darrick J. Wong]

From: Darrick J. Wong <darrick.wong@oracle.com>

Shorten the name of xfs_bitmap to xbitmap since the scrub bitmap has
nothing to do with the libxfs bitmap.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
---
 fs/xfs/scrub/agheader_repair.c |   42 ++++++++++++-----------
 fs/xfs/scrub/bitmap.c          |   72 ++++++++++++++++++++--------------------
 fs/xfs/scrub/bitmap.h          |   22 ++++++------
 fs/xfs/scrub/repair.c          |    8 ++--
 fs/xfs/scrub/repair.h          |    4 +-
 5 files changed, 74 insertions(+), 74 deletions(-)


diff --git a/fs/xfs/scrub/agheader_repair.c b/fs/xfs/scrub/agheader_repair.c
index 8fcd43040c96..9fbb6035f4e2 100644
--- a/fs/xfs/scrub/agheader_repair.c
+++ b/fs/xfs/scrub/agheader_repair.c
@@ -429,10 +429,10 @@ xrep_agf(
 
 struct xrep_agfl {
 	/* Bitmap of other OWN_AG metadata blocks. */
-	struct xfs_bitmap	agmetablocks;
+	struct xbitmap		agmetablocks;
 
 	/* Bitmap of free space. */
-	struct xfs_bitmap	*freesp;
+	struct xbitmap		*freesp;
 
 	struct xfs_scrub	*sc;
 };
@@ -455,12 +455,12 @@ xrep_agfl_walk_rmap(
 	if (rec->rm_owner == XFS_RMAP_OWN_AG) {
 		fsb = XFS_AGB_TO_FSB(cur->bc_mp, cur->bc_private.a.agno,
 				rec->rm_startblock);
-		error = xfs_bitmap_set(ra->freesp, fsb, rec->rm_blockcount);
+		error = xbitmap_set(ra->freesp, fsb, rec->rm_blockcount);
 		if (error)
 			return error;
 	}
 
-	return xfs_bitmap_set_btcur_path(&ra->agmetablocks, cur);
+	return xbitmap_set_btcur_path(&ra->agmetablocks, cur);
 }
 
 /*
@@ -476,19 +476,19 @@ STATIC int
 xrep_agfl_collect_blocks(
 	struct xfs_scrub	*sc,
 	struct xfs_buf		*agf_bp,
-	struct xfs_bitmap	*agfl_extents,
+	struct xbitmap		*agfl_extents,
 	xfs_agblock_t		*flcount)
 {
 	struct xrep_agfl	ra;
 	struct xfs_mount	*mp = sc->mp;
 	struct xfs_btree_cur	*cur;
-	struct xfs_bitmap_range	*br;
-	struct xfs_bitmap_range	*n;
+	struct xbitmap_range	*br;
+	struct xbitmap_range	*n;
 	int			error;
 
 	ra.sc = sc;
 	ra.freesp = agfl_extents;
-	xfs_bitmap_init(&ra.agmetablocks);
+	xbitmap_init(&ra.agmetablocks);
 
 	/* Find all space used by the free space btrees & rmapbt. */
 	cur = xfs_rmapbt_init_cursor(mp, sc->tp, agf_bp, sc->sa.agno);
@@ -500,7 +500,7 @@ xrep_agfl_collect_blocks(
 	/* Find all blocks currently being used by the bnobt. */
 	cur = xfs_allocbt_init_cursor(mp, sc->tp, agf_bp, sc->sa.agno,
 			XFS_BTNUM_BNO);
-	error = xfs_bitmap_set_btblocks(&ra.agmetablocks, cur);
+	error = xbitmap_set_btblocks(&ra.agmetablocks, cur);
 	if (error)
 		goto err;
 	xfs_btree_del_cursor(cur, error);
@@ -508,7 +508,7 @@ xrep_agfl_collect_blocks(
 	/* Find all blocks currently being used by the cntbt. */
 	cur = xfs_allocbt_init_cursor(mp, sc->tp, agf_bp, sc->sa.agno,
 			XFS_BTNUM_CNT);
-	error = xfs_bitmap_set_btblocks(&ra.agmetablocks, cur);
+	error = xbitmap_set_btblocks(&ra.agmetablocks, cur);
 	if (error)
 		goto err;
 
@@ -518,8 +518,8 @@ xrep_agfl_collect_blocks(
 	 * Drop the freesp meta blocks that are in use by btrees.
 	 * The remaining blocks /should/ be AGFL blocks.
 	 */
-	error = xfs_bitmap_disunion(agfl_extents, &ra.agmetablocks);
-	xfs_bitmap_destroy(&ra.agmetablocks);
+	error = xbitmap_disunion(agfl_extents, &ra.agmetablocks);
+	xbitmap_destroy(&ra.agmetablocks);
 	if (error)
 		return error;
 
@@ -528,7 +528,7 @@ xrep_agfl_collect_blocks(
 	 * the AGFL we'll free them later.
 	 */
 	*flcount = 0;
-	for_each_xfs_bitmap_extent(br, n, agfl_extents) {
+	for_each_xbitmap_extent(br, n, agfl_extents) {
 		*flcount += br->len;
 		if (*flcount > xfs_agfl_size(mp))
 			break;
@@ -538,7 +538,7 @@ xrep_agfl_collect_blocks(
 	return 0;
 
 err:
-	xfs_bitmap_destroy(&ra.agmetablocks);
+	xbitmap_destroy(&ra.agmetablocks);
 	xfs_btree_del_cursor(cur, error);
 	return error;
 }
@@ -573,13 +573,13 @@ STATIC void
 xrep_agfl_init_header(
 	struct xfs_scrub	*sc,
 	struct xfs_buf		*agfl_bp,
-	struct xfs_bitmap	*agfl_extents,
+	struct xbitmap		*agfl_extents,
 	xfs_agblock_t		flcount)
 {
 	struct xfs_mount	*mp = sc->mp;
 	__be32			*agfl_bno;
-	struct xfs_bitmap_range	*br;
-	struct xfs_bitmap_range	*n;
+	struct xbitmap_range	*br;
+	struct xbitmap_range	*n;
 	struct xfs_agfl		*agfl;
 	xfs_agblock_t		agbno;
 	unsigned int		fl_off;
@@ -603,7 +603,7 @@ xrep_agfl_init_header(
 	 */
 	fl_off = 0;
 	agfl_bno = XFS_BUF_TO_AGFL_BNO(mp, agfl_bp);
-	for_each_xfs_bitmap_extent(br, n, agfl_extents) {
+	for_each_xbitmap_extent(br, n, agfl_extents) {
 		agbno = XFS_FSB_TO_AGBNO(mp, br->start);
 
 		trace_xrep_agfl_insert(mp, sc->sa.agno, agbno, br->len);
@@ -637,7 +637,7 @@ int
 xrep_agfl(
 	struct xfs_scrub	*sc)
 {
-	struct xfs_bitmap	agfl_extents;
+	struct xbitmap		agfl_extents;
 	struct xfs_mount	*mp = sc->mp;
 	struct xfs_buf		*agf_bp;
 	struct xfs_buf		*agfl_bp;
@@ -649,7 +649,7 @@ xrep_agfl(
 		return -EOPNOTSUPP;
 
 	xchk_perag_get(sc->mp, &sc->sa);
-	xfs_bitmap_init(&agfl_extents);
+	xbitmap_init(&agfl_extents);
 
 	/*
 	 * Read the AGF so that we can query the rmapbt.  We hope that there's
@@ -701,7 +701,7 @@ xrep_agfl(
 	error = xrep_reap_extents(sc, &agfl_extents, &XFS_RMAP_OINFO_AG,
 			XFS_AG_RESV_AGFL);
 err:
-	xfs_bitmap_destroy(&agfl_extents);
+	xbitmap_destroy(&agfl_extents);
 	return error;
 }
 
diff --git a/fs/xfs/scrub/bitmap.c b/fs/xfs/scrub/bitmap.c
index 18a684e18a69..ab26201e9110 100644
--- a/fs/xfs/scrub/bitmap.c
+++ b/fs/xfs/scrub/bitmap.c
@@ -18,14 +18,14 @@
  * This is the logical equivalent of bitmap |= mask(start, len).
  */
 int
-xfs_bitmap_set(
-	struct xfs_bitmap	*bitmap,
+xbitmap_set(
+	struct xbitmap		*bitmap,
 	uint64_t		start,
 	uint64_t		len)
 {
-	struct xfs_bitmap_range	*bmr;
+	struct xbitmap_range	*bmr;
 
-	bmr = kmem_alloc(sizeof(struct xfs_bitmap_range), KM_MAYFAIL);
+	bmr = kmem_alloc(sizeof(struct xbitmap_range), KM_MAYFAIL);
 	if (!bmr)
 		return -ENOMEM;
 
@@ -39,13 +39,13 @@ xfs_bitmap_set(
 
 /* Free everything related to this bitmap. */
 void
-xfs_bitmap_destroy(
-	struct xfs_bitmap	*bitmap)
+xbitmap_destroy(
+	struct xbitmap		*bitmap)
 {
-	struct xfs_bitmap_range	*bmr;
-	struct xfs_bitmap_range	*n;
+	struct xbitmap_range	*bmr;
+	struct xbitmap_range	*n;
 
-	for_each_xfs_bitmap_extent(bmr, n, bitmap) {
+	for_each_xbitmap_extent(bmr, n, bitmap) {
 		list_del(&bmr->list);
 		kmem_free(bmr);
 	}
@@ -53,24 +53,24 @@ xfs_bitmap_destroy(
 
 /* Set up a per-AG block bitmap. */
 void
-xfs_bitmap_init(
-	struct xfs_bitmap	*bitmap)
+xbitmap_init(
+	struct xbitmap		*bitmap)
 {
 	INIT_LIST_HEAD(&bitmap->list);
 }
 
 /* Compare two btree extents. */
 static int
-xfs_bitmap_range_cmp(
+xbitmap_range_cmp(
 	void			*priv,
 	struct list_head	*a,
 	struct list_head	*b)
 {
-	struct xfs_bitmap_range	*ap;
-	struct xfs_bitmap_range	*bp;
+	struct xbitmap_range	*ap;
+	struct xbitmap_range	*bp;
 
-	ap = container_of(a, struct xfs_bitmap_range, list);
-	bp = container_of(b, struct xfs_bitmap_range, list);
+	ap = container_of(a, struct xbitmap_range, list);
+	bp = container_of(b, struct xbitmap_range, list);
 
 	if (ap->start > bp->start)
 		return 1;
@@ -96,14 +96,14 @@ xfs_bitmap_range_cmp(
 #define LEFT_ALIGNED	(1 << 0)
 #define RIGHT_ALIGNED	(1 << 1)
 int
-xfs_bitmap_disunion(
-	struct xfs_bitmap	*bitmap,
-	struct xfs_bitmap	*sub)
+xbitmap_disunion(
+	struct xbitmap		*bitmap,
+	struct xbitmap		*sub)
 {
 	struct list_head	*lp;
-	struct xfs_bitmap_range	*br;
-	struct xfs_bitmap_range	*new_br;
-	struct xfs_bitmap_range	*sub_br;
+	struct xbitmap_range	*br;
+	struct xbitmap_range	*new_br;
+	struct xbitmap_range	*sub_br;
 	uint64_t		sub_start;
 	uint64_t		sub_len;
 	int			state;
@@ -113,8 +113,8 @@ xfs_bitmap_disunion(
 		return 0;
 	ASSERT(!list_empty(&sub->list));
 
-	list_sort(NULL, &bitmap->list, xfs_bitmap_range_cmp);
-	list_sort(NULL, &sub->list, xfs_bitmap_range_cmp);
+	list_sort(NULL, &bitmap->list, xbitmap_range_cmp);
+	list_sort(NULL, &sub->list, xbitmap_range_cmp);
 
 	/*
 	 * Now that we've sorted both lists, we iterate bitmap once, rolling
@@ -124,11 +124,11 @@ xfs_bitmap_disunion(
 	 * list traversal is similar to merge sort, but we're deleting
 	 * instead.  In this manner we avoid O(n^2) operations.
 	 */
-	sub_br = list_first_entry(&sub->list, struct xfs_bitmap_range,
+	sub_br = list_first_entry(&sub->list, struct xbitmap_range,
 			list);
 	lp = bitmap->list.next;
 	while (lp != &bitmap->list) {
-		br = list_entry(lp, struct xfs_bitmap_range, list);
+		br = list_entry(lp, struct xbitmap_range, list);
 
 		/*
 		 * Advance sub_br and/or br until we find a pair that
@@ -181,7 +181,7 @@ xfs_bitmap_disunion(
 			 * Deleting from the middle: add the new right extent
 			 * and then shrink the left extent.
 			 */
-			new_br = kmem_alloc(sizeof(struct xfs_bitmap_range),
+			new_br = kmem_alloc(sizeof(struct xbitmap_range),
 					KM_MAYFAIL);
 			if (!new_br) {
 				error = -ENOMEM;
@@ -247,8 +247,8 @@ xfs_bitmap_disunion(
  * blocks going from the leaf towards the root.
  */
 int
-xfs_bitmap_set_btcur_path(
-	struct xfs_bitmap	*bitmap,
+xbitmap_set_btcur_path(
+	struct xbitmap		*bitmap,
 	struct xfs_btree_cur	*cur)
 {
 	struct xfs_buf		*bp;
@@ -261,7 +261,7 @@ xfs_bitmap_set_btcur_path(
 		if (!bp)
 			continue;
 		fsb = XFS_DADDR_TO_FSB(cur->bc_mp, bp->b_bn);
-		error = xfs_bitmap_set(bitmap, fsb, 1);
+		error = xbitmap_set(bitmap, fsb, 1);
 		if (error)
 			return error;
 	}
@@ -271,12 +271,12 @@ xfs_bitmap_set_btcur_path(
 
 /* Collect a btree's block in the bitmap. */
 STATIC int
-xfs_bitmap_collect_btblock(
+xbitmap_collect_btblock(
 	struct xfs_btree_cur	*cur,
 	int			level,
 	void			*priv)
 {
-	struct xfs_bitmap	*bitmap = priv;
+	struct xbitmap		*bitmap = priv;
 	struct xfs_buf		*bp;
 	xfs_fsblock_t		fsbno;
 
@@ -285,15 +285,15 @@ xfs_bitmap_collect_btblock(
 		return 0;
 
 	fsbno = XFS_DADDR_TO_FSB(cur->bc_mp, bp->b_bn);
-	return xfs_bitmap_set(bitmap, fsbno, 1);
+	return xbitmap_set(bitmap, fsbno, 1);
 }
 
 /* Walk the btree and mark the bitmap wherever a btree block is found. */
 int
-xfs_bitmap_set_btblocks(
-	struct xfs_bitmap	*bitmap,
+xbitmap_set_btblocks(
+	struct xbitmap		*bitmap,
 	struct xfs_btree_cur	*cur)
 {
-	return xfs_btree_visit_blocks(cur, xfs_bitmap_collect_btblock,
+	return xfs_btree_visit_blocks(cur, xbitmap_collect_btblock,
 			XFS_BTREE_VISIT_ALL, bitmap);
 }
diff --git a/fs/xfs/scrub/bitmap.h b/fs/xfs/scrub/bitmap.h
index ae8ecbce6fa6..8db4017ac78e 100644
--- a/fs/xfs/scrub/bitmap.h
+++ b/fs/xfs/scrub/bitmap.h
@@ -6,31 +6,31 @@
 #ifndef __XFS_SCRUB_BITMAP_H__
 #define __XFS_SCRUB_BITMAP_H__
 
-struct xfs_bitmap_range {
+struct xbitmap_range {
 	struct list_head	list;
 	uint64_t		start;
 	uint64_t		len;
 };
 
-struct xfs_bitmap {
+struct xbitmap {
 	struct list_head	list;
 };
 
-void xfs_bitmap_init(struct xfs_bitmap *bitmap);
-void xfs_bitmap_destroy(struct xfs_bitmap *bitmap);
+void xbitmap_init(struct xbitmap *bitmap);
+void xbitmap_destroy(struct xbitmap *bitmap);
 
-#define for_each_xfs_bitmap_extent(bex, n, bitmap) \
+#define for_each_xbitmap_extent(bex, n, bitmap) \
 	list_for_each_entry_safe((bex), (n), &(bitmap)->list, list)
 
-#define for_each_xfs_bitmap_block(b, bex, n, bitmap) \
+#define for_each_xbitmap_block(b, bex, n, bitmap) \
 	list_for_each_entry_safe((bex), (n), &(bitmap)->list, list) \
-		for ((b) = bex->start; (b) < bex->start + bex->len; (b)++)
+		for ((b) = (bex)->start; (b) < (bex)->start + (bex)->len; (b)++)
 
-int xfs_bitmap_set(struct xfs_bitmap *bitmap, uint64_t start, uint64_t len);
-int xfs_bitmap_disunion(struct xfs_bitmap *bitmap, struct xfs_bitmap *sub);
-int xfs_bitmap_set_btcur_path(struct xfs_bitmap *bitmap,
+int xbitmap_set(struct xbitmap *bitmap, uint64_t start, uint64_t len);
+int xbitmap_disunion(struct xbitmap *bitmap, struct xbitmap *sub);
+int xbitmap_set_btcur_path(struct xbitmap *bitmap,
 		struct xfs_btree_cur *cur);
-int xfs_bitmap_set_btblocks(struct xfs_bitmap *bitmap,
+int xbitmap_set_btblocks(struct xbitmap *bitmap,
 		struct xfs_btree_cur *cur);
 
 #endif	/* __XFS_SCRUB_BITMAP_H__ */
diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
index 477df76174b9..6ca2c638aaa0 100644
--- a/fs/xfs/scrub/repair.c
+++ b/fs/xfs/scrub/repair.c
@@ -598,19 +598,19 @@ xrep_reap_block(
 int
 xrep_reap_extents(
 	struct xfs_scrub		*sc,
-	struct xfs_bitmap		*bitmap,
+	struct xbitmap			*bitmap,
 	const struct xfs_owner_info	*oinfo,
 	enum xfs_ag_resv_type		type)
 {
-	struct xfs_bitmap_range		*bmr;
-	struct xfs_bitmap_range		*n;
+	struct xbitmap_range		*bmr;
+	struct xbitmap_range		*n;
 	xfs_fsblock_t			fsbno;
 	unsigned int			deferred = 0;
 	int				error = 0;
 
 	ASSERT(xfs_sb_version_hasrmapbt(&sc->mp->m_sb));
 
-	for_each_xfs_bitmap_block(fsbno, bmr, n, bitmap) {
+	for_each_xbitmap_block(fsbno, bmr, n, bitmap) {
 		ASSERT(sc->ip != NULL ||
 		       XFS_FSB_TO_AGNO(sc->mp, fsbno) == sc->sa.agno);
 		trace_xrep_dispose_btree_extent(sc->mp,
diff --git a/fs/xfs/scrub/repair.h b/fs/xfs/scrub/repair.h
index eab41928990f..479cfe38065e 100644
--- a/fs/xfs/scrub/repair.h
+++ b/fs/xfs/scrub/repair.h
@@ -28,10 +28,10 @@ int xrep_init_btblock(struct xfs_scrub *sc, xfs_fsblock_t fsb,
 		struct xfs_buf **bpp, xfs_btnum_t btnum,
 		const struct xfs_buf_ops *ops);
 
-struct xfs_bitmap;
+struct xbitmap;
 
 int xrep_fix_freelist(struct xfs_scrub *sc, bool can_shrink);
-int xrep_reap_extents(struct xfs_scrub *sc, struct xfs_bitmap *exlist,
+int xrep_reap_extents(struct xfs_scrub *sc, struct xbitmap *exlist,
 		const struct xfs_owner_info *oinfo, enum xfs_ag_resv_type type);
 
 struct xrep_find_ag_btree {

[PATCH 2/5] xfs: replace open-coded bitmap weight logic

[Darrick J. Wong]

From: Darrick J. Wong <darrick.wong@oracle.com>

Add a xbitmap_hweight helper function so that we can get rid of the
open-coded loop.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
---
 fs/xfs/scrub/agheader_repair.c |   12 ++----------
 fs/xfs/scrub/bitmap.c          |   15 +++++++++++++++
 fs/xfs/scrub/bitmap.h          |    1 +
 3 files changed, 18 insertions(+), 10 deletions(-)


diff --git a/fs/xfs/scrub/agheader_repair.c b/fs/xfs/scrub/agheader_repair.c
index 9fbb6035f4e2..f35596cc26fb 100644
--- a/fs/xfs/scrub/agheader_repair.c
+++ b/fs/xfs/scrub/agheader_repair.c
@@ -482,8 +482,6 @@ xrep_agfl_collect_blocks(
 	struct xrep_agfl	ra;
 	struct xfs_mount	*mp = sc->mp;
 	struct xfs_btree_cur	*cur;
-	struct xbitmap_range	*br;
-	struct xbitmap_range	*n;
 	int			error;
 
 	ra.sc = sc;
@@ -527,14 +525,8 @@ xrep_agfl_collect_blocks(
 	 * Calculate the new AGFL size.  If we found more blocks than fit in
 	 * the AGFL we'll free them later.
 	 */
-	*flcount = 0;
-	for_each_xbitmap_extent(br, n, agfl_extents) {
-		*flcount += br->len;
-		if (*flcount > xfs_agfl_size(mp))
-			break;
-	}
-	if (*flcount > xfs_agfl_size(mp))
-		*flcount = xfs_agfl_size(mp);
+	*flcount = min_t(uint64_t, xbitmap_hweight(agfl_extents),
+			 xfs_agfl_size(mp));
 	return 0;
 
 err:
diff --git a/fs/xfs/scrub/bitmap.c b/fs/xfs/scrub/bitmap.c
index ab26201e9110..f88694f22d05 100644
--- a/fs/xfs/scrub/bitmap.c
+++ b/fs/xfs/scrub/bitmap.c
@@ -297,3 +297,18 @@ xbitmap_set_btblocks(
 	return xfs_btree_visit_blocks(cur, xbitmap_collect_btblock,
 			XFS_BTREE_VISIT_ALL, bitmap);
 }
+
+/* How many bits are set in this bitmap? */
+uint64_t
+xbitmap_hweight(
+	struct xbitmap		*bitmap)
+{
+	struct xbitmap_range	*bmr;
+	struct xbitmap_range	*n;
+	uint64_t		ret = 0;
+
+	for_each_xbitmap_extent(bmr, n, bitmap)
+		ret += bmr->len;
+
+	return ret;
+}
diff --git a/fs/xfs/scrub/bitmap.h b/fs/xfs/scrub/bitmap.h
index 8db4017ac78e..900646b72de1 100644
--- a/fs/xfs/scrub/bitmap.h
+++ b/fs/xfs/scrub/bitmap.h
@@ -32,5 +32,6 @@ int xbitmap_set_btcur_path(struct xbitmap *bitmap,
 		struct xfs_btree_cur *cur);
 int xbitmap_set_btblocks(struct xbitmap *bitmap,
 		struct xfs_btree_cur *cur);
+uint64_t xbitmap_hweight(struct xbitmap *bitmap);
 
 #endif	/* __XFS_SCRUB_BITMAP_H__ */

[PATCH 3/5] xfs: remove the for_each_xbitmap_ helpers

[Darrick J. Wong]

From: Darrick J. Wong <darrick.wong@oracle.com>

Remove the for_each_xbitmap_ macros in favor of proper iterator
functions.  We'll soon be switching this data structure over to an
interval tree implementation, which means that we can't allow callers to
modify the bitmap during iteration without telling us.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/scrub/agheader_repair.c |   73 ++++++++++++++++++++++++----------------
 fs/xfs/scrub/bitmap.c          |   59 ++++++++++++++++++++++++++++++++
 fs/xfs/scrub/bitmap.h          |   22 ++++++++----
 fs/xfs/scrub/repair.c          |   60 +++++++++++++++++----------------
 4 files changed, 148 insertions(+), 66 deletions(-)


diff --git a/fs/xfs/scrub/agheader_repair.c b/fs/xfs/scrub/agheader_repair.c
index f35596cc26fb..b618a87b8dcf 100644
--- a/fs/xfs/scrub/agheader_repair.c
+++ b/fs/xfs/scrub/agheader_repair.c
@@ -560,6 +560,40 @@ xrep_agfl_update_agf(
 			XFS_AGF_FLFIRST | XFS_AGF_FLLAST | XFS_AGF_FLCOUNT);
 }
 
+struct xrep_agfl_fill {
+	struct xbitmap		used_extents;
+	struct xfs_scrub	*sc;
+	__be32			*agfl_bno;
+	xfs_agblock_t		flcount;
+	unsigned int		fl_off;
+};
+
+/* Fill the AGFL with whatever blocks are in this extent. */
+static int
+xrep_agfl_fill(
+	uint64_t		start,
+	uint64_t		len,
+	void			*priv)
+{
+	struct xrep_agfl_fill	*af = priv;
+	struct xfs_scrub	*sc = af->sc;
+	xfs_fsblock_t		fsbno = start;
+
+	while (fsbno < start + len && af->fl_off < af->flcount)
+		af->agfl_bno[af->fl_off++] =
+				cpu_to_be32(XFS_FSB_TO_AGBNO(sc->mp, fsbno++));
+
+	trace_xrep_agfl_insert(sc->mp, sc->sa.agno,
+			XFS_FSB_TO_AGBNO(sc->mp, start), len);
+
+	xbitmap_set(&af->used_extents, start, fsbno - 1);
+
+	if (af->fl_off == af->flcount)
+		return -ECANCELED;
+
+	return 0;
+}
+
 /* Write out a totally new AGFL. */
 STATIC void
 xrep_agfl_init_header(
@@ -568,13 +602,12 @@ xrep_agfl_init_header(
 	struct xbitmap		*agfl_extents,
 	xfs_agblock_t		flcount)
 {
+	struct xrep_agfl_fill	af = {
+		.sc		= sc,
+		.flcount	= flcount,
+	};
 	struct xfs_mount	*mp = sc->mp;
-	__be32			*agfl_bno;
-	struct xbitmap_range	*br;
-	struct xbitmap_range	*n;
 	struct xfs_agfl		*agfl;
-	xfs_agblock_t		agbno;
-	unsigned int		fl_off;
 
 	ASSERT(flcount <= xfs_agfl_size(mp));
 
@@ -593,35 +626,15 @@ xrep_agfl_init_header(
 	 * blocks than fit in the AGFL, they will be freed in a subsequent
 	 * step.
 	 */
-	fl_off = 0;
-	agfl_bno = XFS_BUF_TO_AGFL_BNO(mp, agfl_bp);
-	for_each_xbitmap_extent(br, n, agfl_extents) {
-		agbno = XFS_FSB_TO_AGBNO(mp, br->start);
-
-		trace_xrep_agfl_insert(mp, sc->sa.agno, agbno, br->len);
-
-		while (br->len > 0 && fl_off < flcount) {
-			agfl_bno[fl_off] = cpu_to_be32(agbno);
-			fl_off++;
-			agbno++;
-
-			/*
-			 * We've now used br->start by putting it in the AGFL,
-			 * so bump br so that we don't reap the block later.
-			 */
-			br->start++;
-			br->len--;
-		}
-
-		if (br->len)
-			break;
-		list_del(&br->list);
-		kmem_free(br);
-	}
+	xbitmap_init(&af.used_extents);
+	af.agfl_bno = XFS_BUF_TO_AGFL_BNO(mp, agfl_bp),
+	xbitmap_walk(agfl_extents, xrep_agfl_fill, &af);
+	xbitmap_disunion(agfl_extents, &af.used_extents);
 
 	/* Write new AGFL to disk. */
 	xfs_trans_buf_set_type(sc->tp, agfl_bp, XFS_BLFT_AGFL_BUF);
 	xfs_trans_log_buf(sc->tp, agfl_bp, 0, BBTOB(agfl_bp->b_length) - 1);
+	xbitmap_destroy(&af.used_extents);
 }
 
 /* Repair the AGFL. */
diff --git a/fs/xfs/scrub/bitmap.c b/fs/xfs/scrub/bitmap.c
index f88694f22d05..e198983db610 100644
--- a/fs/xfs/scrub/bitmap.c
+++ b/fs/xfs/scrub/bitmap.c
@@ -12,6 +12,9 @@
 #include "xfs_btree.h"
 #include "scrub/bitmap.h"
 
+#define for_each_xbitmap_extent(bex, n, bitmap) \
+	list_for_each_entry_safe((bex), (n), &(bitmap)->list, list)
+
 /*
  * Set a range of this bitmap.  Caller must ensure the range is not set.
  *
@@ -312,3 +315,59 @@ xbitmap_hweight(
 
 	return ret;
 }
+
+/* Call a function for every run of set bits in this bitmap. */
+int
+xbitmap_walk(
+	struct xbitmap		*bitmap,
+	xbitmap_walk_fn	fn,
+	void			*priv)
+{
+	struct xbitmap_range	*bex, *n;
+	int			error;
+
+	for_each_xbitmap_extent(bex, n, bitmap) {
+		error = fn(bex->start, bex->len, priv);
+		if (error)
+			break;
+	}
+
+	return error;
+}
+
+struct xbitmap_walk_bits {
+	xbitmap_walk_bits_fn	fn;
+	void			*priv;
+};
+
+/* Walk all the bits in a run. */
+static int
+xbitmap_walk_bits_in_run(
+	uint64_t			start,
+	uint64_t			len,
+	void				*priv)
+{
+	struct xbitmap_walk_bits	*wb = priv;
+	uint64_t			i;
+	int				error;
+
+	for (i = start; i < start + len; i++) {
+		error = wb->fn(i, wb->priv);
+		if (error)
+			break;
+	}
+
+	return error;
+}
+
+/* Call a function for every set bit in this bitmap. */
+int
+xbitmap_walk_bits(
+	struct xbitmap			*bitmap,
+	xbitmap_walk_bits_fn		fn,
+	void				*priv)
+{
+	struct xbitmap_walk_bits	wb = {.fn = fn, .priv = priv};
+
+	return xbitmap_walk(bitmap, xbitmap_walk_bits_in_run, &wb);
+}
diff --git a/fs/xfs/scrub/bitmap.h b/fs/xfs/scrub/bitmap.h
index 900646b72de1..53601d281ffb 100644
--- a/fs/xfs/scrub/bitmap.h
+++ b/fs/xfs/scrub/bitmap.h
@@ -19,13 +19,6 @@ struct xbitmap {
 void xbitmap_init(struct xbitmap *bitmap);
 void xbitmap_destroy(struct xbitmap *bitmap);
 
-#define for_each_xbitmap_extent(bex, n, bitmap) \
-	list_for_each_entry_safe((bex), (n), &(bitmap)->list, list)
-
-#define for_each_xbitmap_block(b, bex, n, bitmap) \
-	list_for_each_entry_safe((bex), (n), &(bitmap)->list, list) \
-		for ((b) = (bex)->start; (b) < (bex)->start + (bex)->len; (b)++)
-
 int xbitmap_set(struct xbitmap *bitmap, uint64_t start, uint64_t len);
 int xbitmap_disunion(struct xbitmap *bitmap, struct xbitmap *sub);
 int xbitmap_set_btcur_path(struct xbitmap *bitmap,
@@ -34,4 +27,19 @@ int xbitmap_set_btblocks(struct xbitmap *bitmap,
 		struct xfs_btree_cur *cur);
 uint64_t xbitmap_hweight(struct xbitmap *bitmap);
 
+/*
+ * Return codes for the bitmap iterator functions are 0 to continue iterating,
+ * and non-zero to stop iterating.  Any non-zero value will be passed up to the
+ * iteration caller.  The special value -ECANCELED can be used to stop
+ * iteration, because neither bitmap iterator ever generates that error code on
+ * its own.  Callers must not modify the bitmap while walking it.
+ */
+typedef int (*xbitmap_walk_fn)(uint64_t start, uint64_t len, void *priv);
+int xbitmap_walk(struct xbitmap *bitmap, xbitmap_walk_fn fn,
+		void *priv);
+
+typedef int (*xbitmap_walk_bits_fn)(uint64_t bit, void *priv);
+int xbitmap_walk_bits(struct xbitmap *bitmap, xbitmap_walk_bits_fn fn,
+		void *priv);
+
 #endif	/* __XFS_SCRUB_BITMAP_H__ */
diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
index 6ca2c638aaa0..088dbd7df096 100644
--- a/fs/xfs/scrub/repair.c
+++ b/fs/xfs/scrub/repair.c
@@ -505,15 +505,21 @@ xrep_reap_invalidate_block(
 	xfs_trans_binval(sc->tp, bp);
 }
 
+struct xrep_reap_block {
+	struct xfs_scrub		*sc;
+	const struct xfs_owner_info	*oinfo;
+	enum xfs_ag_resv_type		resv;
+	unsigned int			deferred;
+};
+
 /* Dispose of a single block. */
 STATIC int
 xrep_reap_block(
-	struct xfs_scrub		*sc,
-	xfs_fsblock_t			fsbno,
-	const struct xfs_owner_info	*oinfo,
-	enum xfs_ag_resv_type		resv,
-	unsigned int			*deferred)
+	uint64_t			fsbno,
+	void				*priv)
 {
+	struct xrep_reap_block		*rb = priv;
+	struct xfs_scrub		*sc = rb->sc;
 	struct xfs_btree_cur		*cur;
 	struct xfs_buf			*agf_bp = NULL;
 	xfs_agnumber_t			agno;
@@ -525,6 +531,10 @@ xrep_reap_block(
 	agno = XFS_FSB_TO_AGNO(sc->mp, fsbno);
 	agbno = XFS_FSB_TO_AGBNO(sc->mp, fsbno);
 
+	ASSERT(sc->ip != NULL || agno == sc->sa.agno);
+
+	trace_xrep_dispose_btree_extent(sc->mp, agno, agbno, 1);
+
 	/*
 	 * If we are repairing per-inode metadata, we need to read in the AGF
 	 * buffer.  Otherwise, we're repairing a per-AG structure, so reuse
@@ -542,7 +552,8 @@ xrep_reap_block(
 	cur = xfs_rmapbt_init_cursor(sc->mp, sc->tp, agf_bp, agno);
 
 	/* Can we find any other rmappings? */
-	error = xfs_rmap_has_other_keys(cur, agbno, 1, oinfo, &has_other_rmap);
+	error = xfs_rmap_has_other_keys(cur, agbno, 1, rb->oinfo,
+			&has_other_rmap);
 	xfs_btree_del_cursor(cur, error);
 	if (error)
 		goto out_free;
@@ -561,8 +572,9 @@ xrep_reap_block(
 	 * to run xfs_repair.
 	 */
 	if (has_other_rmap) {
-		error = xfs_rmap_free(sc->tp, agf_bp, agno, agbno, 1, oinfo);
-	} else if (resv == XFS_AG_RESV_AGFL) {
+		error = xfs_rmap_free(sc->tp, agf_bp, agno, agbno, 1,
+				rb->oinfo);
+	} else if (rb->resv == XFS_AG_RESV_AGFL) {
 		xrep_reap_invalidate_block(sc, fsbno);
 		error = xrep_put_freelist(sc, agbno);
 	} else {
@@ -574,16 +586,16 @@ xrep_reap_block(
 		 * reservation.
 		 */
 		xrep_reap_invalidate_block(sc, fsbno);
-		__xfs_bmap_add_free(sc->tp, fsbno, 1, oinfo, false);
-		(*deferred)++;
-		need_roll = *deferred > 100;
+		__xfs_bmap_add_free(sc->tp, fsbno, 1, rb->oinfo, false);
+		rb->deferred++;
+		need_roll = rb->deferred > 100;
 	}
 	if (agf_bp != sc->sa.agf_bp)
 		xfs_trans_brelse(sc->tp, agf_bp);
 	if (error || !need_roll)
 		return error;
 
-	*deferred = 0;
+	rb->deferred = 0;
 	if (sc->ip)
 		return xfs_trans_roll_inode(&sc->tp, sc->ip);
 	return xrep_roll_ag_trans(sc);
@@ -602,27 +614,17 @@ xrep_reap_extents(
 	const struct xfs_owner_info	*oinfo,
 	enum xfs_ag_resv_type		type)
 {
-	struct xbitmap_range		*bmr;
-	struct xbitmap_range		*n;
-	xfs_fsblock_t			fsbno;
-	unsigned int			deferred = 0;
+	struct xrep_reap_block		rb = {
+		.sc			= sc,
+		.oinfo			= oinfo,
+		.resv			= type,
+	};
 	int				error = 0;
 
 	ASSERT(xfs_sb_version_hasrmapbt(&sc->mp->m_sb));
 
-	for_each_xbitmap_block(fsbno, bmr, n, bitmap) {
-		ASSERT(sc->ip != NULL ||
-		       XFS_FSB_TO_AGNO(sc->mp, fsbno) == sc->sa.agno);
-		trace_xrep_dispose_btree_extent(sc->mp,
-				XFS_FSB_TO_AGNO(sc->mp, fsbno),
-				XFS_FSB_TO_AGBNO(sc->mp, fsbno), 1);
-
-		error = xrep_reap_block(sc, fsbno, oinfo, type, &deferred);
-		if (error)
-			break;
-	}
-
-	if (error || deferred == 0)
+	error = xbitmap_walk_bits(bitmap, xrep_reap_block, &rb);
+	if (error || rb.deferred == 0)
 		return error;
 
 	if (sc->ip)

[PATCH 4/5] xfs: drop the _safe behavior from the xbitmap foreach macro

[Darrick J. Wong]

From: Darrick J. Wong <darrick.wong@oracle.com>

It's not safe to edit bitmap intervals while we're iterating them with
for_each_xbitmap_extent.  None of the existing callers actually need
that ability anyway, so drop the safe variable.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/scrub/bitmap.c |   17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)


diff --git a/fs/xfs/scrub/bitmap.c b/fs/xfs/scrub/bitmap.c
index e198983db610..7a7554fb2793 100644
--- a/fs/xfs/scrub/bitmap.c
+++ b/fs/xfs/scrub/bitmap.c
@@ -12,8 +12,9 @@
 #include "xfs_btree.h"
 #include "scrub/bitmap.h"
 
-#define for_each_xbitmap_extent(bex, n, bitmap) \
-	list_for_each_entry_safe((bex), (n), &(bitmap)->list, list)
+/* Iterate each interval of a bitmap.  Do not change the bitmap. */
+#define for_each_xbitmap_extent(bex, bitmap) \
+	list_for_each_entry((bex), &(bitmap)->list, list)
 
 /*
  * Set a range of this bitmap.  Caller must ensure the range is not set.
@@ -45,10 +46,9 @@ void
 xbitmap_destroy(
 	struct xbitmap		*bitmap)
 {
-	struct xbitmap_range	*bmr;
-	struct xbitmap_range	*n;
+	struct xbitmap_range	*bmr, *n;
 
-	for_each_xbitmap_extent(bmr, n, bitmap) {
+	list_for_each_entry_safe(bmr, n, &bitmap->list, list) {
 		list_del(&bmr->list);
 		kmem_free(bmr);
 	}
@@ -307,10 +307,9 @@ xbitmap_hweight(
 	struct xbitmap		*bitmap)
 {
 	struct xbitmap_range	*bmr;
-	struct xbitmap_range	*n;
 	uint64_t		ret = 0;
 
-	for_each_xbitmap_extent(bmr, n, bitmap)
+	for_each_xbitmap_extent(bmr, bitmap)
 		ret += bmr->len;
 
 	return ret;
@@ -323,10 +322,10 @@ xbitmap_walk(
 	xbitmap_walk_fn	fn,
 	void			*priv)
 {
-	struct xbitmap_range	*bex, *n;
+	struct xbitmap_range	*bex;
 	int			error;
 
-	for_each_xbitmap_extent(bex, n, bitmap) {
+	for_each_xbitmap_extent(bex, bitmap) {
 		error = fn(bex->start, bex->len, priv);
 		if (error)
 			break;

[PATCH 5/5] xfs: convert xbitmap to interval tree

[Darrick J. Wong]

From: Darrick J. Wong <darrick.wong@oracle.com>

Convert the xbitmap code to use interval trees instead of linked lists.
This reduces the amount of coding required to handle the disunion
operation and in the future will make it easier to set bits in arbitrary
order yet later be able to extract maximally sized extents, which we'll
need for rebuilding certain structures.  We define our own interval tree
type so that it can deal with 64-bit indices even on 32-bit machines.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/scrub/agheader_repair.c |    4 -
 fs/xfs/scrub/bitmap.c          |  300 ++++++++++++++++++++--------------------
 fs/xfs/scrub/bitmap.h          |   13 +-
 3 files changed, 155 insertions(+), 162 deletions(-)


diff --git a/fs/xfs/scrub/agheader_repair.c b/fs/xfs/scrub/agheader_repair.c
index b618a87b8dcf..4ddae4ecece6 100644
--- a/fs/xfs/scrub/agheader_repair.c
+++ b/fs/xfs/scrub/agheader_repair.c
@@ -516,10 +516,8 @@ xrep_agfl_collect_blocks(
 	 * Drop the freesp meta blocks that are in use by btrees.
 	 * The remaining blocks /should/ be AGFL blocks.
 	 */
-	error = xbitmap_disunion(agfl_extents, &ra.agmetablocks);
+	xbitmap_disunion(agfl_extents, &ra.agmetablocks);
 	xbitmap_destroy(&ra.agmetablocks);
-	if (error)
-		return error;
 
 	/*
 	 * Calculate the new AGFL size.  If we found more blocks than fit in
diff --git a/fs/xfs/scrub/bitmap.c b/fs/xfs/scrub/bitmap.c
index 7a7554fb2793..4fad962a360b 100644
--- a/fs/xfs/scrub/bitmap.c
+++ b/fs/xfs/scrub/bitmap.c
@@ -12,31 +12,139 @@
 #include "xfs_btree.h"
 #include "scrub/bitmap.h"
 
-/* Iterate each interval of a bitmap.  Do not change the bitmap. */
-#define for_each_xbitmap_extent(bex, bitmap) \
-	list_for_each_entry((bex), &(bitmap)->list, list)
+#include <linux/interval_tree_generic.h>
+
+struct xbitmap_node {
+	struct rb_node	bn_rbnode;
+
+	/* First set bit of this interval and subtree. */
+	uint64_t	bn_start;
+
+	/* Last set bit of this interval. */
+	uint64_t	bn_last;
+
+	/* Last set bit of this subtree.  Do not touch this. */
+	uint64_t	__bn_subtree_last;
+};
+
+/* Define our own interval tree type with uint64_t parameters. */
+
+#define START(node) ((node)->bn_start)
+#define LAST(node)  ((node)->bn_last)
 
 /*
- * Set a range of this bitmap.  Caller must ensure the range is not set.
- *
- * This is the logical equivalent of bitmap |= mask(start, len).
+ * These functions are defined by the INTERVAL_TREE_DEFINE macro, but we'll
+ * forward-declare them anyway for clarity.
  */
+static inline void
+xbitmap_tree_insert(struct xbitmap_node *node, struct rb_root_cached *root);
+
+static inline void
+xbitmap_tree_remove(struct xbitmap_node *node, struct rb_root_cached *root);
+
+static inline struct xbitmap_node *
+xbitmap_tree_iter_first(struct rb_root_cached *root, uint64_t start,
+			uint64_t last);
+
+static inline struct xbitmap_node *
+xbitmap_tree_iter_next(struct xbitmap_node *node, uint64_t start,
+		       uint64_t last);
+
+INTERVAL_TREE_DEFINE(struct xbitmap_node, bn_rbnode, uint64_t,
+		__bn_subtree_last, START, LAST, static inline, xbitmap_tree)
+
+/* Iterate each interval of a bitmap.  Do not change the bitmap. */
+#define for_each_xbitmap_extent(bn, bitmap) \
+	for ((bn) = rb_entry_safe(rb_first(&(bitmap)->xb_root.rb_root), \
+				   struct xbitmap_node, bn_rbnode); \
+	     (bn) != NULL; \
+	     (bn) = rb_entry_safe(rb_next(&(bn)->bn_rbnode), \
+				   struct xbitmap_node, bn_rbnode))
+
+/* Clear a range of this bitmap. */
+void
+xbitmap_clear(
+	struct xbitmap		*bitmap,
+	uint64_t		start,
+	uint64_t		len)
+{
+	struct xbitmap_node	*bn;
+	uint64_t		last = start + len - 1;
+
+	while ((bn = xbitmap_tree_iter_first(&bitmap->xb_root, start, last))) {
+		if (bn->bn_start < start) {
+			/* overlaps with the left side of the clearing range */
+			xbitmap_tree_remove(bn, &bitmap->xb_root);
+			bn->bn_last = start - 1;
+			xbitmap_tree_insert(bn, &bitmap->xb_root);
+		} else if (bn->bn_last > last) {
+			/* overlaps with the right side of the clearing range */
+			xbitmap_tree_remove(bn, &bitmap->xb_root);
+			bn->bn_start = last + 1;
+			xbitmap_tree_insert(bn, &bitmap->xb_root);
+			break;
+		} else {
+			/* in the middle of the clearing range */
+			xbitmap_tree_remove(bn, &bitmap->xb_root);
+			kmem_free(bn);
+		}
+	}
+}
+
+/* Set a range of this bitmap. */
 int
 xbitmap_set(
 	struct xbitmap		*bitmap,
 	uint64_t		start,
 	uint64_t		len)
 {
-	struct xbitmap_range	*bmr;
+	struct xbitmap_node	*left;
+	struct xbitmap_node	*right;
+	uint64_t		last = start + len - 1;
 
-	bmr = kmem_alloc(sizeof(struct xbitmap_range), KM_MAYFAIL);
-	if (!bmr)
-		return -ENOMEM;
+	/* Is this whole range already set? */
+	left = xbitmap_tree_iter_first(&bitmap->xb_root, start, last);
+	if (left && left->bn_start <= start && left->bn_last >= last)
+		return 0;
 
-	INIT_LIST_HEAD(&bmr->list);
-	bmr->start = start;
-	bmr->len = len;
-	list_add_tail(&bmr->list, &bitmap->list);
+	/* Clear out everything in the range we want to set. */
+	xbitmap_clear(bitmap, start, len);
+
+	/* Do we have a left-adjacent extent? */
+	left = xbitmap_tree_iter_first(&bitmap->xb_root, start - 1, start - 1);
+	ASSERT(!left || left->bn_last + 1 == start);
+
+	/* Do we have a right-adjacent extent? */
+	right = xbitmap_tree_iter_first(&bitmap->xb_root, last + 1, last + 1);
+	ASSERT(!right || right->bn_start == last + 1);
+
+	if (left && right) {
+		/* combine left and right adjacent extent */
+		xbitmap_tree_remove(left, &bitmap->xb_root);
+		xbitmap_tree_remove(right, &bitmap->xb_root);
+		left->bn_last = right->bn_last;
+		xbitmap_tree_insert(left, &bitmap->xb_root);
+		kmem_free(right);
+	} else if (left) {
+		/* combine with left extent */
+		xbitmap_tree_remove(left, &bitmap->xb_root);
+		left->bn_last = last;
+		xbitmap_tree_insert(left, &bitmap->xb_root);
+	} else if (right) {
+		/* combine with right extent */
+		xbitmap_tree_remove(right, &bitmap->xb_root);
+		right->bn_start = start;
+		xbitmap_tree_insert(right, &bitmap->xb_root);
+	} else {
+		/* add an extent */
+		left = kmem_alloc(sizeof(struct xbitmap_node),
+				KM_MAYFAIL);
+		if (!left)
+			return -ENOMEM;
+		left->bn_start = start;
+		left->bn_last = last;
+		xbitmap_tree_insert(left, &bitmap->xb_root);
+	}
 
 	return 0;
 }
@@ -46,11 +154,11 @@ void
 xbitmap_destroy(
 	struct xbitmap		*bitmap)
 {
-	struct xbitmap_range	*bmr, *n;
+	struct xbitmap_node	*bn;
 
-	list_for_each_entry_safe(bmr, n, &bitmap->list, list) {
-		list_del(&bmr->list);
-		kmem_free(bmr);
+	while ((bn = xbitmap_tree_iter_first(&bitmap->xb_root, 0, -1ULL))) {
+		xbitmap_tree_remove(bn, &bitmap->xb_root);
+		kfree(bn);
 	}
 }
 
@@ -59,27 +167,7 @@ void
 xbitmap_init(
 	struct xbitmap		*bitmap)
 {
-	INIT_LIST_HEAD(&bitmap->list);
-}
-
-/* Compare two btree extents. */
-static int
-xbitmap_range_cmp(
-	void			*priv,
-	struct list_head	*a,
-	struct list_head	*b)
-{
-	struct xbitmap_range	*ap;
-	struct xbitmap_range	*bp;
-
-	ap = container_of(a, struct xbitmap_range, list);
-	bp = container_of(b, struct xbitmap_range, list);
-
-	if (ap->start > bp->start)
-		return 1;
-	if (ap->start < bp->start)
-		return -1;
-	return 0;
+	bitmap->xb_root = RB_ROOT_CACHED;
 }
 
 /*
@@ -96,118 +184,20 @@ xbitmap_range_cmp(
  *
  * This is the logical equivalent of bitmap &= ~sub.
  */
-#define LEFT_ALIGNED	(1 << 0)
-#define RIGHT_ALIGNED	(1 << 1)
-int
+void
 xbitmap_disunion(
 	struct xbitmap		*bitmap,
 	struct xbitmap		*sub)
 {
-	struct list_head	*lp;
-	struct xbitmap_range	*br;
-	struct xbitmap_range	*new_br;
-	struct xbitmap_range	*sub_br;
-	uint64_t		sub_start;
-	uint64_t		sub_len;
-	int			state;
-	int			error = 0;
-
-	if (list_empty(&bitmap->list) || list_empty(&sub->list))
-		return 0;
-	ASSERT(!list_empty(&sub->list));
-
-	list_sort(NULL, &bitmap->list, xbitmap_range_cmp);
-	list_sort(NULL, &sub->list, xbitmap_range_cmp);
-
-	/*
-	 * Now that we've sorted both lists, we iterate bitmap once, rolling
-	 * forward through sub and/or bitmap as necessary until we find an
-	 * overlap or reach the end of either list.  We do not reset lp to the
-	 * head of bitmap nor do we reset sub_br to the head of sub.  The
-	 * list traversal is similar to merge sort, but we're deleting
-	 * instead.  In this manner we avoid O(n^2) operations.
-	 */
-	sub_br = list_first_entry(&sub->list, struct xbitmap_range,
-			list);
-	lp = bitmap->list.next;
-	while (lp != &bitmap->list) {
-		br = list_entry(lp, struct xbitmap_range, list);
-
-		/*
-		 * Advance sub_br and/or br until we find a pair that
-		 * intersect or we run out of extents.
-		 */
-		while (sub_br->start + sub_br->len <= br->start) {
-			if (list_is_last(&sub_br->list, &sub->list))
-				goto out;
-			sub_br = list_next_entry(sub_br, list);
-		}
-		if (sub_br->start >= br->start + br->len) {
-			lp = lp->next;
-			continue;
-		}
+	struct xbitmap_node	*bn;
 
-		/* trim sub_br to fit the extent we have */
-		sub_start = sub_br->start;
-		sub_len = sub_br->len;
-		if (sub_br->start < br->start) {
-			sub_len -= br->start - sub_br->start;
-			sub_start = br->start;
-		}
-		if (sub_len > br->len)
-			sub_len = br->len;
-
-		state = 0;
-		if (sub_start == br->start)
-			state |= LEFT_ALIGNED;
-		if (sub_start + sub_len == br->start + br->len)
-			state |= RIGHT_ALIGNED;
-		switch (state) {
-		case LEFT_ALIGNED:
-			/* Coincides with only the left. */
-			br->start += sub_len;
-			br->len -= sub_len;
-			break;
-		case RIGHT_ALIGNED:
-			/* Coincides with only the right. */
-			br->len -= sub_len;
-			lp = lp->next;
-			break;
-		case LEFT_ALIGNED | RIGHT_ALIGNED:
-			/* Total overlap, just delete ex. */
-			lp = lp->next;
-			list_del(&br->list);
-			kmem_free(br);
-			break;
-		case 0:
-			/*
-			 * Deleting from the middle: add the new right extent
-			 * and then shrink the left extent.
-			 */
-			new_br = kmem_alloc(sizeof(struct xbitmap_range),
-					KM_MAYFAIL);
-			if (!new_br) {
-				error = -ENOMEM;
-				goto out;
-			}
-			INIT_LIST_HEAD(&new_br->list);
-			new_br->start = sub_start + sub_len;
-			new_br->len = br->start + br->len - new_br->start;
-			list_add(&new_br->list, &br->list);
-			br->len = sub_start - br->start;
-			lp = lp->next;
-			break;
-		default:
-			ASSERT(0);
-			break;
-		}
-	}
+	if (xbitmap_empty(bitmap) || xbitmap_empty(sub))
+		return;
 
-out:
-	return error;
+	for_each_xbitmap_extent(bn, sub)
+		xbitmap_clear(bitmap, bn->bn_start,
+				bn->bn_last - bn->bn_start + 1);
 }
-#undef LEFT_ALIGNED
-#undef RIGHT_ALIGNED
 
 /*
  * Record all btree blocks seen while iterating all records of a btree.
@@ -306,11 +296,11 @@ uint64_t
 xbitmap_hweight(
 	struct xbitmap		*bitmap)
 {
-	struct xbitmap_range	*bmr;
+	struct xbitmap_node	*bn;
 	uint64_t		ret = 0;
 
-	for_each_xbitmap_extent(bmr, bitmap)
-		ret += bmr->len;
+	for_each_xbitmap_extent(bn, bitmap)
+		ret += bn->bn_last - bn->bn_start + 1;
 
 	return ret;
 }
@@ -319,14 +309,14 @@ xbitmap_hweight(
 int
 xbitmap_walk(
 	struct xbitmap		*bitmap,
-	xbitmap_walk_fn	fn,
+	xbitmap_walk_fn		fn,
 	void			*priv)
 {
-	struct xbitmap_range	*bex;
+	struct xbitmap_node	*bn;
 	int			error;
 
-	for_each_xbitmap_extent(bex, bitmap) {
-		error = fn(bex->start, bex->len, priv);
+	for_each_xbitmap_extent(bn, bitmap) {
+		error = fn(bn->bn_start, bn->bn_last - bn->bn_start + 1, priv);
 		if (error)
 			break;
 	}
@@ -370,3 +360,11 @@ xbitmap_walk_bits(
 
 	return xbitmap_walk(bitmap, xbitmap_walk_bits_in_run, &wb);
 }
+
+/* Does this bitmap have no bits set at all? */
+bool
+xbitmap_empty(
+	struct xbitmap		*bitmap)
+{
+	return bitmap->xb_root.rb_root.rb_node == NULL;
+}
diff --git a/fs/xfs/scrub/bitmap.h b/fs/xfs/scrub/bitmap.h
index 53601d281ffb..102ab5c89012 100644
--- a/fs/xfs/scrub/bitmap.h
+++ b/fs/xfs/scrub/bitmap.h
@@ -6,21 +6,16 @@
 #ifndef __XFS_SCRUB_BITMAP_H__
 #define __XFS_SCRUB_BITMAP_H__
 
-struct xbitmap_range {
-	struct list_head	list;
-	uint64_t		start;
-	uint64_t		len;
-};
-
 struct xbitmap {
-	struct list_head	list;
+	struct rb_root_cached	xb_root;
 };
 
 void xbitmap_init(struct xbitmap *bitmap);
 void xbitmap_destroy(struct xbitmap *bitmap);
 
+void xbitmap_clear(struct xbitmap *bitmap, uint64_t start, uint64_t len);
 int xbitmap_set(struct xbitmap *bitmap, uint64_t start, uint64_t len);
-int xbitmap_disunion(struct xbitmap *bitmap, struct xbitmap *sub);
+void xbitmap_disunion(struct xbitmap *bitmap, struct xbitmap *sub);
 int xbitmap_set_btcur_path(struct xbitmap *bitmap,
 		struct xfs_btree_cur *cur);
 int xbitmap_set_btblocks(struct xbitmap *bitmap,
@@ -42,4 +37,6 @@ typedef int (*xbitmap_walk_bits_fn)(uint64_t bit, void *priv);
 int xbitmap_walk_bits(struct xbitmap *bitmap, xbitmap_walk_bits_fn fn,
 		void *priv);
 
+bool xbitmap_empty(struct xbitmap *bitmap);
+
 #endif	/* __XFS_SCRUB_BITMAP_H__ */

[PATCH v2 0/5] xfs: rework online repair incore bitmap

[Darrick J. Wong]

Hi all,

In this series, we make some changes to the incore bitmap code: First,
we shorten the prefix to 'xbitmap'.  Then, we rework some utility
functions for later use by online repair and clarify how the walk
functions are supposed to be used.

Finally, we use all these new pieces to convert the incore bitmap to use
an interval tree instead of linked lists.  This lifts the limitation
that callers had to be careful not to set a range that was already set;
and gets us ready for the btree rebuilder functions needing to be able
to set bits in a bitmap and generate maximal contiguous extents for the
set ranges.

If you're going to start using this mess, you probably ought to just
pull from my git trees, which are linked below.

This is an extraordinary way to destroy everything.  Enjoy!
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=repair-bitmap-rework