/* -*- mode: c; c-basic-offset: 8; -*- * vim: noexpandtab sw=8 ts=8 sts=0: * * reservations.c * * Allocation reservations implementation * * Some code borrowed from fs/ext3/balloc.c and is: * * Copyright (C) 1992, 1993, 1994, 1995 * Remy Card (card@masi.ibp.fr) * Laboratoire MASI - Institut Blaise Pascal * Universite Pierre et Marie Curie (Paris VI) * * The rest is copyright (C) 2010 Novell. All rights reserved. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public * License version 2 as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. */ #include <linux/fs.h> #include <linux/types.h> #include <linux/highmem.h> #include <linux/bitops.h> #include <linux/list.h> #include <cluster/masklog.h> #include "ocfs2.h" #include "ocfs2_trace.h" #ifdef CONFIG_OCFS2_DEBUG_FS #define OCFS2_CHECK_RESERVATIONS #endif static DEFINE_SPINLOCK(resv_lock); #define OCFS2_MIN_RESV_WINDOW_BITS 8 #define OCFS2_MAX_RESV_WINDOW_BITS 1024 int ocfs2_dir_resv_allowed(struct ocfs2_super *osb) { return (osb->osb_resv_level && osb->osb_dir_resv_level); } static unsigned int ocfs2_resv_window_bits(struct ocfs2_reservation_map *resmap, struct ocfs2_alloc_reservation *resv) { struct ocfs2_super *osb = resmap->m_osb; unsigned int bits; if (!(resv->r_flags & OCFS2_RESV_FLAG_DIR)) { /* 8, 16, 32, 64, 128, 256, 512, 1024 */ bits = 4 << osb->osb_resv_level; } else { bits = 4 << osb->osb_dir_resv_level; } return bits; } static inline unsigned int ocfs2_resv_end(struct ocfs2_alloc_reservation *resv) { if (resv->r_len) return resv->r_start + resv->r_len - 1; return resv->r_start; } static inline int ocfs2_resv_empty(struct ocfs2_alloc_reservation *resv) { return !!(resv->r_len == 0); } static inline int ocfs2_resmap_disabled(struct ocfs2_reservation_map *resmap) { if (resmap->m_osb->osb_resv_level == 0) return 1; return 0; } static void ocfs2_dump_resv(struct ocfs2_reservation_map *resmap) { struct ocfs2_super *osb = resmap->m_osb; struct rb_node *node; struct ocfs2_alloc_reservation *resv; int i = 0; mlog(ML_NOTICE, "Dumping resmap for device %s. Bitmap length: %u\n", osb->dev_str, resmap->m_bitmap_len); node = rb_first(&resmap->m_reservations); while (node) { resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node); mlog(ML_NOTICE, "start: %u\tend: %u\tlen: %u\tlast_start: %u" "\tlast_len: %u\n", resv->r_start, ocfs2_resv_end(resv), resv->r_len, resv->r_last_start, resv->r_last_len); node = rb_next(node); i++; } mlog(ML_NOTICE, "%d reservations found. LRU follows\n", i); i = 0; list_for_each_entry(resv, &resmap->m_lru, r_lru) { mlog(ML_NOTICE, "LRU(%d) start: %u\tend: %u\tlen: %u\t" "last_start: %u\tlast_len: %u\n", i, resv->r_start, ocfs2_resv_end(resv), resv->r_len, resv->r_last_start, resv->r_last_len); i++; } } #ifdef OCFS2_CHECK_RESERVATIONS static int ocfs2_validate_resmap_bits(struct ocfs2_reservation_map *resmap, int i, struct ocfs2_alloc_reservation *resv) { char *disk_bitmap = resmap->m_disk_bitmap; unsigned int start = resv->r_start; unsigned int end = ocfs2_resv_end(resv); while (start <= end) { if (ocfs2_test_bit(start, disk_bitmap)) { mlog(ML_ERROR, "reservation %d covers an allocated area " "starting at bit %u!\n", i, start); return 1; } start++; } return 0; } static void ocfs2_check_resmap(struct ocfs2_reservation_map *resmap) { unsigned int off = 0; int i = 0; struct rb_node *node; struct ocfs2_alloc_reservation *resv; node = rb_first(&resmap->m_reservations); while (node) { resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node); if (i > 0 && resv->r_start <= off) { mlog(ML_ERROR, "reservation %d has bad start off!\n", i); goto bad; } if (resv->r_len == 0) { mlog(ML_ERROR, "reservation %d has no length!\n", i); goto bad; } if (resv->r_start > ocfs2_resv_end(resv)) { mlog(ML_ERROR, "reservation %d has invalid range!\n", i); goto bad; } if (ocfs2_resv_end(resv) >= resmap->m_bitmap_len) { mlog(ML_ERROR, "reservation %d extends past bitmap!\n", i); goto bad; } if (ocfs2_validate_resmap_bits(resmap, i, resv)) goto bad; off = ocfs2_resv_end(resv); node = rb_next(node); i++; } return; bad: ocfs2_dump_resv(resmap); BUG(); } #else static inline void ocfs2_check_resmap(struct ocfs2_reservation_map *resmap) { } #endif void ocfs2_resv_init_once(struct ocfs2_alloc_reservation *resv) { memset(resv, 0, sizeof(*resv)); INIT_LIST_HEAD(&resv->r_lru); } void ocfs2_resv_set_type(struct ocfs2_alloc_reservation *resv, unsigned int flags) { BUG_ON(flags & ~OCFS2_RESV_TYPES); resv->r_flags |= flags; } int ocfs2_resmap_init(struct ocfs2_super *osb, struct ocfs2_reservation_map *resmap) { memset(resmap, 0, sizeof(*resmap)); resmap->m_osb = osb; resmap->m_reservations = RB_ROOT; /* m_bitmap_len is initialized to zero by the above memset. */ INIT_LIST_HEAD(&resmap->m_lru); return 0; } static void ocfs2_resv_mark_lru(struct ocfs2_reservation_map *resmap, struct ocfs2_alloc_reservation *resv) { assert_spin_locked(&resv_lock); if (!list_empty(&resv->r_lru)) list_del_init(&resv->r_lru); list_add_tail(&resv->r_lru, &resmap->m_lru); } static void __ocfs2_resv_trunc(struct ocfs2_alloc_reservation *resv) { resv->r_len = 0; resv->r_start = 0; } static void ocfs2_resv_remove(struct ocfs2_reservation_map *resmap, struct ocfs2_alloc_reservation *resv) { if (resv->r_flags & OCFS2_RESV_FLAG_INUSE) { list_del_init(&resv->r_lru); rb_erase(&resv->r_node, &resmap->m_reservations); resv->r_flags &= ~OCFS2_RESV_FLAG_INUSE; } } static void __ocfs2_resv_discard(struct ocfs2_reservation_map *resmap, struct ocfs2_alloc_reservation *resv) { assert_spin_locked(&resv_lock); __ocfs2_resv_trunc(resv); /* * last_len and last_start no longer make sense if * we're changing the range of our allocations. */ resv->r_last_len = resv->r_last_start = 0; ocfs2_resv_remove(resmap, resv); } /* does nothing if 'resv' is null */ void ocfs2_resv_discard(struct ocfs2_reservation_map *resmap, struct ocfs2_alloc_reservation *resv) { if (resv) { spin_lock(&resv_lock); __ocfs2_resv_discard(resmap, resv); spin_unlock(&resv_lock); } } static void ocfs2_resmap_clear_all_resv(struct ocfs2_reservation_map *resmap) { struct rb_node *node; struct ocfs2_alloc_reservation *resv; assert_spin_locked(&resv_lock); while ((node = rb_last(&resmap->m_reservations)) != NULL) { resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node); __ocfs2_resv_discard(resmap, resv); } } void ocfs2_resmap_restart(struct ocfs2_reservation_map *resmap, unsigned int clen, char *disk_bitmap) { if (ocfs2_resmap_disabled(resmap)) return; spin_lock(&resv_lock); ocfs2_resmap_clear_all_resv(resmap); resmap->m_bitmap_len = clen; resmap->m_disk_bitmap = disk_bitmap; spin_unlock(&resv_lock); } void ocfs2_resmap_uninit(struct ocfs2_reservation_map *resmap) { /* Does nothing for now. Keep this around for API symmetry */ } static void ocfs2_resv_insert(struct ocfs2_reservation_map *resmap, struct ocfs2_alloc_reservation *new) { struct rb_root *root = &resmap->m_reservations; struct rb_node *parent = NULL; struct rb_node **p = &root->rb_node; struct ocfs2_alloc_reservation *tmp; assert_spin_locked(&resv_lock); trace_ocfs2_resv_insert(new->r_start, new->r_len); while (*p) { parent = *p; tmp = rb_entry(parent, struct ocfs2_alloc_reservation, r_node); if (new->r_start < tmp->r_start) { p = &(*p)->rb_left; /* * This is a good place to check for * overlapping reservations. */ BUG_ON(ocfs2_resv_end(new) >= tmp->r_start); } else if (new->r_start > ocfs2_resv_end(tmp)) { p = &(*p)->rb_right; } else { /* This should never happen! */ mlog(ML_ERROR, "Duplicate reservation window!\n"); BUG(); } } rb_link_node(&new->r_node, parent, p); rb_insert_color(&new->r_node, root); new->r_flags |= OCFS2_RESV_FLAG_INUSE; ocfs2_resv_mark_lru(resmap, new); ocfs2_check_resmap(resmap); } /** * ocfs2_find_resv_lhs() - find the window which contains goal * @resmap: reservation map to search * @goal: which bit to search for * * If a window containing that goal is not found, we return the window * which comes before goal. Returns NULL on empty rbtree or no window * before goal. */ static struct ocfs2_alloc_reservation * ocfs2_find_resv_lhs(struct ocfs2_reservation_map *resmap, unsigned int goal) { struct ocfs2_alloc_reservation *resv = NULL; struct ocfs2_alloc_reservation *prev_resv = NULL; struct rb_node *node = resmap->m_reservations.rb_node; assert_spin_locked(&resv_lock); if (!node) return NULL; node = rb_first(&resmap->m_reservations); while (node) { resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node); if (resv->r_start <= goal && ocfs2_resv_end(resv) >= goal) break; /* Check if we overshot the reservation just before goal? */ if (resv->r_start > goal) { resv = prev_resv; break; } prev_resv = resv; node = rb_next(node); } return resv; } /* * We are given a range within the bitmap, which corresponds to a gap * inside the reservations tree (search_start, search_len). The range * can be anything from the whole bitmap, to a gap between * reservations. * * The start value of *rstart is insignificant. * * This function searches the bitmap range starting at search_start * with length search_len for a set of contiguous free bits. We try * to find up to 'wanted' bits, but can sometimes return less. * * Returns the length of allocation, 0 if no free bits are found. * * *cstart and *clen will also be populated with the result. */ static int ocfs2_resmap_find_free_bits(struct ocfs2_reservation_map *resmap, unsigned int wanted, unsigned int search_start, unsigned int search_len, unsigned int *rstart, unsigned int *rlen) { void *bitmap = resmap->m_disk_bitmap; unsigned int best_start, best_len = 0; int offset, start, found; trace_ocfs2_resmap_find_free_bits_begin(search_start, search_len, wanted, resmap->m_bitmap_len); found = best_start = best_len = 0; start = search_start; while ((offset = ocfs2_find_next_zero_bit(bitmap, resmap->m_bitmap_len, start)) != -1) { /* Search reached end of the region */ if (offset >= (search_start + search_len)) break; if (offset == start) { /* we found a zero */ found++; /* move start to the next bit to test */ start++; } else { /* got a zero after some ones */ found = 1; start = offset + 1; } if (found > best_len) { best_len = found; best_start = start - found; } if (found >= wanted) break; } if (best_len == 0) return 0; if (best_len >= wanted) best_len = wanted; *rlen = best_len; *rstart = best_start; trace_ocfs2_resmap_find_free_bits_end(best_start, best_len); return *rlen; } static void __ocfs2_resv_find_window(struct ocfs2_reservation_map *resmap, struct ocfs2_alloc_reservation *resv, unsigned int goal, unsigned int wanted) { struct rb_root *root = &resmap->m_reservations; unsigned int gap_start, gap_end, gap_len; struct ocfs2_alloc_reservation *prev_resv, *next_resv; struct rb_node *prev, *next; unsigned int cstart, clen; unsigned int best_start = 0, best_len = 0; /* * Nasty cases to consider: * * - rbtree is empty * - our window should be first in all reservations * - our window should be last in all reservations * - need to make sure we don't go past end of bitmap */ trace_ocfs2_resv_find_window_begin(resv->r_start, ocfs2_resv_end(resv), goal, wanted, RB_EMPTY_ROOT(root)); assert_spin_locked(&resv_lock); if (RB_EMPTY_ROOT(root)) { /* * Easiest case - empty tree. We can just take * whatever window of free bits we want. */ clen = ocfs2_resmap_find_free_bits(resmap, wanted, goal, resmap->m_bitmap_len - goal, &cstart, &clen); /* * This should never happen - the local alloc window * will always have free bits when we're called. */ BUG_ON(goal == 0 && clen == 0); if (clen == 0) return; resv->r_start = cstart; resv->r_len = clen; ocfs2_resv_insert(resmap, resv); return; } prev_resv = ocfs2_find_resv_lhs(resmap, goal); if (prev_resv == NULL) { /* * A NULL here means that the search code couldn't * find a window that starts before goal. * * However, we can take the first window after goal, * which is also by definition, the leftmost window in * the entire tree. If we can find free bits in the * gap between goal and the LHS window, then the * reservation can safely be placed there. * * Otherwise we fall back to a linear search, checking * the gaps in between windows for a place to * allocate. */ next = rb_first(root); next_resv = rb_entry(next, struct ocfs2_alloc_reservation, r_node); /* * The search should never return such a window. (see * comment above */ if (next_resv->r_start <= goal) { mlog(ML_ERROR, "goal: %u next_resv: start %u len %u\n", goal, next_resv->r_start, next_resv->r_len); ocfs2_dump_resv(resmap); BUG(); } clen = ocfs2_resmap_find_free_bits(resmap, wanted, goal, next_resv->r_start - goal, &cstart, &clen); if (clen) { best_len = clen; best_start = cstart; if (best_len == wanted) goto out_insert; } prev_resv = next_resv; next_resv = NULL; } trace_ocfs2_resv_find_window_prev(prev_resv->r_start, ocfs2_resv_end(prev_resv)); prev = &prev_resv->r_node; /* Now we do a linear search for a window, starting at 'prev_rsv' */ while (1) { next = rb_next(prev); if (next) { next_resv = rb_entry(next, struct ocfs2_alloc_reservation, r_node); gap_start = ocfs2_resv_end(prev_resv) + 1; gap_end = next_resv->r_start - 1; gap_len = gap_end - gap_start + 1; } else { /* * We're at the rightmost edge of the * tree. See if a reservation between this * window and the end of the bitmap will work. */ gap_start = ocfs2_resv_end(prev_resv) + 1; gap_len = resmap->m_bitmap_len - gap_start; gap_end = resmap->m_bitmap_len - 1; } trace_ocfs2_resv_find_window_next(next ? next_resv->r_start: -1, next ? ocfs2_resv_end(next_resv) : -1); /* * No need to check this gap if we have already found * a larger region of free bits. */ if (gap_len <= best_len) goto next_resv; clen = ocfs2_resmap_find_free_bits(resmap, wanted, gap_start, gap_len, &cstart, &clen); if (clen == wanted) { best_len = clen; best_start = cstart; goto out_insert; } else if (clen > best_len) { best_len = clen; best_start = cstart; } next_resv: if (!next) break; prev = next; prev_resv = rb_entry(prev, struct ocfs2_alloc_reservation, r_node); } out_insert: if (best_len) { resv->r_start = best_start; resv->r_len = best_len; ocfs2_resv_insert(resmap, resv); } } static void ocfs2_cannibalize_resv(struct ocfs2_reservation_map *resmap, struct ocfs2_alloc_reservation *resv, unsigned int wanted) { struct ocfs2_alloc_reservation *lru_resv; int tmpwindow = !!(resv->r_flags & OCFS2_RESV_FLAG_TMP); unsigned int min_bits; if (!tmpwindow) min_bits = ocfs2_resv_window_bits(resmap, resv) >> 1; else min_bits = wanted; /* We at know the temp window will use all * of these bits */ /* * Take the first reservation off the LRU as our 'target'. We * don't try to be smart about it. There might be a case for * searching based on size but I don't have enough data to be * sure. --Mark (3/16/2010) */ lru_resv = list_first_entry(&resmap->m_lru, struct ocfs2_alloc_reservation, r_lru); trace_ocfs2_cannibalize_resv_begin(lru_resv->r_start, lru_resv->r_len, ocfs2_resv_end(lru_resv)); /* * Cannibalize (some or all) of the target reservation and * feed it to the current window. */ if (lru_resv->r_len <= min_bits) { /* * Discard completely if size is less than or equal to a * reasonable threshold - 50% of window bits for non temporary * windows. */ resv->r_start = lru_resv->r_start; resv->r_len = lru_resv->r_len; __ocfs2_resv_discard(resmap, lru_resv); } else { unsigned int shrink; if (tmpwindow) shrink = min_bits; else shrink = lru_resv->r_len / 2; lru_resv->r_len -= shrink; resv->r_start = ocfs2_resv_end(lru_resv) + 1; resv->r_len = shrink; } trace_ocfs2_cannibalize_resv_end(resv->r_start, ocfs2_resv_end(resv), resv->r_len, resv->r_last_start, resv->r_last_len); ocfs2_resv_insert(resmap, resv); } static void ocfs2_resv_find_window(struct ocfs2_reservation_map *resmap, struct ocfs2_alloc_reservation *resv, unsigned int wanted) { unsigned int goal = 0; BUG_ON(!ocfs2_resv_empty(resv)); /* * Begin by trying to get a window as close to the previous * one as possible. Using the most recent allocation as a * start goal makes sense. */ if (resv->r_last_len) { goal = resv->r_last_start + resv->r_last_len; if (goal >= resmap->m_bitmap_len) goal = 0; } __ocfs2_resv_find_window(resmap, resv, goal, wanted); /* Search from last alloc didn't work, try once more from beginning. */ if (ocfs2_resv_empty(resv) && goal != 0) __ocfs2_resv_find_window(resmap, resv, 0, wanted); if (ocfs2_resv_empty(resv)) { /* * Still empty? Pull oldest one off the LRU, remove it from * tree, put this one in it's place. */ ocfs2_cannibalize_resv(resmap, resv, wanted); } BUG_ON(ocfs2_resv_empty(resv)); } int ocfs2_resmap_resv_bits(struct ocfs2_reservation_map *resmap, struct ocfs2_alloc_reservation *resv, int *cstart, int *clen) { if (resv == NULL || ocfs2_resmap_disabled(resmap)) return -ENOSPC; spin_lock(&resv_lock); if (ocfs2_resv_empty(resv)) { /* * We don't want to over-allocate for temporary * windows. Otherwise, we run the risk of fragmenting the * allocation space. */ unsigned int wanted = ocfs2_resv_window_bits(resmap, resv); if ((resv->r_flags & OCFS2_RESV_FLAG_TMP) || wanted < *clen) wanted = *clen; /* * Try to get a window here. If it works, we must fall * through and test the bitmap . This avoids some * ping-ponging of windows due to non-reserved space * being allocation before we initialize a window for * that inode. */ ocfs2_resv_find_window(resmap, resv, wanted); trace_ocfs2_resmap_resv_bits(resv->r_start, resv->r_len); } BUG_ON(ocfs2_resv_empty(resv)); *cstart = resv->r_start; *clen = resv->r_len; spin_unlock(&resv_lock); return 0; } static void ocfs2_adjust_resv_from_alloc(struct ocfs2_reservation_map *resmap, struct ocfs2_alloc_reservation *resv, unsigned int start, unsigned int end) { unsigned int rhs = 0; unsigned int old_end = ocfs2_resv_end(resv); BUG_ON(start != resv->r_start || old_end < end); /* * Completely used? We can remove it then. */ if (old_end == end) { __ocfs2_resv_discard(resmap, resv); return; } rhs = old_end - end; /* * This should have been trapped above. */ BUG_ON(rhs == 0); resv->r_start = end + 1; resv->r_len = old_end - resv->r_start + 1; } void ocfs2_resmap_claimed_bits(struct ocfs2_reservation_map *resmap, struct ocfs2_alloc_reservation *resv, u32 cstart, u32 clen) { unsigned int cend = cstart + clen - 1; if (resmap == NULL || ocfs2_resmap_disabled(resmap)) return; if (resv == NULL) return; BUG_ON(cstart != resv->r_start); spin_lock(&resv_lock); trace_ocfs2_resmap_claimed_bits_begin(cstart, cend, clen, resv->r_start, ocfs2_resv_end(resv), resv->r_len, resv->r_last_start, resv->r_last_len); BUG_ON(cstart < resv->r_start); BUG_ON(cstart > ocfs2_resv_end(resv)); BUG_ON(cend > ocfs2_resv_end(resv)); ocfs2_adjust_resv_from_alloc(resmap, resv, cstart, cend); resv->r_last_start = cstart; resv->r_last_len = clen; /* * May have been discarded above from * ocfs2_adjust_resv_from_alloc(). */ if (!ocfs2_resv_empty(resv)) ocfs2_resv_mark_lru(resmap, resv); trace_ocfs2_resmap_claimed_bits_end(resv->r_start, ocfs2_resv_end(resv), resv->r_len, resv->r_last_start, resv->r_last_len); ocfs2_check_resmap(resmap); spin_unlock(&resv_lock); }