diff options
Diffstat (limited to 'fs/ocfs2/reservations.c')
| -rw-r--r-- | fs/ocfs2/reservations.c | 839 |
1 files changed, 839 insertions, 0 deletions
diff --git a/fs/ocfs2/reservations.c b/fs/ocfs2/reservations.c new file mode 100644 index 00000000..41ffd36c --- /dev/null +++ b/fs/ocfs2/reservations.c @@ -0,0 +1,839 @@ +/* -*- 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 + +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); +} |