Merge tag 'realtime-reflink_2024-12-23' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into for-next

xfs: reflink on the realtime device [v6.2 05/14]

This patchset enables use of the file data block sharing feature (i.e.
reflink) on the realtime device.  It follows the same basic sequence as
the realtime rmap series -- first a few cleanups; then  introduction of
the new btree format and inode fork format.  Next comes enabling CoW and
remapping for the rt device; new scrub, repair, and health reporting
code; and at the end we implement some code to lengthen write requests
so that rt extents are always CoWed fully.

This has been running on the djcloud for months with no problems.  Enjoy!

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>

1 files changed, 757 insertions, 0 deletions

diff --git a/fs/xfs/libxfs/xfs_rtrefcount_btree.c b/fs/xfs/libxfs/xfs_rtrefcount_btree.c
new file mode 100644
index 000000000000..3db5e7a4a945
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_rtrefcount_btree.c
@@ -0,0 +1,757 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2021-2024 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#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_rtrefcount_btree.h"
+#include "xfs_refcount.h"
+#include "xfs_trace.h"
+#include "xfs_cksum.h"
+#include "xfs_error.h"
+#include "xfs_extent_busy.h"
+#include "xfs_rtgroup.h"
+#include "xfs_rtbitmap.h"
+#include "xfs_metafile.h"
+#include "xfs_health.h"
+
+static struct kmem_cache	*xfs_rtrefcountbt_cur_cache;
+
+/*
+ * Realtime Reference Count btree.
+ *
+ * This is a btree used to track the owner(s) of a given extent in the realtime
+ * device.  See the comments in xfs_refcount_btree.c for more information.
+ *
+ * This tree is basically the same as the regular refcount btree except that
+ * it's rooted in an inode.
+ */
+
+static struct xfs_btree_cur *
+xfs_rtrefcountbt_dup_cursor(
+	struct xfs_btree_cur	*cur)
+{
+	return xfs_rtrefcountbt_init_cursor(cur->bc_tp, to_rtg(cur->bc_group));
+}
+
+STATIC int
+xfs_rtrefcountbt_get_minrecs(
+	struct xfs_btree_cur	*cur,
+	int			level)
+{
+	if (level == cur->bc_nlevels - 1) {
+		struct xfs_ifork	*ifp = xfs_btree_ifork_ptr(cur);
+
+		return xfs_rtrefcountbt_maxrecs(cur->bc_mp, ifp->if_broot_bytes,
+				level == 0) / 2;
+	}
+
+	return cur->bc_mp->m_rtrefc_mnr[level != 0];
+}
+
+STATIC int
+xfs_rtrefcountbt_get_maxrecs(
+	struct xfs_btree_cur	*cur,
+	int			level)
+{
+	if (level == cur->bc_nlevels - 1) {
+		struct xfs_ifork	*ifp = xfs_btree_ifork_ptr(cur);
+
+		return xfs_rtrefcountbt_maxrecs(cur->bc_mp, ifp->if_broot_bytes,
+				level == 0);
+	}
+
+	return cur->bc_mp->m_rtrefc_mxr[level != 0];
+}
+
+/*
+ * Calculate number of records in a realtime refcount btree inode root.
+ */
+unsigned int
+xfs_rtrefcountbt_droot_maxrecs(
+	unsigned int		blocklen,
+	bool			leaf)
+{
+	blocklen -= sizeof(struct xfs_rtrefcount_root);
+
+	if (leaf)
+		return blocklen / sizeof(struct xfs_refcount_rec);
+	return blocklen / (2 * sizeof(struct xfs_refcount_key) +
+			sizeof(xfs_rtrefcount_ptr_t));
+}
+
+/*
+ * Get the maximum records we could store in the on-disk format.
+ *
+ * For non-root nodes this is equivalent to xfs_rtrefcountbt_get_maxrecs, but
+ * for the root node this checks the available space in the dinode fork so that
+ * we can resize the in-memory buffer to match it.  After a resize to the
+ * maximum size this function returns the same value as
+ * xfs_rtrefcountbt_get_maxrecs for the root node, too.
+ */
+STATIC int
+xfs_rtrefcountbt_get_dmaxrecs(
+	struct xfs_btree_cur	*cur,
+	int			level)
+{
+	if (level != cur->bc_nlevels - 1)
+		return cur->bc_mp->m_rtrefc_mxr[level != 0];
+	return xfs_rtrefcountbt_droot_maxrecs(cur->bc_ino.forksize, level == 0);
+}
+
+STATIC void
+xfs_rtrefcountbt_init_key_from_rec(
+	union xfs_btree_key		*key,
+	const union xfs_btree_rec	*rec)
+{
+	key->refc.rc_startblock = rec->refc.rc_startblock;
+}
+
+STATIC void
+xfs_rtrefcountbt_init_high_key_from_rec(
+	union xfs_btree_key		*key,
+	const union xfs_btree_rec	*rec)
+{
+	__u32				x;
+
+	x = be32_to_cpu(rec->refc.rc_startblock);
+	x += be32_to_cpu(rec->refc.rc_blockcount) - 1;
+	key->refc.rc_startblock = cpu_to_be32(x);
+}
+
+STATIC void
+xfs_rtrefcountbt_init_rec_from_cur(
+	struct xfs_btree_cur	*cur,
+	union xfs_btree_rec	*rec)
+{
+	const struct xfs_refcount_irec *irec = &cur->bc_rec.rc;
+	uint32_t		start;
+
+	start = xfs_refcount_encode_startblock(irec->rc_startblock,
+			irec->rc_domain);
+	rec->refc.rc_startblock = cpu_to_be32(start);
+	rec->refc.rc_blockcount = cpu_to_be32(cur->bc_rec.rc.rc_blockcount);
+	rec->refc.rc_refcount = cpu_to_be32(cur->bc_rec.rc.rc_refcount);
+}
+
+STATIC void
+xfs_rtrefcountbt_init_ptr_from_cur(
+	struct xfs_btree_cur	*cur,
+	union xfs_btree_ptr	*ptr)
+{
+	ptr->l = 0;
+}
+
+STATIC int64_t
+xfs_rtrefcountbt_key_diff(
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_key	*key)
+{
+	const struct xfs_refcount_key	*kp = &key->refc;
+	const struct xfs_refcount_irec	*irec = &cur->bc_rec.rc;
+	uint32_t			start;
+
+	start = xfs_refcount_encode_startblock(irec->rc_startblock,
+			irec->rc_domain);
+	return (int64_t)be32_to_cpu(kp->rc_startblock) - start;
+}
+
+STATIC int64_t
+xfs_rtrefcountbt_diff_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)
+{
+	ASSERT(!mask || mask->refc.rc_startblock);
+
+	return (int64_t)be32_to_cpu(k1->refc.rc_startblock) -
+			be32_to_cpu(k2->refc.rc_startblock);
+}
+
+static xfs_failaddr_t
+xfs_rtrefcountbt_verify(
+	struct xfs_buf		*bp)
+{
+	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
+	xfs_failaddr_t		fa;
+	int			level;
+
+	if (!xfs_verify_magic(bp, block->bb_magic))
+		return __this_address;
+
+	if (!xfs_has_reflink(mp))
+		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 > mp->m_rtrefc_maxlevels)
+		return __this_address;
+
+	return xfs_btree_fsblock_verify(bp, mp->m_rtrefc_mxr[level != 0]);
+}
+
+static void
+xfs_rtrefcountbt_read_verify(
+	struct xfs_buf	*bp)
+{
+	xfs_failaddr_t	fa;
+
+	if (!xfs_btree_fsblock_verify_crc(bp))
+		xfs_verifier_error(bp, -EFSBADCRC, __this_address);
+	else {
+		fa = xfs_rtrefcountbt_verify(bp);
+		if (fa)
+			xfs_verifier_error(bp, -EFSCORRUPTED, fa);
+	}
+
+	if (bp->b_error)
+		trace_xfs_btree_corrupt(bp, _RET_IP_);
+}
+
+static void
+xfs_rtrefcountbt_write_verify(
+	struct xfs_buf	*bp)
+{
+	xfs_failaddr_t	fa;
+
+	fa = xfs_rtrefcountbt_verify(bp);
+	if (fa) {
+		trace_xfs_btree_corrupt(bp, _RET_IP_);
+		xfs_verifier_error(bp, -EFSCORRUPTED, fa);
+		return;
+	}
+	xfs_btree_fsblock_calc_crc(bp);
+
+}
+
+const struct xfs_buf_ops xfs_rtrefcountbt_buf_ops = {
+	.name			= "xfs_rtrefcountbt",
+	.magic			= { 0, cpu_to_be32(XFS_RTREFC_CRC_MAGIC) },
+	.verify_read		= xfs_rtrefcountbt_read_verify,
+	.verify_write		= xfs_rtrefcountbt_write_verify,
+	.verify_struct		= xfs_rtrefcountbt_verify,
+};
+
+STATIC int
+xfs_rtrefcountbt_keys_inorder(
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_key	*k1,
+	const union xfs_btree_key	*k2)
+{
+	return be32_to_cpu(k1->refc.rc_startblock) <
+	       be32_to_cpu(k2->refc.rc_startblock);
+}
+
+STATIC int
+xfs_rtrefcountbt_recs_inorder(
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_rec	*r1,
+	const union xfs_btree_rec	*r2)
+{
+	return  be32_to_cpu(r1->refc.rc_startblock) +
+		be32_to_cpu(r1->refc.rc_blockcount) <=
+		be32_to_cpu(r2->refc.rc_startblock);
+}
+
+STATIC enum xbtree_key_contig
+xfs_rtrefcountbt_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->refc.rc_startblock);
+
+	return xbtree_key_contig(be32_to_cpu(key1->refc.rc_startblock),
+				 be32_to_cpu(key2->refc.rc_startblock));
+}
+
+static inline void
+xfs_rtrefcountbt_move_ptrs(
+	struct xfs_mount	*mp,
+	struct xfs_btree_block	*broot,
+	short			old_size,
+	size_t			new_size,
+	unsigned int		numrecs)
+{
+	void			*dptr;
+	void			*sptr;
+
+	sptr = xfs_rtrefcount_broot_ptr_addr(mp, broot, 1, old_size);
+	dptr = xfs_rtrefcount_broot_ptr_addr(mp, broot, 1, new_size);
+	memmove(dptr, sptr, numrecs * sizeof(xfs_rtrefcount_ptr_t));
+}
+
+static struct xfs_btree_block *
+xfs_rtrefcountbt_broot_realloc(
+	struct xfs_btree_cur	*cur,
+	unsigned int		new_numrecs)
+{
+	struct xfs_mount	*mp = cur->bc_mp;
+	struct xfs_ifork	*ifp = xfs_btree_ifork_ptr(cur);
+	struct xfs_btree_block	*broot;
+	unsigned int		new_size;
+	unsigned int		old_size = ifp->if_broot_bytes;
+	const unsigned int	level = cur->bc_nlevels - 1;
+
+	new_size = xfs_rtrefcount_broot_space_calc(mp, level, new_numrecs);
+
+	/* Handle the nop case quietly. */
+	if (new_size == old_size)
+		return ifp->if_broot;
+
+	if (new_size > old_size) {
+		unsigned int	old_numrecs;
+
+		/*
+		 * If there wasn't any memory allocated before, just allocate
+		 * it now and get out.
+		 */
+		if (old_size == 0)
+			return xfs_broot_realloc(ifp, new_size);
+
+		/*
+		 * If there is already an existing if_broot, then we need to
+		 * realloc it and possibly move the node block pointers because
+		 * those are not butted up against the btree block header.
+		 */
+		old_numrecs = xfs_rtrefcountbt_maxrecs(mp, old_size, level);
+		broot = xfs_broot_realloc(ifp, new_size);
+		if (level > 0)
+			xfs_rtrefcountbt_move_ptrs(mp, broot, old_size,
+					new_size, old_numrecs);
+		goto out_broot;
+	}
+
+	/*
+	 * We're reducing numrecs.  If we're going all the way to zero, just
+	 * free the block.
+	 */
+	ASSERT(ifp->if_broot != NULL && old_size > 0);
+	if (new_size == 0)
+		return xfs_broot_realloc(ifp, 0);
+
+	/*
+	 * Shrink the btree root by possibly moving the rtrmapbt pointers,
+	 * since they are not butted up against the btree block header.  Then
+	 * reallocate broot.
+	 */
+	if (level > 0)
+		xfs_rtrefcountbt_move_ptrs(mp, ifp->if_broot, old_size,
+				new_size, new_numrecs);
+	broot = xfs_broot_realloc(ifp, new_size);
+
+out_broot:
+	ASSERT(xfs_rtrefcount_droot_space(broot) <=
+	       xfs_inode_fork_size(cur->bc_ino.ip, cur->bc_ino.whichfork));
+	return broot;
+}
+
+const struct xfs_btree_ops xfs_rtrefcountbt_ops = {
+	.name			= "rtrefcount",
+	.type			= XFS_BTREE_TYPE_INODE,
+	.geom_flags		= XFS_BTGEO_IROOT_RECORDS,
+
+	.rec_len		= sizeof(struct xfs_refcount_rec),
+	.key_len		= sizeof(struct xfs_refcount_key),
+	.ptr_len		= XFS_BTREE_LONG_PTR_LEN,
+
+	.lru_refs		= XFS_REFC_BTREE_REF,
+	.statoff		= XFS_STATS_CALC_INDEX(xs_rtrefcbt_2),
+	.sick_mask		= XFS_SICK_RG_REFCNTBT,
+
+	.dup_cursor		= xfs_rtrefcountbt_dup_cursor,
+	.alloc_block		= xfs_btree_alloc_metafile_block,
+	.free_block		= xfs_btree_free_metafile_block,
+	.get_minrecs		= xfs_rtrefcountbt_get_minrecs,
+	.get_maxrecs		= xfs_rtrefcountbt_get_maxrecs,
+	.get_dmaxrecs		= xfs_rtrefcountbt_get_dmaxrecs,
+	.init_key_from_rec	= xfs_rtrefcountbt_init_key_from_rec,
+	.init_high_key_from_rec	= xfs_rtrefcountbt_init_high_key_from_rec,
+	.init_rec_from_cur	= xfs_rtrefcountbt_init_rec_from_cur,
+	.init_ptr_from_cur	= xfs_rtrefcountbt_init_ptr_from_cur,
+	.key_diff		= xfs_rtrefcountbt_key_diff,
+	.buf_ops		= &xfs_rtrefcountbt_buf_ops,
+	.diff_two_keys		= xfs_rtrefcountbt_diff_two_keys,
+	.keys_inorder		= xfs_rtrefcountbt_keys_inorder,
+	.recs_inorder		= xfs_rtrefcountbt_recs_inorder,
+	.keys_contiguous	= xfs_rtrefcountbt_keys_contiguous,
+	.broot_realloc		= xfs_rtrefcountbt_broot_realloc,
+};
+
+/* Allocate a new rt refcount btree cursor. */
+struct xfs_btree_cur *
+xfs_rtrefcountbt_init_cursor(
+	struct xfs_trans	*tp,
+	struct xfs_rtgroup	*rtg)
+{
+	struct xfs_inode	*ip = rtg_refcount(rtg);
+	struct xfs_mount	*mp = rtg_mount(rtg);
+	struct xfs_btree_cur	*cur;
+
+	xfs_assert_ilocked(ip, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL);
+
+	cur = xfs_btree_alloc_cursor(mp, tp, &xfs_rtrefcountbt_ops,
+			mp->m_rtrefc_maxlevels, xfs_rtrefcountbt_cur_cache);
+
+	cur->bc_ino.ip = ip;
+	cur->bc_refc.nr_ops = 0;
+	cur->bc_refc.shape_changes = 0;
+	cur->bc_group = xfs_group_hold(rtg_group(rtg));
+	cur->bc_nlevels = be16_to_cpu(ip->i_df.if_broot->bb_level) + 1;
+	cur->bc_ino.forksize = xfs_inode_fork_size(ip, XFS_DATA_FORK);
+	cur->bc_ino.whichfork = XFS_DATA_FORK;
+	return cur;
+}
+
+/*
+ * Install a new rt reverse mapping btree root.  Caller is responsible for
+ * invalidating and freeing the old btree blocks.
+ */
+void
+xfs_rtrefcountbt_commit_staged_btree(
+	struct xfs_btree_cur	*cur,
+	struct xfs_trans	*tp)
+{
+	struct xbtree_ifakeroot	*ifake = cur->bc_ino.ifake;
+	struct xfs_ifork	*ifp;
+	int			flags = XFS_ILOG_CORE | XFS_ILOG_DBROOT;
+
+	ASSERT(cur->bc_flags & XFS_BTREE_STAGING);
+	ASSERT(ifake->if_fork->if_format == XFS_DINODE_FMT_META_BTREE);
+
+	/*
+	 * Free any resources hanging off the real fork, then shallow-copy the
+	 * staging fork's contents into the real fork to transfer everything
+	 * we just built.
+	 */
+	ifp = xfs_ifork_ptr(cur->bc_ino.ip, XFS_DATA_FORK);
+	xfs_idestroy_fork(ifp);
+	memcpy(ifp, ifake->if_fork, sizeof(struct xfs_ifork));
+
+	cur->bc_ino.ip->i_projid = cur->bc_group->xg_gno;
+	xfs_trans_log_inode(tp, cur->bc_ino.ip, flags);
+	xfs_btree_commit_ifakeroot(cur, tp, XFS_DATA_FORK);
+}
+
+/* Calculate number of records in a realtime refcount btree block. */
+static inline unsigned int
+xfs_rtrefcountbt_block_maxrecs(
+	unsigned int		blocklen,
+	bool			leaf)
+{
+
+	if (leaf)
+		return blocklen / sizeof(struct xfs_refcount_rec);
+	return blocklen / (sizeof(struct xfs_refcount_key) +
+			   sizeof(xfs_rtrefcount_ptr_t));
+}
+
+/*
+ * Calculate number of records in an refcount btree block.
+ */
+unsigned int
+xfs_rtrefcountbt_maxrecs(
+	struct xfs_mount	*mp,
+	unsigned int		blocklen,
+	bool			leaf)
+{
+	blocklen -= XFS_RTREFCOUNT_BLOCK_LEN;
+	return xfs_rtrefcountbt_block_maxrecs(blocklen, leaf);
+}
+
+/* Compute the max possible height for realtime refcount btrees. */
+unsigned int
+xfs_rtrefcountbt_maxlevels_ondisk(void)
+{
+	unsigned int		minrecs[2];
+	unsigned int		blocklen;
+
+	blocklen = XFS_MIN_CRC_BLOCKSIZE - XFS_BTREE_LBLOCK_CRC_LEN;
+
+	minrecs[0] = xfs_rtrefcountbt_block_maxrecs(blocklen, true) / 2;
+	minrecs[1] = xfs_rtrefcountbt_block_maxrecs(blocklen, false) / 2;
+
+	/* We need at most one record for every block in an rt group. */
+	return xfs_btree_compute_maxlevels(minrecs, XFS_MAX_RGBLOCKS);
+}
+
+int __init
+xfs_rtrefcountbt_init_cur_cache(void)
+{
+	xfs_rtrefcountbt_cur_cache = kmem_cache_create("xfs_rtrefcountbt_cur",
+			xfs_btree_cur_sizeof(
+					xfs_rtrefcountbt_maxlevels_ondisk()),
+			0, 0, NULL);
+
+	if (!xfs_rtrefcountbt_cur_cache)
+		return -ENOMEM;
+	return 0;
+}
+
+void
+xfs_rtrefcountbt_destroy_cur_cache(void)
+{
+	kmem_cache_destroy(xfs_rtrefcountbt_cur_cache);
+	xfs_rtrefcountbt_cur_cache = NULL;
+}
+
+/* Compute the maximum height of a realtime refcount btree. */
+void
+xfs_rtrefcountbt_compute_maxlevels(
+	struct xfs_mount	*mp)
+{
+	unsigned int		d_maxlevels, r_maxlevels;
+
+	if (!xfs_has_rtreflink(mp)) {
+		mp->m_rtrefc_maxlevels = 0;
+		return;
+	}
+
+	/*
+	 * The realtime refcountbt lives on the data device, which means that
+	 * its maximum height is constrained by the size of the data device and
+	 * the height required to store one refcount record for each rtextent
+	 * in an rt group.
+	 */
+	d_maxlevels = xfs_btree_space_to_height(mp->m_rtrefc_mnr,
+				mp->m_sb.sb_dblocks);
+	r_maxlevels = xfs_btree_compute_maxlevels(mp->m_rtrefc_mnr,
+				mp->m_sb.sb_rgextents);
+
+	/* Add one level to handle the inode root level. */
+	mp->m_rtrefc_maxlevels = min(d_maxlevels, r_maxlevels) + 1;
+}
+
+/* Calculate the rtrefcount btree size for some records. */
+unsigned long long
+xfs_rtrefcountbt_calc_size(
+	struct xfs_mount	*mp,
+	unsigned long long	len)
+{
+	return xfs_btree_calc_size(mp->m_rtrefc_mnr, len);
+}
+
+/*
+ * Calculate the maximum refcount btree size.
+ */
+static unsigned long long
+xfs_rtrefcountbt_max_size(
+	struct xfs_mount	*mp,
+	xfs_rtblock_t		rtblocks)
+{
+	/* Bail out if we're uninitialized, which can happen in mkfs. */
+	if (mp->m_rtrefc_mxr[0] == 0)
+		return 0;
+
+	return xfs_rtrefcountbt_calc_size(mp, rtblocks);
+}
+
+/*
+ * Figure out how many blocks to reserve and how many are used by this btree.
+ * We need enough space to hold one record for every rt extent in the rtgroup.
+ */
+xfs_filblks_t
+xfs_rtrefcountbt_calc_reserves(
+	struct xfs_mount	*mp)
+{
+	if (!xfs_has_rtreflink(mp))
+		return 0;
+
+	return xfs_rtrefcountbt_max_size(mp, mp->m_sb.sb_rgextents);
+}
+
+/*
+ * Convert on-disk form of btree root to in-memory form.
+ */
+STATIC void
+xfs_rtrefcountbt_from_disk(
+	struct xfs_inode		*ip,
+	struct xfs_rtrefcount_root	*dblock,
+	int				dblocklen,
+	struct xfs_btree_block		*rblock)
+{
+	struct xfs_mount		*mp = ip->i_mount;
+	struct xfs_refcount_key	*fkp;
+	__be64				*fpp;
+	struct xfs_refcount_key	*tkp;
+	__be64				*tpp;
+	struct xfs_refcount_rec	*frp;
+	struct xfs_refcount_rec	*trp;
+	unsigned int			numrecs;
+	unsigned int			maxrecs;
+	unsigned int			rblocklen;
+
+	rblocklen = xfs_rtrefcount_broot_space(mp, dblock);
+
+	xfs_btree_init_block(mp, rblock, &xfs_rtrefcountbt_ops, 0, 0,
+			ip->i_ino);
+
+	rblock->bb_level = dblock->bb_level;
+	rblock->bb_numrecs = dblock->bb_numrecs;
+
+	if (be16_to_cpu(rblock->bb_level) > 0) {
+		maxrecs = xfs_rtrefcountbt_droot_maxrecs(dblocklen, false);
+		fkp = xfs_rtrefcount_droot_key_addr(dblock, 1);
+		tkp = xfs_rtrefcount_key_addr(rblock, 1);
+		fpp = xfs_rtrefcount_droot_ptr_addr(dblock, 1, maxrecs);
+		tpp = xfs_rtrefcount_broot_ptr_addr(mp, rblock, 1, rblocklen);
+		numrecs = be16_to_cpu(dblock->bb_numrecs);
+		memcpy(tkp, fkp, 2 * sizeof(*fkp) * numrecs);
+		memcpy(tpp, fpp, sizeof(*fpp) * numrecs);
+	} else {
+		frp = xfs_rtrefcount_droot_rec_addr(dblock, 1);
+		trp = xfs_rtrefcount_rec_addr(rblock, 1);
+		numrecs = be16_to_cpu(dblock->bb_numrecs);
+		memcpy(trp, frp, sizeof(*frp) * numrecs);
+	}
+}
+
+/* Load a realtime reference count btree root in from disk. */
+int
+xfs_iformat_rtrefcount(
+	struct xfs_inode	*ip,
+	struct xfs_dinode	*dip)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_rtrefcount_root *dfp = XFS_DFORK_PTR(dip, XFS_DATA_FORK);
+	struct xfs_btree_block	*broot;
+	unsigned int		numrecs;
+	unsigned int		level;
+	int			dsize;
+
+	/*
+	 * growfs must create the rtrefcount inodes before adding a realtime
+	 * volume to the filesystem, so we cannot use the rtrefcount predicate
+	 * here.
+	 */
+	if (!xfs_has_reflink(ip->i_mount)) {
+		xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
+		return -EFSCORRUPTED;
+	}
+
+	dsize = XFS_DFORK_SIZE(dip, mp, XFS_DATA_FORK);
+	numrecs = be16_to_cpu(dfp->bb_numrecs);
+	level = be16_to_cpu(dfp->bb_level);
+
+	if (level > mp->m_rtrefc_maxlevels ||
+	    xfs_rtrefcount_droot_space_calc(level, numrecs) > dsize) {
+		xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
+		return -EFSCORRUPTED;
+	}
+
+	broot = xfs_broot_alloc(xfs_ifork_ptr(ip, XFS_DATA_FORK),
+			xfs_rtrefcount_broot_space_calc(mp, level, numrecs));
+	if (broot)
+		xfs_rtrefcountbt_from_disk(ip, dfp, dsize, broot);
+	return 0;
+}
+
+/*
+ * Convert in-memory form of btree root to on-disk form.
+ */
+void
+xfs_rtrefcountbt_to_disk(
+	struct xfs_mount		*mp,
+	struct xfs_btree_block		*rblock,
+	int				rblocklen,
+	struct xfs_rtrefcount_root	*dblock,
+	int				dblocklen)
+{
+	struct xfs_refcount_key	*fkp;
+	__be64				*fpp;
+	struct xfs_refcount_key	*tkp;
+	__be64				*tpp;
+	struct xfs_refcount_rec	*frp;
+	struct xfs_refcount_rec	*trp;
+	unsigned int			maxrecs;
+	unsigned int			numrecs;
+
+	ASSERT(rblock->bb_magic == cpu_to_be32(XFS_RTREFC_CRC_MAGIC));
+	ASSERT(uuid_equal(&rblock->bb_u.l.bb_uuid, &mp->m_sb.sb_meta_uuid));
+	ASSERT(rblock->bb_u.l.bb_blkno == cpu_to_be64(XFS_BUF_DADDR_NULL));
+	ASSERT(rblock->bb_u.l.bb_leftsib == cpu_to_be64(NULLFSBLOCK));
+	ASSERT(rblock->bb_u.l.bb_rightsib == cpu_to_be64(NULLFSBLOCK));
+
+	dblock->bb_level = rblock->bb_level;
+	dblock->bb_numrecs = rblock->bb_numrecs;
+
+	if (be16_to_cpu(rblock->bb_level) > 0) {
+		maxrecs = xfs_rtrefcountbt_droot_maxrecs(dblocklen, false);
+		fkp = xfs_rtrefcount_key_addr(rblock, 1);
+		tkp = xfs_rtrefcount_droot_key_addr(dblock, 1);
+		fpp = xfs_rtrefcount_broot_ptr_addr(mp, rblock, 1, rblocklen);
+		tpp = xfs_rtrefcount_droot_ptr_addr(dblock, 1, maxrecs);
+		numrecs = be16_to_cpu(rblock->bb_numrecs);
+		memcpy(tkp, fkp, 2 * sizeof(*fkp) * numrecs);
+		memcpy(tpp, fpp, sizeof(*fpp) * numrecs);
+	} else {
+		frp = xfs_rtrefcount_rec_addr(rblock, 1);
+		trp = xfs_rtrefcount_droot_rec_addr(dblock, 1);
+		numrecs = be16_to_cpu(rblock->bb_numrecs);
+		memcpy(trp, frp, sizeof(*frp) * numrecs);
+	}
+}
+
+/* Flush a realtime reference count btree root out to disk. */
+void
+xfs_iflush_rtrefcount(
+	struct xfs_inode	*ip,
+	struct xfs_dinode	*dip)
+{
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, XFS_DATA_FORK);
+	struct xfs_rtrefcount_root *dfp = XFS_DFORK_PTR(dip, XFS_DATA_FORK);
+
+	ASSERT(ifp->if_broot != NULL);
+	ASSERT(ifp->if_broot_bytes > 0);
+	ASSERT(xfs_rtrefcount_droot_space(ifp->if_broot) <=
+			xfs_inode_fork_size(ip, XFS_DATA_FORK));
+	xfs_rtrefcountbt_to_disk(ip->i_mount, ifp->if_broot,
+			ifp->if_broot_bytes, dfp,
+			XFS_DFORK_SIZE(dip, ip->i_mount, XFS_DATA_FORK));
+}
+
+/*
+ * Create a realtime refcount btree inode.
+ */
+int
+xfs_rtrefcountbt_create(
+	struct xfs_rtgroup	*rtg,
+	struct xfs_inode	*ip,
+	struct xfs_trans	*tp,
+	bool			init)
+{
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, XFS_DATA_FORK);
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_btree_block	*broot;
+
+	ifp->if_format = XFS_DINODE_FMT_META_BTREE;
+	ASSERT(ifp->if_broot_bytes == 0);
+	ASSERT(ifp->if_bytes == 0);
+
+	/* Initialize the empty incore btree root. */
+	broot = xfs_broot_realloc(ifp,
+			xfs_rtrefcount_broot_space_calc(mp, 0, 0));
+	if (broot)
+		xfs_btree_init_block(mp, broot, &xfs_rtrefcountbt_ops, 0, 0,
+				ip->i_ino);
+	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE | XFS_ILOG_DBROOT);
+	return 0;
+}