source: mainline/uspace/lib/ext4/libext4_balloc.c@ 35b8bfe

/*
 * Copyright (c) 2012 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"

/** Compute number of block group from block address.
 *
 * @param sb         Superblock pointer.
 * @param block_addr Absolute address of block.
 *
 * @return Block group index
 *
 */
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;
}

/** Free block.
 *
 * @param inode_ref  Inode, where the block is allocated
 * @param block_addr Absolute block address to free
 *
 * @return Error code
 *
 */
int ext4_balloc_free_block(ext4_inode_ref_t *inode_ref, uint32_t block_addr)
{
        ext4_filesystem_t *fs = inode_ref->fs;
        ext4_superblock_t *sb = fs->superblock;
        
        /* Compute indexes */
        uint32_t block_group = ext4_balloc_get_bgid_of_block(sb, block_addr);
        uint32_t index_in_group =
            ext4_filesystem_blockaddr2_index_in_group(sb, block_addr);
        
        /* Load block group reference */
        ext4_block_group_ref_t *bg_ref;
        int rc = ext4_filesystem_get_block_group_ref(fs, block_group, &bg_ref);
        if (rc != EOK)
                return rc;
        
        /* Load block with bitmap */
        uint32_t bitmap_block_addr =
            ext4_block_group_get_block_bitmap(bg_ref->block_group, sb);
        block_t *bitmap_block;
        rc = block_get(&bitmap_block, fs->device, bitmap_block_addr, 0);
        if (rc != EOK) {
                ext4_filesystem_put_block_group_ref(bg_ref);
                return rc;
        }
        
        /* Modify bitmap */
        ext4_bitmap_free_bit(bitmap_block->data, index_in_group);
        bitmap_block->dirty = true;
        
        /* Release block with bitmap */
        rc = block_put(bitmap_block);
        if (rc != EOK) {
                /* Error in saving bitmap */
                ext4_filesystem_put_block_group_ref(bg_ref);
                return rc;
        }
        
        uint32_t block_size = ext4_superblock_get_block_size(sb);
        
        /* Update superblock free blocks count */
        uint32_t sb_free_blocks =
            ext4_superblock_get_free_blocks_count(sb);
        sb_free_blocks++;
        ext4_superblock_set_free_blocks_count(sb, sb_free_blocks);
        
        /* Update inode blocks count */
        uint64_t ino_blocks =
            ext4_inode_get_blocks_count(sb, inode_ref->inode);
        ino_blocks -= block_size / EXT4_INODE_BLOCK_SIZE;
        ext4_inode_set_blocks_count(sb, 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, sb);
        free_blocks++;
        ext4_block_group_set_free_blocks_count(bg_ref->block_group,
            sb, free_blocks);
        bg_ref->dirty = true;
        
        /* Release block group reference */
        return ext4_filesystem_put_block_group_ref(bg_ref);
}

/** Free continuous set of blocks.
 *
 * @param inode_ref Inode, where the blocks are allocated
 * @param first     First block to release
 * @param count     Number of blocks to release
 *
 */
int ext4_balloc_free_blocks(ext4_inode_ref_t *inode_ref,
    uint32_t first, uint32_t count)
{
        ext4_filesystem_t *fs = inode_ref->fs;
        ext4_superblock_t *sb = fs->superblock;
        
        /* Compute indexes */
        uint32_t block_group_first =
            ext4_balloc_get_bgid_of_block(sb, first);
        uint32_t block_group_last =
            ext4_balloc_get_bgid_of_block(sb, first + count - 1);
        
        assert(block_group_first == block_group_last);
        
        /* Load block group reference */
        ext4_block_group_ref_t *bg_ref;
        int rc = ext4_filesystem_get_block_group_ref(fs, block_group_first, &bg_ref);
        if (rc != EOK)
                return rc;
        
        uint32_t index_in_group_first =
            ext4_filesystem_blockaddr2_index_in_group(sb, first);
        
        /* Load block with bitmap */
        uint32_t bitmap_block_addr =
            ext4_block_group_get_block_bitmap(bg_ref->block_group, sb);
        
        block_t *bitmap_block;
        rc = block_get(&bitmap_block, fs->device, bitmap_block_addr, 0);
        if (rc != EOK) {
                ext4_filesystem_put_block_group_ref(bg_ref);
                return rc;
        }
        
        /* Modify bitmap */
        ext4_bitmap_free_bits(bitmap_block->data, index_in_group_first, count);
        bitmap_block->dirty = true;
        
        /* Release block with bitmap */
        rc = block_put(bitmap_block);
        if (rc != EOK) {
                /* Error in saving bitmap */
                ext4_filesystem_put_block_group_ref(bg_ref);
                return rc;
        }
        
        uint32_t block_size = ext4_superblock_get_block_size(sb);
        
        /* Update superblock free blocks count */
        uint32_t sb_free_blocks =
            ext4_superblock_get_free_blocks_count(sb);
        sb_free_blocks += count;
        ext4_superblock_set_free_blocks_count(sb, sb_free_blocks);
        
        /* Update inode blocks count */
        uint64_t ino_blocks =
            ext4_inode_get_blocks_count(sb, inode_ref->inode);
        ino_blocks -= count * (block_size / EXT4_INODE_BLOCK_SIZE);
        ext4_inode_set_blocks_count(sb, 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, sb);
        free_blocks += count;
        ext4_block_group_set_free_blocks_count(bg_ref->block_group,
            sb, free_blocks);
        bg_ref->dirty = true;
        
        /* Release block group reference */
        return ext4_filesystem_put_block_group_ref(bg_ref);
}

/** Compute first block for data in block group.
 *
 * @param sb   Pointer to superblock
 * @param bg   Pointer to block group
 * @param bgid Index of block group
 *
 * @return Absolute block index of first block
 *
 */
uint32_t ext4_balloc_get_first_data_block_in_group(ext4_superblock_t *sb,
    ext4_block_group_ref_t *bg_ref)
{
        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_ref->block_group, 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 (bg_ref->index < 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;
}

/** Compute 'goal' for allocation algorithm.
 *
 * @param inode_ref Reference to inode, to allocate block for
 *
 * @return Goal block number
 *
 */
static int ext4_balloc_find_goal(ext4_inode_ref_t *inode_ref, uint32_t *goal)
{
        *goal = 0;
        ext4_superblock_t *sb = inode_ref->fs->superblock;
        
        uint64_t inode_size = ext4_inode_get_size(sb, inode_ref->inode);
        uint32_t block_size = ext4_superblock_get_block_size(sb);
        uint32_t inode_block_count = inode_size / block_size;
        
        if (inode_size % block_size != 0)
                inode_block_count++;
        
        /* If inode has some blocks, get last block address + 1 */
        if (inode_block_count > 0) {
                int rc = ext4_filesystem_get_inode_data_block_index(inode_ref,
                    inode_block_count - 1, goal);
                if (rc != EOK)
                        return rc;
                
                if (goal != 0) {
                        (*goal)++;
                        return EOK;
                }
                
                /* If goal == 0, sparse file -> continue */
        }
        
        /* Identify block group of inode */
        uint32_t inodes_per_group = ext4_superblock_get_inodes_per_group(sb);
        uint32_t block_group = (inode_ref->index - 1) / inodes_per_group;
        block_size = ext4_superblock_get_block_size(sb);
        
        /* Load block group reference */
        ext4_block_group_ref_t *bg_ref;
        int rc = ext4_filesystem_get_block_group_ref(inode_ref->fs,
            block_group, &bg_ref);
        if (rc != EOK)
                return rc;
        
        /* Compute indexes */
        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_ref->block_group, sb);
        uint16_t inode_table_item_size = ext4_superblock_get_inode_size(sb);
        uint32_t inode_table_bytes;
        
        /* Check for last block group */
        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(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++;
        
        *goal = inode_table_first_block + inode_table_blocks;
        
        return ext4_filesystem_put_block_group_ref(bg_ref);
}

/** Data block allocation algorithm.
 *
 * @param inode_ref Inode to allocate block for
 * @param fblock    Allocated block address
 *
 * @return Error code
 *
 */
int ext4_balloc_alloc_block(ext4_inode_ref_t *inode_ref, uint32_t *fblock)
{
        uint32_t allocated_block = 0;
        
        uint32_t bitmap_block_addr;
        block_t *bitmap_block;
        uint32_t rel_block_idx = 0;
        uint32_t free_blocks;
        uint32_t goal;
        
        /* Find GOAL */
        int rc = ext4_balloc_find_goal(inode_ref, &goal);
        if (rc != EOK)
                return rc;

        ext4_superblock_t *sb = inode_ref->fs->superblock;
        
        /* Load block group number for goal and relative index */
        uint32_t block_group = ext4_balloc_get_bgid_of_block(sb, goal);
        uint32_t index_in_group =
            ext4_filesystem_blockaddr2_index_in_group(sb, goal);
        
        /* Load block group reference */
        ext4_block_group_ref_t *bg_ref;
        rc = ext4_filesystem_get_block_group_ref(inode_ref->fs,
            block_group, &bg_ref);
        if (rc != EOK)
                return rc;

        free_blocks =
            ext4_block_group_get_free_blocks_count(bg_ref->block_group, sb);
        if (free_blocks == 0) {
                /* This group has no free blocks */
                goto goal_failed;
        }
        
        /* Compute indexes */
        uint32_t first_in_group =
            ext4_balloc_get_first_data_block_in_group(sb, bg_ref);
        
        uint32_t first_in_group_index =
            ext4_filesystem_blockaddr2_index_in_group(sb, first_in_group);
        
        if (index_in_group < first_in_group_index)
                index_in_group = first_in_group_index;
        
        /* Load block with bitmap */
        bitmap_block_addr =
            ext4_block_group_get_block_bitmap(bg_ref->block_group, sb);
        
        rc = block_get(&bitmap_block, inode_ref->fs->device,
            bitmap_block_addr, BLOCK_FLAGS_NONE);
        if (rc != EOK) {
                ext4_filesystem_put_block_group_ref(bg_ref);
                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) {
                        ext4_filesystem_put_block_group_ref(bg_ref);
                        return rc;
                }
                
                allocated_block =
                    ext4_filesystem_index_in_group2blockaddr(sb, index_in_group,
                    block_group);
                
                goto success;
        }
        
        uint32_t blocks_in_group =
            ext4_superblock_get_blocks_in_group(sb, 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)
                                return rc;
                        
                        allocated_block =
                            ext4_filesystem_index_in_group2blockaddr(sb, 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)
                        return rc;
                
                allocated_block =
                    ext4_filesystem_index_in_group2blockaddr(sb, 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)
                        return rc;
                
                allocated_block =
                    ext4_filesystem_index_in_group2blockaddr(sb, rel_block_idx,
                    block_group);
                
                goto success;
        }
        
        /* No free block found yet */
        rc = block_put(bitmap_block);
        if (rc != EOK) {
                ext4_filesystem_put_block_group_ref(bg_ref);
                return rc;
        }

goal_failed:

        rc = ext4_filesystem_put_block_group_ref(bg_ref);
        if (rc != EOK)
                return rc;
        
        /* Try other block groups */
        uint32_t block_group_count = ext4_superblock_get_block_group_count(sb);
        
        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(inode_ref->fs, bgid,
                    &bg_ref);
                if (rc != EOK)
                        return rc;

                free_blocks =
                     ext4_block_group_get_free_blocks_count(bg_ref->block_group, sb);
                if (free_blocks == 0) {
                        /* This group has no free blocks */
                        goto next_group;
                }

                /* Load block with bitmap */
                bitmap_block_addr =
                    ext4_block_group_get_block_bitmap(bg_ref->block_group, sb);
                
                rc = block_get(&bitmap_block, inode_ref->fs->device,
                    bitmap_block_addr, 0);
                if (rc != EOK) {
                        ext4_filesystem_put_block_group_ref(bg_ref);
                        return rc;
                }
                
                /* Compute indexes */
                first_in_group =
                    ext4_balloc_get_first_data_block_in_group(sb, bg_ref);
                index_in_group =
                    ext4_filesystem_blockaddr2_index_in_group(sb, first_in_group);
                blocks_in_group = ext4_superblock_get_blocks_in_group(sb, bgid);
                
                first_in_group_index =
                    ext4_filesystem_blockaddr2_index_in_group(sb, first_in_group);
                
                if (index_in_group < first_in_group_index)
                        index_in_group = first_in_group_index;
                
                /* Try to 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) {
                                ext4_filesystem_put_block_group_ref(bg_ref);
                                return rc;
                        }
                        
                        allocated_block =
                            ext4_filesystem_index_in_group2blockaddr(sb, rel_block_idx,
                            bgid);
                        
                        goto success;
                }
                
                /* Try to 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) {
                                ext4_filesystem_put_block_group_ref(bg_ref);
                                return rc;
                        }
                        
                        allocated_block =
                            ext4_filesystem_index_in_group2blockaddr(sb, rel_block_idx,
                            bgid);
                        
                        goto success;
                }
                
                rc = block_put(bitmap_block);
                if (rc != EOK) {
                        ext4_filesystem_put_block_group_ref(bg_ref);
                        return rc;
                }

next_group:
                rc = ext4_filesystem_put_block_group_ref(bg_ref);
                if (rc != EOK)
                        return rc;
                
                /* Goto next group */
                bgid = (bgid + 1) % block_group_count;
                count--;
        }
        
        return ENOSPC;
        
success:
        /* Empty command - because of syntax */
        ;
        
        uint32_t block_size = ext4_superblock_get_block_size(sb);
        
        /* Update superblock free blocks count */
        uint32_t sb_free_blocks = ext4_superblock_get_free_blocks_count(sb);
        sb_free_blocks--;
        ext4_superblock_set_free_blocks_count(sb, sb_free_blocks);
        
        /* Update inode blocks (different block size!) count */
        uint64_t ino_blocks =
            ext4_inode_get_blocks_count(sb, inode_ref->inode);
        ino_blocks += block_size / EXT4_INODE_BLOCK_SIZE;
        ext4_inode_set_blocks_count(sb, 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, sb);
        bg_free_blocks--;
        ext4_block_group_set_free_blocks_count(bg_ref->block_group, sb,
            bg_free_blocks);
        bg_ref->dirty = true;
        
        rc = ext4_filesystem_put_block_group_ref(bg_ref);
        
        *fblock = allocated_block;
        return rc;
}

/** Try to allocate concrete block.
 *
 * @param inode_ref Inode to allocate block for
 * @param fblock    Block address to allocate
 * @param free      Output value - if target block is free
 *
 * @return Error code
 *
 */
int ext4_balloc_try_alloc_block(ext4_inode_ref_t *inode_ref, uint32_t fblock,
    bool *free)
{
        int rc;
        
        ext4_filesystem_t *fs = inode_ref->fs;
        ext4_superblock_t *sb = fs->superblock;
        
        /* Compute indexes */
        uint32_t block_group = ext4_balloc_get_bgid_of_block(sb, fblock);
        uint32_t index_in_group =
            ext4_filesystem_blockaddr2_index_in_group(sb, fblock);
        
        /* Load block group reference */
        ext4_block_group_ref_t *bg_ref;
        rc = ext4_filesystem_get_block_group_ref(fs, block_group, &bg_ref);
        if (rc != EOK)
                return rc;
        
        /* Load block with bitmap */
        uint32_t bitmap_block_addr =
            ext4_block_group_get_block_bitmap(bg_ref->block_group, sb);
        block_t *bitmap_block;
        rc = block_get(&bitmap_block, fs->device, bitmap_block_addr, 0);
        if (rc != EOK) {
                ext4_filesystem_put_block_group_ref(bg_ref);
                return rc;
        }
        
        /* Check if block is free */
        *free = ext4_bitmap_is_free_bit(bitmap_block->data, index_in_group);
        
        /* Allocate block if possible */
        if (*free) {
                ext4_bitmap_set_bit(bitmap_block->data, index_in_group);
                bitmap_block->dirty = true;
        }
        
        /* Release block with bitmap */
        rc = block_put(bitmap_block);
        if (rc != EOK) {
                /* Error in saving bitmap */
                ext4_filesystem_put_block_group_ref(bg_ref);
                return rc;
        }
        
        /* If block is not free, return */
        if (!(*free))
                goto terminate;
        
        uint32_t block_size = ext4_superblock_get_block_size(sb);
        
        /* Update superblock free blocks count */
        uint32_t sb_free_blocks = ext4_superblock_get_free_blocks_count(sb);
        sb_free_blocks--;
        ext4_superblock_set_free_blocks_count(sb, sb_free_blocks);
        
        /* Update inode blocks count */
        uint64_t ino_blocks =
            ext4_inode_get_blocks_count(sb, inode_ref->inode);
        ino_blocks += block_size / EXT4_INODE_BLOCK_SIZE;
        ext4_inode_set_blocks_count(sb, 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, sb);
        free_blocks--;
        ext4_block_group_set_free_blocks_count(bg_ref->block_group,
            sb, free_blocks);
        bg_ref->dirty = true;
        
terminate:
        return ext4_filesystem_put_block_group_ref(bg_ref);
}

/**
 * @}
 */