source: mainline/uspace/lib/ext4/libext4_balloc.c@ a872fc09

/*
 * Copyright (c) 2011 Frantisek Princ
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup libext4
 * @{
 */ 

/**
 * @file        libext4_balloc.c
 * @brief       Physical block allocator.
 */

#include <errno.h>
#include <sys/types.h>
#include "libext4.h"

static uint32_t ext4_balloc_blockaddr2_index_in_group(ext4_superblock_t *sb,
                uint32_t block_addr)
{
        uint32_t blocks_per_group = ext4_superblock_get_blocks_per_group(sb);
        uint32_t first_block = ext4_superblock_get_first_data_block(sb);

        // First block == 0 or 1
        if (first_block == 0) {
                return block_addr % blocks_per_group;
        } else {
                return (block_addr - 1) % blocks_per_group;
        }
}

static uint32_t ext4_balloc_index_in_group2blockaddr(ext4_superblock_t *sb,
                uint32_t index, uint32_t bgid)
{
        uint32_t blocks_per_group = ext4_superblock_get_blocks_per_group(sb);

        if (ext4_superblock_get_first_data_block(sb) == 0) {
                return bgid * blocks_per_group + index;
        } else {
                return bgid * blocks_per_group + index + 1;
        }

}

static uint32_t ext4_balloc_get_bgid_of_block(ext4_superblock_t *sb,
                uint32_t block_addr)
{
        uint32_t blocks_per_group = ext4_superblock_get_blocks_per_group(sb);
        uint32_t first_block = ext4_superblock_get_first_data_block(sb);

        // First block == 0 or 1
        if (first_block == 0) {
                return block_addr / blocks_per_group;
        } else {
                return (block_addr - 1) / blocks_per_group;
        }
}


int ext4_balloc_free_block(ext4_filesystem_t *fs, ext4_inode_ref_t *inode_ref, uint32_t block_addr)
{
        int rc;

        uint32_t block_group = ext4_balloc_get_bgid_of_block(fs->superblock, block_addr);
        uint32_t index_in_group = ext4_balloc_blockaddr2_index_in_group(fs->superblock, block_addr);

        ext4_block_group_ref_t *bg_ref;
        rc = ext4_filesystem_get_block_group_ref(fs, block_group, &bg_ref);
        if (rc != EOK) {
                EXT4FS_DBG("error in loading bg_ref \%d", rc);
                return rc;
        }

        uint32_t bitmap_block_addr = ext4_block_group_get_block_bitmap(
                        bg_ref->block_group, fs->superblock);
        block_t *bitmap_block;
        rc = block_get(&bitmap_block, fs->device, bitmap_block_addr, 0);
        if (rc != EOK) {
                EXT4FS_DBG("error in loading bitmap \%d", rc);
                return rc;
        }

        ext4_bitmap_free_bit(bitmap_block->data, index_in_group);
        bitmap_block->dirty = true;

        rc = block_put(bitmap_block);
        if (rc != EOK) {
                // Error in saving bitmap
                ext4_filesystem_put_block_group_ref(bg_ref);
                EXT4FS_DBG("error in saving bitmap \%d", rc);
                return rc;
        }

        uint32_t block_size = ext4_superblock_get_block_size(fs->superblock);

        // Update superblock free blocks count
        uint32_t sb_free_blocks = ext4_superblock_get_free_blocks_count(fs->superblock);
        sb_free_blocks--;
        ext4_superblock_set_free_blocks_count(fs->superblock, sb_free_blocks);

        // Update inode blocks count
        uint64_t ino_blocks = ext4_inode_get_blocks_count(fs->superblock, inode_ref->inode);
        ino_blocks -= block_size / EXT4_INODE_BLOCK_SIZE;
        ext4_inode_set_blocks_count(fs->superblock, inode_ref->inode, ino_blocks);
        inode_ref->dirty = true;

        // Update block group free blocks count
        uint32_t free_blocks = ext4_block_group_get_free_blocks_count(
                        bg_ref->block_group, fs->superblock);
        free_blocks++;
        ext4_block_group_set_free_blocks_count(bg_ref->block_group,
                        fs->superblock, free_blocks);
        bg_ref->dirty = true;

        rc = ext4_filesystem_put_block_group_ref(bg_ref);
        if (rc != EOK) {
                EXT4FS_DBG("error in saving bg_ref \%d", rc);
                // TODO error
                return rc;
        }

        return EOK;
}

static uint32_t ext4_balloc_get_first_data_block_in_group(
                ext4_superblock_t *sb, ext4_block_group_t *bg, uint32_t bgid)
{
        uint32_t block_group_count = ext4_superblock_get_block_group_count(sb);
        uint32_t inode_table_first_block = ext4_block_group_get_inode_table_first_block(
                        bg, sb);
        uint16_t inode_table_item_size = ext4_superblock_get_inode_size(sb);
        uint32_t inodes_per_group = ext4_superblock_get_inodes_per_group(sb);
        uint32_t block_size = ext4_superblock_get_block_size(sb);
        uint32_t inode_table_bytes;

        if (bgid < block_group_count - 1) {
                inode_table_bytes = inodes_per_group * inode_table_item_size;
        } else {
                // last block group could be smaller
                uint32_t inodes_count_total = ext4_superblock_get_inodes_count(sb);
                inode_table_bytes =
                                (inodes_count_total - ((block_group_count - 1) * inodes_per_group))
                                * inode_table_item_size;
        }

        uint32_t inode_table_blocks = inode_table_bytes / block_size;

        if (inode_table_bytes % block_size) {
                inode_table_blocks++;
        }

        return inode_table_first_block + inode_table_blocks;
}


static uint32_t ext4_balloc_find_goal(ext4_filesystem_t *fs, ext4_inode_ref_t *inode_ref)
{
        int rc;
        uint32_t goal = 0;

        uint64_t inode_size = ext4_inode_get_size(fs->superblock, inode_ref->inode);
        uint32_t block_size = ext4_superblock_get_block_size(fs->superblock);
        uint32_t inode_block_count = inode_size / block_size;

        if (inode_size % block_size != 0) {
                inode_block_count++;
        }

        if (inode_block_count > 0) {
                // TODO check retval
                ext4_filesystem_get_inode_data_block_index(fs, inode_ref->inode, inode_block_count - 1, &goal);

                // TODO
                // If goal == 0 -> SPARSE file !!!

                goal++;
                return goal;
        }

        // Identify block group of inode
        uint32_t inodes_per_group = ext4_superblock_get_inodes_per_group(fs->superblock);
        uint32_t block_group = (inode_ref->index - 1) / inodes_per_group;
        block_size = ext4_superblock_get_block_size(fs->superblock);

        ext4_block_group_ref_t *bg_ref;
        rc = ext4_filesystem_get_block_group_ref(fs, block_group, &bg_ref);
        if (rc != EOK) {
                return 0;
        }

        uint32_t block_group_count = ext4_superblock_get_block_group_count(fs->superblock);
        uint32_t inode_table_first_block = ext4_block_group_get_inode_table_first_block(
                        bg_ref->block_group, fs->superblock);
        uint16_t inode_table_item_size = ext4_superblock_get_inode_size(fs->superblock);
        uint32_t inode_table_bytes;

        if (block_group < block_group_count - 1) {
                inode_table_bytes = inodes_per_group * inode_table_item_size;
        } else {
                // last block group could be smaller
                uint32_t inodes_count_total = ext4_superblock_get_inodes_count(fs->superblock);
                inode_table_bytes =
                                (inodes_count_total - ((block_group_count - 1) * inodes_per_group))
                                * inode_table_item_size;
        }

        uint32_t inode_table_blocks = inode_table_bytes / block_size;

        if (inode_table_bytes % block_size) {
                inode_table_blocks++;
        }

        goal = inode_table_first_block + inode_table_blocks;

        ext4_filesystem_put_block_group_ref(bg_ref);

        return goal;
}

int ext4_balloc_alloc_block(ext4_filesystem_t *fs,
                ext4_inode_ref_t *inode_ref, uint32_t *fblock)
{
        int rc;
        uint32_t allocated_block = 0;

        uint32_t bitmap_block_addr;
        block_t *bitmap_block;
        uint32_t rel_block_idx = 0;

        // Find GOAL
        uint32_t goal = ext4_balloc_find_goal(fs, inode_ref);
        if (goal == 0) {
                // TODO
                EXT4FS_DBG("ERRORR (goal == 0)");
                return ENOSPC;
        }

        // Load block group number for goal and relative index
        uint32_t block_group = ext4_balloc_get_bgid_of_block(fs->superblock, goal);
        uint32_t index_in_group = ext4_balloc_blockaddr2_index_in_group(fs->superblock, goal);


        ext4_block_group_ref_t *bg_ref;
        rc = ext4_filesystem_get_block_group_ref(fs, block_group, &bg_ref);
        if (rc != EOK) {
                EXT4FS_DBG("initial BG ref not loaded");
                return rc;
        }

        uint32_t first_in_group =
                        ext4_balloc_get_first_data_block_in_group(fs->superblock,
                                        bg_ref->block_group, block_group);

        uint32_t first_in_group_index = ext4_balloc_blockaddr2_index_in_group(
                        fs->superblock, first_in_group);

        if (index_in_group < first_in_group_index) {
                index_in_group = first_in_group_index;
        }

        // Load bitmap
        bitmap_block_addr = ext4_block_group_get_block_bitmap(bg_ref->block_group,
                        fs->superblock);

        rc = block_get(&bitmap_block, fs->device, bitmap_block_addr, 0);
        if (rc != EOK) {
                ext4_filesystem_put_block_group_ref(bg_ref);
                EXT4FS_DBG("initial bitmap not loaded");
                return rc;
        }

        // Check if goal is free
        if (ext4_bitmap_is_free_bit(bitmap_block->data, index_in_group)) {
                ext4_bitmap_set_bit(bitmap_block->data, index_in_group);
                bitmap_block->dirty = true;
                rc = block_put(bitmap_block);
                if (rc != EOK) {
                        // TODO error
                        EXT4FS_DBG("goal check: error in saving initial bitmap \%d", rc);
                        ext4_filesystem_put_block_group_ref(bg_ref);
                        return rc;
                }

                allocated_block = goal;
                goto success;

        }

        uint32_t blocks_in_group = ext4_superblock_get_blocks_in_group(fs->superblock, block_group);

        uint32_t end_idx = (index_in_group + 63) & ~63;
        if (end_idx > blocks_in_group) {
                end_idx = blocks_in_group;
        }

        // Try to find free block near to goal
        for (uint32_t tmp_idx = index_in_group + 1; tmp_idx < end_idx; ++tmp_idx) {
                if (ext4_bitmap_is_free_bit(bitmap_block->data, tmp_idx)) {

                        ext4_bitmap_set_bit(bitmap_block->data, tmp_idx);
                        bitmap_block->dirty = true;
                        rc = block_put(bitmap_block);
                        if (rc != EOK) {
                                // TODO error
                                EXT4FS_DBG("near blocks: error in saving initial bitmap \%d", rc);
                        }

                        allocated_block = ext4_balloc_index_in_group2blockaddr(
                                        fs->superblock, tmp_idx, block_group);

                        goto success;
                }

        }

        // Find free BYTE in bitmap
        rc = ext4_bitmap_find_free_byte_and_set_bit(bitmap_block->data, index_in_group, &rel_block_idx, blocks_in_group);
        if (rc == EOK) {
                bitmap_block->dirty = true;
                rc = block_put(bitmap_block);
                if (rc != EOK) {
                        // TODO error
                        EXT4FS_DBG("free byte: error in saving initial bitmap \%d", rc);
                }

                allocated_block = ext4_balloc_index_in_group2blockaddr(
                                fs->superblock, rel_block_idx, block_group);

                goto success;
        }

        // Find free bit in bitmap
        rc = ext4_bitmap_find_free_bit_and_set(bitmap_block->data, index_in_group, &rel_block_idx, blocks_in_group);
        if (rc == EOK) {
                bitmap_block->dirty = true;
                rc = block_put(bitmap_block);
                if (rc != EOK) {
                        // TODO error
                        EXT4FS_DBG("free bit: error in saving initial bitmap \%d", rc);
                }

                allocated_block = ext4_balloc_index_in_group2blockaddr(
                                fs->superblock, rel_block_idx, block_group);

                goto success;
        }

        // No free block found yet
        block_put(bitmap_block);
        ext4_filesystem_put_block_group_ref(bg_ref);

        // Try other block groups
        uint32_t block_group_count = ext4_superblock_get_block_group_count(fs->superblock);

        uint32_t bgid = (block_group + 1) % block_group_count;
        uint32_t count = block_group_count;

        while (count > 0) {
                rc = ext4_filesystem_get_block_group_ref(fs, bgid, &bg_ref);
                if (rc != EOK) {
                        EXT4FS_DBG("errrrrrrrrrrr");
                        return rc;
                }

                // Load bitmap
                bitmap_block_addr = ext4_block_group_get_block_bitmap(
                                bg_ref->block_group, fs->superblock);

                rc = block_get(&bitmap_block, fs->device, bitmap_block_addr, 0);
                if (rc != EOK) {
                        ext4_filesystem_put_block_group_ref(bg_ref);
                        EXT4FS_DBG("errrrrrrrrrr");
                        return rc;
                }

                first_in_group = ext4_balloc_get_first_data_block_in_group(
                                fs->superblock, bg_ref->block_group, bgid);
                index_in_group = ext4_balloc_blockaddr2_index_in_group(fs->superblock,
                                                first_in_group);
                blocks_in_group = ext4_superblock_get_blocks_in_group(fs->superblock, bgid);

                first_in_group_index = ext4_balloc_blockaddr2_index_in_group(
                        fs->superblock, first_in_group);

                if (index_in_group < first_in_group_index) {
                        index_in_group = first_in_group_index;
                }


                rc = ext4_bitmap_find_free_byte_and_set_bit(bitmap_block->data, index_in_group, &rel_block_idx, blocks_in_group);
                if (rc == EOK) {
                        bitmap_block->dirty = true;
                        rc = block_put(bitmap_block);
                        if (rc != EOK) {
                                // TODO error
                                EXT4FS_DBG("error in saving bitmap \%d", rc);
                        }

                        allocated_block = ext4_balloc_index_in_group2blockaddr(
                                        fs->superblock, rel_block_idx, bgid);

                        goto success;
                }

                // Find free bit in bitmap
                rc = ext4_bitmap_find_free_bit_and_set(bitmap_block->data, index_in_group, &rel_block_idx, blocks_in_group);
                if (rc == EOK) {
                        bitmap_block->dirty = true;
                        rc = block_put(bitmap_block);
                        if (rc != EOK) {
                                // TODO error
                                EXT4FS_DBG("error in saving bitmap \%d", rc);
                        }

                        allocated_block = ext4_balloc_index_in_group2blockaddr(
                                        fs->superblock, rel_block_idx, bgid);

                        goto success;
                }


                // Next group
                block_put(bitmap_block);
                ext4_filesystem_put_block_group_ref(bg_ref);
                bgid = (bgid + 1) % block_group_count;
                count--;
        }

        return ENOSPC;

success:
        ;       // Empty command - because of syntax
        
        uint32_t block_size = ext4_superblock_get_block_size(fs->superblock);

        // Update superblock free blocks count
        uint32_t sb_free_blocks = ext4_superblock_get_free_blocks_count(fs->superblock);
        sb_free_blocks--;
        ext4_superblock_set_free_blocks_count(fs->superblock, sb_free_blocks);

        // Update inode blocks (different block size!) count

        uint64_t ino_blocks = ext4_inode_get_blocks_count(fs->superblock, inode_ref->inode);
        ino_blocks += block_size / EXT4_INODE_BLOCK_SIZE;
        ext4_inode_set_blocks_count(fs->superblock, inode_ref->inode, ino_blocks);
        inode_ref->dirty = true;

        // Update block group free blocks count
        uint32_t bg_free_blocks = ext4_block_group_get_free_blocks_count(
                        bg_ref->block_group, fs->superblock);
        bg_free_blocks--;
        ext4_block_group_set_free_blocks_count(bg_ref->block_group,
                        fs->superblock, bg_free_blocks);
        bg_ref->dirty = true;

        ext4_filesystem_put_block_group_ref(bg_ref);

        *fblock = allocated_block;
        return EOK;
}


/**
 * @}
 */