/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * extent_map.c
 *
 * Block/Cluster mapping functions
 *
 * Copyright (C) 2004 Oracle.  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.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include <linux/fs.h>
#include <linux/init.h>
#include <linux/types.h>

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

#include "ocfs2.h"

#include "alloc.h"
#include "extent_map.h"
#include "inode.h"
#include "super.h"

#include "buffer_head_io.h"

/*
 * The extent caching implementation is intentionally trivial.
 *
 * We only cache a small number of extents stored directly on the
 * inode, so linear order operations are acceptable. If we ever want
 * to increase the size of the extent map, then these algorithms must
 * get smarter.
 */

void ocfs2_extent_map_init(struct inode *inode)
{
        struct ocfs2_inode_info *oi = OCFS2_I(inode);

        oi->ip_extent_map.em_num_items = 0;
        INIT_LIST_HEAD(&oi->ip_extent_map.em_list);
}

static void __ocfs2_extent_map_lookup(struct ocfs2_extent_map *em,
                                      unsigned int cpos,
                                      struct ocfs2_extent_map_item **ret_emi)
{
        unsigned int range;
        struct ocfs2_extent_map_item *emi;

        *ret_emi = NULL;

        list_for_each_entry(emi, &em->em_list, ei_list) {
                range = emi->ei_cpos + emi->ei_clusters;

                if (cpos >= emi->ei_cpos && cpos < range) {
                        list_move(&emi->ei_list, &em->em_list);

                        *ret_emi = emi;
                        break;
                }
        }
}

static int ocfs2_extent_map_lookup(struct inode *inode, unsigned int cpos,
                                   unsigned int *phys, unsigned int *len,
                                   unsigned int *flags)
{
        unsigned int coff;
        struct ocfs2_inode_info *oi = OCFS2_I(inode);
        struct ocfs2_extent_map_item *emi;

        spin_lock(&oi->ip_lock);

        __ocfs2_extent_map_lookup(&oi->ip_extent_map, cpos, &emi);
        if (emi) {
                coff = cpos - emi->ei_cpos;
                *phys = emi->ei_phys + coff;
                if (len)
                        *len = emi->ei_clusters - coff;
                if (flags)
                        *flags = emi->ei_flags;
        }

        spin_unlock(&oi->ip_lock);

        if (emi == NULL)
                return -ENOENT;

        return 0;
}

/*
 * Forget about all clusters equal to or greater than cpos.
 */
void ocfs2_extent_map_trunc(struct inode *inode, unsigned int cpos)
{
        struct ocfs2_extent_map_item *emi, *n;
        struct ocfs2_inode_info *oi = OCFS2_I(inode);
        struct ocfs2_extent_map *em = &oi->ip_extent_map;
        LIST_HEAD(tmp_list);
        unsigned int range;

        spin_lock(&oi->ip_lock);
        list_for_each_entry_safe(emi, n, &em->em_list, ei_list) {
                if (emi->ei_cpos >= cpos) {
                        /* Full truncate of this record. */
                        list_move(&emi->ei_list, &tmp_list);
                        BUG_ON(em->em_num_items == 0);
                        em->em_num_items--;
                        continue;
                }

                range = emi->ei_cpos + emi->ei_clusters;
                if (range > cpos) {
                        /* Partial truncate */
                        emi->ei_clusters = cpos - emi->ei_cpos;
                }
        }
        spin_unlock(&oi->ip_lock);

        list_for_each_entry_safe(emi, n, &tmp_list, ei_list) {
                list_del(&emi->ei_list);
                kfree(emi);
        }
}

/*
 * Is any part of emi2 contained within emi1
 */
static int ocfs2_ei_is_contained(struct ocfs2_extent_map_item *emi1,
                                 struct ocfs2_extent_map_item *emi2)
{
        unsigned int range1, range2;

        /*
         * Check if logical start of emi2 is inside emi1
         */
        range1 = emi1->ei_cpos + emi1->ei_clusters;
        if (emi2->ei_cpos >= emi1->ei_cpos && emi2->ei_cpos < range1)
                return 1;

        /*
         * Check if logical end of emi2 is inside emi1
         */
        range2 = emi2->ei_cpos + emi2->ei_clusters;
        if (range2 > emi1->ei_cpos && range2 <= range1)
                return 1;

        return 0;
}

static void ocfs2_copy_emi_fields(struct ocfs2_extent_map_item *dest,
                                  struct ocfs2_extent_map_item *src)
{
        dest->ei_cpos = src->ei_cpos;
        dest->ei_phys = src->ei_phys;
        dest->ei_clusters = src->ei_clusters;
        dest->ei_flags = src->ei_flags;
}

/*
 * Try to merge emi with ins. Returns 1 if merge succeeds, zero
 * otherwise.
 */
static int ocfs2_try_to_merge_extent_map(struct ocfs2_extent_map_item *emi,
                                         struct ocfs2_extent_map_item *ins)
{
        /*
         * Handle contiguousness
         */
        if (ins->ei_phys == (emi->ei_phys + emi->ei_clusters) &&
            ins->ei_cpos == (emi->ei_cpos + emi->ei_clusters) &&
            ins->ei_flags == emi->ei_flags) {
                emi->ei_clusters += ins->ei_clusters;
                return 1;
        } else if ((ins->ei_phys + ins->ei_clusters) == emi->ei_phys &&
                   (ins->ei_cpos + ins->ei_clusters) == emi->ei_phys &&
                   ins->ei_flags == emi->ei_flags) {
                emi->ei_phys = ins->ei_phys;
                emi->ei_cpos = ins->ei_cpos;
                emi->ei_clusters += ins->ei_clusters;
                return 1;
        }

        /*
         * Overlapping extents - this shouldn't happen unless we've
         * split an extent to change it's flags. That is exceedingly
         * rare, so there's no sense in trying to optimize it yet.
         */
        if (ocfs2_ei_is_contained(emi, ins) ||
            ocfs2_ei_is_contained(ins, emi)) {
                ocfs2_copy_emi_fields(emi, ins);
                return 1;
        }

        /* No merge was possible. */
        return 0;
}

/*
 * In order to reduce complexity on the caller, this insert function
 * is intentionally liberal in what it will accept.
 *
 * The only rule is that the truncate call *must* be used whenever
 * records have been deleted. This avoids inserting overlapping
 * records with different physical mappings.
 */
void ocfs2_extent_map_insert_rec(struct inode *inode,
                                 struct ocfs2_extent_rec *rec)
{
        struct ocfs2_inode_info *oi = OCFS2_I(inode);
        struct ocfs2_extent_map *em = &oi->ip_extent_map;
        struct ocfs2_extent_map_item *emi, *new_emi = NULL;
        struct ocfs2_extent_map_item ins;

        ins.ei_cpos = le32_to_cpu(rec->e_cpos);
        ins.ei_phys = ocfs2_blocks_to_clusters(inode->i_sb,
                                               le64_to_cpu(rec->e_blkno));
        ins.ei_clusters = le16_to_cpu(rec->e_leaf_clusters);
        ins.ei_flags = rec->e_flags;

search:
        spin_lock(&oi->ip_lock);

        list_for_each_entry(emi, &em->em_list, ei_list) {
                if (ocfs2_try_to_merge_extent_map(emi, &ins)) {
                        list_move(&emi->ei_list, &em->em_list);
                        spin_unlock(&oi->ip_lock);
                        goto out;
                }
        }

        /*
         * No item could be merged.
         *
         * Either allocate and add a new item, or overwrite the last recently
         * inserted.
         */

        if (em->em_num_items < OCFS2_MAX_EXTENT_MAP_ITEMS) {
                if (new_emi == NULL) {
                        spin_unlock(&oi->ip_lock);

                        new_emi = kmalloc(sizeof(*new_emi), GFP_NOFS);
                        if (new_emi == NULL)
                                goto out;

                        goto search;
                }

                ocfs2_copy_emi_fields(new_emi, &ins);
                list_add(&new_emi->ei_list, &em->em_list);
                em->em_num_items++;
                new_emi = NULL;
        } else {
                BUG_ON(list_empty(&em->em_list) || em->em_num_items == 0);
                emi = list_entry(em->em_list.prev,
                                 struct ocfs2_extent_map_item, ei_list);
                list_move(&emi->ei_list, &em->em_list);
                ocfs2_copy_emi_fields(emi, &ins);
        }

        spin_unlock(&oi->ip_lock);

out:
        if (new_emi)
                kfree(new_emi);
}

/*
 * Return the 1st index within el which contains an extent start
 * larger than v_cluster.
 */
static int ocfs2_search_for_hole_index(struct ocfs2_extent_list *el,
                                       u32 v_cluster)
{
        int i;
        struct ocfs2_extent_rec *rec;

        for(i = 0; i < le16_to_cpu(el->l_next_free_rec); i++) {
                rec = &el->l_recs[i];

                if (v_cluster < le32_to_cpu(rec->e_cpos))
                        break;
        }

        return i;
}

/*
 * Figure out the size of a hole which starts at v_cluster within the given
 * extent list.
 *
 * If there is no more allocation past v_cluster, we return the maximum
 * cluster size minus v_cluster.
 *
 * If we have in-inode extents, then el points to the dinode list and
 * eb_bh is NULL. Otherwise, eb_bh should point to the extent block
 * containing el.
 */
static int ocfs2_figure_hole_clusters(struct inode *inode,
                                      struct ocfs2_extent_list *el,
                                      struct buffer_head *eb_bh,
                                      u32 v_cluster,
                                      u32 *num_clusters)
{
        int ret, i;
        struct buffer_head *next_eb_bh = NULL;
        struct ocfs2_extent_block *eb, *next_eb;

        i = ocfs2_search_for_hole_index(el, v_cluster);

        if (i == le16_to_cpu(el->l_next_free_rec) && eb_bh) {
                eb = (struct ocfs2_extent_block *)eb_bh->b_data;

                /*
                 * Check the next leaf for any extents.
                 */

                if (le64_to_cpu(eb->h_next_leaf_blk) == 0ULL)
                        goto no_more_extents;

                ret = ocfs2_read_block(OCFS2_SB(inode->i_sb),
                                       le64_to_cpu(eb->h_next_leaf_blk),
                                       &next_eb_bh, OCFS2_BH_CACHED, inode);
                if (ret) {
                        mlog_errno(ret);
                        goto out;
                }
                next_eb = (struct ocfs2_extent_block *)next_eb_bh->b_data;

                if (!OCFS2_IS_VALID_EXTENT_BLOCK(next_eb)) {
                        ret = -EROFS;
                        OCFS2_RO_ON_INVALID_EXTENT_BLOCK(inode->i_sb, next_eb);
                        goto out;
                }

                el = &next_eb->h_list;

                i = ocfs2_search_for_hole_index(el, v_cluster);
        }

no_more_extents:
        if (i == le16_to_cpu(el->l_next_free_rec)) {
                /*
                 * We're at the end of our existing allocation. Just
                 * return the maximum number of clusters we could
                 * possibly allocate.
                 */
                *num_clusters = UINT_MAX - v_cluster;
        } else {
                *num_clusters = le32_to_cpu(el->l_recs[i].e_cpos) - v_cluster;
        }

        ret = 0;
out:
        brelse(next_eb_bh);
        return ret;
}

int ocfs2_get_clusters(struct inode *inode, u32 v_cluster,
                       u32 *p_cluster, u32 *num_clusters,
                       unsigned int *extent_flags)
{
        int ret, i;
        unsigned int flags = 0;
        struct buffer_head *di_bh = NULL;
        struct buffer_head *eb_bh = NULL;
        struct ocfs2_dinode *di;
        struct ocfs2_extent_block *eb;
        struct ocfs2_extent_list *el;
        struct ocfs2_extent_rec *rec;
        u32 coff;

        if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
                ret = -ERANGE;
                mlog_errno(ret);
                goto out;
        }

        ret = ocfs2_extent_map_lookup(inode, v_cluster, p_cluster,
                                      num_clusters, extent_flags);
        if (ret == 0)
                goto out;

        ret = ocfs2_read_block(OCFS2_SB(inode->i_sb), OCFS2_I(inode)->ip_blkno,
                               &di_bh, OCFS2_BH_CACHED, inode);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        di = (struct ocfs2_dinode *) di_bh->b_data;
        el = &di->id2.i_list;

        if (el->l_tree_depth) {
                ret = ocfs2_find_leaf(inode, el, v_cluster, &eb_bh);
                if (ret) {
                        mlog_errno(ret);
                        goto out;
                }

                eb = (struct ocfs2_extent_block *) eb_bh->b_data;
                el = &eb->h_list;

                if (el->l_tree_depth) {
                        ocfs2_error(inode->i_sb,
                                    "Inode %lu has non zero tree depth in "
                                    "leaf block %llu\n", inode->i_ino,
                                    (unsigned long long)eb_bh->b_blocknr);
                        ret = -EROFS;
                        goto out;
                }
        }

        i = ocfs2_search_extent_list(el, v_cluster);
        if (i == -1) {
                /*
                 * A hole was found. Return some canned values that
                 * callers can key on. If asked for, num_clusters will
                 * be populated with the size of the hole.
                 */
                *p_cluster = 0;
                if (num_clusters) {
                        ret = ocfs2_figure_hole_clusters(inode, el, eb_bh,
                                                         v_cluster,
                                                         num_clusters);
                        if (ret) {
                                mlog_errno(ret);
                                goto out;
                        }
                }
        } else {
                rec = &el->l_recs[i];

                BUG_ON(v_cluster < le32_to_cpu(rec->e_cpos));

                if (!rec->e_blkno) {
                        ocfs2_error(inode->i_sb, "Inode %lu has bad extent "
                                    "record (%u, %u, 0)", inode->i_ino,
                                    le32_to_cpu(rec->e_cpos),
                                    ocfs2_rec_clusters(el, rec));
                        ret = -EROFS;
                        goto out;
                }

                coff = v_cluster - le32_to_cpu(rec->e_cpos);

                *p_cluster = ocfs2_blocks_to_clusters(inode->i_sb,
                                                    le64_to_cpu(rec->e_blkno));
                *p_cluster = *p_cluster + coff;

                if (num_clusters)
                        *num_clusters = ocfs2_rec_clusters(el, rec) - coff;

                flags = rec->e_flags;

                ocfs2_extent_map_insert_rec(inode, rec);
        }

        if (extent_flags)
                *extent_flags = flags;

out:
        brelse(di_bh);
        brelse(eb_bh);
        return ret;
}

/*
 * This expects alloc_sem to be held. The allocation cannot change at
 * all while the map is in the process of being updated.
 */
int ocfs2_extent_map_get_blocks(struct inode *inode, u64 v_blkno, u64 *p_blkno,
                                u64 *ret_count, unsigned int *extent_flags)
{
        int ret;
        int bpc = ocfs2_clusters_to_blocks(inode->i_sb, 1);
        u32 cpos, num_clusters, p_cluster;
        u64 boff = 0;

        cpos = ocfs2_blocks_to_clusters(inode->i_sb, v_blkno);

        ret = ocfs2_get_clusters(inode, cpos, &p_cluster, &num_clusters,
                                 extent_flags);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        /*
         * p_cluster == 0 indicates a hole.
         */
        if (p_cluster) {
                boff = ocfs2_clusters_to_blocks(inode->i_sb, p_cluster);
                boff += (v_blkno & (u64)(bpc - 1));
        }

        *p_blkno = boff;

        if (ret_count) {
                *ret_count = ocfs2_clusters_to_blocks(inode->i_sb, num_clusters);
                *ret_count -= v_blkno & (u64)(bpc - 1);
        }

out:
        return ret;
}