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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
commit2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch)
tree848558de17fb3008cdf4d861b01ac7781903ce39 /fs/xfs/libxfs/xfs_rmap_btree.c
parentInitial commit. (diff)
downloadlinux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz
linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'fs/xfs/libxfs/xfs_rmap_btree.c')
-rw-r--r--fs/xfs/libxfs/xfs_rmap_btree.c696
1 files changed, 696 insertions, 0 deletions
diff --git a/fs/xfs/libxfs/xfs_rmap_btree.c b/fs/xfs/libxfs/xfs_rmap_btree.c
new file mode 100644
index 000000000..7f83f62e5
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_rmap_btree.c
@@ -0,0 +1,696 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2014 Red Hat, Inc.
+ * All Rights Reserved.
+ */
+#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_mount.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_trace.h"
+#include "xfs_error.h"
+#include "xfs_extent_busy.h"
+#include "xfs_ag.h"
+#include "xfs_ag_resv.h"
+
+static struct kmem_cache *xfs_rmapbt_cur_cache;
+
+/*
+ * Reverse map btree.
+ *
+ * This is a per-ag tree used to track the owner(s) of a given extent. With
+ * reflink it is possible for there to be multiple owners, which is a departure
+ * from classic XFS. Owner records for data extents are inserted when the
+ * extent is mapped and removed when an extent is unmapped. Owner records for
+ * all other block types (i.e. metadata) are inserted when an extent is
+ * allocated and removed when an extent is freed. There can only be one owner
+ * of a metadata extent, usually an inode or some other metadata structure like
+ * an AG btree.
+ *
+ * The rmap btree is part of the free space management, so blocks for the tree
+ * are sourced from the agfl. Hence we need transaction reservation support for
+ * this tree so that the freelist is always large enough. This also impacts on
+ * the minimum space we need to leave free in the AG.
+ *
+ * The tree is ordered by [ag block, owner, offset]. This is a large key size,
+ * but it is the only way to enforce unique keys when a block can be owned by
+ * multiple files at any offset. There's no need to order/search by extent
+ * size for online updating/management of the tree. It is intended that most
+ * reverse lookups will be to find the owner(s) of a particular block, or to
+ * try to recover tree and file data from corrupt primary metadata.
+ */
+
+static struct xfs_btree_cur *
+xfs_rmapbt_dup_cursor(
+ struct xfs_btree_cur *cur)
+{
+ return xfs_rmapbt_init_cursor(cur->bc_mp, cur->bc_tp,
+ cur->bc_ag.agbp, cur->bc_ag.pag);
+}
+
+STATIC void
+xfs_rmapbt_set_root(
+ struct xfs_btree_cur *cur,
+ const union xfs_btree_ptr *ptr,
+ int inc)
+{
+ struct xfs_buf *agbp = cur->bc_ag.agbp;
+ struct xfs_agf *agf = agbp->b_addr;
+ int btnum = cur->bc_btnum;
+
+ ASSERT(ptr->s != 0);
+
+ agf->agf_roots[btnum] = ptr->s;
+ be32_add_cpu(&agf->agf_levels[btnum], inc);
+ cur->bc_ag.pag->pagf_levels[btnum] += 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,
+ const union xfs_btree_ptr *start,
+ union xfs_btree_ptr *new,
+ int *stat)
+{
+ struct xfs_buf *agbp = cur->bc_ag.agbp;
+ struct xfs_agf *agf = agbp->b_addr;
+ struct xfs_perag *pag = cur->bc_ag.pag;
+ int error;
+ xfs_agblock_t bno;
+
+ /* Allocate the new block from the freelist. If we can't, give up. */
+ 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, pag->pag_agno, bno, 1);
+ if (bno == NULLAGBLOCK) {
+ *stat = 0;
+ return 0;
+ }
+
+ xfs_extent_busy_reuse(cur->bc_mp, pag, bno, 1, false);
+
+ 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, pag->pag_agno);
+
+ *stat = 1;
+ return 0;
+}
+
+STATIC int
+xfs_rmapbt_free_block(
+ struct xfs_btree_cur *cur,
+ struct xfs_buf *bp)
+{
+ struct xfs_buf *agbp = cur->bc_ag.agbp;
+ struct xfs_agf *agf = agbp->b_addr;
+ struct xfs_perag *pag = cur->bc_ag.pag;
+ xfs_agblock_t bno;
+ int error;
+
+ bno = xfs_daddr_to_agbno(cur->bc_mp, xfs_buf_daddr(bp));
+ trace_xfs_rmapbt_free_block(cur->bc_mp, pag->pag_agno,
+ bno, 1);
+ 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(pag, cur->bc_tp, agbp, NULL, bno, 1);
+ if (error)
+ return error;
+
+ xfs_extent_busy_insert(cur->bc_tp, pag, bno, 1,
+ XFS_EXTENT_BUSY_SKIP_DISCARD);
+
+ xfs_ag_resv_free_extent(pag, XFS_AG_RESV_RMAPBT, NULL, 1);
+ return 0;
+}
+
+STATIC int
+xfs_rmapbt_get_minrecs(
+ struct xfs_btree_cur *cur,
+ int level)
+{
+ return cur->bc_mp->m_rmap_mnr[level != 0];
+}
+
+STATIC int
+xfs_rmapbt_get_maxrecs(
+ struct xfs_btree_cur *cur,
+ int level)
+{
+ return cur->bc_mp->m_rmap_mxr[level != 0];
+}
+
+STATIC void
+xfs_rmapbt_init_key_from_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;
+}
+
+/*
+ * The high key for a reverse mapping record can be computed by shifting
+ * the startblock and offset to the highest value that would still map
+ * to that record. In practice this means that we add blockcount-1 to
+ * the startblock for all records, and if the record is for a data/attr
+ * fork mapping, we add blockcount-1 to the offset too.
+ */
+STATIC void
+xfs_rmapbt_init_high_key_from_rec(
+ union xfs_btree_key *key,
+ const union xfs_btree_rec *rec)
+{
+ 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;
+ 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;
+ off = be64_to_cpu(key->rmap.rm_offset);
+ off = (XFS_RMAP_OFF(off) + adj) | (off & ~XFS_RMAP_OFF_MASK);
+ key->rmap.rm_offset = cpu_to_be64(off);
+}
+
+STATIC void
+xfs_rmapbt_init_rec_from_cur(
+ struct xfs_btree_cur *cur,
+ union xfs_btree_rec *rec)
+{
+ rec->rmap.rm_startblock = cpu_to_be32(cur->bc_rec.r.rm_startblock);
+ rec->rmap.rm_blockcount = cpu_to_be32(cur->bc_rec.r.rm_blockcount);
+ rec->rmap.rm_owner = cpu_to_be64(cur->bc_rec.r.rm_owner);
+ rec->rmap.rm_offset = cpu_to_be64(
+ xfs_rmap_irec_offset_pack(&cur->bc_rec.r));
+}
+
+STATIC void
+xfs_rmapbt_init_ptr_from_cur(
+ struct xfs_btree_cur *cur,
+ union xfs_btree_ptr *ptr)
+{
+ struct xfs_agf *agf = cur->bc_ag.agbp->b_addr;
+
+ ASSERT(cur->bc_ag.pag->pag_agno == be32_to_cpu(agf->agf_seqno));
+
+ ptr->s = agf->agf_roots[cur->bc_btnum];
+}
+
+STATIC int64_t
+xfs_rmapbt_key_diff(
+ 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;
+ __u64 x, y;
+ int64_t d;
+
+ d = (int64_t)be32_to_cpu(kp->rm_startblock) - rec->rm_startblock;
+ if (d)
+ return d;
+
+ x = be64_to_cpu(kp->rm_owner);
+ y = rec->rm_owner;
+ if (x > y)
+ return 1;
+ else if (y > x)
+ return -1;
+
+ 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;
+}
+
+STATIC int64_t
+xfs_rmapbt_diff_two_keys(
+ struct xfs_btree_cur *cur,
+ const union xfs_btree_key *k1,
+ const union xfs_btree_key *k2)
+{
+ const struct xfs_rmap_key *kp1 = &k1->rmap;
+ const struct xfs_rmap_key *kp2 = &k2->rmap;
+ int64_t d;
+ __u64 x, y;
+
+ d = (int64_t)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;
+
+ 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;
+}
+
+static xfs_failaddr_t
+xfs_rmapbt_verify(
+ struct xfs_buf *bp)
+{
+ 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;
+ unsigned int level;
+
+ /*
+ * magic number and level verification
+ *
+ * During growfs operations, we can't verify the exact level or owner as
+ * the perag is not fully initialised and hence not attached to the
+ * buffer. In this case, check against the maximum tree depth.
+ *
+ * Similarly, during log recovery we will have a perag structure
+ * attached, but the agf information will not yet have been initialised
+ * from the on disk AGF. Again, we can only check against maximum limits
+ * in this case.
+ */
+ if (!xfs_verify_magic(bp, block->bb_magic))
+ return __this_address;
+
+ if (!xfs_has_rmapbt(mp))
+ return __this_address;
+ fa = xfs_btree_sblock_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])
+ 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]);
+}
+
+static void
+xfs_rmapbt_read_verify(
+ struct xfs_buf *bp)
+{
+ xfs_failaddr_t fa;
+
+ if (!xfs_btree_sblock_verify_crc(bp))
+ xfs_verifier_error(bp, -EFSBADCRC, __this_address);
+ else {
+ fa = xfs_rmapbt_verify(bp);
+ if (fa)
+ xfs_verifier_error(bp, -EFSCORRUPTED, fa);
+ }
+
+ if (bp->b_error)
+ trace_xfs_btree_corrupt(bp, _RET_IP_);
+}
+
+static void
+xfs_rmapbt_write_verify(
+ struct xfs_buf *bp)
+{
+ xfs_failaddr_t fa;
+
+ fa = xfs_rmapbt_verify(bp);
+ if (fa) {
+ trace_xfs_btree_corrupt(bp, _RET_IP_);
+ xfs_verifier_error(bp, -EFSCORRUPTED, fa);
+ return;
+ }
+ xfs_btree_sblock_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,
+};
+
+STATIC int
+xfs_rmapbt_keys_inorder(
+ struct xfs_btree_cur *cur,
+ const union xfs_btree_key *k1,
+ const union xfs_btree_key *k2)
+{
+ uint32_t x;
+ uint32_t y;
+ uint64_t a;
+ uint64_t b;
+
+ x = be32_to_cpu(k1->rmap.rm_startblock);
+ y = be32_to_cpu(k2->rmap.rm_startblock);
+ if (x < y)
+ return 1;
+ else if (x > y)
+ return 0;
+ a = be64_to_cpu(k1->rmap.rm_owner);
+ b = be64_to_cpu(k2->rmap.rm_owner);
+ if (a < b)
+ 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));
+ if (a <= b)
+ return 1;
+ return 0;
+}
+
+STATIC int
+xfs_rmapbt_recs_inorder(
+ struct xfs_btree_cur *cur,
+ const union xfs_btree_rec *r1,
+ const union xfs_btree_rec *r2)
+{
+ uint32_t x;
+ uint32_t y;
+ uint64_t a;
+ uint64_t b;
+
+ x = be32_to_cpu(r1->rmap.rm_startblock);
+ y = be32_to_cpu(r2->rmap.rm_startblock);
+ if (x < y)
+ return 1;
+ else if (x > y)
+ return 0;
+ a = be64_to_cpu(r1->rmap.rm_owner);
+ b = be64_to_cpu(r2->rmap.rm_owner);
+ if (a < b)
+ 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));
+ if (a <= b)
+ return 1;
+ return 0;
+}
+
+static const struct xfs_btree_ops xfs_rmapbt_ops = {
+ .rec_len = sizeof(struct xfs_rmap_rec),
+ .key_len = 2 * sizeof(struct xfs_rmap_key),
+
+ .dup_cursor = xfs_rmapbt_dup_cursor,
+ .set_root = xfs_rmapbt_set_root,
+ .alloc_block = xfs_rmapbt_alloc_block,
+ .free_block = xfs_rmapbt_free_block,
+ .get_minrecs = xfs_rmapbt_get_minrecs,
+ .get_maxrecs = xfs_rmapbt_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 = xfs_rmapbt_init_ptr_from_cur,
+ .key_diff = xfs_rmapbt_key_diff,
+ .buf_ops = &xfs_rmapbt_buf_ops,
+ .diff_two_keys = xfs_rmapbt_diff_two_keys,
+ .keys_inorder = xfs_rmapbt_keys_inorder,
+ .recs_inorder = xfs_rmapbt_recs_inorder,
+};
+
+static struct xfs_btree_cur *
+xfs_rmapbt_init_common(
+ struct xfs_mount *mp,
+ struct xfs_trans *tp,
+ struct xfs_perag *pag)
+{
+ struct xfs_btree_cur *cur;
+
+ /* Overlapping btree; 2 keys per pointer. */
+ cur = xfs_btree_alloc_cursor(mp, tp, XFS_BTNUM_RMAP,
+ mp->m_rmap_maxlevels, xfs_rmapbt_cur_cache);
+ cur->bc_flags = XFS_BTREE_CRC_BLOCKS | XFS_BTREE_OVERLAPPING;
+ cur->bc_statoff = XFS_STATS_CALC_INDEX(xs_rmap_2);
+ cur->bc_ops = &xfs_rmapbt_ops;
+
+ /* take a reference for the cursor */
+ atomic_inc(&pag->pag_ref);
+ cur->bc_ag.pag = pag;
+
+ return cur;
+}
+
+/* Create a new reverse mapping btree cursor. */
+struct xfs_btree_cur *
+xfs_rmapbt_init_cursor(
+ struct xfs_mount *mp,
+ struct xfs_trans *tp,
+ struct xfs_buf *agbp,
+ struct xfs_perag *pag)
+{
+ struct xfs_agf *agf = agbp->b_addr;
+ struct xfs_btree_cur *cur;
+
+ cur = xfs_rmapbt_init_common(mp, tp, pag);
+ cur->bc_nlevels = be32_to_cpu(agf->agf_levels[XFS_BTNUM_RMAP]);
+ cur->bc_ag.agbp = agbp;
+ return cur;
+}
+
+/* Create a new reverse mapping btree cursor with a fake root for staging. */
+struct xfs_btree_cur *
+xfs_rmapbt_stage_cursor(
+ struct xfs_mount *mp,
+ struct xbtree_afakeroot *afake,
+ struct xfs_perag *pag)
+{
+ struct xfs_btree_cur *cur;
+
+ cur = xfs_rmapbt_init_common(mp, NULL, pag);
+ xfs_btree_stage_afakeroot(cur, afake);
+ return cur;
+}
+
+/*
+ * Install a new reverse mapping btree root. Caller is responsible for
+ * invalidating and freeing the old btree blocks.
+ */
+void
+xfs_rmapbt_commit_staged_btree(
+ struct xfs_btree_cur *cur,
+ struct xfs_trans *tp,
+ struct xfs_buf *agbp)
+{
+ struct xfs_agf *agf = agbp->b_addr;
+ struct xbtree_afakeroot *afake = cur->bc_ag.afake;
+
+ ASSERT(cur->bc_flags & XFS_BTREE_STAGING);
+
+ agf->agf_roots[cur->bc_btnum] = cpu_to_be32(afake->af_root);
+ agf->agf_levels[cur->bc_btnum] = 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, &xfs_rmapbt_ops);
+}
+
+/* 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.
+ */
+int
+xfs_rmapbt_maxrecs(
+ int blocklen,
+ int 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 xfs_btree_space_to_height(minrecs, XFS_MAX_CRC_AG_BLOCKS);
+}
+
+/* Compute the maximum height of an rmap btree. */
+void
+xfs_rmapbt_compute_maxlevels(
+ struct xfs_mount *mp)
+{
+ 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. */
+xfs_extlen_t
+xfs_rmapbt_calc_size(
+ struct xfs_mount *mp,
+ unsigned long long len)
+{
+ return xfs_btree_calc_size(mp->m_rmap_mnr, len);
+}
+
+/*
+ * Calculate the maximum refcount btree size.
+ */
+xfs_extlen_t
+xfs_rmapbt_max_size(
+ struct xfs_mount *mp,
+ xfs_agblock_t agblocks)
+{
+ /* Bail out if we're uninitialized, which can happen in mkfs. */
+ if (mp->m_rmap_mxr[0] == 0)
+ return 0;
+
+ return xfs_rmapbt_calc_size(mp, agblocks);
+}
+
+/*
+ * Figure out how many blocks to reserve and how many are used by this btree.
+ */
+int
+xfs_rmapbt_calc_reserves(
+ struct xfs_mount *mp,
+ struct xfs_trans *tp,
+ struct xfs_perag *pag,
+ xfs_extlen_t *ask,
+ xfs_extlen_t *used)
+{
+ struct xfs_buf *agbp;
+ struct xfs_agf *agf;
+ xfs_agblock_t agblocks;
+ xfs_extlen_t tree_len;
+ int error;
+
+ if (!xfs_has_rmapbt(mp))
+ return 0;
+
+ error = xfs_alloc_read_agf(pag, tp, 0, &agbp);
+ if (error)
+ return error;
+
+ 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->pag_agno))
+ 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;
+}