xfs: introduce refcount btree definitions

[thirdparty/xfsprogs-dev.git] / libxfs / xfs_rmap_btree.c

/*
 * Copyright (c) 2014 Red Hat, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "libxfs_priv.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_rmap.h"
#include "xfs_rmap_btree.h"
#include "xfs_trace.h"
#include "xfs_cksum.h"

/*
 * 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_private.a.agbp, cur->bc_private.a.agno);
}

STATIC void
xfs_rmapbt_set_root(
        struct xfs_btree_cur    *cur,
        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);

        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);

        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_buf          *agbp = cur->bc_private.a.agbp;
        struct xfs_agf          *agf = XFS_BUF_TO_AGF(agbp);
        int                     error;
        xfs_agblock_t           bno;

        XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);

        /* 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,
                                       &bno, 1);
        if (error) {
                XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
                return error;
        }

        trace_xfs_rmapbt_alloc_block(cur->bc_mp, cur->bc_private.a.agno,
                        bno, 1);
        if (bno == NULLAGBLOCK) {
                XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
                *stat = 0;
                return 0;
        }

        xfs_extent_busy_reuse(cur->bc_mp, cur->bc_private.a.agno, 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_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
        *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_private.a.agbp;
        struct xfs_agf          *agf = XFS_BUF_TO_AGF(agbp);
        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);
        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);
        if (error)
                return error;

        xfs_extent_busy_insert(cur->bc_tp, be32_to_cpu(agf->agf_seqno), bno, 1,
                              XFS_EXTENT_BUSY_SKIP_DISCARD);
        xfs_trans_agbtree_delta(cur->bc_tp, -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,
        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,
        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 = XFS_BUF_TO_AGF(cur->bc_private.a.agbp);

        ASSERT(cur->bc_private.a.agno == be32_to_cpu(agf->agf_seqno));
        ASSERT(agf->agf_roots[cur->bc_btnum] != 0);

        ptr->s = agf->agf_roots[cur->bc_btnum];
}

STATIC __int64_t
xfs_rmapbt_key_diff(
        struct xfs_btree_cur    *cur,
        union xfs_btree_key     *key)
{
        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;

        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,
        union xfs_btree_key     *k1,
        union xfs_btree_key     *k2)
{
        struct xfs_rmap_key     *kp1 = &k1->rmap;
        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 bool
xfs_rmapbt_verify(
        struct xfs_buf          *bp)
{
        struct xfs_mount        *mp = bp->b_target->bt_mount;
        struct xfs_btree_block  *block = XFS_BUF_TO_BLOCK(bp);
        struct xfs_perag        *pag = bp->b_pag;
        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 (block->bb_magic != cpu_to_be32(XFS_RMAP_CRC_MAGIC))
                return false;

        if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
                return false;
        if (!xfs_btree_sblock_v5hdr_verify(bp))
                return false;

        level = be16_to_cpu(block->bb_level);
        if (pag && pag->pagf_init) {
                if (level >= pag->pagf_levels[XFS_BTNUM_RMAPi])
                        return false;
        } else if (level >= mp->m_rmap_maxlevels)
                return false;

        return xfs_btree_sblock_verify(bp, mp->m_rmap_mxr[level != 0]);
}

static void
xfs_rmapbt_read_verify(
        struct xfs_buf  *bp)
{
        if (!xfs_btree_sblock_verify_crc(bp))
                xfs_buf_ioerror(bp, -EFSBADCRC);
        else if (!xfs_rmapbt_verify(bp))
                xfs_buf_ioerror(bp, -EFSCORRUPTED);

        if (bp->b_error) {
                trace_xfs_btree_corrupt(bp, _RET_IP_);
                xfs_verifier_error(bp);
        }
}

static void
xfs_rmapbt_write_verify(
        struct xfs_buf  *bp)
{
        if (!xfs_rmapbt_verify(bp)) {
                trace_xfs_btree_corrupt(bp, _RET_IP_);
                xfs_buf_ioerror(bp, -EFSCORRUPTED);
                xfs_verifier_error(bp);
                return;
        }
        xfs_btree_sblock_calc_crc(bp);

}

const struct xfs_buf_ops xfs_rmapbt_buf_ops = {
        .name                   = "xfs_rmapbt",
        .verify_read            = xfs_rmapbt_read_verify,
        .verify_write           = xfs_rmapbt_write_verify,
};

#if defined(DEBUG) || defined(XFS_WARN)
STATIC int
xfs_rmapbt_keys_inorder(
        struct xfs_btree_cur    *cur,
        union xfs_btree_key     *k1,
        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,
        union xfs_btree_rec     *r1,
        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;
}
#endif  /* DEBUG */

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,
#if defined(DEBUG) || defined(XFS_WARN)
        .keys_inorder           = xfs_rmapbt_keys_inorder,
        .recs_inorder           = xfs_rmapbt_recs_inorder,
#endif
};

/*
 * Allocate a new allocation btree cursor.
 */
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_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;
        /* 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_private.a.agbp = agbp;
        cur->bc_private.a.agno = agno;

        return cur;
}

/*
 * Calculate number of records in an rmap btree block.
 */
int
xfs_rmapbt_maxrecs(
        struct xfs_mount        *mp,
        int                     blocklen,
        int                     leaf)
{
        blocklen -= XFS_RMAP_BLOCK_LEN;

        if (leaf)
                return blocklen / sizeof(struct xfs_rmap_rec);
        return blocklen /
                (2 * sizeof(struct xfs_rmap_key) + sizeof(xfs_rmap_ptr_t));
}

/* 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
                mp->m_rmap_maxlevels = xfs_btree_compute_maxlevels(mp,
                                mp->m_rmap_mnr, mp->m_sb.sb_agblocks);
}