1 files changed, 452 insertions, 165 deletions

diff --git a/fs/xfs/libxfs/xfs_rmap_btree.c b/fs/xfs/libxfs/xfs_rmap_btree.c
index f79cf040d745..bf16aee50d73 100644
--- a/fs/xfs/libxfs/xfs_rmap_btree.c
+++ b/fs/xfs/libxfs/xfs_rmap_btree.c
@@ -9,21 +9,23 @@
 #include "xfs_format.h"
 #include "xfs_log_format.h"
 #include "xfs_trans_resv.h"
-#include "xfs_bit.h"
-#include "xfs_sb.h"
 #include "xfs_mount.h"
-#include "xfs_defer.h"
-#include "xfs_inode.h"
 #include "xfs_trans.h"
 #include "xfs_alloc.h"
 #include "xfs_btree.h"
+#include "xfs_btree_staging.h"
 #include "xfs_rmap.h"
 #include "xfs_rmap_btree.h"
+#include "xfs_health.h"
 #include "xfs_trace.h"
-#include "xfs_cksum.h"
 #include "xfs_error.h"
 #include "xfs_extent_busy.h"
+#include "xfs_ag.h"
 #include "xfs_ag_resv.h"
+#include "xfs_buf_mem.h"
+#include "xfs_btree_mem.h"
+
+static struct kmem_cache	*xfs_rmapbt_cur_cache;
 
 /*
  * Reverse map btree.
@@ -55,65 +57,63 @@ xfs_rmapbt_dup_cursor(
 	struct xfs_btree_cur	*cur)
 {
 	return xfs_rmapbt_init_cursor(cur->bc_mp, cur->bc_tp,
-			cur->bc_private.a.agbp, cur->bc_private.a.agno);
+				cur->bc_ag.agbp, to_perag(cur->bc_group));
 }
 
 STATIC void
 xfs_rmapbt_set_root(
-	struct xfs_btree_cur	*cur,
-	union xfs_btree_ptr	*ptr,
-	int			inc)
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_ptr	*ptr,
+	int				inc)
 {
-	struct xfs_buf		*agbp = cur->bc_private.a.agbp;
-	struct xfs_agf		*agf = XFS_BUF_TO_AGF(agbp);
-	xfs_agnumber_t		seqno = be32_to_cpu(agf->agf_seqno);
-	int			btnum = cur->bc_btnum;
-	struct xfs_perag	*pag = xfs_perag_get(cur->bc_mp, seqno);
+	struct xfs_buf			*agbp = cur->bc_ag.agbp;
+	struct xfs_agf			*agf = agbp->b_addr;
+	struct xfs_perag		*pag = to_perag(cur->bc_group);
 
 	ASSERT(ptr->s != 0);
 
-	agf->agf_roots[btnum] = ptr->s;
-	be32_add_cpu(&agf->agf_levels[btnum], inc);
-	pag->pagf_levels[btnum] += inc;
-	xfs_perag_put(pag);
+	agf->agf_rmap_root = ptr->s;
+	be32_add_cpu(&agf->agf_rmap_level, inc);
+	pag->pagf_rmap_level += inc;
 
 	xfs_alloc_log_agf(cur->bc_tp, agbp, XFS_AGF_ROOTS | XFS_AGF_LEVELS);
 }
 
 STATIC int
 xfs_rmapbt_alloc_block(
-	struct xfs_btree_cur	*cur,
-	union xfs_btree_ptr	*start,
-	union xfs_btree_ptr	*new,
-	int			*stat)
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_ptr	*start,
+	union xfs_btree_ptr		*new,
+	int				*stat)
 {
-	struct xfs_buf		*agbp = cur->bc_private.a.agbp;
-	struct xfs_agf		*agf = XFS_BUF_TO_AGF(agbp);
+	struct xfs_buf		*agbp = cur->bc_ag.agbp;
+	struct xfs_agf		*agf = agbp->b_addr;
+	struct xfs_perag	*pag = to_perag(cur->bc_group);
+	struct xfs_alloc_arg    args = { .len = 1 };
 	int			error;
 	xfs_agblock_t		bno;
 
 	/* Allocate the new block from the freelist. If we can't, give up.  */
-	error = xfs_alloc_get_freelist(cur->bc_tp, cur->bc_private.a.agbp,
+	error = xfs_alloc_get_freelist(pag, cur->bc_tp, cur->bc_ag.agbp,
 				       &bno, 1);
 	if (error)
 		return error;
-
-	trace_xfs_rmapbt_alloc_block(cur->bc_mp, cur->bc_private.a.agno,
-			bno, 1);
 	if (bno == NULLAGBLOCK) {
 		*stat = 0;
 		return 0;
 	}
 
-	xfs_extent_busy_reuse(cur->bc_mp, cur->bc_private.a.agno, bno, 1,
-			false);
+	xfs_extent_busy_reuse(pag_group(pag), bno, 1, false);
 
-	xfs_trans_agbtree_delta(cur->bc_tp, 1);
 	new->s = cpu_to_be32(bno);
 	be32_add_cpu(&agf->agf_rmap_blocks, 1);
 	xfs_alloc_log_agf(cur->bc_tp, agbp, XFS_AGF_RMAP_BLOCKS);
 
-	xfs_ag_resv_rmapbt_alloc(cur->bc_mp, cur->bc_private.a.agno);
+	/*
+	 * Since rmapbt blocks are sourced from the AGFL, they are allocated one
+	 * at a time and the reservation updates don't require a transaction.
+	 */
+	xfs_ag_resv_alloc_extent(pag, XFS_AG_RESV_RMAPBT, &args);
 
 	*stat = 1;
 	return 0;
@@ -124,26 +124,23 @@ xfs_rmapbt_free_block(
 	struct xfs_btree_cur	*cur,
 	struct xfs_buf		*bp)
 {
-	struct xfs_buf		*agbp = cur->bc_private.a.agbp;
-	struct xfs_agf		*agf = XFS_BUF_TO_AGF(agbp);
+	struct xfs_buf		*agbp = cur->bc_ag.agbp;
+	struct xfs_agf		*agf = agbp->b_addr;
+	struct xfs_perag	*pag = to_perag(cur->bc_group);
 	xfs_agblock_t		bno;
 	int			error;
 
-	bno = xfs_daddr_to_agbno(cur->bc_mp, XFS_BUF_ADDR(bp));
-	trace_xfs_rmapbt_free_block(cur->bc_mp, cur->bc_private.a.agno,
-			bno, 1);
+	bno = xfs_daddr_to_agbno(cur->bc_mp, xfs_buf_daddr(bp));
 	be32_add_cpu(&agf->agf_rmap_blocks, -1);
 	xfs_alloc_log_agf(cur->bc_tp, agbp, XFS_AGF_RMAP_BLOCKS);
-	error = xfs_alloc_put_freelist(cur->bc_tp, agbp, NULL, bno, 1);
+	error = xfs_alloc_put_freelist(pag, cur->bc_tp, agbp, NULL, bno, 1);
 	if (error)
 		return error;
 
-	xfs_extent_busy_insert(cur->bc_tp, be32_to_cpu(agf->agf_seqno), bno, 1,
+	xfs_extent_busy_insert(cur->bc_tp, pag_group(pag), bno, 1,
 			      XFS_EXTENT_BUSY_SKIP_DISCARD);
-	xfs_trans_agbtree_delta(cur->bc_tp, -1);
-
-	xfs_ag_resv_rmapbt_free(cur->bc_mp, cur->bc_private.a.agno);
 
+	xfs_ag_resv_free_extent(pag, XFS_AG_RESV_RMAPBT, NULL, 1);
 	return 0;
 }
 
@@ -163,14 +160,24 @@ xfs_rmapbt_get_maxrecs(
 	return cur->bc_mp->m_rmap_mxr[level != 0];
 }
 
+/*
+ * Convert the ondisk record's offset field into the ondisk key's offset field.
+ * Fork and bmbt are significant parts of the rmap record key, but written
+ * status is merely a record attribute.
+ */
+static inline __be64 ondisk_rec_offset_to_key(const union xfs_btree_rec *rec)
+{
+	return rec->rmap.rm_offset & ~cpu_to_be64(XFS_RMAP_OFF_UNWRITTEN);
+}
+
 STATIC void
 xfs_rmapbt_init_key_from_rec(
-	union xfs_btree_key	*key,
-	union xfs_btree_rec	*rec)
+	union xfs_btree_key		*key,
+	const union xfs_btree_rec	*rec)
 {
 	key->rmap.rm_startblock = rec->rmap.rm_startblock;
 	key->rmap.rm_owner = rec->rmap.rm_owner;
-	key->rmap.rm_offset = rec->rmap.rm_offset;
+	key->rmap.rm_offset = ondisk_rec_offset_to_key(rec);
 }
 
 /*
@@ -182,18 +189,18 @@ xfs_rmapbt_init_key_from_rec(
  */
 STATIC void
 xfs_rmapbt_init_high_key_from_rec(
-	union xfs_btree_key	*key,
-	union xfs_btree_rec	*rec)
+	union xfs_btree_key		*key,
+	const union xfs_btree_rec	*rec)
 {
-	uint64_t		off;
-	int			adj;
+	uint64_t			off;
+	int				adj;
 
 	adj = be32_to_cpu(rec->rmap.rm_blockcount) - 1;
 
 	key->rmap.rm_startblock = rec->rmap.rm_startblock;
 	be32_add_cpu(&key->rmap.rm_startblock, adj);
 	key->rmap.rm_owner = rec->rmap.rm_owner;
-	key->rmap.rm_offset = rec->rmap.rm_offset;
+	key->rmap.rm_offset = ondisk_rec_offset_to_key(rec);
 	if (XFS_RMAP_NON_INODE_OWNER(be64_to_cpu(rec->rmap.rm_owner)) ||
 	    XFS_RMAP_IS_BMBT_BLOCK(be64_to_cpu(rec->rmap.rm_offset)))
 		return;
@@ -219,72 +226,73 @@ xfs_rmapbt_init_ptr_from_cur(
 	struct xfs_btree_cur	*cur,
 	union xfs_btree_ptr	*ptr)
 {
-	struct xfs_agf		*agf = XFS_BUF_TO_AGF(cur->bc_private.a.agbp);
+	struct xfs_agf		*agf = cur->bc_ag.agbp->b_addr;
 
-	ASSERT(cur->bc_private.a.agno == be32_to_cpu(agf->agf_seqno));
+	ASSERT(cur->bc_group->xg_gno == be32_to_cpu(agf->agf_seqno));
 
-	ptr->s = agf->agf_roots[cur->bc_btnum];
+	ptr->s = agf->agf_rmap_root;
 }
 
-STATIC int64_t
-xfs_rmapbt_key_diff(
-	struct xfs_btree_cur	*cur,
-	union xfs_btree_key	*key)
+/*
+ * Mask the appropriate parts of the ondisk key field for a key comparison.
+ * Fork and bmbt are significant parts of the rmap record key, but written
+ * status is merely a record attribute.
+ */
+static inline uint64_t offset_keymask(uint64_t offset)
 {
-	struct xfs_rmap_irec	*rec = &cur->bc_rec.r;
-	struct xfs_rmap_key	*kp = &key->rmap;
-	__u64			x, y;
-	int64_t			d;
-
-	d = (int64_t)be32_to_cpu(kp->rm_startblock) - rec->rm_startblock;
-	if (d)
-		return d;
+	return offset & ~XFS_RMAP_OFF_UNWRITTEN;
+}
 
-	x = be64_to_cpu(kp->rm_owner);
-	y = rec->rm_owner;
-	if (x > y)
-		return 1;
-	else if (y > x)
-		return -1;
+STATIC int
+xfs_rmapbt_cmp_key_with_cur(
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_key	*key)
+{
+	struct xfs_rmap_irec		*rec = &cur->bc_rec.r;
+	const struct xfs_rmap_key	*kp = &key->rmap;
 
-	x = XFS_RMAP_OFF(be64_to_cpu(kp->rm_offset));
-	y = rec->rm_offset;
-	if (x > y)
-		return 1;
-	else if (y > x)
-		return -1;
-	return 0;
+	return cmp_int(be32_to_cpu(kp->rm_startblock), rec->rm_startblock) ?:
+	       cmp_int(be64_to_cpu(kp->rm_owner), rec->rm_owner) ?:
+	       cmp_int(offset_keymask(be64_to_cpu(kp->rm_offset)),
+		       offset_keymask(xfs_rmap_irec_offset_pack(rec)));
 }
 
-STATIC int64_t
-xfs_rmapbt_diff_two_keys(
-	struct xfs_btree_cur	*cur,
-	union xfs_btree_key	*k1,
-	union xfs_btree_key	*k2)
+STATIC int
+xfs_rmapbt_cmp_two_keys(
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_key	*k1,
+	const union xfs_btree_key	*k2,
+	const union xfs_btree_key	*mask)
 {
-	struct xfs_rmap_key	*kp1 = &k1->rmap;
-	struct xfs_rmap_key	*kp2 = &k2->rmap;
-	int64_t			d;
-	__u64			x, y;
+	const struct xfs_rmap_key	*kp1 = &k1->rmap;
+	const struct xfs_rmap_key	*kp2 = &k2->rmap;
+	int				d;
+
+	/* Doesn't make sense to mask off the physical space part */
+	ASSERT(!mask || mask->rmap.rm_startblock);
 
-	d = (int64_t)be32_to_cpu(kp1->rm_startblock) -
-		       be32_to_cpu(kp2->rm_startblock);
+	d = cmp_int(be32_to_cpu(kp1->rm_startblock),
+		    be32_to_cpu(kp2->rm_startblock));
 	if (d)
 		return d;
 
-	x = be64_to_cpu(kp1->rm_owner);
-	y = be64_to_cpu(kp2->rm_owner);
-	if (x > y)
-		return 1;
-	else if (y > x)
-		return -1;
+	if (!mask || mask->rmap.rm_owner) {
+		d = cmp_int(be64_to_cpu(kp1->rm_owner),
+			    be64_to_cpu(kp2->rm_owner));
+		if (d)
+			return d;
+	}
+
+	if (!mask || mask->rmap.rm_offset) {
+		/* Doesn't make sense to allow offset but not owner */
+		ASSERT(!mask || mask->rmap.rm_owner);
+
+		d = cmp_int(offset_keymask(be64_to_cpu(kp1->rm_offset)),
+			    offset_keymask(be64_to_cpu(kp2->rm_offset)));
+		if (d)
+			return d;
+	}
 
-	x = XFS_RMAP_OFF(be64_to_cpu(kp1->rm_offset));
-	y = XFS_RMAP_OFF(be64_to_cpu(kp2->rm_offset));
-	if (x > y)
-		return 1;
-	else if (y > x)
-		return -1;
 	return 0;
 }
 
@@ -292,7 +300,7 @@ static xfs_failaddr_t
 xfs_rmapbt_verify(
 	struct xfs_buf		*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
 	struct xfs_perag	*pag = bp->b_pag;
 	xfs_failaddr_t		fa;
@@ -310,23 +318,34 @@ xfs_rmapbt_verify(
 	 * from the on disk AGF. Again, we can only check against maximum limits
 	 * in this case.
 	 */
-	if (block->bb_magic != cpu_to_be32(XFS_RMAP_CRC_MAGIC))
+	if (!xfs_verify_magic(bp, block->bb_magic))
 		return __this_address;
 
-	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
+	if (!xfs_has_rmapbt(mp))
 		return __this_address;
-	fa = xfs_btree_sblock_v5hdr_verify(bp);
+	fa = xfs_btree_agblock_v5hdr_verify(bp);
 	if (fa)
 		return fa;
 
 	level = be16_to_cpu(block->bb_level);
-	if (pag && pag->pagf_init) {
-		if (level >= pag->pagf_levels[XFS_BTNUM_RMAPi])
+	if (pag && xfs_perag_initialised_agf(pag)) {
+		unsigned int	maxlevel = pag->pagf_rmap_level;
+
+#ifdef CONFIG_XFS_ONLINE_REPAIR
+		/*
+		 * Online repair could be rewriting the free space btrees, so
+		 * we'll validate against the larger of either tree while this
+		 * is going on.
+		 */
+		maxlevel = max_t(unsigned int, maxlevel,
+				pag->pagf_repair_rmap_level);
+#endif
+		if (level >= maxlevel)
 			return __this_address;
 	} else if (level >= mp->m_rmap_maxlevels)
 		return __this_address;
 
-	return xfs_btree_sblock_verify(bp, mp->m_rmap_mxr[level != 0]);
+	return xfs_btree_agblock_verify(bp, mp->m_rmap_mxr[level != 0]);
 }
 
 static void
@@ -335,7 +354,7 @@ xfs_rmapbt_read_verify(
 {
 	xfs_failaddr_t	fa;
 
-	if (!xfs_btree_sblock_verify_crc(bp))
+	if (!xfs_btree_agblock_verify_crc(bp))
 		xfs_verifier_error(bp, -EFSBADCRC, __this_address);
 	else {
 		fa = xfs_rmapbt_verify(bp);
@@ -359,12 +378,13 @@ xfs_rmapbt_write_verify(
 		xfs_verifier_error(bp, -EFSCORRUPTED, fa);
 		return;
 	}
-	xfs_btree_sblock_calc_crc(bp);
+	xfs_btree_agblock_calc_crc(bp);
 
 }
 
 const struct xfs_buf_ops xfs_rmapbt_buf_ops = {
 	.name			= "xfs_rmapbt",
+	.magic			= { 0, cpu_to_be32(XFS_RMAP_CRC_MAGIC) },
 	.verify_read		= xfs_rmapbt_read_verify,
 	.verify_write		= xfs_rmapbt_write_verify,
 	.verify_struct		= xfs_rmapbt_verify,
@@ -372,9 +392,9 @@ const struct xfs_buf_ops xfs_rmapbt_buf_ops = {
 
 STATIC int
 xfs_rmapbt_keys_inorder(
-	struct xfs_btree_cur	*cur,
-	union xfs_btree_key	*k1,
-	union xfs_btree_key	*k2)
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_key	*k1,
+	const union xfs_btree_key	*k2)
 {
 	uint32_t		x;
 	uint32_t		y;
@@ -393,8 +413,8 @@ xfs_rmapbt_keys_inorder(
 		return 1;
 	else if (a > b)
 		return 0;
-	a = XFS_RMAP_OFF(be64_to_cpu(k1->rmap.rm_offset));
-	b = XFS_RMAP_OFF(be64_to_cpu(k2->rmap.rm_offset));
+	a = offset_keymask(be64_to_cpu(k1->rmap.rm_offset));
+	b = offset_keymask(be64_to_cpu(k2->rmap.rm_offset));
 	if (a <= b)
 		return 1;
 	return 0;
@@ -402,9 +422,9 @@ xfs_rmapbt_keys_inorder(
 
 STATIC int
 xfs_rmapbt_recs_inorder(
-	struct xfs_btree_cur	*cur,
-	union xfs_btree_rec	*r1,
-	union xfs_btree_rec	*r2)
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_rec	*r1,
+	const union xfs_btree_rec	*r2)
 {
 	uint32_t		x;
 	uint32_t		y;
@@ -423,16 +443,46 @@ xfs_rmapbt_recs_inorder(
 		return 1;
 	else if (a > b)
 		return 0;
-	a = XFS_RMAP_OFF(be64_to_cpu(r1->rmap.rm_offset));
-	b = XFS_RMAP_OFF(be64_to_cpu(r2->rmap.rm_offset));
+	a = offset_keymask(be64_to_cpu(r1->rmap.rm_offset));
+	b = offset_keymask(be64_to_cpu(r2->rmap.rm_offset));
 	if (a <= b)
 		return 1;
 	return 0;
 }
 
-static const struct xfs_btree_ops xfs_rmapbt_ops = {
+STATIC enum xbtree_key_contig
+xfs_rmapbt_keys_contiguous(
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_key	*key1,
+	const union xfs_btree_key	*key2,
+	const union xfs_btree_key	*mask)
+{
+	ASSERT(!mask || mask->rmap.rm_startblock);
+
+	/*
+	 * We only support checking contiguity of the physical space component.
+	 * If any callers ever need more specificity than that, they'll have to
+	 * implement it here.
+	 */
+	ASSERT(!mask || (!mask->rmap.rm_owner && !mask->rmap.rm_offset));
+
+	return xbtree_key_contig(be32_to_cpu(key1->rmap.rm_startblock),
+				 be32_to_cpu(key2->rmap.rm_startblock));
+}
+
+const struct xfs_btree_ops xfs_rmapbt_ops = {
+	.name			= "rmap",
+	.type			= XFS_BTREE_TYPE_AG,
+	.geom_flags		= XFS_BTGEO_OVERLAPPING,
+
 	.rec_len		= sizeof(struct xfs_rmap_rec),
+	/* Overlapping btree; 2 keys per pointer. */
 	.key_len		= 2 * sizeof(struct xfs_rmap_key),
+	.ptr_len		= XFS_BTREE_SHORT_PTR_LEN,
+
+	.lru_refs		= XFS_RMAP_BTREE_REF,
+	.statoff		= XFS_STATS_CALC_INDEX(xs_rmap_2),
+	.sick_mask		= XFS_SICK_AG_RMAPBT,
 
 	.dup_cursor		= xfs_rmapbt_dup_cursor,
 	.set_root		= xfs_rmapbt_set_root,
@@ -444,84 +494,294 @@ static const struct xfs_btree_ops xfs_rmapbt_ops = {
 	.init_high_key_from_rec	= xfs_rmapbt_init_high_key_from_rec,
 	.init_rec_from_cur	= xfs_rmapbt_init_rec_from_cur,
 	.init_ptr_from_cur	= xfs_rmapbt_init_ptr_from_cur,
-	.key_diff		= xfs_rmapbt_key_diff,
+	.cmp_key_with_cur	= xfs_rmapbt_cmp_key_with_cur,
 	.buf_ops		= &xfs_rmapbt_buf_ops,
-	.diff_two_keys		= xfs_rmapbt_diff_two_keys,
+	.cmp_two_keys		= xfs_rmapbt_cmp_two_keys,
 	.keys_inorder		= xfs_rmapbt_keys_inorder,
 	.recs_inorder		= xfs_rmapbt_recs_inorder,
+	.keys_contiguous	= xfs_rmapbt_keys_contiguous,
 };
 
 /*
- * Allocate a new allocation btree cursor.
+ * Create a new reverse mapping btree cursor.
+ *
+ * For staging cursors tp and agbp are NULL.
  */
 struct xfs_btree_cur *
 xfs_rmapbt_init_cursor(
 	struct xfs_mount	*mp,
 	struct xfs_trans	*tp,
 	struct xfs_buf		*agbp,
-	xfs_agnumber_t		agno)
+	struct xfs_perag	*pag)
 {
-	struct xfs_agf		*agf = XFS_BUF_TO_AGF(agbp);
 	struct xfs_btree_cur	*cur;
 
-	cur = kmem_zone_zalloc(xfs_btree_cur_zone, KM_NOFS);
-	cur->bc_tp = tp;
-	cur->bc_mp = mp;
+	cur = xfs_btree_alloc_cursor(mp, tp, &xfs_rmapbt_ops,
+			mp->m_rmap_maxlevels, xfs_rmapbt_cur_cache);
+	cur->bc_group = xfs_group_hold(pag_group(pag));
+	cur->bc_ag.agbp = agbp;
+	if (agbp) {
+		struct xfs_agf		*agf = agbp->b_addr;
+
+		cur->bc_nlevels = be32_to_cpu(agf->agf_rmap_level);
+	}
+	return cur;
+}
+
+#ifdef CONFIG_XFS_BTREE_IN_MEM
+static inline unsigned int
+xfs_rmapbt_mem_block_maxrecs(
+	unsigned int		blocklen,
+	bool			leaf)
+{
+	if (leaf)
+		return blocklen / sizeof(struct xfs_rmap_rec);
+	return blocklen /
+		(2 * sizeof(struct xfs_rmap_key) + sizeof(__be64));
+}
+
+/*
+ * Validate an in-memory rmap btree block.  Callers are allowed to generate an
+ * in-memory btree even if the ondisk feature is not enabled.
+ */
+static xfs_failaddr_t
+xfs_rmapbt_mem_verify(
+	struct xfs_buf		*bp)
+{
+	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
+	xfs_failaddr_t		fa;
+	unsigned int		level;
+	unsigned int		maxrecs;
+
+	if (!xfs_verify_magic(bp, block->bb_magic))
+		return __this_address;
+
+	fa = xfs_btree_fsblock_v5hdr_verify(bp, XFS_RMAP_OWN_UNKNOWN);
+	if (fa)
+		return fa;
+
+	level = be16_to_cpu(block->bb_level);
+	if (level >= xfs_rmapbt_maxlevels_ondisk())
+		return __this_address;
+
+	maxrecs = xfs_rmapbt_mem_block_maxrecs(
+			XFBNO_BLOCKSIZE - XFS_BTREE_LBLOCK_CRC_LEN, level == 0);
+	return xfs_btree_memblock_verify(bp, maxrecs);
+}
+
+static void
+xfs_rmapbt_mem_rw_verify(
+	struct xfs_buf	*bp)
+{
+	xfs_failaddr_t	fa = xfs_rmapbt_mem_verify(bp);
+
+	if (fa)
+		xfs_verifier_error(bp, -EFSCORRUPTED, fa);
+}
+
+/* skip crc checks on in-memory btrees to save time */
+static const struct xfs_buf_ops xfs_rmapbt_mem_buf_ops = {
+	.name			= "xfs_rmapbt_mem",
+	.magic			= { 0, cpu_to_be32(XFS_RMAP_CRC_MAGIC) },
+	.verify_read		= xfs_rmapbt_mem_rw_verify,
+	.verify_write		= xfs_rmapbt_mem_rw_verify,
+	.verify_struct		= xfs_rmapbt_mem_verify,
+};
+
+const struct xfs_btree_ops xfs_rmapbt_mem_ops = {
+	.name			= "mem_rmap",
+	.type			= XFS_BTREE_TYPE_MEM,
+	.geom_flags		= XFS_BTGEO_OVERLAPPING,
+
+	.rec_len		= sizeof(struct xfs_rmap_rec),
 	/* Overlapping btree; 2 keys per pointer. */
-	cur->bc_btnum = XFS_BTNUM_RMAP;
-	cur->bc_flags = XFS_BTREE_CRC_BLOCKS | XFS_BTREE_OVERLAPPING;
-	cur->bc_blocklog = mp->m_sb.sb_blocklog;
-	cur->bc_ops = &xfs_rmapbt_ops;
-	cur->bc_nlevels = be32_to_cpu(agf->agf_levels[XFS_BTNUM_RMAP]);
-	cur->bc_statoff = XFS_STATS_CALC_INDEX(xs_rmap_2);
+	.key_len		= 2 * sizeof(struct xfs_rmap_key),
+	.ptr_len		= XFS_BTREE_LONG_PTR_LEN,
+
+	.lru_refs		= XFS_RMAP_BTREE_REF,
+	.statoff		= XFS_STATS_CALC_INDEX(xs_rmap_mem_2),
+
+	.dup_cursor		= xfbtree_dup_cursor,
+	.set_root		= xfbtree_set_root,
+	.alloc_block		= xfbtree_alloc_block,
+	.free_block		= xfbtree_free_block,
+	.get_minrecs		= xfbtree_get_minrecs,
+	.get_maxrecs		= xfbtree_get_maxrecs,
+	.init_key_from_rec	= xfs_rmapbt_init_key_from_rec,
+	.init_high_key_from_rec	= xfs_rmapbt_init_high_key_from_rec,
+	.init_rec_from_cur	= xfs_rmapbt_init_rec_from_cur,
+	.init_ptr_from_cur	= xfbtree_init_ptr_from_cur,
+	.cmp_key_with_cur	= xfs_rmapbt_cmp_key_with_cur,
+	.buf_ops		= &xfs_rmapbt_mem_buf_ops,
+	.cmp_two_keys		= xfs_rmapbt_cmp_two_keys,
+	.keys_inorder		= xfs_rmapbt_keys_inorder,
+	.recs_inorder		= xfs_rmapbt_recs_inorder,
+	.keys_contiguous	= xfs_rmapbt_keys_contiguous,
+};
+
+/* Create a cursor for an in-memory btree. */
+struct xfs_btree_cur *
+xfs_rmapbt_mem_cursor(
+	struct xfs_perag	*pag,
+	struct xfs_trans	*tp,
+	struct xfbtree		*xfbt)
+{
+	struct xfs_btree_cur	*cur;
 
-	cur->bc_private.a.agbp = agbp;
-	cur->bc_private.a.agno = agno;
+	cur = xfs_btree_alloc_cursor(pag_mount(pag), tp, &xfs_rmapbt_mem_ops,
+			xfs_rmapbt_maxlevels_ondisk(), xfs_rmapbt_cur_cache);
+	cur->bc_mem.xfbtree = xfbt;
+	cur->bc_nlevels = xfbt->nlevels;
 
+	cur->bc_group = xfs_group_hold(pag_group(pag));
 	return cur;
 }
 
+/* Create an in-memory rmap btree. */
+int
+xfs_rmapbt_mem_init(
+	struct xfs_mount	*mp,
+	struct xfbtree		*xfbt,
+	struct xfs_buftarg	*btp,
+	xfs_agnumber_t		agno)
+{
+	xfbt->owner = agno;
+	return xfbtree_init(mp, xfbt, btp, &xfs_rmapbt_mem_ops);
+}
+
+/* Compute the max possible height for reverse mapping btrees in memory. */
+static unsigned int
+xfs_rmapbt_mem_maxlevels(void)
+{
+	unsigned int		minrecs[2];
+	unsigned int		blocklen;
+
+	blocklen = XFBNO_BLOCKSIZE - XFS_BTREE_LBLOCK_CRC_LEN;
+
+	minrecs[0] = xfs_rmapbt_mem_block_maxrecs(blocklen, true) / 2;
+	minrecs[1] = xfs_rmapbt_mem_block_maxrecs(blocklen, false) / 2;
+
+	/*
+	 * How tall can an in-memory rmap btree become if we filled the entire
+	 * AG with rmap records?
+	 */
+	return xfs_btree_compute_maxlevels(minrecs,
+			XFS_MAX_AG_BYTES / sizeof(struct xfs_rmap_rec));
+}
+#else
+# define xfs_rmapbt_mem_maxlevels()	(0)
+#endif /* CONFIG_XFS_BTREE_IN_MEM */
+
 /*
- * Calculate number of records in an rmap btree block.
+ * Install a new reverse mapping btree root.  Caller is responsible for
+ * invalidating and freeing the old btree blocks.
  */
-int
-xfs_rmapbt_maxrecs(
-	int			blocklen,
-	int			leaf)
+void
+xfs_rmapbt_commit_staged_btree(
+	struct xfs_btree_cur	*cur,
+	struct xfs_trans	*tp,
+	struct xfs_buf		*agbp)
 {
-	blocklen -= XFS_RMAP_BLOCK_LEN;
+	struct xfs_agf		*agf = agbp->b_addr;
+	struct xbtree_afakeroot	*afake = cur->bc_ag.afake;
 
+	ASSERT(cur->bc_flags & XFS_BTREE_STAGING);
+
+	agf->agf_rmap_root = cpu_to_be32(afake->af_root);
+	agf->agf_rmap_level = cpu_to_be32(afake->af_levels);
+	agf->agf_rmap_blocks = cpu_to_be32(afake->af_blocks);
+	xfs_alloc_log_agf(tp, agbp, XFS_AGF_ROOTS | XFS_AGF_LEVELS |
+				    XFS_AGF_RMAP_BLOCKS);
+	xfs_btree_commit_afakeroot(cur, tp, agbp);
+}
+
+/* Calculate number of records in a reverse mapping btree block. */
+static inline unsigned int
+xfs_rmapbt_block_maxrecs(
+	unsigned int		blocklen,
+	bool			leaf)
+{
 	if (leaf)
 		return blocklen / sizeof(struct xfs_rmap_rec);
 	return blocklen /
 		(2 * sizeof(struct xfs_rmap_key) + sizeof(xfs_rmap_ptr_t));
 }
 
+/*
+ * Calculate number of records in an rmap btree block.
+ */
+unsigned int
+xfs_rmapbt_maxrecs(
+	struct xfs_mount	*mp,
+	unsigned int		blocklen,
+	bool			leaf)
+{
+	blocklen -= XFS_RMAP_BLOCK_LEN;
+	return xfs_rmapbt_block_maxrecs(blocklen, leaf);
+}
+
+/* Compute the max possible height for reverse mapping btrees. */
+unsigned int
+xfs_rmapbt_maxlevels_ondisk(void)
+{
+	unsigned int		minrecs[2];
+	unsigned int		blocklen;
+
+	blocklen = XFS_MIN_CRC_BLOCKSIZE - XFS_BTREE_SBLOCK_CRC_LEN;
+
+	minrecs[0] = xfs_rmapbt_block_maxrecs(blocklen, true) / 2;
+	minrecs[1] = xfs_rmapbt_block_maxrecs(blocklen, false) / 2;
+
+	/*
+	 * Compute the asymptotic maxlevels for an rmapbt on any reflink fs.
+	 *
+	 * On a reflink filesystem, each AG block can have up to 2^32 (per the
+	 * refcount record format) owners, which means that theoretically we
+	 * could face up to 2^64 rmap records.  However, we're likely to run
+	 * out of blocks in the AG long before that happens, which means that
+	 * we must compute the max height based on what the btree will look
+	 * like if it consumes almost all the blocks in the AG due to maximal
+	 * sharing factor.
+	 */
+	return max(xfs_btree_space_to_height(minrecs, XFS_MAX_CRC_AG_BLOCKS),
+		   xfs_rmapbt_mem_maxlevels());
+}
+
 /* Compute the maximum height of an rmap btree. */
 void
 xfs_rmapbt_compute_maxlevels(
 	struct xfs_mount		*mp)
 {
-	/*
-	 * On a non-reflink filesystem, the maximum number of rmap
-	 * records is the number of blocks in the AG, hence the max
-	 * rmapbt height is log_$maxrecs($agblocks).  However, with
-	 * reflink each AG block can have up to 2^32 (per the refcount
-	 * record format) owners, which means that theoretically we
-	 * could face up to 2^64 rmap records.
-	 *
-	 * That effectively means that the max rmapbt height must be
-	 * XFS_BTREE_MAXLEVELS.  "Fortunately" we'll run out of AG
-	 * blocks to feed the rmapbt long before the rmapbt reaches
-	 * maximum height.  The reflink code uses ag_resv_critical to
-	 * disallow reflinking when less than 10% of the per-AG metadata
-	 * block reservation since the fallback is a regular file copy.
-	 */
-	if (xfs_sb_version_hasreflink(&mp->m_sb))
-		mp->m_rmap_maxlevels = XFS_BTREE_MAXLEVELS;
-	else
+	if (!xfs_has_rmapbt(mp)) {
+		mp->m_rmap_maxlevels = 0;
+		return;
+	}
+
+	if (xfs_has_reflink(mp)) {
+		/*
+		 * Compute the asymptotic maxlevels for an rmap btree on a
+		 * filesystem that supports reflink.
+		 *
+		 * On a reflink filesystem, each AG block can have up to 2^32
+		 * (per the refcount record format) owners, which means that
+		 * theoretically we could face up to 2^64 rmap records.
+		 * However, we're likely to run out of blocks in the AG long
+		 * before that happens, which means that we must compute the
+		 * max height based on what the btree will look like if it
+		 * consumes almost all the blocks in the AG due to maximal
+		 * sharing factor.
+		 */
+		mp->m_rmap_maxlevels = xfs_btree_space_to_height(mp->m_rmap_mnr,
+				mp->m_sb.sb_agblocks);
+	} else {
+		/*
+		 * If there's no block sharing, compute the maximum rmapbt
+		 * height assuming one rmap record per AG block.
+		 */
 		mp->m_rmap_maxlevels = xfs_btree_compute_maxlevels(
 				mp->m_rmap_mnr, mp->m_sb.sb_agblocks);
+	}
+	ASSERT(mp->m_rmap_maxlevels <= xfs_rmapbt_maxlevels_ondisk());
 }
 
 /* Calculate the refcount btree size for some records. */
@@ -555,7 +815,7 @@ int
 xfs_rmapbt_calc_reserves(
 	struct xfs_mount	*mp,
 	struct xfs_trans	*tp,
-	xfs_agnumber_t		agno,
+	struct xfs_perag	*pag,
 	xfs_extlen_t		*ask,
 	xfs_extlen_t		*used)
 {
@@ -565,21 +825,48 @@ xfs_rmapbt_calc_reserves(
 	xfs_extlen_t		tree_len;
 	int			error;
 
-	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
+	if (!xfs_has_rmapbt(mp))
 		return 0;
 
-	error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp);
+	error = xfs_alloc_read_agf(pag, tp, 0, &agbp);
 	if (error)
 		return error;
 
-	agf = XFS_BUF_TO_AGF(agbp);
+	agf = agbp->b_addr;
 	agblocks = be32_to_cpu(agf->agf_length);
 	tree_len = be32_to_cpu(agf->agf_rmap_blocks);
 	xfs_trans_brelse(tp, agbp);
 
+	/*
+	 * The log is permanently allocated, so the space it occupies will
+	 * never be available for the kinds of things that would require btree
+	 * expansion.  We therefore can pretend the space isn't there.
+	 */
+	if (xfs_ag_contains_log(mp, pag_agno(pag)))
+		agblocks -= mp->m_sb.sb_logblocks;
+
 	/* Reserve 1% of the AG or enough for 1 block per record. */
 	*ask += max(agblocks / 100, xfs_rmapbt_max_size(mp, agblocks));
 	*used += tree_len;
 
 	return error;
 }
+
+int __init
+xfs_rmapbt_init_cur_cache(void)
+{
+	xfs_rmapbt_cur_cache = kmem_cache_create("xfs_rmapbt_cur",
+			xfs_btree_cur_sizeof(xfs_rmapbt_maxlevels_ondisk()),
+			0, 0, NULL);
+
+	if (!xfs_rmapbt_cur_cache)
+		return -ENOMEM;
+	return 0;
+}
+
+void
+xfs_rmapbt_destroy_cur_cache(void)
+{
+	kmem_cache_destroy(xfs_rmapbt_cur_cache);
+	xfs_rmapbt_cur_cache = NULL;
+}