ref: 733c5d6645b133b60d304c38fcb1398f94d0618c
dir: /sys/src/cmd/ext4srv/ext4_ialloc.c/
#include "ext4_config.h"
#include "ext4_types.h"
#include "ext4_misc.h"
#include "ext4_debug.h"
#include "ext4_trans.h"
#include "ext4_ialloc.h"
#include "ext4_super.h"
#include "ext4_crc32.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 u32int ext4_ialloc_inode_to_bgidx(struct ext4_sblock *sb,
u32int inode)
{
u32int 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 u32int ext4_ialloc_bgidx_to_inode(struct ext4_sblock *sb,
u32int index, u32int bgid)
{
u32int 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 u32int ext4_ialloc_get_bgid_of_inode(struct ext4_sblock *sb,
u32int inode)
{
u32int inodes_per_group = ext4_get32(sb, inodes_per_group);
return (inode - 1) / inodes_per_group;
}
static u32int ext4_ialloc_bitmap_csum(struct ext4_fs *fs, void *bitmap)
{
u32int csum = 0;
if (ext4_sb_feature_ro_com(&fs->sb, EXT4_FRO_COM_METADATA_CSUM)) {
u32int inodes_per_group =
ext4_get32(&fs->sb, inodes_per_group);
/* First calculate crc32 checksum against fs uuid */
csum = fs->uuid_crc32c;
/* Then calculate crc32 checksum against inode bitmap */
csum = ext4_crc32c(csum, bitmap, (inodes_per_group + 7) / 8);
}
return csum;
}
void ext4_ialloc_set_bitmap_csum(struct ext4_fs *fs, struct ext4_bgroup *bg, void *bitmap)
{
int desc_size = ext4_sb_get_desc_size(&fs->sb);
u32int csum = ext4_ialloc_bitmap_csum(fs, bitmap);
u16int lo_csum = to_le16(csum & 0xFFFF),
hi_csum = to_le16(csum >> 16);
if (!ext4_sb_feature_ro_com(&fs->sb, EXT4_FRO_COM_METADATA_CSUM))
return;
/* See if we need to assign a 32bit checksum */
bg->inode_bitmap_csum_lo = lo_csum;
if (desc_size == EXT4_MAX_BLOCK_GROUP_DESCRIPTOR_SIZE)
bg->inode_bitmap_csum_hi = hi_csum;
}
static bool
ext4_ialloc_verify_bitmap_csum(struct ext4_fs *fs, struct ext4_bgroup *bg, void *bitmap)
{
int desc_size = ext4_sb_get_desc_size(&fs->sb);
u32int csum = ext4_ialloc_bitmap_csum(fs, bitmap);
u16int lo_csum = to_le16(csum & 0xFFFF),
hi_csum = to_le16(csum >> 16);
if (!ext4_sb_feature_ro_com(&fs->sb, EXT4_FRO_COM_METADATA_CSUM))
return true;
if (bg->inode_bitmap_csum_lo != lo_csum)
return false;
if (desc_size == EXT4_MAX_BLOCK_GROUP_DESCRIPTOR_SIZE)
if (bg->inode_bitmap_csum_hi != hi_csum)
return false;
return true;
}
int ext4_ialloc_free_inode(struct ext4_fs *fs, u32int index, bool is_dir)
{
struct ext4_sblock *sb = &fs->sb;
/* Compute index of block group and load it */
u32int 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 != 0)
return rc;
struct ext4_bgroup *bg = bg_ref.block_group;
/* Load i-node bitmap */
ext4_fsblk_t bitmap_block_addr =
ext4_bg_get_inode_bitmap(bg, sb);
struct ext4_block b;
rc = ext4_trans_block_get(fs->bdev, &b, bitmap_block_addr);
if (rc != 0)
return rc;
if (!ext4_ialloc_verify_bitmap_csum(fs, bg, b.data)) {
ext4_dbg(DEBUG_IALLOC,
DBG_WARN "Bitmap checksum failed."
"Group: %ud\n",
bg_ref.index);
}
/* Free i-node in the bitmap */
u32int index_in_group = ext4_ialloc_inode_to_bgidx(sb, index);
ext4_bmap_bit_clr(b.data, index_in_group);
ext4_ialloc_set_bitmap_csum(fs, bg, b.data);
ext4_trans_set_block_dirty(b.buf);
/* Put back the block with bitmap */
rc = ext4_block_set(fs->bdev, &b);
if (rc != 0) {
/* 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) {
u32int bg_used_dirs = ext4_bg_get_used_dirs_count(bg, sb);
bg_used_dirs--;
ext4_bg_set_used_dirs_count(bg, sb, bg_used_dirs);
}
/* Update block group free inodes count */
u32int free_inodes = ext4_bg_get_free_inodes_count(bg, sb);
free_inodes++;
ext4_bg_set_free_inodes_count(bg, sb, free_inodes);
bg_ref.dirty = true;
/* Put back the modified block group */
rc = ext4_fs_put_block_group_ref(&bg_ref);
if (rc != 0)
return rc;
/* Update superblock free inodes count */
ext4_set32(sb, free_inodes_count,
ext4_get32(sb, free_inodes_count) + 1);
return 0;
}
int ext4_ialloc_alloc_inode(struct ext4_fs *fs, u32int *idx, bool is_dir)
{
struct ext4_sblock *sb = &fs->sb;
u32int bgid = fs->last_inode_bg_id;
u32int bg_count = ext4_block_group_cnt(sb);
u32int 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 != 0)
return rc;
struct ext4_bgroup *bg = bg_ref.block_group;
/* Read necessary values for algorithm */
u32int free_inodes = ext4_bg_get_free_inodes_count(bg, sb);
u32int 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 */
ext4_fsblk_t bmp_blk_add = ext4_bg_get_inode_bitmap(bg, sb);
struct ext4_block b;
rc = ext4_trans_block_get(fs->bdev, &b, bmp_blk_add);
if (rc != 0) {
ext4_fs_put_block_group_ref(&bg_ref);
return rc;
}
if (!ext4_ialloc_verify_bitmap_csum(fs, bg, b.data)) {
ext4_dbg(DEBUG_IALLOC,
DBG_WARN "Bitmap checksum failed."
"Group: %ud\n",
bg_ref.index);
}
/* Try to allocate i-node in the bitmap */
u32int inodes_in_bg;
u32int idx_in_bg;
inodes_in_bg = ext4_inodes_in_group_cnt(sb, bgid);
bool no_space;
rc = ext4_bmap_bit_find_clr(b.data, 0, inodes_in_bg, &idx_in_bg, &no_space);
/* Block group does not have any free i-node */
if (no_space) {
rc = ext4_block_set(fs->bdev, &b);
if (rc != 0) {
ext4_fs_put_block_group_ref(&bg_ref);
return rc;
}
rc = ext4_fs_put_block_group_ref(&bg_ref);
if (rc != 0)
return rc;
continue;
}
ext4_bmap_bit_set(b.data, idx_in_bg);
/* Free i-node found, save the bitmap */
ext4_ialloc_set_bitmap_csum(fs, bg, b.data);
ext4_trans_set_block_dirty(b.buf);
ext4_block_set(fs->bdev, &b);
if (rc != 0) {
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 */
u32int unused =
ext4_bg_get_itable_unused(bg, sb);
u32int free = inodes_in_bg - unused;
if (idx_in_bg >= free) {
unused = inodes_in_bg - (idx_in_bg + 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 != 0)
return rc;
/* Update superblock */
sb_free_inodes--;
ext4_set32(sb, free_inodes_count, sb_free_inodes);
/* Compute the absolute i-nodex number */
*idx = ext4_ialloc_bgidx_to_inode(sb, idx_in_bg, bgid);
fs->last_inode_bg_id = bgid;
return 0;
}
/* Block group not modified, put it and jump to the next block
* group */
ext4_fs_put_block_group_ref(&bg_ref);
if (rc != 0)
return rc;
++bgid;
}
werrstr(Enospc);
return -1;
}