/* -*- 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>

#define MLOG_MASK_PREFIX ML_RESERVATIONS
#include <cluster/masklog.h>

#include "ocfs2.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);

        mlog(0, "Insert reservation start: %u len: %u\n", 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;

        mlog(0, "Find %u bits within range (%u, len %u) resmap len: %u\n",
             wanted, search_start, search_len, 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;

        mlog(0, "Found start: %u len: %u\n", 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
         */

        mlog(0, "resv start: %u resv end: %u goal: %u wanted: %u\n",
             resv->r_start, ocfs2_resv_end(resv), goal, wanted);

        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.
                 */

                mlog(0, "Empty root\n");

                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) {
                mlog(0, "Goal on LHS of leftmost window\n");

                /*
                 * 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;
        }

        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) {
                        mlog(0, "One more resv found in linear search\n");
                        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 {
                        mlog(0, "No next node\n");
                        /*
                         * 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;
                }

                /*
                 * 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);

        mlog(0, "lru resv: start: %u len: %u end: %u\n", 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;
        }

        mlog(0, "Reservation now looks like: r_start: %u r_end: %u "
             "r_len: %u r_last_start: %u r_last_len: %u\n",
             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;

                mlog(0, "empty reservation, find new window\n");
                /*
                 * 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);
        }

        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);

        mlog(0, "claim bits: cstart: %u cend: %u clen: %u r_start: %u "
             "r_end: %u r_len: %u, r_last_start: %u r_last_len: %u\n",
             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);

        mlog(0, "Reservation now looks like: r_start: %u r_end: %u "
             "r_len: %u r_last_start: %u r_last_len: %u\n",
             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);
}