Merge git://git.kernel.org/pub/scm/linux/kernel/git/sfrench/cifs-2.6
[safe/jmp/linux-2.6] / fs / xfs / xfs_alloc_btree.c
index 3ce2645..c10c3a2 100644 (file)
 #include "xfs_dinode.h"
 #include "xfs_inode.h"
 #include "xfs_btree.h"
+#include "xfs_btree_trace.h"
 #include "xfs_ialloc.h"
 #include "xfs_alloc.h"
 #include "xfs_error.h"
 
-/*
- * Prototypes for internal functions.
- */
-
-STATIC void xfs_alloc_log_block(xfs_trans_t *, xfs_buf_t *, int);
-STATIC void xfs_alloc_log_keys(xfs_btree_cur_t *, xfs_buf_t *, int, int);
-STATIC void xfs_alloc_log_ptrs(xfs_btree_cur_t *, xfs_buf_t *, int, int);
-STATIC void xfs_alloc_log_recs(xfs_btree_cur_t *, xfs_buf_t *, int, int);
-STATIC int xfs_alloc_lshift(xfs_btree_cur_t *, int, int *);
-STATIC int xfs_alloc_newroot(xfs_btree_cur_t *, int *);
-STATIC int xfs_alloc_rshift(xfs_btree_cur_t *, int, int *);
-STATIC int xfs_alloc_split(xfs_btree_cur_t *, int, xfs_agblock_t *,
-               xfs_alloc_key_t *, xfs_btree_cur_t **, int *);
-STATIC int xfs_alloc_updkey(xfs_btree_cur_t *, xfs_alloc_key_t *, int);
-
-/*
- * Internal functions.
- */
-
-/*
- * Single level of the xfs_alloc_delete record deletion routine.
- * Delete record pointed to by cur/level.
- * Remove the record from its block then rebalance the tree.
- * Return 0 for error, 1 for done, 2 to go on to the next level.
- */
-STATIC int                             /* error */
-xfs_alloc_delrec(
-       xfs_btree_cur_t         *cur,   /* btree cursor */
-       int                     level,  /* level removing record from */
-       int                     *stat)  /* fail/done/go-on */
-{
-       xfs_agf_t               *agf;   /* allocation group freelist header */
-       xfs_alloc_block_t       *block; /* btree block record/key lives in */
-       xfs_agblock_t           bno;    /* btree block number */
-       xfs_buf_t               *bp;    /* buffer for block */
-       int                     error;  /* error return value */
-       int                     i;      /* loop index */
-       xfs_alloc_key_t         key;    /* kp points here if block is level 0 */
-       xfs_agblock_t           lbno;   /* left block's block number */
-       xfs_buf_t               *lbp;   /* left block's buffer pointer */
-       xfs_alloc_block_t       *left;  /* left btree block */
-       xfs_alloc_key_t         *lkp=NULL;      /* left block key pointer */
-       xfs_alloc_ptr_t         *lpp=NULL;      /* left block address pointer */
-       int                     lrecs=0;        /* number of records in left block */
-       xfs_alloc_rec_t         *lrp;   /* left block record pointer */
-       xfs_mount_t             *mp;    /* mount structure */
-       int                     ptr;    /* index in btree block for this rec */
-       xfs_agblock_t           rbno;   /* right block's block number */
-       xfs_buf_t               *rbp;   /* right block's buffer pointer */
-       xfs_alloc_block_t       *right; /* right btree block */
-       xfs_alloc_key_t         *rkp;   /* right block key pointer */
-       xfs_alloc_ptr_t         *rpp;   /* right block address pointer */
-       int                     rrecs=0;        /* number of records in right block */
-       int                     numrecs;
-       xfs_alloc_rec_t         *rrp;   /* right block record pointer */
-       xfs_btree_cur_t         *tcur;  /* temporary btree cursor */
-
-       /*
-        * Get the index of the entry being deleted, check for nothing there.
-        */
-       ptr = cur->bc_ptrs[level];
-       if (ptr == 0) {
-               *stat = 0;
-               return 0;
-       }
-       /*
-        * Get the buffer & block containing the record or key/ptr.
-        */
-       bp = cur->bc_bufs[level];
-       block = XFS_BUF_TO_ALLOC_BLOCK(bp);
-#ifdef DEBUG
-       if ((error = xfs_btree_check_sblock(cur, block, level, bp)))
-               return error;
-#endif
-       /*
-        * Fail if we're off the end of the block.
-        */
-       numrecs = be16_to_cpu(block->bb_numrecs);
-       if (ptr > numrecs) {
-               *stat = 0;
-               return 0;
-       }
-       XFS_STATS_INC(xs_abt_delrec);
-       /*
-        * It's a nonleaf.  Excise the key and ptr being deleted, by
-        * sliding the entries past them down one.
-        * Log the changed areas of the block.
-        */
-       if (level > 0) {
-               lkp = XFS_ALLOC_KEY_ADDR(block, 1, cur);
-               lpp = XFS_ALLOC_PTR_ADDR(block, 1, cur);
-#ifdef DEBUG
-               for (i = ptr; i < numrecs; i++) {
-                       if ((error = xfs_btree_check_sptr(cur, be32_to_cpu(lpp[i]), level)))
-                               return error;
-               }
-#endif
-               if (ptr < numrecs) {
-                       memmove(&lkp[ptr - 1], &lkp[ptr],
-                               (numrecs - ptr) * sizeof(*lkp));
-                       memmove(&lpp[ptr - 1], &lpp[ptr],
-                               (numrecs - ptr) * sizeof(*lpp));
-                       xfs_alloc_log_ptrs(cur, bp, ptr, numrecs - 1);
-                       xfs_alloc_log_keys(cur, bp, ptr, numrecs - 1);
-               }
-       }
-       /*
-        * It's a leaf.  Excise the record being deleted, by sliding the
-        * entries past it down one.  Log the changed areas of the block.
-        */
-       else {
-               lrp = XFS_ALLOC_REC_ADDR(block, 1, cur);
-               if (ptr < numrecs) {
-                       memmove(&lrp[ptr - 1], &lrp[ptr],
-                               (numrecs - ptr) * sizeof(*lrp));
-                       xfs_alloc_log_recs(cur, bp, ptr, numrecs - 1);
-               }
-               /*
-                * If it's the first record in the block, we'll need a key
-                * structure to pass up to the next level (updkey).
-                */
-               if (ptr == 1) {
-                       key.ar_startblock = lrp->ar_startblock;
-                       key.ar_blockcount = lrp->ar_blockcount;
-                       lkp = &key;
-               }
-       }
-       /*
-        * Decrement and log the number of entries in the block.
-        */
-       numrecs--;
-       block->bb_numrecs = cpu_to_be16(numrecs);
-       xfs_alloc_log_block(cur->bc_tp, bp, XFS_BB_NUMRECS);
-       /*
-        * See if the longest free extent in the allocation group was
-        * changed by this operation.  True if it's the by-size btree, and
-        * this is the leaf level, and there is no right sibling block,
-        * and this was the last record.
-        */
-       agf = XFS_BUF_TO_AGF(cur->bc_private.a.agbp);
-       mp = cur->bc_mp;
-
-       if (level == 0 &&
-           cur->bc_btnum == XFS_BTNUM_CNT &&
-           be32_to_cpu(block->bb_rightsib) == NULLAGBLOCK &&
-           ptr > numrecs) {
-               ASSERT(ptr == numrecs + 1);
-               /*
-                * There are still records in the block.  Grab the size
-                * from the last one.
-                */
-               if (numrecs) {
-                       rrp = XFS_ALLOC_REC_ADDR(block, numrecs, cur);
-                       agf->agf_longest = rrp->ar_blockcount;
-               }
-               /*
-                * No free extents left.
-                */
-               else
-                       agf->agf_longest = 0;
-               mp->m_perag[be32_to_cpu(agf->agf_seqno)].pagf_longest =
-                       be32_to_cpu(agf->agf_longest);
-               xfs_alloc_log_agf(cur->bc_tp, cur->bc_private.a.agbp,
-                       XFS_AGF_LONGEST);
-       }
-       /*
-        * Is this the root level?  If so, we're almost done.
-        */
-       if (level == cur->bc_nlevels - 1) {
-               /*
-                * If this is the root level,
-                * and there's only one entry left,
-                * and it's NOT the leaf level,
-                * then we can get rid of this level.
-                */
-               if (numrecs == 1 && level > 0) {
-                       /*
-                        * lpp is still set to the first pointer in the block.
-                        * Make it the new root of the btree.
-                        */
-                       bno = be32_to_cpu(agf->agf_roots[cur->bc_btnum]);
-                       agf->agf_roots[cur->bc_btnum] = *lpp;
-                       be32_add_cpu(&agf->agf_levels[cur->bc_btnum], -1);
-                       mp->m_perag[be32_to_cpu(agf->agf_seqno)].pagf_levels[cur->bc_btnum]--;
-                       /*
-                        * Put this buffer/block on the ag's freelist.
-                        */
-                       error = xfs_alloc_put_freelist(cur->bc_tp,
-                                       cur->bc_private.a.agbp, NULL, bno, 1);
-                       if (error)
-                               return error;
-                       /*
-                        * Since blocks move to the free list without the
-                        * coordination used in xfs_bmap_finish, we can't allow
-                        * block to be available for reallocation and
-                        * non-transaction writing (user data) until we know
-                        * that the transaction that moved it to the free list
-                        * is permanently on disk. We track the blocks by
-                        * declaring these blocks as "busy"; the busy list is
-                        * maintained on a per-ag basis and each transaction
-                        * records which entries should be removed when the
-                        * iclog commits to disk. If a busy block is
-                        * allocated, the iclog is pushed up to the LSN
-                        * that freed the block.
-                        */
-                       xfs_alloc_mark_busy(cur->bc_tp,
-                               be32_to_cpu(agf->agf_seqno), bno, 1);
-
-                       xfs_trans_agbtree_delta(cur->bc_tp, -1);
-                       xfs_alloc_log_agf(cur->bc_tp, cur->bc_private.a.agbp,
-                               XFS_AGF_ROOTS | XFS_AGF_LEVELS);
-                       /*
-                        * Update the cursor so there's one fewer level.
-                        */
-                       xfs_btree_setbuf(cur, level, NULL);
-                       cur->bc_nlevels--;
-               } else if (level > 0 &&
-                          (error = xfs_alloc_decrement(cur, level, &i)))
-                       return error;
-               *stat = 1;
-               return 0;
-       }
-       /*
-        * If we deleted the leftmost entry in the block, update the
-        * key values above us in the tree.
-        */
-       if (ptr == 1 && (error = xfs_alloc_updkey(cur, lkp, level + 1)))
-               return error;
-       /*
-        * If the number of records remaining in the block is at least
-        * the minimum, we're done.
-        */
-       if (numrecs >= XFS_ALLOC_BLOCK_MINRECS(level, cur)) {
-               if (level > 0 && (error = xfs_alloc_decrement(cur, level, &i)))
-                       return error;
-               *stat = 1;
-               return 0;
-       }
-       /*
-        * Otherwise, we have to move some records around to keep the
-        * tree balanced.  Look at the left and right sibling blocks to
-        * see if we can re-balance by moving only one record.
-        */
-       rbno = be32_to_cpu(block->bb_rightsib);
-       lbno = be32_to_cpu(block->bb_leftsib);
-       bno = NULLAGBLOCK;
-       ASSERT(rbno != NULLAGBLOCK || lbno != NULLAGBLOCK);
-       /*
-        * Duplicate the cursor so our btree manipulations here won't
-        * disrupt the next level up.
-        */
-       if ((error = xfs_btree_dup_cursor(cur, &tcur)))
-               return error;
-       /*
-        * If there's a right sibling, see if it's ok to shift an entry
-        * out of it.
-        */
-       if (rbno != NULLAGBLOCK) {
-               /*
-                * Move the temp cursor to the last entry in the next block.
-                * Actually any entry but the first would suffice.
-                */
-               i = xfs_btree_lastrec(tcur, level);
-               XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
-               if ((error = xfs_alloc_increment(tcur, level, &i)))
-                       goto error0;
-               XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
-               i = xfs_btree_lastrec(tcur, level);
-               XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
-               /*
-                * Grab a pointer to the block.
-                */
-               rbp = tcur->bc_bufs[level];
-               right = XFS_BUF_TO_ALLOC_BLOCK(rbp);
-#ifdef DEBUG
-               if ((error = xfs_btree_check_sblock(cur, right, level, rbp)))
-                       goto error0;
-#endif
-               /*
-                * Grab the current block number, for future use.
-                */
-               bno = be32_to_cpu(right->bb_leftsib);
-               /*
-                * If right block is full enough so that removing one entry
-                * won't make it too empty, and left-shifting an entry out
-                * of right to us works, we're done.
-                */
-               if (be16_to_cpu(right->bb_numrecs) - 1 >=
-                    XFS_ALLOC_BLOCK_MINRECS(level, cur)) {
-                       if ((error = xfs_alloc_lshift(tcur, level, &i)))
-                               goto error0;
-                       if (i) {
-                               ASSERT(be16_to_cpu(block->bb_numrecs) >=
-                                      XFS_ALLOC_BLOCK_MINRECS(level, cur));
-                               xfs_btree_del_cursor(tcur,
-                                                    XFS_BTREE_NOERROR);
-                               if (level > 0 &&
-                                   (error = xfs_alloc_decrement(cur, level,
-                                           &i)))
-                                       return error;
-                               *stat = 1;
-                               return 0;
-                       }
-               }
-               /*
-                * Otherwise, grab the number of records in right for
-                * future reference, and fix up the temp cursor to point
-                * to our block again (last record).
-                */
-               rrecs = be16_to_cpu(right->bb_numrecs);
-               if (lbno != NULLAGBLOCK) {
-                       i = xfs_btree_firstrec(tcur, level);
-                       XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
-                       if ((error = xfs_alloc_decrement(tcur, level, &i)))
-                               goto error0;
-                       XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
-               }
-       }
-       /*
-        * If there's a left sibling, see if it's ok to shift an entry
-        * out of it.
-        */
-       if (lbno != NULLAGBLOCK) {
-               /*
-                * Move the temp cursor to the first entry in the
-                * previous block.
-                */
-               i = xfs_btree_firstrec(tcur, level);
-               XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
-               if ((error = xfs_alloc_decrement(tcur, level, &i)))
-                       goto error0;
-               XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
-               xfs_btree_firstrec(tcur, level);
-               /*
-                * Grab a pointer to the block.
-                */
-               lbp = tcur->bc_bufs[level];
-               left = XFS_BUF_TO_ALLOC_BLOCK(lbp);
-#ifdef DEBUG
-               if ((error = xfs_btree_check_sblock(cur, left, level, lbp)))
-                       goto error0;
-#endif
-               /*
-                * Grab the current block number, for future use.
-                */
-               bno = be32_to_cpu(left->bb_rightsib);
-               /*
-                * If left block is full enough so that removing one entry
-                * won't make it too empty, and right-shifting an entry out
-                * of left to us works, we're done.
-                */
-               if (be16_to_cpu(left->bb_numrecs) - 1 >=
-                    XFS_ALLOC_BLOCK_MINRECS(level, cur)) {
-                       if ((error = xfs_alloc_rshift(tcur, level, &i)))
-                               goto error0;
-                       if (i) {
-                               ASSERT(be16_to_cpu(block->bb_numrecs) >=
-                                      XFS_ALLOC_BLOCK_MINRECS(level, cur));
-                               xfs_btree_del_cursor(tcur,
-                                                    XFS_BTREE_NOERROR);
-                               if (level == 0)
-                                       cur->bc_ptrs[0]++;
-                               *stat = 1;
-                               return 0;
-                       }
-               }
-               /*
-                * Otherwise, grab the number of records in right for
-                * future reference.
-                */
-               lrecs = be16_to_cpu(left->bb_numrecs);
-       }
-       /*
-        * Delete the temp cursor, we're done with it.
-        */
-       xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
-       /*
-        * If here, we need to do a join to keep the tree balanced.
-        */
-       ASSERT(bno != NULLAGBLOCK);
-       /*
-        * See if we can join with the left neighbor block.
-        */
-       if (lbno != NULLAGBLOCK &&
-           lrecs + numrecs <= XFS_ALLOC_BLOCK_MAXRECS(level, cur)) {
-               /*
-                * Set "right" to be the starting block,
-                * "left" to be the left neighbor.
-                */
-               rbno = bno;
-               right = block;
-               rrecs = be16_to_cpu(right->bb_numrecs);
-               rbp = bp;
-               if ((error = xfs_btree_read_bufs(mp, cur->bc_tp,
-                               cur->bc_private.a.agno, lbno, 0, &lbp,
-                               XFS_ALLOC_BTREE_REF)))
-                       return error;
-               left = XFS_BUF_TO_ALLOC_BLOCK(lbp);
-               lrecs = be16_to_cpu(left->bb_numrecs);
-               if ((error = xfs_btree_check_sblock(cur, left, level, lbp)))
-                       return error;
-       }
-       /*
-        * If that won't work, see if we can join with the right neighbor block.
-        */
-       else if (rbno != NULLAGBLOCK &&
-                rrecs + numrecs <= XFS_ALLOC_BLOCK_MAXRECS(level, cur)) {
-               /*
-                * Set "left" to be the starting block,
-                * "right" to be the right neighbor.
-                */
-               lbno = bno;
-               left = block;
-               lrecs = be16_to_cpu(left->bb_numrecs);
-               lbp = bp;
-               if ((error = xfs_btree_read_bufs(mp, cur->bc_tp,
-                               cur->bc_private.a.agno, rbno, 0, &rbp,
-                               XFS_ALLOC_BTREE_REF)))
-                       return error;
-               right = XFS_BUF_TO_ALLOC_BLOCK(rbp);
-               rrecs = be16_to_cpu(right->bb_numrecs);
-               if ((error = xfs_btree_check_sblock(cur, right, level, rbp)))
-                       return error;
-       }
-       /*
-        * Otherwise, we can't fix the imbalance.
-        * Just return.  This is probably a logic error, but it's not fatal.
-        */
-       else {
-               if (level > 0 && (error = xfs_alloc_decrement(cur, level, &i)))
-                       return error;
-               *stat = 1;
-               return 0;
-       }
-       /*
-        * We're now going to join "left" and "right" by moving all the stuff
-        * in "right" to "left" and deleting "right".
-        */
-       if (level > 0) {
-               /*
-                * It's a non-leaf.  Move keys and pointers.
-                */
-               lkp = XFS_ALLOC_KEY_ADDR(left, lrecs + 1, cur);
-               lpp = XFS_ALLOC_PTR_ADDR(left, lrecs + 1, cur);
-               rkp = XFS_ALLOC_KEY_ADDR(right, 1, cur);
-               rpp = XFS_ALLOC_PTR_ADDR(right, 1, cur);
-#ifdef DEBUG
-               for (i = 0; i < rrecs; i++) {
-                       if ((error = xfs_btree_check_sptr(cur, be32_to_cpu(rpp[i]), level)))
-                               return error;
-               }
-#endif
-               memcpy(lkp, rkp, rrecs * sizeof(*lkp));
-               memcpy(lpp, rpp, rrecs * sizeof(*lpp));
-               xfs_alloc_log_keys(cur, lbp, lrecs + 1, lrecs + rrecs);
-               xfs_alloc_log_ptrs(cur, lbp, lrecs + 1, lrecs + rrecs);
-       } else {
-               /*
-                * It's a leaf.  Move records.
-                */
-               lrp = XFS_ALLOC_REC_ADDR(left, lrecs + 1, cur);
-               rrp = XFS_ALLOC_REC_ADDR(right, 1, cur);
-               memcpy(lrp, rrp, rrecs * sizeof(*lrp));
-               xfs_alloc_log_recs(cur, lbp, lrecs + 1, lrecs + rrecs);
-       }
-       /*
-        * If we joined with the left neighbor, set the buffer in the
-        * cursor to the left block, and fix up the index.
-        */
-       if (bp != lbp) {
-               xfs_btree_setbuf(cur, level, lbp);
-               cur->bc_ptrs[level] += lrecs;
-       }
-       /*
-        * If we joined with the right neighbor and there's a level above
-        * us, increment the cursor at that level.
-        */
-       else if (level + 1 < cur->bc_nlevels &&
-                (error = xfs_alloc_increment(cur, level + 1, &i)))
-               return error;
-       /*
-        * Fix up the number of records in the surviving block.
-        */
-       lrecs += rrecs;
-       left->bb_numrecs = cpu_to_be16(lrecs);
-       /*
-        * Fix up the right block pointer in the surviving block, and log it.
-        */
-       left->bb_rightsib = right->bb_rightsib;
-       xfs_alloc_log_block(cur->bc_tp, lbp, XFS_BB_NUMRECS | XFS_BB_RIGHTSIB);
-       /*
-        * If there is a right sibling now, make it point to the
-        * remaining block.
-        */
-       if (be32_to_cpu(left->bb_rightsib) != NULLAGBLOCK) {
-               xfs_alloc_block_t       *rrblock;
-               xfs_buf_t               *rrbp;
-
-               if ((error = xfs_btree_read_bufs(mp, cur->bc_tp,
-                               cur->bc_private.a.agno, be32_to_cpu(left->bb_rightsib), 0,
-                               &rrbp, XFS_ALLOC_BTREE_REF)))
-                       return error;
-               rrblock = XFS_BUF_TO_ALLOC_BLOCK(rrbp);
-               if ((error = xfs_btree_check_sblock(cur, rrblock, level, rrbp)))
-                       return error;
-               rrblock->bb_leftsib = cpu_to_be32(lbno);
-               xfs_alloc_log_block(cur->bc_tp, rrbp, XFS_BB_LEFTSIB);
-       }
-       /*
-        * Free the deleting block by putting it on the freelist.
-        */
-       error = xfs_alloc_put_freelist(cur->bc_tp,
-                                        cur->bc_private.a.agbp, NULL, rbno, 1);
-       if (error)
-               return error;
-       /*
-        * Since blocks move to the free list without the coordination
-        * used in xfs_bmap_finish, we can't allow block to be available
-        * for reallocation and non-transaction writing (user data)
-        * until we know that the transaction that moved it to the free
-        * list is permanently on disk. We track the blocks by declaring
-        * these blocks as "busy"; the busy list is maintained on a
-        * per-ag basis and each transaction records which entries
-        * should be removed when the iclog commits to disk. If a
-        * busy block is allocated, the iclog is pushed up to the
-        * LSN that freed the block.
-        */
-       xfs_alloc_mark_busy(cur->bc_tp, be32_to_cpu(agf->agf_seqno), bno, 1);
-       xfs_trans_agbtree_delta(cur->bc_tp, -1);
-
-       /*
-        * Adjust the current level's cursor so that we're left referring
-        * to the right node, after we're done.
-        * If this leaves the ptr value 0 our caller will fix it up.
-        */
-       if (level > 0)
-               cur->bc_ptrs[level]--;
-       /*
-        * Return value means the next level up has something to do.
-        */
-       *stat = 2;
-       return 0;
-
-error0:
-       xfs_btree_del_cursor(tcur, XFS_BTREE_ERROR);
-       return error;
-}
-
-/*
- * Insert one record/level.  Return information to the caller
- * allowing the next level up to proceed if necessary.
- */
-STATIC int                             /* error */
-xfs_alloc_insrec(
-       xfs_btree_cur_t         *cur,   /* btree cursor */
-       int                     level,  /* level to insert record at */
-       xfs_agblock_t           *bnop,  /* i/o: block number inserted */
-       xfs_alloc_rec_t         *recp,  /* i/o: record data inserted */
-       xfs_btree_cur_t         **curp, /* output: new cursor replacing cur */
-       int                     *stat)  /* output: success/failure */
-{
-       xfs_agf_t               *agf;   /* allocation group freelist header */
-       xfs_alloc_block_t       *block; /* btree block record/key lives in */
-       xfs_buf_t               *bp;    /* buffer for block */
-       int                     error;  /* error return value */
-       int                     i;      /* loop index */
-       xfs_alloc_key_t         key;    /* key value being inserted */
-       xfs_alloc_key_t         *kp;    /* pointer to btree keys */
-       xfs_agblock_t           nbno;   /* block number of allocated block */
-       xfs_btree_cur_t         *ncur;  /* new cursor to be used at next lvl */
-       xfs_alloc_key_t         nkey;   /* new key value, from split */
-       xfs_alloc_rec_t         nrec;   /* new record value, for caller */
-       int                     numrecs;
-       int                     optr;   /* old ptr value */
-       xfs_alloc_ptr_t         *pp;    /* pointer to btree addresses */
-       int                     ptr;    /* index in btree block for this rec */
-       xfs_alloc_rec_t         *rp;    /* pointer to btree records */
-
-       ASSERT(be32_to_cpu(recp->ar_blockcount) > 0);
-
-       /*
-        * GCC doesn't understand the (arguably complex) control flow in
-        * this function and complains about uninitialized structure fields
-        * without this.
-        */
-       memset(&nrec, 0, sizeof(nrec));
-
-       /*
-        * If we made it to the root level, allocate a new root block
-        * and we're done.
-        */
-       if (level >= cur->bc_nlevels) {
-               XFS_STATS_INC(xs_abt_insrec);
-               if ((error = xfs_alloc_newroot(cur, &i)))
-                       return error;
-               *bnop = NULLAGBLOCK;
-               *stat = i;
-               return 0;
-       }
-       /*
-        * Make a key out of the record data to be inserted, and save it.
-        */
-       key.ar_startblock = recp->ar_startblock;
-       key.ar_blockcount = recp->ar_blockcount;
-       optr = ptr = cur->bc_ptrs[level];
-       /*
-        * If we're off the left edge, return failure.
-        */
-       if (ptr == 0) {
-               *stat = 0;
-               return 0;
-       }
-       XFS_STATS_INC(xs_abt_insrec);
-       /*
-        * Get pointers to the btree buffer and block.
-        */
-       bp = cur->bc_bufs[level];
-       block = XFS_BUF_TO_ALLOC_BLOCK(bp);
-       numrecs = be16_to_cpu(block->bb_numrecs);
-#ifdef DEBUG
-       if ((error = xfs_btree_check_sblock(cur, block, level, bp)))
-               return error;
-       /*
-        * Check that the new entry is being inserted in the right place.
-        */
-       if (ptr <= numrecs) {
-               if (level == 0) {
-                       rp = XFS_ALLOC_REC_ADDR(block, ptr, cur);
-                       xfs_btree_check_rec(cur->bc_btnum, recp, rp);
-               } else {
-                       kp = XFS_ALLOC_KEY_ADDR(block, ptr, cur);
-                       xfs_btree_check_key(cur->bc_btnum, &key, kp);
-               }
-       }
-#endif
-       nbno = NULLAGBLOCK;
-       ncur = NULL;
-       /*
-        * If the block is full, we can't insert the new entry until we
-        * make the block un-full.
-        */
-       if (numrecs == XFS_ALLOC_BLOCK_MAXRECS(level, cur)) {
-               /*
-                * First, try shifting an entry to the right neighbor.
-                */
-               if ((error = xfs_alloc_rshift(cur, level, &i)))
-                       return error;
-               if (i) {
-                       /* nothing */
-               }
-               /*
-                * Next, try shifting an entry to the left neighbor.
-                */
-               else {
-                       if ((error = xfs_alloc_lshift(cur, level, &i)))
-                               return error;
-                       if (i)
-                               optr = ptr = cur->bc_ptrs[level];
-                       else {
-                               /*
-                                * Next, try splitting the current block in
-                                * half. If this works we have to re-set our
-                                * variables because we could be in a
-                                * different block now.
-                                */
-                               if ((error = xfs_alloc_split(cur, level, &nbno,
-                                               &nkey, &ncur, &i)))
-                                       return error;
-                               if (i) {
-                                       bp = cur->bc_bufs[level];
-                                       block = XFS_BUF_TO_ALLOC_BLOCK(bp);
-#ifdef DEBUG
-                                       if ((error =
-                                               xfs_btree_check_sblock(cur,
-                                                       block, level, bp)))
-                                               return error;
-#endif
-                                       ptr = cur->bc_ptrs[level];
-                                       nrec.ar_startblock = nkey.ar_startblock;
-                                       nrec.ar_blockcount = nkey.ar_blockcount;
-                               }
-                               /*
-                                * Otherwise the insert fails.
-                                */
-                               else {
-                                       *stat = 0;
-                                       return 0;
-                               }
-                       }
-               }
-       }
-       /*
-        * At this point we know there's room for our new entry in the block
-        * we're pointing at.
-        */
-       numrecs = be16_to_cpu(block->bb_numrecs);
-       if (level > 0) {
-               /*
-                * It's a non-leaf entry.  Make a hole for the new data
-                * in the key and ptr regions of the block.
-                */
-               kp = XFS_ALLOC_KEY_ADDR(block, 1, cur);
-               pp = XFS_ALLOC_PTR_ADDR(block, 1, cur);
-#ifdef DEBUG
-               for (i = numrecs; i >= ptr; i--) {
-                       if ((error = xfs_btree_check_sptr(cur, be32_to_cpu(pp[i - 1]), level)))
-                               return error;
-               }
-#endif
-               memmove(&kp[ptr], &kp[ptr - 1],
-                       (numrecs - ptr + 1) * sizeof(*kp));
-               memmove(&pp[ptr], &pp[ptr - 1],
-                       (numrecs - ptr + 1) * sizeof(*pp));
-#ifdef DEBUG
-               if ((error = xfs_btree_check_sptr(cur, *bnop, level)))
-                       return error;
-#endif
-               /*
-                * Now stuff the new data in, bump numrecs and log the new data.
-                */
-               kp[ptr - 1] = key;
-               pp[ptr - 1] = cpu_to_be32(*bnop);
-               numrecs++;
-               block->bb_numrecs = cpu_to_be16(numrecs);
-               xfs_alloc_log_keys(cur, bp, ptr, numrecs);
-               xfs_alloc_log_ptrs(cur, bp, ptr, numrecs);
-#ifdef DEBUG
-               if (ptr < numrecs)
-                       xfs_btree_check_key(cur->bc_btnum, kp + ptr - 1,
-                               kp + ptr);
-#endif
-       } else {
-               /*
-                * It's a leaf entry.  Make a hole for the new record.
-                */
-               rp = XFS_ALLOC_REC_ADDR(block, 1, cur);
-               memmove(&rp[ptr], &rp[ptr - 1],
-                       (numrecs - ptr + 1) * sizeof(*rp));
-               /*
-                * Now stuff the new record in, bump numrecs
-                * and log the new data.
-                */
-               rp[ptr - 1] = *recp;
-               numrecs++;
-               block->bb_numrecs = cpu_to_be16(numrecs);
-               xfs_alloc_log_recs(cur, bp, ptr, numrecs);
-#ifdef DEBUG
-               if (ptr < numrecs)
-                       xfs_btree_check_rec(cur->bc_btnum, rp + ptr - 1,
-                               rp + ptr);
-#endif
-       }
-       /*
-        * Log the new number of records in the btree header.
-        */
-       xfs_alloc_log_block(cur->bc_tp, bp, XFS_BB_NUMRECS);
-       /*
-        * If we inserted at the start of a block, update the parents' keys.
-        */
-       if (optr == 1 && (error = xfs_alloc_updkey(cur, &key, level + 1)))
-               return error;
-       /*
-        * Look to see if the longest extent in the allocation group
-        * needs to be updated.
-        */
 
-       agf = XFS_BUF_TO_AGF(cur->bc_private.a.agbp);
-       if (level == 0 &&
-           cur->bc_btnum == XFS_BTNUM_CNT &&
-           be32_to_cpu(block->bb_rightsib) == NULLAGBLOCK &&
-           be32_to_cpu(recp->ar_blockcount) > be32_to_cpu(agf->agf_longest)) {
-               /*
-                * If this is a leaf in the by-size btree and there
-                * is no right sibling block and this block is bigger
-                * than the previous longest block, update it.
-                */
-               agf->agf_longest = recp->ar_blockcount;
-               cur->bc_mp->m_perag[be32_to_cpu(agf->agf_seqno)].pagf_longest
-                       = be32_to_cpu(recp->ar_blockcount);
-               xfs_alloc_log_agf(cur->bc_tp, cur->bc_private.a.agbp,
-                       XFS_AGF_LONGEST);
-       }
-       /*
-        * Return the new block number, if any.
-        * If there is one, give back a record value and a cursor too.
-        */
-       *bnop = nbno;
-       if (nbno != NULLAGBLOCK) {
-               *recp = nrec;
-               *curp = ncur;
-       }
-       *stat = 1;
-       return 0;
-}
-
-/*
- * Log header fields from a btree block.
- */
-STATIC void
-xfs_alloc_log_block(
-       xfs_trans_t             *tp,    /* transaction pointer */
-       xfs_buf_t               *bp,    /* buffer containing btree block */
-       int                     fields) /* mask of fields: XFS_BB_... */
+STATIC struct xfs_btree_cur *
+xfs_allocbt_dup_cursor(
+       struct xfs_btree_cur    *cur)
 {
-       int                     first;  /* first byte offset logged */
-       int                     last;   /* last byte offset logged */
-       static const short      offsets[] = {   /* table of offsets */
-               offsetof(xfs_alloc_block_t, bb_magic),
-               offsetof(xfs_alloc_block_t, bb_level),
-               offsetof(xfs_alloc_block_t, bb_numrecs),
-               offsetof(xfs_alloc_block_t, bb_leftsib),
-               offsetof(xfs_alloc_block_t, bb_rightsib),
-               sizeof(xfs_alloc_block_t)
-       };
-
-       xfs_btree_offsets(fields, offsets, XFS_BB_NUM_BITS, &first, &last);
-       xfs_trans_log_buf(tp, bp, first, last);
+       return xfs_allocbt_init_cursor(cur->bc_mp, cur->bc_tp,
+                       cur->bc_private.a.agbp, cur->bc_private.a.agno,
+                       cur->bc_btnum);
 }
-
-/*
- * Log keys from a btree block (nonleaf).
- */
-STATIC void
-xfs_alloc_log_keys(
-       xfs_btree_cur_t         *cur,   /* btree cursor */
-       xfs_buf_t               *bp,    /* buffer containing btree block */
-       int                     kfirst, /* index of first key to log */
-       int                     klast)  /* index of last key to log */
-{
-       xfs_alloc_block_t       *block; /* btree block to log from */
-       int                     first;  /* first byte offset logged */
-       xfs_alloc_key_t         *kp;    /* key pointer in btree block */
-       int                     last;   /* last byte offset logged */
-
-       block = XFS_BUF_TO_ALLOC_BLOCK(bp);
-       kp = XFS_ALLOC_KEY_ADDR(block, 1, cur);
-       first = (int)((xfs_caddr_t)&kp[kfirst - 1] - (xfs_caddr_t)block);
-       last = (int)(((xfs_caddr_t)&kp[klast] - 1) - (xfs_caddr_t)block);
-       xfs_trans_log_buf(cur->bc_tp, bp, first, last);
-}
-
-/*
- * Log block pointer fields from a btree block (nonleaf).
- */
-STATIC void
-xfs_alloc_log_ptrs(
-       xfs_btree_cur_t         *cur,   /* btree cursor */
-       xfs_buf_t               *bp,    /* buffer containing btree block */
-       int                     pfirst, /* index of first pointer to log */
-       int                     plast)  /* index of last pointer to log */
-{
-       xfs_alloc_block_t       *block; /* btree block to log from */
-       int                     first;  /* first byte offset logged */
-       int                     last;   /* last byte offset logged */
-       xfs_alloc_ptr_t         *pp;    /* block-pointer pointer in btree blk */
-
-       block = XFS_BUF_TO_ALLOC_BLOCK(bp);
-       pp = XFS_ALLOC_PTR_ADDR(block, 1, cur);
-       first = (int)((xfs_caddr_t)&pp[pfirst - 1] - (xfs_caddr_t)block);
-       last = (int)(((xfs_caddr_t)&pp[plast] - 1) - (xfs_caddr_t)block);
-       xfs_trans_log_buf(cur->bc_tp, bp, first, last);
-}
-
-/*
- * Log records from a btree block (leaf).
- */
-STATIC void
-xfs_alloc_log_recs(
-       xfs_btree_cur_t         *cur,   /* btree cursor */
-       xfs_buf_t               *bp,    /* buffer containing btree block */
-       int                     rfirst, /* index of first record to log */
-       int                     rlast)  /* index of last record to log */
-{
-       xfs_alloc_block_t       *block; /* btree block to log from */
-       int                     first;  /* first byte offset logged */
-       int                     last;   /* last byte offset logged */
-       xfs_alloc_rec_t         *rp;    /* record pointer for btree block */
-
-
-       block = XFS_BUF_TO_ALLOC_BLOCK(bp);
-       rp = XFS_ALLOC_REC_ADDR(block, 1, cur);
-#ifdef DEBUG
-       {
-               xfs_agf_t       *agf;
-               xfs_alloc_rec_t *p;
-
-               agf = XFS_BUF_TO_AGF(cur->bc_private.a.agbp);
-               for (p = &rp[rfirst - 1]; p <= &rp[rlast - 1]; p++)
-                       ASSERT(be32_to_cpu(p->ar_startblock) +
-                              be32_to_cpu(p->ar_blockcount) <=
-                              be32_to_cpu(agf->agf_length));
-       }
-#endif
-       first = (int)((xfs_caddr_t)&rp[rfirst - 1] - (xfs_caddr_t)block);
-       last = (int)(((xfs_caddr_t)&rp[rlast] - 1) - (xfs_caddr_t)block);
-       xfs_trans_log_buf(cur->bc_tp, bp, first, last);
-}
-
-/*
- * Lookup the record.  The cursor is made to point to it, based on dir.
- * Return 0 if can't find any such record, 1 for success.
- */
-STATIC int                             /* error */
-xfs_alloc_lookup(
-       xfs_btree_cur_t         *cur,   /* btree cursor */
-       xfs_lookup_t            dir,    /* <=, ==, or >= */
-       int                     *stat)  /* success/failure */
-{
-       xfs_agblock_t           agbno;  /* a.g. relative btree block number */
-       xfs_agnumber_t          agno;   /* allocation group number */
-       xfs_alloc_block_t       *block=NULL;    /* current btree block */
-       int                     diff;   /* difference for the current key */
-       int                     error;  /* error return value */
-       int                     keyno=0;        /* current key number */
-       int                     level;  /* level in the btree */
-       xfs_mount_t             *mp;    /* file system mount point */
-
-       XFS_STATS_INC(xs_abt_lookup);
-       /*
-        * Get the allocation group header, and the root block number.
-        */
-       mp = cur->bc_mp;
-
-       {
-               xfs_agf_t       *agf;   /* a.g. freespace header */
-
-               agf = XFS_BUF_TO_AGF(cur->bc_private.a.agbp);
-               agno = be32_to_cpu(agf->agf_seqno);
-               agbno = be32_to_cpu(agf->agf_roots[cur->bc_btnum]);
-       }
-       /*
-        * Iterate over each level in the btree, starting at the root.
-        * For each level above the leaves, find the key we need, based
-        * on the lookup record, then follow the corresponding block
-        * pointer down to the next level.
-        */
-       for (level = cur->bc_nlevels - 1, diff = 1; level >= 0; level--) {
-               xfs_buf_t       *bp;    /* buffer pointer for btree block */
-               xfs_daddr_t     d;      /* disk address of btree block */
-
-               /*
-                * Get the disk address we're looking for.
-                */
-               d = XFS_AGB_TO_DADDR(mp, agno, agbno);
-               /*
-                * If the old buffer at this level is for a different block,
-                * throw it away, otherwise just use it.
-                */
-               bp = cur->bc_bufs[level];
-               if (bp && XFS_BUF_ADDR(bp) != d)
-                       bp = NULL;
-               if (!bp) {
-                       /*
-                        * Need to get a new buffer.  Read it, then
-                        * set it in the cursor, releasing the old one.
-                        */
-                       if ((error = xfs_btree_read_bufs(mp, cur->bc_tp, agno,
-                                       agbno, 0, &bp, XFS_ALLOC_BTREE_REF)))
-                               return error;
-                       xfs_btree_setbuf(cur, level, bp);
-                       /*
-                        * Point to the btree block, now that we have the buffer
-                        */
-                       block = XFS_BUF_TO_ALLOC_BLOCK(bp);
-                       if ((error = xfs_btree_check_sblock(cur, block, level,
-                                       bp)))
-                               return error;
-               } else
-                       block = XFS_BUF_TO_ALLOC_BLOCK(bp);
-               /*
-                * If we already had a key match at a higher level, we know
-                * we need to use the first entry in this block.
-                */
-               if (diff == 0)
-                       keyno = 1;
-               /*
-                * Otherwise we need to search this block.  Do a binary search.
-                */
-               else {
-                       int             high;   /* high entry number */
-                       xfs_alloc_key_t *kkbase=NULL;/* base of keys in block */
-                       xfs_alloc_rec_t *krbase=NULL;/* base of records in block */
-                       int             low;    /* low entry number */
-
-                       /*
-                        * Get a pointer to keys or records.
-                        */
-                       if (level > 0)
-                               kkbase = XFS_ALLOC_KEY_ADDR(block, 1, cur);
-                       else
-                               krbase = XFS_ALLOC_REC_ADDR(block, 1, cur);
-                       /*
-                        * Set low and high entry numbers, 1-based.
-                        */
-                       low = 1;
-                       if (!(high = be16_to_cpu(block->bb_numrecs))) {
-                               /*
-                                * If the block is empty, the tree must
-                                * be an empty leaf.
-                                */
-                               ASSERT(level == 0 && cur->bc_nlevels == 1);
-                               cur->bc_ptrs[0] = dir != XFS_LOOKUP_LE;
-                               *stat = 0;
-                               return 0;
-                       }
-                       /*
-                        * Binary search the block.
-                        */
-                       while (low <= high) {
-                               xfs_extlen_t    blockcount;     /* key value */
-                               xfs_agblock_t   startblock;     /* key value */
-
-                               XFS_STATS_INC(xs_abt_compare);
-                               /*
-                                * keyno is average of low and high.
-                                */
-                               keyno = (low + high) >> 1;
-                               /*
-                                * Get startblock & blockcount.
-                                */
-                               if (level > 0) {
-                                       xfs_alloc_key_t *kkp;
-
-                                       kkp = kkbase + keyno - 1;
-                                       startblock = be32_to_cpu(kkp->ar_startblock);
-                                       blockcount = be32_to_cpu(kkp->ar_blockcount);
-                               } else {
-                                       xfs_alloc_rec_t *krp;
-
-                                       krp = krbase + keyno - 1;
-                                       startblock = be32_to_cpu(krp->ar_startblock);
-                                       blockcount = be32_to_cpu(krp->ar_blockcount);
-                               }
-                               /*
-                                * Compute difference to get next direction.
-                                */
-                               if (cur->bc_btnum == XFS_BTNUM_BNO)
-                                       diff = (int)startblock -
-                                              (int)cur->bc_rec.a.ar_startblock;
-                               else if (!(diff = (int)blockcount -
-                                           (int)cur->bc_rec.a.ar_blockcount))
-                                       diff = (int)startblock -
-                                           (int)cur->bc_rec.a.ar_startblock;
-                               /*
-                                * Less than, move right.
-                                */
-                               if (diff < 0)
-                                       low = keyno + 1;
-                               /*
-                                * Greater than, move left.
-                                */
-                               else if (diff > 0)
-                                       high = keyno - 1;
-                               /*
-                                * Equal, we're done.
-                                */
-                               else
-                                       break;
-                       }
-               }
-               /*
-                * If there are more levels, set up for the next level
-                * by getting the block number and filling in the cursor.
-                */
-               if (level > 0) {
-                       /*
-                        * If we moved left, need the previous key number,
-                        * unless there isn't one.
-                        */
-                       if (diff > 0 && --keyno < 1)
-                               keyno = 1;
-                       agbno = be32_to_cpu(*XFS_ALLOC_PTR_ADDR(block, keyno, cur));
-#ifdef DEBUG
-                       if ((error = xfs_btree_check_sptr(cur, agbno, level)))
-                               return error;
-#endif
-                       cur->bc_ptrs[level] = keyno;
-               }
-       }
-       /*
-        * Done with the search.
-        * See if we need to adjust the results.
-        */
-       if (dir != XFS_LOOKUP_LE && diff < 0) {
-               keyno++;
-               /*
-                * If ge search and we went off the end of the block, but it's
-                * not the last block, we're in the wrong block.
-                */
-               if (dir == XFS_LOOKUP_GE &&
-                   keyno > be16_to_cpu(block->bb_numrecs) &&
-                   be32_to_cpu(block->bb_rightsib) != NULLAGBLOCK) {
-                       int     i;
-
-                       cur->bc_ptrs[0] = keyno;
-                       if ((error = xfs_alloc_increment(cur, 0, &i)))
-                               return error;
-                       XFS_WANT_CORRUPTED_RETURN(i == 1);
-                       *stat = 1;
-                       return 0;
-               }
-       }
-       else if (dir == XFS_LOOKUP_LE && diff > 0)
-               keyno--;
-       cur->bc_ptrs[0] = keyno;
-       /*
-        * Return if we succeeded or not.
-        */
-       if (keyno == 0 || keyno > be16_to_cpu(block->bb_numrecs))
-               *stat = 0;
-       else
-               *stat = ((dir != XFS_LOOKUP_EQ) || (diff == 0));
-       return 0;
-}
-
-/*
- * Move 1 record left from cur/level if possible.
- * Update cur to reflect the new path.
- */
-STATIC int                             /* error */
-xfs_alloc_lshift(
-       xfs_btree_cur_t         *cur,   /* btree cursor */
-       int                     level,  /* level to shift record on */
-       int                     *stat)  /* success/failure */
-{
-       int                     error;  /* error return value */
-#ifdef DEBUG
-       int                     i;      /* loop index */
-#endif
-       xfs_alloc_key_t         key;    /* key value for leaf level upward */
-       xfs_buf_t               *lbp;   /* buffer for left neighbor block */
-       xfs_alloc_block_t       *left;  /* left neighbor btree block */
-       int                     nrec;   /* new number of left block entries */
-       xfs_buf_t               *rbp;   /* buffer for right (current) block */
-       xfs_alloc_block_t       *right; /* right (current) btree block */
-       xfs_alloc_key_t         *rkp=NULL;      /* key pointer for right block */
-       xfs_alloc_ptr_t         *rpp=NULL;      /* address pointer for right block */
-       xfs_alloc_rec_t         *rrp=NULL;      /* record pointer for right block */
-
-       /*
-        * Set up variables for this block as "right".
-        */
-       rbp = cur->bc_bufs[level];
-       right = XFS_BUF_TO_ALLOC_BLOCK(rbp);
-#ifdef DEBUG
-       if ((error = xfs_btree_check_sblock(cur, right, level, rbp)))
-               return error;
-#endif
-       /*
-        * If we've got no left sibling then we can't shift an entry left.
-        */
-       if (be32_to_cpu(right->bb_leftsib) == NULLAGBLOCK) {
-               *stat = 0;
-               return 0;
-       }
-       /*
-        * If the cursor entry is the one that would be moved, don't
-        * do it... it's too complicated.
-        */
-       if (cur->bc_ptrs[level] <= 1) {
-               *stat = 0;
-               return 0;
-       }
-       /*
-        * Set up the left neighbor as "left".
-        */
-       if ((error = xfs_btree_read_bufs(cur->bc_mp, cur->bc_tp,
-                       cur->bc_private.a.agno, be32_to_cpu(right->bb_leftsib),
-                       0, &lbp, XFS_ALLOC_BTREE_REF)))
-               return error;
-       left = XFS_BUF_TO_ALLOC_BLOCK(lbp);
-       if ((error = xfs_btree_check_sblock(cur, left, level, lbp)))
-               return error;
-       /*
-        * If it's full, it can't take another entry.
-        */
-       if (be16_to_cpu(left->bb_numrecs) == XFS_ALLOC_BLOCK_MAXRECS(level, cur)) {
-               *stat = 0;
-               return 0;
-       }
-       nrec = be16_to_cpu(left->bb_numrecs) + 1;
-       /*
-        * If non-leaf, copy a key and a ptr to the left block.
-        */
-       if (level > 0) {
-               xfs_alloc_key_t *lkp;   /* key pointer for left block */
-               xfs_alloc_ptr_t *lpp;   /* address pointer for left block */
-
-               lkp = XFS_ALLOC_KEY_ADDR(left, nrec, cur);
-               rkp = XFS_ALLOC_KEY_ADDR(right, 1, cur);
-               *lkp = *rkp;
-               xfs_alloc_log_keys(cur, lbp, nrec, nrec);
-               lpp = XFS_ALLOC_PTR_ADDR(left, nrec, cur);
-               rpp = XFS_ALLOC_PTR_ADDR(right, 1, cur);
-#ifdef DEBUG
-               if ((error = xfs_btree_check_sptr(cur, be32_to_cpu(*rpp), level)))
-                       return error;
-#endif
-               *lpp = *rpp;
-               xfs_alloc_log_ptrs(cur, lbp, nrec, nrec);
-               xfs_btree_check_key(cur->bc_btnum, lkp - 1, lkp);
-       }
-       /*
-        * If leaf, copy a record to the left block.
-        */
-       else {
-               xfs_alloc_rec_t *lrp;   /* record pointer for left block */
-
-               lrp = XFS_ALLOC_REC_ADDR(left, nrec, cur);
-               rrp = XFS_ALLOC_REC_ADDR(right, 1, cur);
-               *lrp = *rrp;
-               xfs_alloc_log_recs(cur, lbp, nrec, nrec);
-               xfs_btree_check_rec(cur->bc_btnum, lrp - 1, lrp);
-       }
-       /*
-        * Bump and log left's numrecs, decrement and log right's numrecs.
-        */
-       be16_add_cpu(&left->bb_numrecs, 1);
-       xfs_alloc_log_block(cur->bc_tp, lbp, XFS_BB_NUMRECS);
-       be16_add_cpu(&right->bb_numrecs, -1);
-       xfs_alloc_log_block(cur->bc_tp, rbp, XFS_BB_NUMRECS);
-       /*
-        * Slide the contents of right down one entry.
-        */
-       if (level > 0) {
-#ifdef DEBUG
-               for (i = 0; i < be16_to_cpu(right->bb_numrecs); i++) {
-                       if ((error = xfs_btree_check_sptr(cur, be32_to_cpu(rpp[i + 1]),
-                                       level)))
-                               return error;
-               }
-#endif
-               memmove(rkp, rkp + 1, be16_to_cpu(right->bb_numrecs) * sizeof(*rkp));
-               memmove(rpp, rpp + 1, be16_to_cpu(right->bb_numrecs) * sizeof(*rpp));
-               xfs_alloc_log_keys(cur, rbp, 1, be16_to_cpu(right->bb_numrecs));
-               xfs_alloc_log_ptrs(cur, rbp, 1, be16_to_cpu(right->bb_numrecs));
-       } else {
-               memmove(rrp, rrp + 1, be16_to_cpu(right->bb_numrecs) * sizeof(*rrp));
-               xfs_alloc_log_recs(cur, rbp, 1, be16_to_cpu(right->bb_numrecs));
-               key.ar_startblock = rrp->ar_startblock;
-               key.ar_blockcount = rrp->ar_blockcount;
-               rkp = &key;
-       }
-       /*
-        * Update the parent key values of right.
-        */
-       if ((error = xfs_alloc_updkey(cur, rkp, level + 1)))
-               return error;
-       /*
-        * Slide the cursor value left one.
-        */
-       cur->bc_ptrs[level]--;
-       *stat = 1;
-       return 0;
-}
-
-/*
- * Allocate a new root block, fill it in.
- */
-STATIC int                             /* error */
-xfs_alloc_newroot(
-       xfs_btree_cur_t         *cur,   /* btree cursor */
-       int                     *stat)  /* success/failure */
-{
-       int                     error;  /* error return value */
-       xfs_agblock_t           lbno;   /* left block number */
-       xfs_buf_t               *lbp;   /* left btree buffer */
-       xfs_alloc_block_t       *left;  /* left btree block */
-       xfs_mount_t             *mp;    /* mount structure */
-       xfs_agblock_t           nbno;   /* new block number */
-       xfs_buf_t               *nbp;   /* new (root) buffer */
-       xfs_alloc_block_t       *new;   /* new (root) btree block */
-       int                     nptr;   /* new value for key index, 1 or 2 */
-       xfs_agblock_t           rbno;   /* right block number */
-       xfs_buf_t               *rbp;   /* right btree buffer */
-       xfs_alloc_block_t       *right; /* right btree block */
-
-       mp = cur->bc_mp;
-
-       ASSERT(cur->bc_nlevels < XFS_AG_MAXLEVELS(mp));
-       /*
-        * Get a buffer from the freelist blocks, for the new root.
-        */
-       error = xfs_alloc_get_freelist(cur->bc_tp,
-                                       cur->bc_private.a.agbp, &nbno, 1);
-       if (error)
-               return error;
-       /*
-        * None available, we fail.
-        */
-       if (nbno == NULLAGBLOCK) {
-               *stat = 0;
-               return 0;
-       }
-       xfs_trans_agbtree_delta(cur->bc_tp, 1);
-       nbp = xfs_btree_get_bufs(mp, cur->bc_tp, cur->bc_private.a.agno, nbno,
-               0);
-       new = XFS_BUF_TO_ALLOC_BLOCK(nbp);
-       /*
-        * Set the root data in the a.g. freespace structure.
-        */
-       {
-               xfs_agf_t       *agf;   /* a.g. freespace header */
-               xfs_agnumber_t  seqno;
-
-               agf = XFS_BUF_TO_AGF(cur->bc_private.a.agbp);
-               agf->agf_roots[cur->bc_btnum] = cpu_to_be32(nbno);
-               be32_add_cpu(&agf->agf_levels[cur->bc_btnum], 1);
-               seqno = be32_to_cpu(agf->agf_seqno);
-               mp->m_perag[seqno].pagf_levels[cur->bc_btnum]++;
-               xfs_alloc_log_agf(cur->bc_tp, cur->bc_private.a.agbp,
-                       XFS_AGF_ROOTS | XFS_AGF_LEVELS);
-       }
-       /*
-        * At the previous root level there are now two blocks: the old
-        * root, and the new block generated when it was split.
-        * We don't know which one the cursor is pointing at, so we
-        * set up variables "left" and "right" for each case.
-        */
-       lbp = cur->bc_bufs[cur->bc_nlevels - 1];
-       left = XFS_BUF_TO_ALLOC_BLOCK(lbp);
-#ifdef DEBUG
-       if ((error = xfs_btree_check_sblock(cur, left, cur->bc_nlevels - 1, lbp)))
-               return error;
-#endif
-       if (be32_to_cpu(left->bb_rightsib) != NULLAGBLOCK) {
-               /*
-                * Our block is left, pick up the right block.
-                */
-               lbno = XFS_DADDR_TO_AGBNO(mp, XFS_BUF_ADDR(lbp));
-               rbno = be32_to_cpu(left->bb_rightsib);
-               if ((error = xfs_btree_read_bufs(mp, cur->bc_tp,
-                               cur->bc_private.a.agno, rbno, 0, &rbp,
-                               XFS_ALLOC_BTREE_REF)))
-                       return error;
-               right = XFS_BUF_TO_ALLOC_BLOCK(rbp);
-               if ((error = xfs_btree_check_sblock(cur, right,
-                               cur->bc_nlevels - 1, rbp)))
-                       return error;
-               nptr = 1;
-       } else {
-               /*
-                * Our block is right, pick up the left block.
-                */
-               rbp = lbp;
-               right = left;
-               rbno = XFS_DADDR_TO_AGBNO(mp, XFS_BUF_ADDR(rbp));
-               lbno = be32_to_cpu(right->bb_leftsib);
-               if ((error = xfs_btree_read_bufs(mp, cur->bc_tp,
-                               cur->bc_private.a.agno, lbno, 0, &lbp,
-                               XFS_ALLOC_BTREE_REF)))
-                       return error;
-               left = XFS_BUF_TO_ALLOC_BLOCK(lbp);
-               if ((error = xfs_btree_check_sblock(cur, left,
-                               cur->bc_nlevels - 1, lbp)))
-                       return error;
-               nptr = 2;
-       }
-       /*
-        * Fill in the new block's btree header and log it.
-        */
-       new->bb_magic = cpu_to_be32(xfs_magics[cur->bc_btnum]);
-       new->bb_level = cpu_to_be16(cur->bc_nlevels);
-       new->bb_numrecs = cpu_to_be16(2);
-       new->bb_leftsib = cpu_to_be32(NULLAGBLOCK);
-       new->bb_rightsib = cpu_to_be32(NULLAGBLOCK);
-       xfs_alloc_log_block(cur->bc_tp, nbp, XFS_BB_ALL_BITS);
-       ASSERT(lbno != NULLAGBLOCK && rbno != NULLAGBLOCK);
-       /*
-        * Fill in the key data in the new root.
-        */
-       {
-               xfs_alloc_key_t         *kp;    /* btree key pointer */
-
-               kp = XFS_ALLOC_KEY_ADDR(new, 1, cur);
-               if (be16_to_cpu(left->bb_level) > 0) {
-                       kp[0] = *XFS_ALLOC_KEY_ADDR(left, 1, cur);
-                       kp[1] = *XFS_ALLOC_KEY_ADDR(right, 1, cur);
-               } else {
-                       xfs_alloc_rec_t *rp;    /* btree record pointer */
-
-                       rp = XFS_ALLOC_REC_ADDR(left, 1, cur);
-                       kp[0].ar_startblock = rp->ar_startblock;
-                       kp[0].ar_blockcount = rp->ar_blockcount;
-                       rp = XFS_ALLOC_REC_ADDR(right, 1, cur);
-                       kp[1].ar_startblock = rp->ar_startblock;
-                       kp[1].ar_blockcount = rp->ar_blockcount;
-               }
-       }
-       xfs_alloc_log_keys(cur, nbp, 1, 2);
-       /*
-        * Fill in the pointer data in the new root.
-        */
-       {
-               xfs_alloc_ptr_t         *pp;    /* btree address pointer */
-
-               pp = XFS_ALLOC_PTR_ADDR(new, 1, cur);
-               pp[0] = cpu_to_be32(lbno);
-               pp[1] = cpu_to_be32(rbno);
-       }
-       xfs_alloc_log_ptrs(cur, nbp, 1, 2);
-       /*
-        * Fix up the cursor.
-        */
-       xfs_btree_setbuf(cur, cur->bc_nlevels, nbp);
-       cur->bc_ptrs[cur->bc_nlevels] = nptr;
-       cur->bc_nlevels++;
-       *stat = 1;
-       return 0;
-}
-
-/*
- * Move 1 record right from cur/level if possible.
- * Update cur to reflect the new path.
- */
-STATIC int                             /* error */
-xfs_alloc_rshift(
-       xfs_btree_cur_t         *cur,   /* btree cursor */
-       int                     level,  /* level to shift record on */
-       int                     *stat)  /* success/failure */
-{
-       int                     error;  /* error return value */
-       int                     i;      /* loop index */
-       xfs_alloc_key_t         key;    /* key value for leaf level upward */
-       xfs_buf_t               *lbp;   /* buffer for left (current) block */
-       xfs_alloc_block_t       *left;  /* left (current) btree block */
-       xfs_buf_t               *rbp;   /* buffer for right neighbor block */
-       xfs_alloc_block_t       *right; /* right neighbor btree block */
-       xfs_alloc_key_t         *rkp;   /* key pointer for right block */
-       xfs_btree_cur_t         *tcur;  /* temporary cursor */
-
-       /*
-        * Set up variables for this block as "left".
-        */
-       lbp = cur->bc_bufs[level];
-       left = XFS_BUF_TO_ALLOC_BLOCK(lbp);
-#ifdef DEBUG
-       if ((error = xfs_btree_check_sblock(cur, left, level, lbp)))
-               return error;
-#endif
-       /*
-        * If we've got no right sibling then we can't shift an entry right.
-        */
-       if (be32_to_cpu(left->bb_rightsib) == NULLAGBLOCK) {
-               *stat = 0;
-               return 0;
-       }
-       /*
-        * If the cursor entry is the one that would be moved, don't
-        * do it... it's too complicated.
-        */
-       if (cur->bc_ptrs[level] >= be16_to_cpu(left->bb_numrecs)) {
-               *stat = 0;
-               return 0;
-       }
-       /*
-        * Set up the right neighbor as "right".
-        */
-       if ((error = xfs_btree_read_bufs(cur->bc_mp, cur->bc_tp,
-                       cur->bc_private.a.agno, be32_to_cpu(left->bb_rightsib),
-                       0, &rbp, XFS_ALLOC_BTREE_REF)))
-               return error;
-       right = XFS_BUF_TO_ALLOC_BLOCK(rbp);
-       if ((error = xfs_btree_check_sblock(cur, right, level, rbp)))
+
+STATIC void
+xfs_allocbt_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;
+
+       ASSERT(ptr->s != 0);
+
+       agf->agf_roots[btnum] = ptr->s;
+       be32_add_cpu(&agf->agf_levels[btnum], inc);
+       cur->bc_mp->m_perag[seqno].pagf_levels[btnum] += inc;
+
+       xfs_alloc_log_agf(cur->bc_tp, agbp, XFS_AGF_ROOTS | XFS_AGF_LEVELS);
+}
+
+STATIC int
+xfs_allocbt_alloc_block(
+       struct xfs_btree_cur    *cur,
+       union xfs_btree_ptr     *start,
+       union xfs_btree_ptr     *new,
+       int                     length,
+       int                     *stat)
+{
+       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;
-       /*
-        * If it's full, it can't take another entry.
-        */
-       if (be16_to_cpu(right->bb_numrecs) == XFS_ALLOC_BLOCK_MAXRECS(level, cur)) {
+       }
+
+       if (bno == NULLAGBLOCK) {
+               XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
                *stat = 0;
                return 0;
        }
-       /*
-        * Make a hole at the start of the right neighbor block, then
-        * copy the last left block entry to the hole.
-        */
-       if (level > 0) {
-               xfs_alloc_key_t *lkp;   /* key pointer for left block */
-               xfs_alloc_ptr_t *lpp;   /* address pointer for left block */
-               xfs_alloc_ptr_t *rpp;   /* address pointer for right block */
 
-               lkp = XFS_ALLOC_KEY_ADDR(left, be16_to_cpu(left->bb_numrecs), cur);
-               lpp = XFS_ALLOC_PTR_ADDR(left, be16_to_cpu(left->bb_numrecs), cur);
-               rkp = XFS_ALLOC_KEY_ADDR(right, 1, cur);
-               rpp = XFS_ALLOC_PTR_ADDR(right, 1, cur);
-#ifdef DEBUG
-               for (i = be16_to_cpu(right->bb_numrecs) - 1; i >= 0; i--) {
-                       if ((error = xfs_btree_check_sptr(cur, be32_to_cpu(rpp[i]), level)))
-                               return error;
-               }
-#endif
-               memmove(rkp + 1, rkp, be16_to_cpu(right->bb_numrecs) * sizeof(*rkp));
-               memmove(rpp + 1, rpp, be16_to_cpu(right->bb_numrecs) * sizeof(*rpp));
-#ifdef DEBUG
-               if ((error = xfs_btree_check_sptr(cur, be32_to_cpu(*lpp), level)))
-                       return error;
-#endif
-               *rkp = *lkp;
-               *rpp = *lpp;
-               xfs_alloc_log_keys(cur, rbp, 1, be16_to_cpu(right->bb_numrecs) + 1);
-               xfs_alloc_log_ptrs(cur, rbp, 1, be16_to_cpu(right->bb_numrecs) + 1);
-               xfs_btree_check_key(cur->bc_btnum, rkp, rkp + 1);
-       } else {
-               xfs_alloc_rec_t *lrp;   /* record pointer for left block */
-               xfs_alloc_rec_t *rrp;   /* record pointer for right block */
+       xfs_trans_agbtree_delta(cur->bc_tp, 1);
+       new->s = cpu_to_be32(bno);
 
-               lrp = XFS_ALLOC_REC_ADDR(left, be16_to_cpu(left->bb_numrecs), cur);
-               rrp = XFS_ALLOC_REC_ADDR(right, 1, cur);
-               memmove(rrp + 1, rrp, be16_to_cpu(right->bb_numrecs) * sizeof(*rrp));
-               *rrp = *lrp;
-               xfs_alloc_log_recs(cur, rbp, 1, be16_to_cpu(right->bb_numrecs) + 1);
-               key.ar_startblock = rrp->ar_startblock;
-               key.ar_blockcount = rrp->ar_blockcount;
-               rkp = &key;
-               xfs_btree_check_rec(cur->bc_btnum, rrp, rrp + 1);
-       }
-       /*
-        * Decrement and log left's numrecs, bump and log right's numrecs.
-        */
-       be16_add_cpu(&left->bb_numrecs, -1);
-       xfs_alloc_log_block(cur->bc_tp, lbp, XFS_BB_NUMRECS);
-       be16_add_cpu(&right->bb_numrecs, 1);
-       xfs_alloc_log_block(cur->bc_tp, rbp, XFS_BB_NUMRECS);
-       /*
-        * Using a temporary cursor, update the parent key values of the
-        * block on the right.
-        */
-       if ((error = xfs_btree_dup_cursor(cur, &tcur)))
-               return error;
-       i = xfs_btree_lastrec(tcur, level);
-       XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
-       if ((error = xfs_alloc_increment(tcur, level, &i)) ||
-           (error = xfs_alloc_updkey(tcur, rkp, level + 1)))
-               goto error0;
-       xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
+       XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
        *stat = 1;
        return 0;
-error0:
-       xfs_btree_del_cursor(tcur, XFS_BTREE_ERROR);
-       return error;
 }
 
-/*
- * Split cur/level block in half.
- * Return new block number and its first record (to be inserted into parent).
- */
-STATIC int                             /* error */
-xfs_alloc_split(
-       xfs_btree_cur_t         *cur,   /* btree cursor */
-       int                     level,  /* level to split */
-       xfs_agblock_t           *bnop,  /* output: block number allocated */
-       xfs_alloc_key_t         *keyp,  /* output: first key of new block */
-       xfs_btree_cur_t         **curp, /* output: new cursor */
-       int                     *stat)  /* success/failure */
+STATIC int
+xfs_allocbt_free_block(
+       struct xfs_btree_cur    *cur,
+       struct xfs_buf          *bp)
 {
-       int                     error;  /* error return value */
-       int                     i;      /* loop index/record number */
-       xfs_agblock_t           lbno;   /* left (current) block number */
-       xfs_buf_t               *lbp;   /* buffer for left block */
-       xfs_alloc_block_t       *left;  /* left (current) btree block */
-       xfs_agblock_t           rbno;   /* right (new) block number */
-       xfs_buf_t               *rbp;   /* buffer for right block */
-       xfs_alloc_block_t       *right; /* right (new) btree block */
+       struct xfs_buf          *agbp = cur->bc_private.a.agbp;
+       struct xfs_agf          *agf = XFS_BUF_TO_AGF(agbp);
+       xfs_agblock_t           bno;
+       int                     error;
 
-       /*
-        * Allocate the new block from the freelist.
-        * If we can't do it, we're toast.  Give up.
-        */
-       error = xfs_alloc_get_freelist(cur->bc_tp,
-                                        cur->bc_private.a.agbp, &rbno, 1);
+       bno = xfs_daddr_to_agbno(cur->bc_mp, XFS_BUF_ADDR(bp));
+       error = xfs_alloc_put_freelist(cur->bc_tp, agbp, NULL, bno, 1);
        if (error)
                return error;
-       if (rbno == NULLAGBLOCK) {
-               *stat = 0;
-               return 0;
-       }
-       xfs_trans_agbtree_delta(cur->bc_tp, 1);
-       rbp = xfs_btree_get_bufs(cur->bc_mp, cur->bc_tp, cur->bc_private.a.agno,
-               rbno, 0);
-       /*
-        * Set up the new block as "right".
-        */
-       right = XFS_BUF_TO_ALLOC_BLOCK(rbp);
-       /*
-        * "Left" is the current (according to the cursor) block.
-        */
-       lbp = cur->bc_bufs[level];
-       left = XFS_BUF_TO_ALLOC_BLOCK(lbp);
-#ifdef DEBUG
-       if ((error = xfs_btree_check_sblock(cur, left, level, lbp)))
-               return error;
-#endif
-       /*
-        * Fill in the btree header for the new block.
-        */
-       right->bb_magic = cpu_to_be32(xfs_magics[cur->bc_btnum]);
-       right->bb_level = left->bb_level;
-       right->bb_numrecs = cpu_to_be16(be16_to_cpu(left->bb_numrecs) / 2);
-       /*
-        * Make sure that if there's an odd number of entries now, that
-        * each new block will have the same number of entries.
-        */
-       if ((be16_to_cpu(left->bb_numrecs) & 1) &&
-           cur->bc_ptrs[level] <= be16_to_cpu(right->bb_numrecs) + 1)
-               be16_add_cpu(&right->bb_numrecs, 1);
-       i = be16_to_cpu(left->bb_numrecs) - be16_to_cpu(right->bb_numrecs) + 1;
-       /*
-        * For non-leaf blocks, copy keys and addresses over to the new block.
-        */
-       if (level > 0) {
-               xfs_alloc_key_t *lkp;   /* left btree key pointer */
-               xfs_alloc_ptr_t *lpp;   /* left btree address pointer */
-               xfs_alloc_key_t *rkp;   /* right btree key pointer */
-               xfs_alloc_ptr_t *rpp;   /* right btree address pointer */
-
-               lkp = XFS_ALLOC_KEY_ADDR(left, i, cur);
-               lpp = XFS_ALLOC_PTR_ADDR(left, i, cur);
-               rkp = XFS_ALLOC_KEY_ADDR(right, 1, cur);
-               rpp = XFS_ALLOC_PTR_ADDR(right, 1, cur);
-#ifdef DEBUG
-               for (i = 0; i < be16_to_cpu(right->bb_numrecs); i++) {
-                       if ((error = xfs_btree_check_sptr(cur, be32_to_cpu(lpp[i]), level)))
-                               return error;
-               }
-#endif
-               memcpy(rkp, lkp, be16_to_cpu(right->bb_numrecs) * sizeof(*rkp));
-               memcpy(rpp, lpp, be16_to_cpu(right->bb_numrecs) * sizeof(*rpp));
-               xfs_alloc_log_keys(cur, rbp, 1, be16_to_cpu(right->bb_numrecs));
-               xfs_alloc_log_ptrs(cur, rbp, 1, be16_to_cpu(right->bb_numrecs));
-               *keyp = *rkp;
-       }
-       /*
-        * For leaf blocks, copy records over to the new block.
-        */
-       else {
-               xfs_alloc_rec_t *lrp;   /* left btree record pointer */
-               xfs_alloc_rec_t *rrp;   /* right btree record pointer */
-
-               lrp = XFS_ALLOC_REC_ADDR(left, i, cur);
-               rrp = XFS_ALLOC_REC_ADDR(right, 1, cur);
-               memcpy(rrp, lrp, be16_to_cpu(right->bb_numrecs) * sizeof(*rrp));
-               xfs_alloc_log_recs(cur, rbp, 1, be16_to_cpu(right->bb_numrecs));
-               keyp->ar_startblock = rrp->ar_startblock;
-               keyp->ar_blockcount = rrp->ar_blockcount;
-       }
-       /*
-        * Find the left block number by looking in the buffer.
-        * Adjust numrecs, sibling pointers.
-        */
-       lbno = XFS_DADDR_TO_AGBNO(cur->bc_mp, XFS_BUF_ADDR(lbp));
-       be16_add_cpu(&left->bb_numrecs, -(be16_to_cpu(right->bb_numrecs)));
-       right->bb_rightsib = left->bb_rightsib;
-       left->bb_rightsib = cpu_to_be32(rbno);
-       right->bb_leftsib = cpu_to_be32(lbno);
-       xfs_alloc_log_block(cur->bc_tp, rbp, XFS_BB_ALL_BITS);
-       xfs_alloc_log_block(cur->bc_tp, lbp, XFS_BB_NUMRECS | XFS_BB_RIGHTSIB);
-       /*
-        * If there's a block to the new block's right, make that block
-        * point back to right instead of to left.
-        */
-       if (be32_to_cpu(right->bb_rightsib) != NULLAGBLOCK) {
-               xfs_alloc_block_t       *rrblock;       /* rr btree block */
-               xfs_buf_t               *rrbp;          /* buffer for rrblock */
 
-               if ((error = xfs_btree_read_bufs(cur->bc_mp, cur->bc_tp,
-                               cur->bc_private.a.agno, be32_to_cpu(right->bb_rightsib), 0,
-                               &rrbp, XFS_ALLOC_BTREE_REF)))
-                       return error;
-               rrblock = XFS_BUF_TO_ALLOC_BLOCK(rrbp);
-               if ((error = xfs_btree_check_sblock(cur, rrblock, level, rrbp)))
-                       return error;
-               rrblock->bb_leftsib = cpu_to_be32(rbno);
-               xfs_alloc_log_block(cur->bc_tp, rrbp, XFS_BB_LEFTSIB);
-       }
-       /*
-        * If the cursor is really in the right block, move it there.
-        * If it's just pointing past the last entry in left, then we'll
-        * insert there, so don't change anything in that case.
-        */
-       if (cur->bc_ptrs[level] > be16_to_cpu(left->bb_numrecs) + 1) {
-               xfs_btree_setbuf(cur, level, rbp);
-               cur->bc_ptrs[level] -= be16_to_cpu(left->bb_numrecs);
-       }
        /*
-        * If there are more levels, we'll need another cursor which refers to
-        * the right block, no matter where this cursor was.
+        * Since blocks move to the free list without the coordination used in
+        * xfs_bmap_finish, we can't allow block to be available for
+        * reallocation and non-transaction writing (user data) until we know
+        * that the transaction that moved it to the free list is permanently
+        * on disk. We track the blocks by declaring these blocks as "busy";
+        * the busy list is maintained on a per-ag basis and each transaction
+        * records which entries should be removed when the iclog commits to
+        * disk. If a busy block is allocated, the iclog is pushed up to the
+        * LSN that freed the block.
         */
-       if (level + 1 < cur->bc_nlevels) {
-               if ((error = xfs_btree_dup_cursor(cur, curp)))
-                       return error;
-               (*curp)->bc_ptrs[level + 1]++;
-       }
-       *bnop = rbno;
-       *stat = 1;
+       xfs_alloc_mark_busy(cur->bc_tp, be32_to_cpu(agf->agf_seqno), bno, 1);
+       xfs_trans_agbtree_delta(cur->bc_tp, -1);
        return 0;
 }
 
 /*
- * Update keys at all levels from here to the root along the cursor's path.
+ * Update the longest extent in the AGF
  */
-STATIC int                             /* error */
-xfs_alloc_updkey(
-       xfs_btree_cur_t         *cur,   /* btree cursor */
-       xfs_alloc_key_t         *keyp,  /* new key value to update to */
-       int                     level)  /* starting level for update */
+STATIC void
+xfs_allocbt_update_lastrec(
+       struct xfs_btree_cur    *cur,
+       struct xfs_btree_block  *block,
+       union xfs_btree_rec     *rec,
+       int                     ptr,
+       int                     reason)
 {
-       int                     ptr;    /* index of key in block */
+       struct xfs_agf          *agf = XFS_BUF_TO_AGF(cur->bc_private.a.agbp);
+       xfs_agnumber_t          seqno = be32_to_cpu(agf->agf_seqno);
+       __be32                  len;
+       int                     numrecs;
 
-       /*
-        * Go up the tree from this level toward the root.
-        * At each level, update the key value to the value input.
-        * Stop when we reach a level where the cursor isn't pointing
-        * at the first entry in the block.
-        */
-       for (ptr = 1; ptr == 1 && level < cur->bc_nlevels; level++) {
-               xfs_alloc_block_t       *block; /* btree block */
-               xfs_buf_t               *bp;    /* buffer for block */
-#ifdef DEBUG
-               int                     error;  /* error return value */
-#endif
-               xfs_alloc_key_t         *kp;    /* ptr to btree block keys */
+       ASSERT(cur->bc_btnum == XFS_BTNUM_CNT);
+
+       switch (reason) {
+       case LASTREC_UPDATE:
+               /*
+                * If this is the last leaf block and it's the last record,
+                * then update the size of the longest extent in the AG.
+                */
+               if (ptr != xfs_btree_get_numrecs(block))
+                       return;
+               len = rec->alloc.ar_blockcount;
+               break;
+       case LASTREC_INSREC:
+               if (be32_to_cpu(rec->alloc.ar_blockcount) <=
+                   be32_to_cpu(agf->agf_longest))
+                       return;
+               len = rec->alloc.ar_blockcount;
+               break;
+       case LASTREC_DELREC:
+               numrecs = xfs_btree_get_numrecs(block);
+               if (ptr <= numrecs)
+                       return;
+               ASSERT(ptr == numrecs + 1);
 
-               bp = cur->bc_bufs[level];
-               block = XFS_BUF_TO_ALLOC_BLOCK(bp);
-#ifdef DEBUG
-               if ((error = xfs_btree_check_sblock(cur, block, level, bp)))
-                       return error;
-#endif
-               ptr = cur->bc_ptrs[level];
-               kp = XFS_ALLOC_KEY_ADDR(block, ptr, cur);
-               *kp = *keyp;
-               xfs_alloc_log_keys(cur, bp, ptr, ptr);
+               if (numrecs) {
+                       xfs_alloc_rec_t *rrp;
+
+                       rrp = XFS_ALLOC_REC_ADDR(cur->bc_mp, block, numrecs);
+                       len = rrp->ar_blockcount;
+               } else {
+                       len = 0;
+               }
+
+               break;
+       default:
+               ASSERT(0);
+               return;
        }
-       return 0;
+
+       agf->agf_longest = len;
+       cur->bc_mp->m_perag[seqno].pagf_longest = be32_to_cpu(len);
+       xfs_alloc_log_agf(cur->bc_tp, cur->bc_private.a.agbp, XFS_AGF_LONGEST);
 }
 
-/*
- * Externally visible routines.
- */
+STATIC int
+xfs_allocbt_get_minrecs(
+       struct xfs_btree_cur    *cur,
+       int                     level)
+{
+       return cur->bc_mp->m_alloc_mnr[level != 0];
+}
 
-/*
- * Decrement cursor by one record at the level.
- * For nonzero levels the leaf-ward information is untouched.
- */
-int                                    /* error */
-xfs_alloc_decrement(
-       xfs_btree_cur_t         *cur,   /* btree cursor */
-       int                     level,  /* level in btree, 0 is leaf */
-       int                     *stat)  /* success/failure */
+STATIC int
+xfs_allocbt_get_maxrecs(
+       struct xfs_btree_cur    *cur,
+       int                     level)
 {
-       xfs_alloc_block_t       *block; /* btree block */
-       int                     error;  /* error return value */
-       int                     lev;    /* btree level */
+       return cur->bc_mp->m_alloc_mxr[level != 0];
+}
 
-       ASSERT(level < cur->bc_nlevels);
-       /*
-        * Read-ahead to the left at this level.
-        */
-       xfs_btree_readahead(cur, level, XFS_BTCUR_LEFTRA);
-       /*
-        * Decrement the ptr at this level.  If we're still in the block
-        * then we're done.
-        */
-       if (--cur->bc_ptrs[level] > 0) {
-               *stat = 1;
-               return 0;
-       }
-       /*
-        * Get a pointer to the btree block.
-        */
-       block = XFS_BUF_TO_ALLOC_BLOCK(cur->bc_bufs[level]);
-#ifdef DEBUG
-       if ((error = xfs_btree_check_sblock(cur, block, level,
-                       cur->bc_bufs[level])))
-               return error;
-#endif
-       /*
-        * If we just went off the left edge of the tree, return failure.
-        */
-       if (be32_to_cpu(block->bb_leftsib) == NULLAGBLOCK) {
-               *stat = 0;
-               return 0;
-       }
-       /*
-        * March up the tree decrementing pointers.
-        * Stop when we don't go off the left edge of a block.
-        */
-       for (lev = level + 1; lev < cur->bc_nlevels; lev++) {
-               if (--cur->bc_ptrs[lev] > 0)
-                       break;
-               /*
-                * Read-ahead the left block, we're going to read it
-                * in the next loop.
-                */
-               xfs_btree_readahead(cur, lev, XFS_BTCUR_LEFTRA);
-       }
-       /*
-        * If we went off the root then we are seriously confused.
-        */
-       ASSERT(lev < cur->bc_nlevels);
-       /*
-        * Now walk back down the tree, fixing up the cursor's buffer
-        * pointers and key numbers.
-        */
-       for (block = XFS_BUF_TO_ALLOC_BLOCK(cur->bc_bufs[lev]); lev > level; ) {
-               xfs_agblock_t   agbno;  /* block number of btree block */
-               xfs_buf_t       *bp;    /* buffer pointer for block */
+STATIC void
+xfs_allocbt_init_key_from_rec(
+       union xfs_btree_key     *key,
+       union xfs_btree_rec     *rec)
+{
+       ASSERT(rec->alloc.ar_startblock != 0);
 
-               agbno = be32_to_cpu(*XFS_ALLOC_PTR_ADDR(block, cur->bc_ptrs[lev], cur));
-               if ((error = xfs_btree_read_bufs(cur->bc_mp, cur->bc_tp,
-                               cur->bc_private.a.agno, agbno, 0, &bp,
-                               XFS_ALLOC_BTREE_REF)))
-                       return error;
-               lev--;
-               xfs_btree_setbuf(cur, lev, bp);
-               block = XFS_BUF_TO_ALLOC_BLOCK(bp);
-               if ((error = xfs_btree_check_sblock(cur, block, lev, bp)))
-                       return error;
-               cur->bc_ptrs[lev] = be16_to_cpu(block->bb_numrecs);
-       }
-       *stat = 1;
-       return 0;
+       key->alloc.ar_startblock = rec->alloc.ar_startblock;
+       key->alloc.ar_blockcount = rec->alloc.ar_blockcount;
 }
 
-/*
- * Delete the record pointed to by cur.
- * The cursor refers to the place where the record was (could be inserted)
- * when the operation returns.
- */
-int                                    /* error */
-xfs_alloc_delete(
-       xfs_btree_cur_t *cur,           /* btree cursor */
-       int             *stat)          /* success/failure */
+STATIC void
+xfs_allocbt_init_rec_from_key(
+       union xfs_btree_key     *key,
+       union xfs_btree_rec     *rec)
 {
-       int             error;          /* error return value */
-       int             i;              /* result code */
-       int             level;          /* btree level */
+       ASSERT(key->alloc.ar_startblock != 0);
 
-       /*
-        * Go up the tree, starting at leaf level.
-        * If 2 is returned then a join was done; go to the next level.
-        * Otherwise we are done.
-        */
-       for (level = 0, i = 2; i == 2; level++) {
-               if ((error = xfs_alloc_delrec(cur, level, &i)))
-                       return error;
-       }
-       if (i == 0) {
-               for (level = 1; level < cur->bc_nlevels; level++) {
-                       if (cur->bc_ptrs[level] == 0) {
-                               if ((error = xfs_alloc_decrement(cur, level, &i)))
-                                       return error;
-                               break;
-                       }
-               }
-       }
-       *stat = i;
-       return 0;
+       rec->alloc.ar_startblock = key->alloc.ar_startblock;
+       rec->alloc.ar_blockcount = key->alloc.ar_blockcount;
 }
 
-/*
- * Get the data from the pointed-to record.
- */
-int                                    /* error */
-xfs_alloc_get_rec(
-       xfs_btree_cur_t         *cur,   /* btree cursor */
-       xfs_agblock_t           *bno,   /* output: starting block of extent */
-       xfs_extlen_t            *len,   /* output: length of extent */
-       int                     *stat)  /* output: success/failure */
+STATIC void
+xfs_allocbt_init_rec_from_cur(
+       struct xfs_btree_cur    *cur,
+       union xfs_btree_rec     *rec)
 {
-       xfs_alloc_block_t       *block; /* btree block */
-#ifdef DEBUG
-       int                     error;  /* error return value */
-#endif
-       int                     ptr;    /* record number */
+       ASSERT(cur->bc_rec.a.ar_startblock != 0);
 
-       ptr = cur->bc_ptrs[0];
-       block = XFS_BUF_TO_ALLOC_BLOCK(cur->bc_bufs[0]);
-#ifdef DEBUG
-       if ((error = xfs_btree_check_sblock(cur, block, 0, cur->bc_bufs[0])))
-               return error;
-#endif
-       /*
-        * Off the right end or left end, return failure.
-        */
-       if (ptr > be16_to_cpu(block->bb_numrecs) || ptr <= 0) {
-               *stat = 0;
-               return 0;
-       }
-       /*
-        * Point to the record and extract its data.
-        */
-       {
-               xfs_alloc_rec_t         *rec;   /* record data */
+       rec->alloc.ar_startblock = cpu_to_be32(cur->bc_rec.a.ar_startblock);
+       rec->alloc.ar_blockcount = cpu_to_be32(cur->bc_rec.a.ar_blockcount);
+}
+
+STATIC void
+xfs_allocbt_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_allocbt_key_diff(
+       struct xfs_btree_cur    *cur,
+       union xfs_btree_key     *key)
+{
+       xfs_alloc_rec_incore_t  *rec = &cur->bc_rec.a;
+       xfs_alloc_key_t         *kp = &key->alloc;
+       __int64_t               diff;
 
-               rec = XFS_ALLOC_REC_ADDR(block, ptr, cur);
-               *bno = be32_to_cpu(rec->ar_startblock);
-               *len = be32_to_cpu(rec->ar_blockcount);
+       if (cur->bc_btnum == XFS_BTNUM_BNO) {
+               return (__int64_t)be32_to_cpu(kp->ar_startblock) -
+                               rec->ar_startblock;
        }
-       *stat = 1;
-       return 0;
+
+       diff = (__int64_t)be32_to_cpu(kp->ar_blockcount) - rec->ar_blockcount;
+       if (diff)
+               return diff;
+
+       return (__int64_t)be32_to_cpu(kp->ar_startblock) - rec->ar_startblock;
 }
 
-/*
- * Increment cursor by one record at the level.
- * For nonzero levels the leaf-ward information is untouched.
- */
-int                                    /* error */
-xfs_alloc_increment(
-       xfs_btree_cur_t         *cur,   /* btree cursor */
-       int                     level,  /* level in btree, 0 is leaf */
-       int                     *stat)  /* success/failure */
+STATIC int
+xfs_allocbt_kill_root(
+       struct xfs_btree_cur    *cur,
+       struct xfs_buf          *bp,
+       int                     level,
+       union xfs_btree_ptr     *newroot)
 {
-       xfs_alloc_block_t       *block; /* btree block */
-       xfs_buf_t               *bp;    /* tree block buffer */
-       int                     error;  /* error return value */
-       int                     lev;    /* btree level */
+       int                     error;
+
+       XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
+       XFS_BTREE_STATS_INC(cur, killroot);
 
-       ASSERT(level < cur->bc_nlevels);
-       /*
-        * Read-ahead to the right at this level.
-        */
-       xfs_btree_readahead(cur, level, XFS_BTCUR_RIGHTRA);
        /*
-        * Get a pointer to the btree block.
+        * Update the root pointer, decreasing the level by 1 and then
+        * free the old root.
         */
-       bp = cur->bc_bufs[level];
-       block = XFS_BUF_TO_ALLOC_BLOCK(bp);
-#ifdef DEBUG
-       if ((error = xfs_btree_check_sblock(cur, block, level, bp)))
+       xfs_allocbt_set_root(cur, newroot, -1);
+       error = xfs_allocbt_free_block(cur, bp);
+       if (error) {
+               XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
                return error;
-#endif
-       /*
-        * Increment the ptr at this level.  If we're still in the block
-        * then we're done.
-        */
-       if (++cur->bc_ptrs[level] <= be16_to_cpu(block->bb_numrecs)) {
-               *stat = 1;
-               return 0;
-       }
-       /*
-        * If we just went off the right edge of the tree, return failure.
-        */
-       if (be32_to_cpu(block->bb_rightsib) == NULLAGBLOCK) {
-               *stat = 0;
-               return 0;
        }
-       /*
-        * March up the tree incrementing pointers.
-        * Stop when we don't go off the right edge of a block.
-        */
-       for (lev = level + 1; lev < cur->bc_nlevels; lev++) {
-               bp = cur->bc_bufs[lev];
-               block = XFS_BUF_TO_ALLOC_BLOCK(bp);
+
+       XFS_BTREE_STATS_INC(cur, free);
+
+       xfs_btree_setbuf(cur, level, NULL);
+       cur->bc_nlevels--;
+
+       XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+       return 0;
+}
+
 #ifdef DEBUG
-               if ((error = xfs_btree_check_sblock(cur, block, lev, bp)))
-                       return error;
-#endif
-               if (++cur->bc_ptrs[lev] <= be16_to_cpu(block->bb_numrecs))
-                       break;
-               /*
-                * Read-ahead the right block, we're going to read it
-                * in the next loop.
-                */
-               xfs_btree_readahead(cur, lev, XFS_BTCUR_RIGHTRA);
+STATIC int
+xfs_allocbt_keys_inorder(
+       struct xfs_btree_cur    *cur,
+       union xfs_btree_key     *k1,
+       union xfs_btree_key     *k2)
+{
+       if (cur->bc_btnum == XFS_BTNUM_BNO) {
+               return be32_to_cpu(k1->alloc.ar_startblock) <
+                      be32_to_cpu(k2->alloc.ar_startblock);
+       } else {
+               return be32_to_cpu(k1->alloc.ar_blockcount) <
+                       be32_to_cpu(k2->alloc.ar_blockcount) ||
+                       (k1->alloc.ar_blockcount == k2->alloc.ar_blockcount &&
+                        be32_to_cpu(k1->alloc.ar_startblock) <
+                        be32_to_cpu(k2->alloc.ar_startblock));
        }
-       /*
-        * If we went off the root then we are seriously confused.
-        */
-       ASSERT(lev < cur->bc_nlevels);
-       /*
-        * Now walk back down the tree, fixing up the cursor's buffer
-        * pointers and key numbers.
-        */
-       for (bp = cur->bc_bufs[lev], block = XFS_BUF_TO_ALLOC_BLOCK(bp);
-            lev > level; ) {
-               xfs_agblock_t   agbno;  /* block number of btree block */
+}
 
-               agbno = be32_to_cpu(*XFS_ALLOC_PTR_ADDR(block, cur->bc_ptrs[lev], cur));
-               if ((error = xfs_btree_read_bufs(cur->bc_mp, cur->bc_tp,
-                               cur->bc_private.a.agno, agbno, 0, &bp,
-                               XFS_ALLOC_BTREE_REF)))
-                       return error;
-               lev--;
-               xfs_btree_setbuf(cur, lev, bp);
-               block = XFS_BUF_TO_ALLOC_BLOCK(bp);
-               if ((error = xfs_btree_check_sblock(cur, block, lev, bp)))
-                       return error;
-               cur->bc_ptrs[lev] = 1;
+STATIC int
+xfs_allocbt_recs_inorder(
+       struct xfs_btree_cur    *cur,
+       union xfs_btree_rec     *r1,
+       union xfs_btree_rec     *r2)
+{
+       if (cur->bc_btnum == XFS_BTNUM_BNO) {
+               return be32_to_cpu(r1->alloc.ar_startblock) +
+                       be32_to_cpu(r1->alloc.ar_blockcount) <=
+                       be32_to_cpu(r2->alloc.ar_startblock);
+       } else {
+               return be32_to_cpu(r1->alloc.ar_blockcount) <
+                       be32_to_cpu(r2->alloc.ar_blockcount) ||
+                       (r1->alloc.ar_blockcount == r2->alloc.ar_blockcount &&
+                        be32_to_cpu(r1->alloc.ar_startblock) <
+                        be32_to_cpu(r2->alloc.ar_startblock));
        }
-       *stat = 1;
-       return 0;
 }
+#endif /* DEBUG */
 
-/*
- * Insert the current record at the point referenced by cur.
- * The cursor may be inconsistent on return if splits have been done.
- */
-int                                    /* error */
-xfs_alloc_insert(
-       xfs_btree_cur_t *cur,           /* btree cursor */
-       int             *stat)          /* success/failure */
-{
-       int             error;          /* error return value */
-       int             i;              /* result value, 0 for failure */
-       int             level;          /* current level number in btree */
-       xfs_agblock_t   nbno;           /* new block number (split result) */
-       xfs_btree_cur_t *ncur;          /* new cursor (split result) */
-       xfs_alloc_rec_t nrec;           /* record being inserted this level */
-       xfs_btree_cur_t *pcur;          /* previous level's cursor */
+#ifdef XFS_BTREE_TRACE
+ktrace_t       *xfs_allocbt_trace_buf;
 
-       level = 0;
-       nbno = NULLAGBLOCK;
-       nrec.ar_startblock = cpu_to_be32(cur->bc_rec.a.ar_startblock);
-       nrec.ar_blockcount = cpu_to_be32(cur->bc_rec.a.ar_blockcount);
-       ncur = NULL;
-       pcur = cur;
-       /*
-        * Loop going up the tree, starting at the leaf level.
-        * Stop when we don't get a split block, that must mean that
-        * the insert is finished with this level.
-        */
-       do {
-               /*
-                * Insert nrec/nbno into this level of the tree.
-                * Note if we fail, nbno will be null.
-                */
-               if ((error = xfs_alloc_insrec(pcur, level++, &nbno, &nrec, &ncur,
-                               &i))) {
-                       if (pcur != cur)
-                               xfs_btree_del_cursor(pcur, XFS_BTREE_ERROR);
-                       return error;
-               }
-               /*
-                * See if the cursor we just used is trash.
-                * Can't trash the caller's cursor, but otherwise we should
-                * if ncur is a new cursor or we're about to be done.
-                */
-               if (pcur != cur && (ncur || nbno == NULLAGBLOCK)) {
-                       cur->bc_nlevels = pcur->bc_nlevels;
-                       xfs_btree_del_cursor(pcur, XFS_BTREE_NOERROR);
-               }
-               /*
-                * If we got a new cursor, switch to it.
-                */
-               if (ncur) {
-                       pcur = ncur;
-                       ncur = NULL;
-               }
-       } while (nbno != NULLAGBLOCK);
-       *stat = i;
-       return 0;
+STATIC void
+xfs_allocbt_trace_enter(
+       struct xfs_btree_cur    *cur,
+       const char              *func,
+       char                    *s,
+       int                     type,
+       int                     line,
+       __psunsigned_t          a0,
+       __psunsigned_t          a1,
+       __psunsigned_t          a2,
+       __psunsigned_t          a3,
+       __psunsigned_t          a4,
+       __psunsigned_t          a5,
+       __psunsigned_t          a6,
+       __psunsigned_t          a7,
+       __psunsigned_t          a8,
+       __psunsigned_t          a9,
+       __psunsigned_t          a10)
+{
+       ktrace_enter(xfs_allocbt_trace_buf, (void *)(__psint_t)type,
+               (void *)func, (void *)s, NULL, (void *)cur,
+               (void *)a0, (void *)a1, (void *)a2, (void *)a3,
+               (void *)a4, (void *)a5, (void *)a6, (void *)a7,
+               (void *)a8, (void *)a9, (void *)a10);
 }
 
-/*
- * Lookup the record equal to [bno, len] in the btree given by cur.
- */
-int                                    /* error */
-xfs_alloc_lookup_eq(
-       xfs_btree_cur_t *cur,           /* btree cursor */
-       xfs_agblock_t   bno,            /* starting block of extent */
-       xfs_extlen_t    len,            /* length of extent */
-       int             *stat)          /* success/failure */
+STATIC void
+xfs_allocbt_trace_cursor(
+       struct xfs_btree_cur    *cur,
+       __uint32_t              *s0,
+       __uint64_t              *l0,
+       __uint64_t              *l1)
 {
-       cur->bc_rec.a.ar_startblock = bno;
-       cur->bc_rec.a.ar_blockcount = len;
-       return xfs_alloc_lookup(cur, XFS_LOOKUP_EQ, stat);
+       *s0 = cur->bc_private.a.agno;
+       *l0 = cur->bc_rec.a.ar_startblock;
+       *l1 = cur->bc_rec.a.ar_blockcount;
 }
 
-/*
- * Lookup the first record greater than or equal to [bno, len]
- * in the btree given by cur.
- */
-int                                    /* error */
-xfs_alloc_lookup_ge(
-       xfs_btree_cur_t *cur,           /* btree cursor */
-       xfs_agblock_t   bno,            /* starting block of extent */
-       xfs_extlen_t    len,            /* length of extent */
-       int             *stat)          /* success/failure */
+STATIC void
+xfs_allocbt_trace_key(
+       struct xfs_btree_cur    *cur,
+       union xfs_btree_key     *key,
+       __uint64_t              *l0,
+       __uint64_t              *l1)
 {
-       cur->bc_rec.a.ar_startblock = bno;
-       cur->bc_rec.a.ar_blockcount = len;
-       return xfs_alloc_lookup(cur, XFS_LOOKUP_GE, stat);
+       *l0 = be32_to_cpu(key->alloc.ar_startblock);
+       *l1 = be32_to_cpu(key->alloc.ar_blockcount);
 }
 
-/*
- * Lookup the first record less than or equal to [bno, len]
- * in the btree given by cur.
- */
-int                                    /* error */
-xfs_alloc_lookup_le(
-       xfs_btree_cur_t *cur,           /* btree cursor */
-       xfs_agblock_t   bno,            /* starting block of extent */
-       xfs_extlen_t    len,            /* length of extent */
-       int             *stat)          /* success/failure */
+STATIC void
+xfs_allocbt_trace_record(
+       struct xfs_btree_cur    *cur,
+       union xfs_btree_rec     *rec,
+       __uint64_t              *l0,
+       __uint64_t              *l1,
+       __uint64_t              *l2)
 {
-       cur->bc_rec.a.ar_startblock = bno;
-       cur->bc_rec.a.ar_blockcount = len;
-       return xfs_alloc_lookup(cur, XFS_LOOKUP_LE, stat);
+       *l0 = be32_to_cpu(rec->alloc.ar_startblock);
+       *l1 = be32_to_cpu(rec->alloc.ar_blockcount);
+       *l2 = 0;
 }
+#endif /* XFS_BTREE_TRACE */
+
+static const struct xfs_btree_ops xfs_allocbt_ops = {
+       .rec_len                = sizeof(xfs_alloc_rec_t),
+       .key_len                = sizeof(xfs_alloc_key_t),
+
+       .dup_cursor             = xfs_allocbt_dup_cursor,
+       .set_root               = xfs_allocbt_set_root,
+       .kill_root              = xfs_allocbt_kill_root,
+       .alloc_block            = xfs_allocbt_alloc_block,
+       .free_block             = xfs_allocbt_free_block,
+       .update_lastrec         = xfs_allocbt_update_lastrec,
+       .get_minrecs            = xfs_allocbt_get_minrecs,
+       .get_maxrecs            = xfs_allocbt_get_maxrecs,
+       .init_key_from_rec      = xfs_allocbt_init_key_from_rec,
+       .init_rec_from_key      = xfs_allocbt_init_rec_from_key,
+       .init_rec_from_cur      = xfs_allocbt_init_rec_from_cur,
+       .init_ptr_from_cur      = xfs_allocbt_init_ptr_from_cur,
+       .key_diff               = xfs_allocbt_key_diff,
+
+#ifdef DEBUG
+       .keys_inorder           = xfs_allocbt_keys_inorder,
+       .recs_inorder           = xfs_allocbt_recs_inorder,
+#endif
+
+#ifdef XFS_BTREE_TRACE
+       .trace_enter            = xfs_allocbt_trace_enter,
+       .trace_cursor           = xfs_allocbt_trace_cursor,
+       .trace_key              = xfs_allocbt_trace_key,
+       .trace_record           = xfs_allocbt_trace_record,
+#endif
+};
 
 /*
- * Update the record referred to by cur, to the value given by [bno, len].
- * This either works (return 0) or gets an EFSCORRUPTED error.
+ * Allocate a new allocation btree cursor.
  */
-int                                    /* error */
-xfs_alloc_update(
-       xfs_btree_cur_t         *cur,   /* btree cursor */
-       xfs_agblock_t           bno,    /* starting block of extent */
-       xfs_extlen_t            len)    /* length of extent */
+struct xfs_btree_cur *                 /* new alloc btree cursor */
+xfs_allocbt_init_cursor(
+       struct xfs_mount        *mp,            /* file system mount point */
+       struct xfs_trans        *tp,            /* transaction pointer */
+       struct xfs_buf          *agbp,          /* buffer for agf structure */
+       xfs_agnumber_t          agno,           /* allocation group number */
+       xfs_btnum_t             btnum)          /* btree identifier */
 {
-       xfs_alloc_block_t       *block; /* btree block to update */
-       int                     error;  /* error return value */
-       int                     ptr;    /* current record number (updating) */
+       struct xfs_agf          *agf = XFS_BUF_TO_AGF(agbp);
+       struct xfs_btree_cur    *cur;
 
-       ASSERT(len > 0);
-       /*
-        * Pick up the a.g. freelist struct and the current block.
-        */
-       block = XFS_BUF_TO_ALLOC_BLOCK(cur->bc_bufs[0]);
-#ifdef DEBUG
-       if ((error = xfs_btree_check_sblock(cur, block, 0, cur->bc_bufs[0])))
-               return error;
-#endif
-       /*
-        * Get the address of the rec to be updated.
-        */
-       ptr = cur->bc_ptrs[0];
-       {
-               xfs_alloc_rec_t         *rp;    /* pointer to updated record */
+       ASSERT(btnum == XFS_BTNUM_BNO || btnum == XFS_BTNUM_CNT);
 
-               rp = XFS_ALLOC_REC_ADDR(block, ptr, cur);
-               /*
-                * Fill in the new contents and log them.
-                */
-               rp->ar_startblock = cpu_to_be32(bno);
-               rp->ar_blockcount = cpu_to_be32(len);
-               xfs_alloc_log_recs(cur, cur->bc_bufs[0], ptr, ptr);
-       }
-       /*
-        * If it's the by-size btree and it's the last leaf block and
-        * it's the last record... then update the size of the longest
-        * extent in the a.g., which we cache in the a.g. freelist header.
-        */
-       if (cur->bc_btnum == XFS_BTNUM_CNT &&
-           be32_to_cpu(block->bb_rightsib) == NULLAGBLOCK &&
-           ptr == be16_to_cpu(block->bb_numrecs)) {
-               xfs_agf_t       *agf;   /* a.g. freespace header */
-               xfs_agnumber_t  seqno;
+       cur = kmem_zone_zalloc(xfs_btree_cur_zone, KM_SLEEP);
 
-               agf = XFS_BUF_TO_AGF(cur->bc_private.a.agbp);
-               seqno = be32_to_cpu(agf->agf_seqno);
-               cur->bc_mp->m_perag[seqno].pagf_longest = len;
-               agf->agf_longest = cpu_to_be32(len);
-               xfs_alloc_log_agf(cur->bc_tp, cur->bc_private.a.agbp,
-                       XFS_AGF_LONGEST);
-       }
-       /*
-        * Updating first record in leaf. Pass new key value up to our parent.
-        */
-       if (ptr == 1) {
-               xfs_alloc_key_t key;    /* key containing [bno, len] */
+       cur->bc_tp = tp;
+       cur->bc_mp = mp;
+       cur->bc_nlevels = be32_to_cpu(agf->agf_levels[btnum]);
+       cur->bc_btnum = btnum;
+       cur->bc_blocklog = mp->m_sb.sb_blocklog;
 
-               key.ar_startblock = cpu_to_be32(bno);
-               key.ar_blockcount = cpu_to_be32(len);
-               if ((error = xfs_alloc_updkey(cur, &key, 1)))
-                       return error;
-       }
-       return 0;
+       cur->bc_ops = &xfs_allocbt_ops;
+       if (btnum == XFS_BTNUM_CNT)
+               cur->bc_flags = XFS_BTREE_LASTREC_UPDATE;
+
+       cur->bc_private.a.agbp = agbp;
+       cur->bc_private.a.agno = agno;
+
+       return cur;
+}
+
+/*
+ * Calculate number of records in an alloc btree block.
+ */
+int
+xfs_allocbt_maxrecs(
+       struct xfs_mount        *mp,
+       int                     blocklen,
+       int                     leaf)
+{
+       blocklen -= XFS_ALLOC_BLOCK_LEN(mp);
+
+       if (leaf)
+               return blocklen / sizeof(xfs_alloc_rec_t);
+       return blocklen / (sizeof(xfs_alloc_key_t) + sizeof(xfs_alloc_ptr_t));
 }