xfs: define the on-disk realtime refcount btree format

Start filling out the rtrefcount btree implementation. Start with the
on-disk btree format; add everything needed to read, write and
manipulate refcount btree blocks. This prepares the way for connecting
the btree operations implementation.

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

1 files changed, 251 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..6b28ea655195
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_rtrefcount_btree.c
@@ -0,0 +1,251 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2021 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_trace.h"
+#include "xfs_cksum.h"
+#include "xfs_error.h"
+#include "xfs_extent_busy.h"
+
+/*
+ * 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
+ * the startblock and blockcount fields have been widened to 64 bits.
+ */
+
+static struct xfs_btree_cur *
+xfs_rtrefcountbt_dup_cursor(
+	struct xfs_btree_cur	*cur)
+{
+	struct xfs_btree_cur	*new;
+
+	new = xfs_rtrefcountbt_init_cursor(cur->bc_mp, cur->bc_tp,
+			cur->bc_ino.ip);
+
+	/* Copy the flags values since init cursor doesn't get them. */
+	new->bc_ino.flags = cur->bc_ino.flags;
+
+	return new;
+}
+
+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 (block->bb_magic != cpu_to_be32(XFS_RTREFC_CRC_MAGIC))
+		return __this_address;
+
+	if (!xfs_has_reflink(mp))
+		return __this_address;
+	fa = xfs_btree_lblock_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_lblock_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_lblock_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_lblock_calc_crc(bp);
+
+}
+
+const struct xfs_buf_ops xfs_rtrefcountbt_buf_ops = {
+	.name			= "xfs_rtrefcountbt",
+	.verify_read		= xfs_rtrefcountbt_read_verify,
+	.verify_write		= xfs_rtrefcountbt_write_verify,
+	.verify_struct		= xfs_rtrefcountbt_verify,
+};
+
+static const struct xfs_btree_ops xfs_rtrefcountbt_ops = {
+	.rec_len		= sizeof(struct xfs_rtrefcount_rec),
+	.key_len		= sizeof(struct xfs_rtrefcount_key),
+
+	.dup_cursor		= xfs_rtrefcountbt_dup_cursor,
+	.buf_ops		= &xfs_rtrefcountbt_buf_ops,
+};
+
+/* Initialize a new rt refcount btree cursor. */
+static struct xfs_btree_cur *
+xfs_rtrefcountbt_init_common(
+	struct xfs_mount	*mp,
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip)
+{
+	struct xfs_btree_cur	*cur;
+
+	cur = xfs_btree_alloc_cursor(mp, tp, XFS_BTNUM_RTREFC);
+	cur->bc_flags = XFS_BTREE_LONG_PTRS | XFS_BTREE_ROOT_IN_INODE |
+			XFS_BTREE_CRC_BLOCKS | XFS_BTREE_IROOT_RECORDS;
+	cur->bc_statoff = XFS_STATS_CALC_INDEX(xs_refcbt_2);
+
+	cur->bc_ino.ip = ip;
+	cur->bc_ino.allocated = 0;
+	cur->bc_ino.flags = 0;
+	cur->bc_ino.refc.nr_ops = 0;
+	cur->bc_ino.refc.shape_changes = 0;
+	cur->bc_ops = &xfs_rtrefcountbt_ops;
+
+	return cur;
+}
+
+/* Allocate a new rt refcount btree cursor. */
+struct xfs_btree_cur *
+xfs_rtrefcountbt_init_cursor(
+	struct xfs_mount	*mp,
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip)
+{
+	struct xfs_btree_cur	*cur;
+	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
+
+	cur = xfs_rtrefcountbt_init_common(mp, tp, ip);
+	cur->bc_nlevels = be16_to_cpu(ifp->if_broot->bb_level) + 1;
+	cur->bc_ino.forksize = XFS_IFORK_SIZE(ip, XFS_DATA_FORK);
+	cur->bc_ino.whichfork = XFS_DATA_FORK;
+	return cur;
+}
+
+/* Create a new rt reverse mapping btree cursor with a fake root for staging. */
+struct xfs_btree_cur *
+xfs_rtrefcountbt_stage_cursor(
+	struct xfs_mount	*mp,
+	struct xfs_inode	*ip,
+	struct xbtree_ifakeroot	*ifake)
+{
+	struct xfs_btree_cur	*cur;
+
+	cur = xfs_rtrefcountbt_init_common(mp, NULL, ip);
+	cur->bc_nlevels = ifake->if_levels;
+	cur->bc_ino.forksize = ifake->if_fork_size;
+	cur->bc_ino.whichfork = -1;
+	xfs_btree_stage_ifakeroot(cur, ifake, NULL);
+	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);
+
+	/*
+	 * 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));
+
+	xfs_trans_log_inode(tp, cur->bc_ino.ip, flags);
+	xfs_btree_commit_ifakeroot(cur, tp, XFS_DATA_FORK,
+			&xfs_rtrefcountbt_ops);
+}
+
+/*
+ * 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;
+
+	if (leaf)
+		return blocklen / sizeof(struct xfs_rtrefcount_rec);
+	return blocklen / (sizeof(struct xfs_rtrefcount_key) +
+			   sizeof(xfs_rtrefcount_ptr_t));
+}
+
+/* Compute the maximum height of an refcount btree. */
+unsigned int
+xfs_rtrefcountbt_compute_maxlevels(
+	struct xfs_mount	*mp,
+	xfs_rfsblock_t		dblocks,
+	xfs_rfsblock_t		rblocks)
+{
+	xfs_rtblock_t		rexts;
+	unsigned int		d_maxlevels, r_maxlevels;
+
+	/*
+	 * 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 rt extent.
+	 */
+	rexts = div_u64(rblocks, mp->m_sb.sb_rextsize);
+	d_maxlevels = xfs_btree_compute_maxlevels_size(dblocks,
+			mp->m_rtrefc_mnr[1]);
+	r_maxlevels = xfs_btree_compute_maxlevels(mp->m_rtrefc_mnr, rexts);
+
+	/* Add one level to handle the inode root level. */
+	return min(d_maxlevels, r_maxlevels) + 1;
+}