/*
 *  linux/fs/hfsplus/extents.c
 *
 * Copyright (C) 2001
 * Brad Boyer (flar@allandria.com)
 * (C) 2003 Ardis Technologies <roman@ardistech.com>
 *
 * Handling of Extents both in catalog and extents overflow trees
 */

#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/pagemap.h>

#include "hfsplus_fs.h"
#include "hfsplus_raw.h"

/* Compare two extents keys, returns 0 on same, pos/neg for difference */
int hfsplus_ext_cmp_key(const hfsplus_btree_key *k1,
                        const hfsplus_btree_key *k2)
{
        __be32 k1id, k2id;
        __be32 k1s, k2s;

        k1id = k1->ext.cnid;
        k2id = k2->ext.cnid;
        if (k1id != k2id)
                return be32_to_cpu(k1id) < be32_to_cpu(k2id) ? -1 : 1;

        if (k1->ext.fork_type != k2->ext.fork_type)
                return k1->ext.fork_type < k2->ext.fork_type ? -1 : 1;

        k1s = k1->ext.start_block;
        k2s = k2->ext.start_block;
        if (k1s == k2s)
                return 0;
        return be32_to_cpu(k1s) < be32_to_cpu(k2s) ? -1 : 1;
}

static void hfsplus_ext_build_key(hfsplus_btree_key *key, u32 cnid,
                                  u32 block, u8 type)
{
        key->key_len = cpu_to_be16(HFSPLUS_EXT_KEYLEN - 2);
        key->ext.cnid = cpu_to_be32(cnid);
        key->ext.start_block = cpu_to_be32(block);
        key->ext.fork_type = type;
        key->ext.pad = 0;
}

static u32 hfsplus_ext_find_block(struct hfsplus_extent *ext, u32 off)
{
        int i;
        u32 count;

        for (i = 0; i < 8; ext++, i++) {
                count = be32_to_cpu(ext->block_count);
                if (off < count)
                        return be32_to_cpu(ext->start_block) + off;
                off -= count;
        }
        /* panic? */
        return 0;
}

static int hfsplus_ext_block_count(struct hfsplus_extent *ext)
{
        int i;
        u32 count = 0;

        for (i = 0; i < 8; ext++, i++)
                count += be32_to_cpu(ext->block_count);
        return count;
}

static u32 hfsplus_ext_lastblock(struct hfsplus_extent *ext)
{
        int i;

        ext += 7;
        for (i = 0; i < 7; ext--, i++)
                if (ext->block_count)
                        break;
        return be32_to_cpu(ext->start_block) + be32_to_cpu(ext->block_count);
}

static void __hfsplus_ext_write_extent(struct inode *inode,
                struct hfs_find_data *fd)
{
        struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
        int res;

        WARN_ON(!mutex_is_locked(&hip->extents_lock));

        hfsplus_ext_build_key(fd->search_key, inode->i_ino, hip->cached_start,
                              HFSPLUS_IS_RSRC(inode) ?
                                HFSPLUS_TYPE_RSRC : HFSPLUS_TYPE_DATA);

        res = hfs_brec_find(fd);
        if (hip->extent_state & HFSPLUS_EXT_NEW) {
                if (res != -ENOENT)
                        return;
                hfs_brec_insert(fd, hip->cached_extents,
                                sizeof(hfsplus_extent_rec));
                hip->extent_state &= ~(HFSPLUS_EXT_DIRTY | HFSPLUS_EXT_NEW);
        } else {
                if (res)
                        return;
                hfs_bnode_write(fd->bnode, hip->cached_extents,
                                fd->entryoffset, fd->entrylength);
                hip->extent_state &= ~HFSPLUS_EXT_DIRTY;
        }

        /*
         * We can't just use hfsplus_mark_inode_dirty here, because we
         * also get called from hfsplus_write_inode, which should not
         * redirty the inode.  Instead the callers have to be careful
         * to explicily mark the inode dirty, too.
         */
        set_bit(HFSPLUS_I_EXT_DIRTY, &hip->flags);
}

static void hfsplus_ext_write_extent_locked(struct inode *inode)
{
        if (HFSPLUS_I(inode)->extent_state & HFSPLUS_EXT_DIRTY) {
                struct hfs_find_data fd;

                hfs_find_init(HFSPLUS_SB(inode->i_sb)->ext_tree, &fd);
                __hfsplus_ext_write_extent(inode, &fd);
                hfs_find_exit(&fd);
        }
}

void hfsplus_ext_write_extent(struct inode *inode)
{
        mutex_lock(&HFSPLUS_I(inode)->extents_lock);
        hfsplus_ext_write_extent_locked(inode);
        mutex_unlock(&HFSPLUS_I(inode)->extents_lock);
}

static inline int __hfsplus_ext_read_extent(struct hfs_find_data *fd,
                                            struct hfsplus_extent *extent,
                                            u32 cnid, u32 block, u8 type)
{
        int res;

        hfsplus_ext_build_key(fd->search_key, cnid, block, type);
        fd->key->ext.cnid = 0;
        res = hfs_brec_find(fd);
        if (res && res != -ENOENT)
                return res;
        if (fd->key->ext.cnid != fd->search_key->ext.cnid ||
            fd->key->ext.fork_type != fd->search_key->ext.fork_type)
                return -ENOENT;
        if (fd->entrylength != sizeof(hfsplus_extent_rec))
                return -EIO;
        hfs_bnode_read(fd->bnode, extent, fd->entryoffset,
                sizeof(hfsplus_extent_rec));
        return 0;
}

static inline int __hfsplus_ext_cache_extent(struct hfs_find_data *fd,
                struct inode *inode, u32 block)
{
        struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
        int res;

        WARN_ON(!mutex_is_locked(&hip->extents_lock));

        if (hip->extent_state & HFSPLUS_EXT_DIRTY)
                __hfsplus_ext_write_extent(inode, fd);

        res = __hfsplus_ext_read_extent(fd, hip->cached_extents, inode->i_ino,
                                        block, HFSPLUS_IS_RSRC(inode) ?
                                                HFSPLUS_TYPE_RSRC :
                                                HFSPLUS_TYPE_DATA);
        if (!res) {
                hip->cached_start = be32_to_cpu(fd->key->ext.start_block);
                hip->cached_blocks =
                        hfsplus_ext_block_count(hip->cached_extents);
        } else {
                hip->cached_start = hip->cached_blocks = 0;
                hip->extent_state &= ~(HFSPLUS_EXT_DIRTY | HFSPLUS_EXT_NEW);
        }
        return res;
}

static int hfsplus_ext_read_extent(struct inode *inode, u32 block)
{
        struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
        struct hfs_find_data fd;
        int res;

        if (block >= hip->cached_start &&
            block < hip->cached_start + hip->cached_blocks)
                return 0;

        hfs_find_init(HFSPLUS_SB(inode->i_sb)->ext_tree, &fd);
        res = __hfsplus_ext_cache_extent(&fd, inode, block);
        hfs_find_exit(&fd);
        return res;
}

/* Get a block at iblock for inode, possibly allocating if create */
int hfsplus_get_block(struct inode *inode, sector_t iblock,
                      struct buffer_head *bh_result, int create)
{
        struct super_block *sb = inode->i_sb;
        struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
        struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
        int res = -EIO;
        u32 ablock, dblock, mask;
        int was_dirty = 0;
        int shift;

        /* Convert inode block to disk allocation block */
        shift = sbi->alloc_blksz_shift - sb->s_blocksize_bits;
        ablock = iblock >> sbi->fs_shift;

        if (iblock >= hip->fs_blocks) {
                if (iblock > hip->fs_blocks || !create)
                        return -EIO;
                if (ablock >= hip->alloc_blocks) {
                        res = hfsplus_file_extend(inode);
                        if (res)
                                return res;
                }
        } else
                create = 0;

        if (ablock < hip->first_blocks) {
                dblock = hfsplus_ext_find_block(hip->first_extents, ablock);
                goto done;
        }

        if (inode->i_ino == HFSPLUS_EXT_CNID)
                return -EIO;

        mutex_lock(&hip->extents_lock);

        /*
         * hfsplus_ext_read_extent will write out a cached extent into
         * the extents btree.  In that case we may have to mark the inode
         * dirty even for a pure read of an extent here.
         */
        was_dirty = (hip->extent_state & HFSPLUS_EXT_DIRTY);
        res = hfsplus_ext_read_extent(inode, ablock);
        if (res) {
                mutex_unlock(&hip->extents_lock);
                return -EIO;
        }
        dblock = hfsplus_ext_find_block(hip->cached_extents,
                                        ablock - hip->cached_start);
        mutex_unlock(&hip->extents_lock);

done:
        dprint(DBG_EXTENT, "get_block(%lu): %llu - %u\n",
                inode->i_ino, (long long)iblock, dblock);
        mask = (1 << sbi->fs_shift) - 1;
        map_bh(bh_result, sb,
                (dblock << sbi->fs_shift) + sbi->blockoffset +
                        (iblock & mask));
        if (create) {
                set_buffer_new(bh_result);
                hip->phys_size += sb->s_blocksize;
                hip->fs_blocks++;
                inode_add_bytes(inode, sb->s_blocksize);
        }
        if (create || was_dirty)
                mark_inode_dirty(inode);
        return 0;
}

static void hfsplus_dump_extent(struct hfsplus_extent *extent)
{
        int i;

        dprint(DBG_EXTENT, "   ");
        for (i = 0; i < 8; i++)
                dprint(DBG_EXTENT, " %u:%u", be32_to_cpu(extent[i].start_block),
                                 be32_to_cpu(extent[i].block_count));
        dprint(DBG_EXTENT, "\n");
}

static int hfsplus_add_extent(struct hfsplus_extent *extent, u32 offset,
                              u32 alloc_block, u32 block_count)
{
        u32 count, start;
        int i;

        hfsplus_dump_extent(extent);
        for (i = 0; i < 8; extent++, i++) {
                count = be32_to_cpu(extent->block_count);
                if (offset == count) {
                        start = be32_to_cpu(extent->start_block);
                        if (alloc_block != start + count) {
                                if (++i >= 8)
                                        return -ENOSPC;
                                extent++;
                                extent->start_block = cpu_to_be32(alloc_block);
                        } else
                                block_count += count;
                        extent->block_count = cpu_to_be32(block_count);
                        return 0;
                } else if (offset < count)
                        break;
                offset -= count;
        }
        /* panic? */
        return -EIO;
}

static int hfsplus_free_extents(struct super_block *sb,
                                struct hfsplus_extent *extent,
                                u32 offset, u32 block_nr)
{
        u32 count, start;
        int i;

        hfsplus_dump_extent(extent);
        for (i = 0; i < 8; extent++, i++) {
                count = be32_to_cpu(extent->block_count);
                if (offset == count)
                        goto found;
                else if (offset < count)
                        break;
                offset -= count;
        }
        /* panic? */
        return -EIO;
found:
        for (;;) {
                start = be32_to_cpu(extent->start_block);
                if (count <= block_nr) {
                        hfsplus_block_free(sb, start, count);
                        extent->block_count = 0;
                        extent->start_block = 0;
                        block_nr -= count;
                } else {
                        count -= block_nr;
                        hfsplus_block_free(sb, start + count, block_nr);
                        extent->block_count = cpu_to_be32(count);
                        block_nr = 0;
                }
                if (!block_nr || !i)
                        return 0;
                i--;
                extent--;
                count = be32_to_cpu(extent->block_count);
        }
}

int hfsplus_free_fork(struct super_block *sb, u32 cnid,
                struct hfsplus_fork_raw *fork, int type)
{
        struct hfs_find_data fd;
        hfsplus_extent_rec ext_entry;
        u32 total_blocks, blocks, start;
        int res, i;

        total_blocks = be32_to_cpu(fork->total_blocks);
        if (!total_blocks)
                return 0;

        blocks = 0;
        for (i = 0; i < 8; i++)
                blocks += be32_to_cpu(fork->extents[i].block_count);

        res = hfsplus_free_extents(sb, fork->extents, blocks, blocks);
        if (res)
                return res;
        if (total_blocks == blocks)
                return 0;

        hfs_find_init(HFSPLUS_SB(sb)->ext_tree, &fd);
        do {
                res = __hfsplus_ext_read_extent(&fd, ext_entry, cnid,
                                                total_blocks, type);
                if (res)
                        break;
                start = be32_to_cpu(fd.key->ext.start_block);
                hfsplus_free_extents(sb, ext_entry,
                                     total_blocks - start,
                                     total_blocks);
                hfs_brec_remove(&fd);
                total_blocks = start;
        } while (total_blocks > blocks);
        hfs_find_exit(&fd);

        return res;
}

int hfsplus_file_extend(struct inode *inode)
{
        struct super_block *sb = inode->i_sb;
        struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
        struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
        u32 start, len, goal;
        int res;

        if (sbi->alloc_file->i_size * 8 <
            sbi->total_blocks - sbi->free_blocks + 8) {
                /* extend alloc file */
                printk(KERN_ERR "hfs: extend alloc file! "
                                "(%llu,%u,%u)\n",
                        sbi->alloc_file->i_size * 8,
                        sbi->total_blocks, sbi->free_blocks);
                return -ENOSPC;
        }

        mutex_lock(&hip->extents_lock);
        if (hip->alloc_blocks == hip->first_blocks)
                goal = hfsplus_ext_lastblock(hip->first_extents);
        else {
                res = hfsplus_ext_read_extent(inode, hip->alloc_blocks);
                if (res)
                        goto out;
                goal = hfsplus_ext_lastblock(hip->cached_extents);
        }

        len = hip->clump_blocks;
        start = hfsplus_block_allocate(sb, sbi->total_blocks, goal, &len);
        if (start >= sbi->total_blocks) {
                start = hfsplus_block_allocate(sb, goal, 0, &len);
                if (start >= goal) {
                        res = -ENOSPC;
                        goto out;
                }
        }

        dprint(DBG_EXTENT, "extend %lu: %u,%u\n", inode->i_ino, start, len);

        if (hip->alloc_blocks <= hip->first_blocks) {
                if (!hip->first_blocks) {
                        dprint(DBG_EXTENT, "first extents\n");
                        /* no extents yet */
                        hip->first_extents[0].start_block = cpu_to_be32(start);
                        hip->first_extents[0].block_count = cpu_to_be32(len);
                        res = 0;
                } else {
                        /* try to append to extents in inode */
                        res = hfsplus_add_extent(hip->first_extents,
                                                 hip->alloc_blocks,
                                                 start, len);
                        if (res == -ENOSPC)
                                goto insert_extent;
                }
                if (!res) {
                        hfsplus_dump_extent(hip->first_extents);
                        hip->first_blocks += len;
                }
        } else {
                res = hfsplus_add_extent(hip->cached_extents,
                                         hip->alloc_blocks - hip->cached_start,
                                         start, len);
                if (!res) {
                        hfsplus_dump_extent(hip->cached_extents);
                        hip->extent_state |= HFSPLUS_EXT_DIRTY;
                        hip->cached_blocks += len;
                } else if (res == -ENOSPC)
                        goto insert_extent;
        }
out:
        mutex_unlock(&hip->extents_lock);
        if (!res) {
                hip->alloc_blocks += len;
                hfsplus_mark_inode_dirty(inode, HFSPLUS_I_ALLOC_DIRTY);
        }
        return res;

insert_extent:
        dprint(DBG_EXTENT, "insert new extent\n");
        hfsplus_ext_write_extent_locked(inode);

        memset(hip->cached_extents, 0, sizeof(hfsplus_extent_rec));
        hip->cached_extents[0].start_block = cpu_to_be32(start);
        hip->cached_extents[0].block_count = cpu_to_be32(len);
        hfsplus_dump_extent(hip->cached_extents);
        hip->extent_state |= HFSPLUS_EXT_DIRTY | HFSPLUS_EXT_NEW;
        hip->cached_start = hip->alloc_blocks;
        hip->cached_blocks = len;

        res = 0;
        goto out;
}

void hfsplus_file_truncate(struct inode *inode)
{
        struct super_block *sb = inode->i_sb;
        struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
        struct hfs_find_data fd;
        u32 alloc_cnt, blk_cnt, start;
        int res;

        dprint(DBG_INODE, "truncate: %lu, %llu -> %llu\n",
                inode->i_ino, (long long)hip->phys_size,
                inode->i_size);

        if (inode->i_size > hip->phys_size) {
                struct address_space *mapping = inode->i_mapping;
                struct page *page;
                void *fsdata;
                u32 size = inode->i_size;
                int res;

                res = pagecache_write_begin(NULL, mapping, size, 0,
                                                AOP_FLAG_UNINTERRUPTIBLE,
                                                &page, &fsdata);
                if (res)
                        return;
                res = pagecache_write_end(NULL, mapping, size,
                        0, 0, page, fsdata);
                if (res < 0)
                        return;
                mark_inode_dirty(inode);
                return;
        } else if (inode->i_size == hip->phys_size)
                return;

        blk_cnt = (inode->i_size + HFSPLUS_SB(sb)->alloc_blksz - 1) >>
                        HFSPLUS_SB(sb)->alloc_blksz_shift;
        alloc_cnt = hip->alloc_blocks;
        if (blk_cnt == alloc_cnt)
                goto out;

        mutex_lock(&hip->extents_lock);
        hfs_find_init(HFSPLUS_SB(sb)->ext_tree, &fd);
        while (1) {
                if (alloc_cnt == hip->first_blocks) {
                        hfsplus_free_extents(sb, hip->first_extents,
                                             alloc_cnt, alloc_cnt - blk_cnt);
                        hfsplus_dump_extent(hip->first_extents);
                        hip->first_blocks = blk_cnt;
                        break;
                }
                res = __hfsplus_ext_cache_extent(&fd, inode, alloc_cnt);
                if (res)
                        break;
                start = hip->cached_start;
                hfsplus_free_extents(sb, hip->cached_extents,
                                     alloc_cnt - start, alloc_cnt - blk_cnt);
                hfsplus_dump_extent(hip->cached_extents);
                if (blk_cnt > start) {
                        hip->extent_state |= HFSPLUS_EXT_DIRTY;
                        break;
                }
                alloc_cnt = start;
                hip->cached_start = hip->cached_blocks = 0;
                hip->extent_state &= ~(HFSPLUS_EXT_DIRTY | HFSPLUS_EXT_NEW);
                hfs_brec_remove(&fd);
        }
        hfs_find_exit(&fd);
        mutex_unlock(&hip->extents_lock);

        hip->alloc_blocks = blk_cnt;
out:
        hip->phys_size = inode->i_size;
        hip->fs_blocks = (inode->i_size + sb->s_blocksize - 1) >>
                sb->s_blocksize_bits;
        inode_set_bytes(inode, hip->fs_blocks << sb->s_blocksize_bits);
        hfsplus_mark_inode_dirty(inode, HFSPLUS_I_ALLOC_DIRTY);
}