44  * Free Space Btree Repair
48  * AG.  Therefore, we can recreate the free extent records in an AG by looking
53  * Because the final step of building a new index is to free the space used by
55  * structures that live in the free space (bnobt, cntbt, rmapbt, agfl) share
86  * We use the prefix 'xrep_abt' here because we regenerate both free space
106 	/* Free space extents. */
114 	/* get_records()'s position in the free space record array. */
123 	/* Number of free blocks in this AG. */
126 	/* Longest free extent we found in the AG. */
130 /* Set up to repair AG free space btrees. */
148 /* Check for any obvious conflicts in the free extent. */
191  * Stash a free space record for all the space since the last bno we found
246 	/* ...and all the free space. */  in xrep_abt_walk_rmap()
275  * Compare two free space extents by block number.  We want to sort in order of
294  * Re-sort the free extents by block number so that we can put the records into
322  * Compare two free space extents by length and then block number.  We want
342  * Sort the free extents by length so so that we can put the records into the
357  * unowned space), (2) the OWN_AG extents (which encompass the free space
359  * blocks.  The free space is (1) + (2) - (3) - (4).
417  * We're going to use the observed free space records to reserve blocks for the
418  * new free space btrees, so we play an iterative game where we try to converge
422  * 2. If the first free record has more blocks than we need, we're done.
500 			 * free records doesn't change, so shrink the free  in xrep_abt_reserve_space()
517 		 * move on to the next one.  This changes the number of free  in xrep_abt_reserve_space()
550 	 * For each reserved btree block we didn't use, add it to the free  in xrep_abt_dispose_one()
570  * free space btrees need to have a (deferred) rmap added for the OWN_AG
601 /* Retrieve free space data for bulk load. */
644  * Reset the AGF counters to reflect the free space btrees that we just
657 	 * Compute the contribution to agf_btreeblks for the new free space  in xrep_abt_reset_counters()
668 	 * The AGF header contains extra information related to the free space  in xrep_abt_reset_counters()
698  * Use the collected free space information to stage new free space btrees.
714 	 * Sort the free extents by length so that we can set up the free space  in xrep_abt_build_new_trees()
716 	 * deferred rmap / free work we have to do at the end.  in xrep_abt_build_new_trees()
754 	 * If we need to re-sort the free extents by length, do so so that we  in xrep_abt_build_new_trees()
772 	/* Load the free space by length tree. */  in xrep_abt_build_new_trees()
783 	/* Load the free space by block number tree. */  in xrep_abt_build_new_trees()
821  * old blocks and free them.
830 	/* Free the old btree blocks if they're not in use. */  in xrep_abt_remove_old_trees()
877 	/* Set up enough storage to handle maximally fragmented free space. */  in xrep_allocbt()
878 	descr = xchk_xfile_ag_descr(sc, "free space records");  in xrep_allocbt()
886 	/* Collect the free space data and find the old btree blocks. */  in xrep_allocbt()
892 	/* Rebuild the free space information. */  in xrep_allocbt()