ref: 1cdcbd33bcbd10ce8517be45c8a7f6c4e622409d
dir: /lwext4/ext4_ialloc.c/
/*
* Copyright (c) 2013 Grzegorz Kostka (kostka.grzegorz@gmail.com)
*
*
* HelenOS:
* Copyright (c) 2012 Martin Sucha
* 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 lwext4
* @{
*/
/**
* @file ext4_ialloc.c
* @brief Inode allocation procedures.
*/
#include <ext4_config.h>
#include <ext4_types.h>
#include <ext4_ialloc.h>
#include <ext4_super.h>
#include <ext4_fs.h>
#include <ext4_blockdev.h>
#include <ext4_block_group.h>
#include <ext4_bitmap.h>
/**@brief Convert i-node number to relative index in block group.
* @param sb Superblock
* @param inode I-node number to be converted
* @return Index of the i-node in the block group
*/
static uint32_t ext4_ialloc_inode2index_in_group(struct ext4_sblock *sb,
uint32_t inode)
{
uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);
return (inode - 1) % inodes_per_group;
}
/**@brief Convert relative index of i-node to absolute i-node number.
* @param sb Superblock
* @param index Index to be converted
* @return Absolute number of the i-node
*
*/
static uint32_t ext4_ialloc_index_in_group2inode(struct ext4_sblock *sb,
uint32_t index, uint32_t bgid)
{
uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);
return bgid * inodes_per_group + (index + 1);
}
/**@brief Compute block group number from the i-node number.
* @param sb Superblock
* @param inode I-node number to be found the block group for
* @return Block group number computed from i-node number
*/
static uint32_t ext4_ialloc_get_bgid_of_inode(struct ext4_sblock *sb,
uint32_t inode)
{
uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);
return (inode - 1) / inodes_per_group;
}
int ext4_ialloc_free_inode(struct ext4_fs *fs, uint32_t index, bool is_dir)
{
struct ext4_sblock *sb = &fs->sb;
/* Compute index of block group and load it */
uint32_t block_group = ext4_ialloc_get_bgid_of_inode(sb, index);
struct ext4_block_group_ref bg_ref;
int rc = ext4_fs_get_block_group_ref(fs, block_group, &bg_ref);
if (rc != EOK)
return rc;
/* Load i-node bitmap */
uint32_t bitmap_block_addr =
ext4_bg_get_inode_bitmap(bg_ref.block_group, sb);
struct ext4_block bitmap_block;
rc = ext4_block_get(fs->bdev, &bitmap_block, bitmap_block_addr);
if (rc != EOK)
return rc;
/* Free i-node in the bitmap */
uint32_t index_in_group = ext4_ialloc_inode2index_in_group(sb, index);
ext4_bmap_bit_clr(bitmap_block.data, index_in_group);
bitmap_block.dirty = true;
/* Put back the block with bitmap */
rc = ext4_block_set(fs->bdev, &bitmap_block);
if (rc != EOK) {
/* Error in saving bitmap */
ext4_fs_put_block_group_ref(&bg_ref);
return rc;
}
/* If released i-node is a directory, decrement used directories count */
if (is_dir) {
uint32_t bg_used_dirs =
ext4_bg_get_used_dirs_count(bg_ref.block_group, sb);
bg_used_dirs--;
ext4_bg_set_used_dirs_count(bg_ref.block_group, sb, bg_used_dirs);
}
/* Update block group free inodes count */
uint32_t free_inodes =
ext4_bg_get_free_inodes_count(bg_ref.block_group, sb);
free_inodes++;
ext4_bg_set_free_inodes_count(bg_ref.block_group, sb, free_inodes);
bg_ref.dirty = true;
/* Put back the modified block group */
rc = ext4_fs_put_block_group_ref(&bg_ref);
if (rc != EOK)
return rc;
/* Update superblock free inodes count */
ext4_set32(sb, free_inodes_count, ext4_get32(sb, free_inodes_count) + 1);
return EOK;
}
int ext4_ialloc_alloc_inode(struct ext4_fs *fs, uint32_t *index, bool is_dir)
{
struct ext4_sblock *sb = &fs->sb;
uint32_t bgid = fs->last_inode_bg_id;
uint32_t bg_count = ext4_block_group_cnt(sb);
uint32_t sb_free_inodes = ext4_get32(sb, free_inodes_count);
bool rewind = false;
/* Try to find free i-node in all block groups */
while (bgid <= bg_count) {
if (bgid == bg_count) {
if (rewind)
break;
bg_count = fs->last_inode_bg_id;
bgid = 0;
rewind = true;
continue;
}
/* Load block group to check */
struct ext4_block_group_ref bg_ref;
int rc = ext4_fs_get_block_group_ref(fs, bgid, &bg_ref);
if (rc != EOK)
return rc;
struct ext4_bgroup *bg = bg_ref.block_group;
/* Read necessary values for algorithm */
uint32_t free_inodes = ext4_bg_get_free_inodes_count(bg, sb);
uint32_t used_dirs = ext4_bg_get_used_dirs_count(bg, sb);
/* Check if this block group is good candidate for allocation */
if (free_inodes > 0) {
/* Load block with bitmap */
uint32_t bitmap_block_addr =
ext4_bg_get_inode_bitmap(bg_ref.block_group, sb);
struct ext4_block bitmap_block;
rc = ext4_block_get(fs->bdev, &bitmap_block, bitmap_block_addr);
if (rc != EOK) {
ext4_fs_put_block_group_ref(&bg_ref);
return rc;
}
/* Try to allocate i-node in the bitmap */
uint32_t inodes_in_group = ext4_inodes_in_group_cnt(sb, bgid);
uint32_t index_in_group;
rc = ext4_bmap_bit_find_clr(bitmap_block.data, 0, inodes_in_group,
&index_in_group);
/* Block group has not any free i-node */
if (rc == ENOSPC) {
rc = ext4_block_set(fs->bdev, &bitmap_block);
if (rc != EOK) {
ext4_fs_put_block_group_ref(&bg_ref);
return rc;
}
rc = ext4_fs_put_block_group_ref(&bg_ref);
if (rc != EOK)
return rc;
continue;
}
ext4_bmap_bit_set(bitmap_block.data, index_in_group);
/* Free i-node found, save the bitmap */
bitmap_block.dirty = true;
ext4_block_set(fs->bdev, &bitmap_block);
if (rc != EOK) {
ext4_fs_put_block_group_ref(&bg_ref);
return rc;
}
/* Modify filesystem counters */
free_inodes--;
ext4_bg_set_free_inodes_count(bg, sb, free_inodes);
/* Increment used directories counter */
if (is_dir) {
used_dirs++;
ext4_bg_set_used_dirs_count(bg, sb, used_dirs);
}
/* Decrease unused inodes count */
if (ext4_bg_has_flag(bg, EXT4_BLOCK_GROUP_ITABLE_ZEROED)) {
uint32_t unused = ext4_bg_get_itable_unused(bg, sb);
uint32_t inodes_in_group = ext4_inodes_in_group_cnt(sb, bgid);
uint32_t free = inodes_in_group - unused;
if (index_in_group >= free) {
unused = inodes_in_group - (index_in_group + 1);
ext4_bg_set_itable_unused(bg, sb, unused);
}
}
/* Save modified block group */
bg_ref.dirty = true;
rc = ext4_fs_put_block_group_ref(&bg_ref);
if (rc != EOK)
return rc;
/* Update superblock */
sb_free_inodes--;
ext4_set32(sb, free_inodes_count, sb_free_inodes);
/* Compute the absolute i-nodex number */
*index = ext4_ialloc_index_in_group2inode(sb, index_in_group, bgid);
fs->last_inode_bg_id = bgid;
return EOK;
}
/* Block group not modified, put it and jump to the next block group */
ext4_fs_put_block_group_ref(&bg_ref);
if (rc != EOK)
return rc;
++bgid;
}
return ENOSPC;
}
/**
* @}
*/