spi-topcliff-pch: Fix issue for transmitting over 4KByte

[zen-stable.git] / fs / xfs / xfs_bmap_btree.c

/*
 * Copyright (c) 2000-2003,2005 Silicon Graphics, 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 "xfs.h"
#include "xfs_fs.h"
#include "xfs_types.h"
#include "xfs_bit.h"
#include "xfs_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_inode_item.h"
#include "xfs_alloc.h"
#include "xfs_btree.h"
#include "xfs_itable.h"
#include "xfs_bmap.h"
#include "xfs_error.h"
#include "xfs_quota.h"

/*
 * Determine the extent state.
 */
/* ARGSUSED */
STATIC xfs_exntst_t
xfs_extent_state(
        xfs_filblks_t           blks,
        int                     extent_flag)
{
        if (extent_flag) {
                ASSERT(blks != 0);      /* saved for DMIG */
                return XFS_EXT_UNWRITTEN;
        }
        return XFS_EXT_NORM;
}

/*
 * Convert on-disk form of btree root to in-memory form.
 */
void
xfs_bmdr_to_bmbt(
        struct xfs_mount        *mp,
        xfs_bmdr_block_t        *dblock,
        int                     dblocklen,
        struct xfs_btree_block  *rblock,
        int                     rblocklen)
{
        int                     dmxr;
        xfs_bmbt_key_t          *fkp;
        __be64                  *fpp;
        xfs_bmbt_key_t          *tkp;
        __be64                  *tpp;

        rblock->bb_magic = cpu_to_be32(XFS_BMAP_MAGIC);
        rblock->bb_level = dblock->bb_level;
        ASSERT(be16_to_cpu(rblock->bb_level) > 0);
        rblock->bb_numrecs = dblock->bb_numrecs;
        rblock->bb_u.l.bb_leftsib = cpu_to_be64(NULLDFSBNO);
        rblock->bb_u.l.bb_rightsib = cpu_to_be64(NULLDFSBNO);
        dmxr = xfs_bmdr_maxrecs(mp, dblocklen, 0);
        fkp = XFS_BMDR_KEY_ADDR(dblock, 1);
        tkp = XFS_BMBT_KEY_ADDR(mp, rblock, 1);
        fpp = XFS_BMDR_PTR_ADDR(dblock, 1, dmxr);
        tpp = XFS_BMAP_BROOT_PTR_ADDR(mp, rblock, 1, rblocklen);
        dmxr = be16_to_cpu(dblock->bb_numrecs);
        memcpy(tkp, fkp, sizeof(*fkp) * dmxr);
        memcpy(tpp, fpp, sizeof(*fpp) * dmxr);
}

/*
 * Convert a compressed bmap extent record to an uncompressed form.
 * This code must be in sync with the routines xfs_bmbt_get_startoff,
 * xfs_bmbt_get_startblock, xfs_bmbt_get_blockcount and xfs_bmbt_get_state.
 */
STATIC void
__xfs_bmbt_get_all(
                __uint64_t l0,
                __uint64_t l1,
                xfs_bmbt_irec_t *s)
{
        int     ext_flag;
        xfs_exntst_t st;

        ext_flag = (int)(l0 >> (64 - BMBT_EXNTFLAG_BITLEN));
        s->br_startoff = ((xfs_fileoff_t)l0 &
                           xfs_mask64lo(64 - BMBT_EXNTFLAG_BITLEN)) >> 9;
#if XFS_BIG_BLKNOS
        s->br_startblock = (((xfs_fsblock_t)l0 & xfs_mask64lo(9)) << 43) |
                           (((xfs_fsblock_t)l1) >> 21);
#else
#ifdef DEBUG
        {
                xfs_dfsbno_t    b;

                b = (((xfs_dfsbno_t)l0 & xfs_mask64lo(9)) << 43) |
                    (((xfs_dfsbno_t)l1) >> 21);
                ASSERT((b >> 32) == 0 || isnulldstartblock(b));
                s->br_startblock = (xfs_fsblock_t)b;
        }
#else   /* !DEBUG */
        s->br_startblock = (xfs_fsblock_t)(((xfs_dfsbno_t)l1) >> 21);
#endif  /* DEBUG */
#endif  /* XFS_BIG_BLKNOS */
        s->br_blockcount = (xfs_filblks_t)(l1 & xfs_mask64lo(21));
        /* This is xfs_extent_state() in-line */
        if (ext_flag) {
                ASSERT(s->br_blockcount != 0);  /* saved for DMIG */
                st = XFS_EXT_UNWRITTEN;
        } else
                st = XFS_EXT_NORM;
        s->br_state = st;
}

void
xfs_bmbt_get_all(
        xfs_bmbt_rec_host_t *r,
        xfs_bmbt_irec_t *s)
{
        __xfs_bmbt_get_all(r->l0, r->l1, s);
}

/*
 * Extract the blockcount field from an in memory bmap extent record.
 */
xfs_filblks_t
xfs_bmbt_get_blockcount(
        xfs_bmbt_rec_host_t     *r)
{
        return (xfs_filblks_t)(r->l1 & xfs_mask64lo(21));
}

/*
 * Extract the startblock field from an in memory bmap extent record.
 */
xfs_fsblock_t
xfs_bmbt_get_startblock(
        xfs_bmbt_rec_host_t     *r)
{
#if XFS_BIG_BLKNOS
        return (((xfs_fsblock_t)r->l0 & xfs_mask64lo(9)) << 43) |
               (((xfs_fsblock_t)r->l1) >> 21);
#else
#ifdef DEBUG
        xfs_dfsbno_t    b;

        b = (((xfs_dfsbno_t)r->l0 & xfs_mask64lo(9)) << 43) |
            (((xfs_dfsbno_t)r->l1) >> 21);
        ASSERT((b >> 32) == 0 || isnulldstartblock(b));
        return (xfs_fsblock_t)b;
#else   /* !DEBUG */
        return (xfs_fsblock_t)(((xfs_dfsbno_t)r->l1) >> 21);
#endif  /* DEBUG */
#endif  /* XFS_BIG_BLKNOS */
}

/*
 * Extract the startoff field from an in memory bmap extent record.
 */
xfs_fileoff_t
xfs_bmbt_get_startoff(
        xfs_bmbt_rec_host_t     *r)
{
        return ((xfs_fileoff_t)r->l0 &
                 xfs_mask64lo(64 - BMBT_EXNTFLAG_BITLEN)) >> 9;
}

xfs_exntst_t
xfs_bmbt_get_state(
        xfs_bmbt_rec_host_t     *r)
{
        int     ext_flag;

        ext_flag = (int)((r->l0) >> (64 - BMBT_EXNTFLAG_BITLEN));
        return xfs_extent_state(xfs_bmbt_get_blockcount(r),
                                ext_flag);
}

/*
 * Extract the blockcount field from an on disk bmap extent record.
 */
xfs_filblks_t
xfs_bmbt_disk_get_blockcount(
        xfs_bmbt_rec_t  *r)
{
        return (xfs_filblks_t)(be64_to_cpu(r->l1) & xfs_mask64lo(21));
}

/*
 * Extract the startoff field from a disk format bmap extent record.
 */
xfs_fileoff_t
xfs_bmbt_disk_get_startoff(
        xfs_bmbt_rec_t  *r)
{
        return ((xfs_fileoff_t)be64_to_cpu(r->l0) &
                 xfs_mask64lo(64 - BMBT_EXNTFLAG_BITLEN)) >> 9;
}


/*
 * Set all the fields in a bmap extent record from the arguments.
 */
void
xfs_bmbt_set_allf(
        xfs_bmbt_rec_host_t     *r,
        xfs_fileoff_t           startoff,
        xfs_fsblock_t           startblock,
        xfs_filblks_t           blockcount,
        xfs_exntst_t            state)
{
        int             extent_flag = (state == XFS_EXT_NORM) ? 0 : 1;

        ASSERT(state == XFS_EXT_NORM || state == XFS_EXT_UNWRITTEN);
        ASSERT((startoff & xfs_mask64hi(64-BMBT_STARTOFF_BITLEN)) == 0);
        ASSERT((blockcount & xfs_mask64hi(64-BMBT_BLOCKCOUNT_BITLEN)) == 0);

#if XFS_BIG_BLKNOS
        ASSERT((startblock & xfs_mask64hi(64-BMBT_STARTBLOCK_BITLEN)) == 0);

        r->l0 = ((xfs_bmbt_rec_base_t)extent_flag << 63) |
                ((xfs_bmbt_rec_base_t)startoff << 9) |
                ((xfs_bmbt_rec_base_t)startblock >> 43);
        r->l1 = ((xfs_bmbt_rec_base_t)startblock << 21) |
                ((xfs_bmbt_rec_base_t)blockcount &
                (xfs_bmbt_rec_base_t)xfs_mask64lo(21));
#else   /* !XFS_BIG_BLKNOS */
        if (isnullstartblock(startblock)) {
                r->l0 = ((xfs_bmbt_rec_base_t)extent_flag << 63) |
                        ((xfs_bmbt_rec_base_t)startoff << 9) |
                         (xfs_bmbt_rec_base_t)xfs_mask64lo(9);
                r->l1 = xfs_mask64hi(11) |
                          ((xfs_bmbt_rec_base_t)startblock << 21) |
                          ((xfs_bmbt_rec_base_t)blockcount &
                           (xfs_bmbt_rec_base_t)xfs_mask64lo(21));
        } else {
                r->l0 = ((xfs_bmbt_rec_base_t)extent_flag << 63) |
                        ((xfs_bmbt_rec_base_t)startoff << 9);
                r->l1 = ((xfs_bmbt_rec_base_t)startblock << 21) |
                         ((xfs_bmbt_rec_base_t)blockcount &
                         (xfs_bmbt_rec_base_t)xfs_mask64lo(21));
        }
#endif  /* XFS_BIG_BLKNOS */
}

/*
 * Set all the fields in a bmap extent record from the uncompressed form.
 */
void
xfs_bmbt_set_all(
        xfs_bmbt_rec_host_t *r,
        xfs_bmbt_irec_t *s)
{
        xfs_bmbt_set_allf(r, s->br_startoff, s->br_startblock,
                             s->br_blockcount, s->br_state);
}


/*
 * Set all the fields in a disk format bmap extent record from the arguments.
 */
void
xfs_bmbt_disk_set_allf(
        xfs_bmbt_rec_t          *r,
        xfs_fileoff_t           startoff,
        xfs_fsblock_t           startblock,
        xfs_filblks_t           blockcount,
        xfs_exntst_t            state)
{
        int                     extent_flag = (state == XFS_EXT_NORM) ? 0 : 1;

        ASSERT(state == XFS_EXT_NORM || state == XFS_EXT_UNWRITTEN);
        ASSERT((startoff & xfs_mask64hi(64-BMBT_STARTOFF_BITLEN)) == 0);
        ASSERT((blockcount & xfs_mask64hi(64-BMBT_BLOCKCOUNT_BITLEN)) == 0);

#if XFS_BIG_BLKNOS
        ASSERT((startblock & xfs_mask64hi(64-BMBT_STARTBLOCK_BITLEN)) == 0);

        r->l0 = cpu_to_be64(
                ((xfs_bmbt_rec_base_t)extent_flag << 63) |
                 ((xfs_bmbt_rec_base_t)startoff << 9) |
                 ((xfs_bmbt_rec_base_t)startblock >> 43));
        r->l1 = cpu_to_be64(
                ((xfs_bmbt_rec_base_t)startblock << 21) |
                 ((xfs_bmbt_rec_base_t)blockcount &
                  (xfs_bmbt_rec_base_t)xfs_mask64lo(21)));
#else   /* !XFS_BIG_BLKNOS */
        if (isnullstartblock(startblock)) {
                r->l0 = cpu_to_be64(
                        ((xfs_bmbt_rec_base_t)extent_flag << 63) |
                         ((xfs_bmbt_rec_base_t)startoff << 9) |
                          (xfs_bmbt_rec_base_t)xfs_mask64lo(9));
                r->l1 = cpu_to_be64(xfs_mask64hi(11) |
                          ((xfs_bmbt_rec_base_t)startblock << 21) |
                          ((xfs_bmbt_rec_base_t)blockcount &
                           (xfs_bmbt_rec_base_t)xfs_mask64lo(21)));
        } else {
                r->l0 = cpu_to_be64(
                        ((xfs_bmbt_rec_base_t)extent_flag << 63) |
                         ((xfs_bmbt_rec_base_t)startoff << 9));
                r->l1 = cpu_to_be64(
                        ((xfs_bmbt_rec_base_t)startblock << 21) |
                         ((xfs_bmbt_rec_base_t)blockcount &
                          (xfs_bmbt_rec_base_t)xfs_mask64lo(21)));
        }
#endif  /* XFS_BIG_BLKNOS */
}

/*
 * Set all the fields in a bmap extent record from the uncompressed form.
 */
STATIC void
xfs_bmbt_disk_set_all(
        xfs_bmbt_rec_t  *r,
        xfs_bmbt_irec_t *s)
{
        xfs_bmbt_disk_set_allf(r, s->br_startoff, s->br_startblock,
                                  s->br_blockcount, s->br_state);
}

/*
 * Set the blockcount field in a bmap extent record.
 */
void
xfs_bmbt_set_blockcount(
        xfs_bmbt_rec_host_t *r,
        xfs_filblks_t   v)
{
        ASSERT((v & xfs_mask64hi(43)) == 0);
        r->l1 = (r->l1 & (xfs_bmbt_rec_base_t)xfs_mask64hi(43)) |
                  (xfs_bmbt_rec_base_t)(v & xfs_mask64lo(21));
}

/*
 * Set the startblock field in a bmap extent record.
 */
void
xfs_bmbt_set_startblock(
        xfs_bmbt_rec_host_t *r,
        xfs_fsblock_t   v)
{
#if XFS_BIG_BLKNOS
        ASSERT((v & xfs_mask64hi(12)) == 0);
        r->l0 = (r->l0 & (xfs_bmbt_rec_base_t)xfs_mask64hi(55)) |
                  (xfs_bmbt_rec_base_t)(v >> 43);
        r->l1 = (r->l1 & (xfs_bmbt_rec_base_t)xfs_mask64lo(21)) |
                  (xfs_bmbt_rec_base_t)(v << 21);
#else   /* !XFS_BIG_BLKNOS */
        if (isnullstartblock(v)) {
                r->l0 |= (xfs_bmbt_rec_base_t)xfs_mask64lo(9);
                r->l1 = (xfs_bmbt_rec_base_t)xfs_mask64hi(11) |
                          ((xfs_bmbt_rec_base_t)v << 21) |
                          (r->l1 & (xfs_bmbt_rec_base_t)xfs_mask64lo(21));
        } else {
                r->l0 &= ~(xfs_bmbt_rec_base_t)xfs_mask64lo(9);
                r->l1 = ((xfs_bmbt_rec_base_t)v << 21) |
                          (r->l1 & (xfs_bmbt_rec_base_t)xfs_mask64lo(21));
        }
#endif  /* XFS_BIG_BLKNOS */
}

/*
 * Set the startoff field in a bmap extent record.
 */
void
xfs_bmbt_set_startoff(
        xfs_bmbt_rec_host_t *r,
        xfs_fileoff_t   v)
{
        ASSERT((v & xfs_mask64hi(9)) == 0);
        r->l0 = (r->l0 & (xfs_bmbt_rec_base_t) xfs_mask64hi(1)) |
                ((xfs_bmbt_rec_base_t)v << 9) |
                  (r->l0 & (xfs_bmbt_rec_base_t)xfs_mask64lo(9));
}

/*
 * Set the extent state field in a bmap extent record.
 */
void
xfs_bmbt_set_state(
        xfs_bmbt_rec_host_t *r,
        xfs_exntst_t    v)
{
        ASSERT(v == XFS_EXT_NORM || v == XFS_EXT_UNWRITTEN);
        if (v == XFS_EXT_NORM)
                r->l0 &= xfs_mask64lo(64 - BMBT_EXNTFLAG_BITLEN);
        else
                r->l0 |= xfs_mask64hi(BMBT_EXNTFLAG_BITLEN);
}

/*
 * Convert in-memory form of btree root to on-disk form.
 */
void
xfs_bmbt_to_bmdr(
        struct xfs_mount        *mp,
        struct xfs_btree_block  *rblock,
        int                     rblocklen,
        xfs_bmdr_block_t        *dblock,
        int                     dblocklen)
{
        int                     dmxr;
        xfs_bmbt_key_t          *fkp;
        __be64                  *fpp;
        xfs_bmbt_key_t          *tkp;
        __be64                  *tpp;

        ASSERT(rblock->bb_magic == cpu_to_be32(XFS_BMAP_MAGIC));
        ASSERT(rblock->bb_u.l.bb_leftsib == cpu_to_be64(NULLDFSBNO));
        ASSERT(rblock->bb_u.l.bb_rightsib == cpu_to_be64(NULLDFSBNO));
        ASSERT(rblock->bb_level != 0);
        dblock->bb_level = rblock->bb_level;
        dblock->bb_numrecs = rblock->bb_numrecs;
        dmxr = xfs_bmdr_maxrecs(mp, dblocklen, 0);
        fkp = XFS_BMBT_KEY_ADDR(mp, rblock, 1);
        tkp = XFS_BMDR_KEY_ADDR(dblock, 1);
        fpp = XFS_BMAP_BROOT_PTR_ADDR(mp, rblock, 1, rblocklen);
        tpp = XFS_BMDR_PTR_ADDR(dblock, 1, dmxr);
        dmxr = be16_to_cpu(dblock->bb_numrecs);
        memcpy(tkp, fkp, sizeof(*fkp) * dmxr);
        memcpy(tpp, fpp, sizeof(*fpp) * dmxr);
}

/*
 * Check extent records, which have just been read, for
 * any bit in the extent flag field. ASSERT on debug
 * kernels, as this condition should not occur.
 * Return an error condition (1) if any flags found,
 * otherwise return 0.
 */

int
xfs_check_nostate_extents(
        xfs_ifork_t             *ifp,
        xfs_extnum_t            idx,
        xfs_extnum_t            num)
{
        for (; num > 0; num--, idx++) {
                xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, idx);
                if ((ep->l0 >>
                     (64 - BMBT_EXNTFLAG_BITLEN)) != 0) {
                        ASSERT(0);
                        return 1;
                }
        }
        return 0;
}


STATIC struct xfs_btree_cur *
xfs_bmbt_dup_cursor(
        struct xfs_btree_cur    *cur)
{
        struct xfs_btree_cur    *new;

        new = xfs_bmbt_init_cursor(cur->bc_mp, cur->bc_tp,
                        cur->bc_private.b.ip, cur->bc_private.b.whichfork);

        /*
         * Copy the firstblock, flist, and flags values,
         * since init cursor doesn't get them.
         */
        new->bc_private.b.firstblock = cur->bc_private.b.firstblock;
        new->bc_private.b.flist = cur->bc_private.b.flist;
        new->bc_private.b.flags = cur->bc_private.b.flags;

        return new;
}

STATIC void
xfs_bmbt_update_cursor(
        struct xfs_btree_cur    *src,
        struct xfs_btree_cur    *dst)
{
        ASSERT((dst->bc_private.b.firstblock != NULLFSBLOCK) ||
               (dst->bc_private.b.ip->i_d.di_flags & XFS_DIFLAG_REALTIME));
        ASSERT(dst->bc_private.b.flist == src->bc_private.b.flist);

        dst->bc_private.b.allocated += src->bc_private.b.allocated;
        dst->bc_private.b.firstblock = src->bc_private.b.firstblock;

        src->bc_private.b.allocated = 0;
}

STATIC int
xfs_bmbt_alloc_block(
        struct xfs_btree_cur    *cur,
        union xfs_btree_ptr     *start,
        union xfs_btree_ptr     *new,
        int                     length,
        int                     *stat)
{
        xfs_alloc_arg_t         args;           /* block allocation args */
        int                     error;          /* error return value */

        memset(&args, 0, sizeof(args));
        args.tp = cur->bc_tp;
        args.mp = cur->bc_mp;
        args.fsbno = cur->bc_private.b.firstblock;
        args.firstblock = args.fsbno;

        if (args.fsbno == NULLFSBLOCK) {
                args.fsbno = be64_to_cpu(start->l);
                args.type = XFS_ALLOCTYPE_START_BNO;
                /*
                 * Make sure there is sufficient room left in the AG to
                 * complete a full tree split for an extent insert.  If
                 * we are converting the middle part of an extent then
                 * we may need space for two tree splits.
                 *
                 * We are relying on the caller to make the correct block
                 * reservation for this operation to succeed.  If the
                 * reservation amount is insufficient then we may fail a
                 * block allocation here and corrupt the filesystem.
                 */
                args.minleft = xfs_trans_get_block_res(args.tp);
        } else if (cur->bc_private.b.flist->xbf_low) {
                args.type = XFS_ALLOCTYPE_START_BNO;
        } else {
                args.type = XFS_ALLOCTYPE_NEAR_BNO;
        }

        args.minlen = args.maxlen = args.prod = 1;
        args.wasdel = cur->bc_private.b.flags & XFS_BTCUR_BPRV_WASDEL;
        if (!args.wasdel && xfs_trans_get_block_res(args.tp) == 0) {
                error = XFS_ERROR(ENOSPC);
                goto error0;
        }
        error = xfs_alloc_vextent(&args);
        if (error)
                goto error0;

        if (args.fsbno == NULLFSBLOCK && args.minleft) {
                /*
                 * Could not find an AG with enough free space to satisfy
                 * a full btree split.  Try again without minleft and if
                 * successful activate the lowspace algorithm.
                 */
                args.fsbno = 0;
                args.type = XFS_ALLOCTYPE_FIRST_AG;
                args.minleft = 0;
                error = xfs_alloc_vextent(&args);
                if (error)
                        goto error0;
                cur->bc_private.b.flist->xbf_low = 1;
        }
        if (args.fsbno == NULLFSBLOCK) {
                XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
                *stat = 0;
                return 0;
        }
        ASSERT(args.len == 1);
        cur->bc_private.b.firstblock = args.fsbno;
        cur->bc_private.b.allocated++;
        cur->bc_private.b.ip->i_d.di_nblocks++;
        xfs_trans_log_inode(args.tp, cur->bc_private.b.ip, XFS_ILOG_CORE);
        xfs_trans_mod_dquot_byino(args.tp, cur->bc_private.b.ip,
                        XFS_TRANS_DQ_BCOUNT, 1L);

        new->l = cpu_to_be64(args.fsbno);

        XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
        *stat = 1;
        return 0;

 error0:
        XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
        return error;
}

STATIC int
xfs_bmbt_free_block(
        struct xfs_btree_cur    *cur,
        struct xfs_buf          *bp)
{
        struct xfs_mount        *mp = cur->bc_mp;
        struct xfs_inode        *ip = cur->bc_private.b.ip;
        struct xfs_trans        *tp = cur->bc_tp;
        xfs_fsblock_t           fsbno = XFS_DADDR_TO_FSB(mp, XFS_BUF_ADDR(bp));

        xfs_bmap_add_free(fsbno, 1, cur->bc_private.b.flist, mp);
        ip->i_d.di_nblocks--;

        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
        xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, -1L);
        xfs_trans_binval(tp, bp);
        return 0;
}

STATIC int
xfs_bmbt_get_minrecs(
        struct xfs_btree_cur    *cur,
        int                     level)
{
        if (level == cur->bc_nlevels - 1) {
                struct xfs_ifork        *ifp;

                ifp = XFS_IFORK_PTR(cur->bc_private.b.ip,
                                    cur->bc_private.b.whichfork);

                return xfs_bmbt_maxrecs(cur->bc_mp,
                                        ifp->if_broot_bytes, level == 0) / 2;
        }

        return cur->bc_mp->m_bmap_dmnr[level != 0];
}

int
xfs_bmbt_get_maxrecs(
        struct xfs_btree_cur    *cur,
        int                     level)
{
        if (level == cur->bc_nlevels - 1) {
                struct xfs_ifork        *ifp;

                ifp = XFS_IFORK_PTR(cur->bc_private.b.ip,
                                    cur->bc_private.b.whichfork);

                return xfs_bmbt_maxrecs(cur->bc_mp,
                                        ifp->if_broot_bytes, level == 0);
        }

        return cur->bc_mp->m_bmap_dmxr[level != 0];

}

/*
 * Get the maximum records we could store in the on-disk format.
 *
 * For non-root nodes this is equivalent to xfs_bmbt_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_bmbt_get_maxrecs for the root node, too.
 */
STATIC int
xfs_bmbt_get_dmaxrecs(
        struct xfs_btree_cur    *cur,
        int                     level)
{
        if (level != cur->bc_nlevels - 1)
                return cur->bc_mp->m_bmap_dmxr[level != 0];
        return xfs_bmdr_maxrecs(cur->bc_mp, cur->bc_private.b.forksize,
                                level == 0);
}

STATIC void
xfs_bmbt_init_key_from_rec(
        union xfs_btree_key     *key,
        union xfs_btree_rec     *rec)
{
        key->bmbt.br_startoff =
                cpu_to_be64(xfs_bmbt_disk_get_startoff(&rec->bmbt));
}

STATIC void
xfs_bmbt_init_rec_from_key(
        union xfs_btree_key     *key,
        union xfs_btree_rec     *rec)
{
        ASSERT(key->bmbt.br_startoff != 0);

        xfs_bmbt_disk_set_allf(&rec->bmbt, be64_to_cpu(key->bmbt.br_startoff),
                               0, 0, XFS_EXT_NORM);
}

STATIC void
xfs_bmbt_init_rec_from_cur(
        struct xfs_btree_cur    *cur,
        union xfs_btree_rec     *rec)
{
        xfs_bmbt_disk_set_all(&rec->bmbt, &cur->bc_rec.b);
}

STATIC void
xfs_bmbt_init_ptr_from_cur(
        struct xfs_btree_cur    *cur,
        union xfs_btree_ptr     *ptr)
{
        ptr->l = 0;
}

STATIC __int64_t
xfs_bmbt_key_diff(
        struct xfs_btree_cur    *cur,
        union xfs_btree_key     *key)
{
        return (__int64_t)be64_to_cpu(key->bmbt.br_startoff) -
                                      cur->bc_rec.b.br_startoff;
}

#ifdef DEBUG
STATIC int
xfs_bmbt_keys_inorder(
        struct xfs_btree_cur    *cur,
        union xfs_btree_key     *k1,
        union xfs_btree_key     *k2)
{
        return be64_to_cpu(k1->bmbt.br_startoff) <
                be64_to_cpu(k2->bmbt.br_startoff);
}

STATIC int
xfs_bmbt_recs_inorder(
        struct xfs_btree_cur    *cur,
        union xfs_btree_rec     *r1,
        union xfs_btree_rec     *r2)
{
        return xfs_bmbt_disk_get_startoff(&r1->bmbt) +
                xfs_bmbt_disk_get_blockcount(&r1->bmbt) <=
                xfs_bmbt_disk_get_startoff(&r2->bmbt);
}
#endif  /* DEBUG */

static const struct xfs_btree_ops xfs_bmbt_ops = {
        .rec_len                = sizeof(xfs_bmbt_rec_t),
        .key_len                = sizeof(xfs_bmbt_key_t),

        .dup_cursor             = xfs_bmbt_dup_cursor,
        .update_cursor          = xfs_bmbt_update_cursor,
        .alloc_block            = xfs_bmbt_alloc_block,
        .free_block             = xfs_bmbt_free_block,
        .get_maxrecs            = xfs_bmbt_get_maxrecs,
        .get_minrecs            = xfs_bmbt_get_minrecs,
        .get_dmaxrecs           = xfs_bmbt_get_dmaxrecs,
        .init_key_from_rec      = xfs_bmbt_init_key_from_rec,
        .init_rec_from_key      = xfs_bmbt_init_rec_from_key,
        .init_rec_from_cur      = xfs_bmbt_init_rec_from_cur,
        .init_ptr_from_cur      = xfs_bmbt_init_ptr_from_cur,
        .key_diff               = xfs_bmbt_key_diff,
#ifdef DEBUG
        .keys_inorder           = xfs_bmbt_keys_inorder,
        .recs_inorder           = xfs_bmbt_recs_inorder,
#endif
};

/*
 * Allocate a new bmap btree cursor.
 */
struct xfs_btree_cur *                          /* new bmap btree cursor */
xfs_bmbt_init_cursor(
        struct xfs_mount        *mp,            /* file system mount point */
        struct xfs_trans        *tp,            /* transaction pointer */
        struct xfs_inode        *ip,            /* inode owning the btree */
        int                     whichfork)      /* data or attr fork */
{
        struct xfs_ifork        *ifp = XFS_IFORK_PTR(ip, whichfork);
        struct xfs_btree_cur    *cur;

        cur = kmem_zone_zalloc(xfs_btree_cur_zone, KM_SLEEP);

        cur->bc_tp = tp;
        cur->bc_mp = mp;
        cur->bc_nlevels = be16_to_cpu(ifp->if_broot->bb_level) + 1;
        cur->bc_btnum = XFS_BTNUM_BMAP;
        cur->bc_blocklog = mp->m_sb.sb_blocklog;

        cur->bc_ops = &xfs_bmbt_ops;
        cur->bc_flags = XFS_BTREE_LONG_PTRS | XFS_BTREE_ROOT_IN_INODE;

        cur->bc_private.b.forksize = XFS_IFORK_SIZE(ip, whichfork);
        cur->bc_private.b.ip = ip;
        cur->bc_private.b.firstblock = NULLFSBLOCK;
        cur->bc_private.b.flist = NULL;
        cur->bc_private.b.allocated = 0;
        cur->bc_private.b.flags = 0;
        cur->bc_private.b.whichfork = whichfork;

        return cur;
}

/*
 * Calculate number of records in a bmap btree block.
 */
int
xfs_bmbt_maxrecs(
        struct xfs_mount        *mp,
        int                     blocklen,
        int                     leaf)
{
        blocklen -= XFS_BMBT_BLOCK_LEN(mp);

        if (leaf)
                return blocklen / sizeof(xfs_bmbt_rec_t);
        return blocklen / (sizeof(xfs_bmbt_key_t) + sizeof(xfs_bmbt_ptr_t));
}

/*
 * Calculate number of records in a bmap btree inode root.
 */
int
xfs_bmdr_maxrecs(
        struct xfs_mount        *mp,
        int                     blocklen,
        int                     leaf)
{
        blocklen -= sizeof(xfs_bmdr_block_t);

        if (leaf)
                return blocklen / sizeof(xfs_bmdr_rec_t);
        return blocklen / (sizeof(xfs_bmdr_key_t) + sizeof(xfs_bmdr_ptr_t));
}