ref: a3f2d6d23ed1be69fee607bdedadc0438fd01305
dir: /sys/src/cmd/ext4srv/ext4_dir.c/
#include "ext4_config.h"
#include "ext4_types.h"
#include "ext4_misc.h"
#include "ext4_debug.h"
#include "ext4_trans.h"
#include "ext4_dir.h"
#include "ext4_dir_idx.h"
#include "ext4_crc32.h"
#include "ext4_inode.h"
#include "ext4_fs.h"
/* Walk through a dirent block to find a checksum "dirent" at the tail */
static struct ext4_dir_entry_tail *
ext4_dir_get_tail(struct ext4_inode_ref *inode_ref,
struct ext4_dir_en *de)
{
struct ext4_dir_entry_tail *t;
struct ext4_sblock *sb = &inode_ref->fs->sb;
t = EXT4_DIRENT_TAIL(de, ext4_sb_get_block_size(sb));
if (t->reserved_zero1 || t->reserved_zero2)
return nil;
if (to_le16(t->rec_len) != sizeof(struct ext4_dir_entry_tail))
return nil;
if (t->reserved_ft != EXT4_DIRENTRY_DIR_CSUM)
return nil;
return t;
}
static u32int ext4_dir_csum(struct ext4_inode_ref *inode_ref,
struct ext4_dir_en *dirent, int size)
{
u32int csum;
u32int ino_index = to_le32(inode_ref->index);
u32int ino_gen = to_le32(ext4_inode_get_generation(inode_ref->inode));
/* First calculate crc32 checksum against fs uuid */
csum = inode_ref->fs->uuid_crc32c;
/* Then calculate crc32 checksum against inode number
* and inode generation */
csum = ext4_crc32_u(csum, ino_index);
csum = ext4_crc32_u(csum, ino_gen);
/* Finally calculate crc32 checksum against directory entries */
csum = ext4_crc32c(csum, dirent, size);
return csum;
}
bool ext4_dir_csum_verify(struct ext4_inode_ref *inode_ref,
struct ext4_dir_en *dirent)
{
struct ext4_dir_entry_tail *t;
struct ext4_sblock *sb = &inode_ref->fs->sb;
/* Compute the checksum only if the filesystem supports it */
if (ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_METADATA_CSUM)) {
t = ext4_dir_get_tail(inode_ref, dirent);
if (!t) {
/* There is no space to hold the checksum */
werrstr("no space for checksum");
return false;
}
intptr diff = (char *)t - (char *)dirent;
u32int csum = ext4_dir_csum(inode_ref, dirent, diff);
if (t->checksum != to_le32(csum)) {
werrstr("checksum does not match");
return false;
}
}
return true;
}
void ext4_dir_init_entry_tail(struct ext4_dir_entry_tail *t)
{
memset(t, 0, sizeof(struct ext4_dir_entry_tail));
t->rec_len = to_le16(sizeof(struct ext4_dir_entry_tail));
t->reserved_ft = EXT4_DIRENTRY_DIR_CSUM;
}
void ext4_dir_set_csum(struct ext4_inode_ref *inode_ref,
struct ext4_dir_en *dirent)
{
struct ext4_dir_entry_tail *t;
struct ext4_sblock *sb = &inode_ref->fs->sb;
/* Compute the checksum only if the filesystem supports it */
if (ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_METADATA_CSUM)) {
t = ext4_dir_get_tail(inode_ref, dirent);
if (!t) {
/* There is no space to hold the checksum */
return;
}
intptr diff = (char *)t - (char *)dirent;
t->checksum = to_le32(ext4_dir_csum(inode_ref, dirent, diff));
}
}
/**@brief Do some checks before returning iterator.
* @param it Iterator to be checked
* @param block_size Size of data block
* @return Error code
*/
static int ext4_dir_iterator_set(struct ext4_dir_iter *it,
u32int block_size)
{
u32int off_in_block = it->curr_off % block_size;
struct ext4_sblock *sb = &it->inode_ref->fs->sb;
it->curr = nil;
/* Ensure proper alignment */
if ((off_in_block % 4) != 0)
goto Ioerr;
/* Ensure that the core of the entry does not overflow the block */
if (off_in_block > block_size - 8)
goto Ioerr;
struct ext4_dir_en *en;
en = (void *)(it->curr_blk.data + off_in_block);
/* Ensure that the whole entry does not overflow the block */
u16int length = ext4_dir_en_get_entry_len(en);
if (off_in_block + length > block_size)
goto Ioerr;
/* Ensure the name length is not too large */
if (ext4_dir_en_get_name_len(sb, en) > length - 8)
goto Ioerr;
/* Everything OK - "publish" the entry */
it->curr = en;
return 0;
Ioerr:
werrstr("i/o error");
return -1;
}
/**@brief Seek to next valid directory entry.
* Here can be jumped to the next data block.
* @param it Initialized iterator
* @param pos Position of the next entry
* @return Error code
*/
static int ext4_dir_iterator_seek(struct ext4_dir_iter *it, u64int pos)
{
struct ext4_sblock *sb = &it->inode_ref->fs->sb;
struct ext4_inode *inode = it->inode_ref->inode;
struct ext4_blockdev *bdev = it->inode_ref->fs->bdev;
u64int size = ext4_inode_get_size(sb, inode);
int r;
/* The iterator is not valid until we seek to the desired position */
it->curr = nil;
/* Are we at the end? */
if (pos >= size) {
if (it->curr_blk.lb_id) {
r = ext4_block_set(bdev, &it->curr_blk);
it->curr_blk.lb_id = 0;
if (r != 0)
return r;
}
it->curr_off = pos;
return 0;
}
/* Compute next block address */
u32int block_size = ext4_sb_get_block_size(sb);
u64int current_blk_idx = it->curr_off / block_size;
u32int next_blk_idx = (u32int)(pos / block_size);
/*
* If we don't have a block or are moving across block boundary,
* we need to get another block
*/
if ((it->curr_blk.lb_id == 0) ||
(current_blk_idx != next_blk_idx)) {
if (it->curr_blk.lb_id) {
r = ext4_block_set(bdev, &it->curr_blk);
it->curr_blk.lb_id = 0;
if (r != 0)
return r;
}
ext4_fsblk_t next_blk;
r = ext4_fs_get_inode_dblk_idx(it->inode_ref, next_blk_idx,
&next_blk, false);
if (r != 0)
return r;
r = ext4_trans_block_get(bdev, &it->curr_blk, next_blk);
if (r != 0) {
it->curr_blk.lb_id = 0;
return r;
}
}
it->curr_off = pos;
return ext4_dir_iterator_set(it, block_size);
}
int ext4_dir_iterator_init(struct ext4_dir_iter *it,
struct ext4_inode_ref *inode_ref, u64int pos)
{
it->inode_ref = inode_ref;
it->curr = 0;
it->curr_off = 0;
it->curr_blk.lb_id = 0;
return ext4_dir_iterator_seek(it, pos);
}
int ext4_dir_iterator_next(struct ext4_dir_iter *it)
{
int r = 0;
u16int skip;
while (r == 0) {
skip = ext4_dir_en_get_entry_len(it->curr);
r = ext4_dir_iterator_seek(it, it->curr_off + skip);
if (!it->curr)
break;
/*Skip nil referenced entry*/
if (ext4_dir_en_get_inode(it->curr) != 0)
break;
}
return r;
}
int ext4_dir_iterator_fini(struct ext4_dir_iter *it)
{
it->curr = 0;
if (it->curr_blk.lb_id)
return ext4_block_set(it->inode_ref->fs->bdev, &it->curr_blk);
return 0;
}
void ext4_dir_write_entry(struct ext4_sblock *sb, struct ext4_dir_en *en,
u16int entry_len, struct ext4_inode_ref *child,
const char *name, usize name_len)
{
/* Check maximum entry length */
assert(entry_len <= ext4_sb_get_block_size(sb));
/* Set type of entry */
switch (ext4_inode_type(sb, child->inode)) {
case EXT4_INODE_MODE_DIRECTORY:
ext4_dir_en_set_inode_type(sb, en, EXT4_DE_DIR);
break;
case EXT4_INODE_MODE_FILE:
ext4_dir_en_set_inode_type(sb, en, EXT4_DE_REG_FILE);
break;
case EXT4_INODE_MODE_SOFTLINK:
ext4_dir_en_set_inode_type(sb, en, EXT4_DE_SYMLINK);
break;
case EXT4_INODE_MODE_CHARDEV:
ext4_dir_en_set_inode_type(sb, en, EXT4_DE_CHRDEV);
break;
case EXT4_INODE_MODE_BLOCKDEV:
ext4_dir_en_set_inode_type(sb, en, EXT4_DE_BLKDEV);
break;
case EXT4_INODE_MODE_FIFO:
ext4_dir_en_set_inode_type(sb, en, EXT4_DE_FIFO);
break;
case EXT4_INODE_MODE_SOCKET:
ext4_dir_en_set_inode_type(sb, en, EXT4_DE_SOCK);
break;
default:
/* FIXME: unsupported filetype */
ext4_dir_en_set_inode_type(sb, en, EXT4_DE_UNKNOWN);
}
/* Set basic attributes */
ext4_dir_en_set_inode(en, child->index);
ext4_dir_en_set_entry_len(en, entry_len);
ext4_dir_en_set_name_len(sb, en, (u16int)name_len);
/* Write name */
memcpy(en->name, name, name_len);
}
int ext4_dir_add_entry(struct ext4_inode_ref *parent, const char *name,
u32int name_len, struct ext4_inode_ref *child)
{
int r;
struct ext4_fs *fs = parent->fs;
struct ext4_sblock *sb = &parent->fs->sb;
/* Index adding (if allowed) */
if ((ext4_sb_feature_com(sb, EXT4_FCOM_DIR_INDEX)) &&
(ext4_inode_has_flag(parent->inode, EXT4_INODE_FLAG_INDEX))) {
r = ext4_dir_dx_add_entry(parent, child, name, name_len);
/* Check if index is corrupted */
if (r == EXT4_ERR_BAD_DX_DIR) {
/* Needed to clear dir index flag if corrupted */
ext4_inode_clear_flag(parent->inode, EXT4_INODE_FLAG_INDEX);
parent->dirty = true;
}
return r;
}
/* Linear algorithm */
u32int iblock = 0;
ext4_fsblk_t fblock = 0;
u32int block_size = ext4_sb_get_block_size(sb);
u64int inode_size = ext4_inode_get_size(sb, parent->inode);
u32int total_blocks = (u32int)(inode_size / block_size);
/* Find block, where is space for new entry and try to add */
bool success = false;
for (iblock = 0; iblock < total_blocks; ++iblock) {
r = ext4_fs_get_inode_dblk_idx(parent, iblock, &fblock, false);
if (r != 0)
return r;
struct ext4_block block;
r = ext4_trans_block_get(fs->bdev, &block, fblock);
if (r != 0)
return r;
if (!ext4_dir_csum_verify(parent, (void *)block.data)) {
ext4_dbg(DEBUG_DIR,
DBG_WARN "Leaf block checksum failed."
"Inode: %ud, "
"Block: %ud\n",
parent->index,
iblock);
}
/* If adding is successful, function can finish */
r = ext4_dir_try_insert_entry(sb, parent, &block, child,
name, name_len);
if (r == 0)
success = true;
r = ext4_block_set(fs->bdev, &block);
if (r != 0)
return r;
if (success)
return 0;
}
/* No free block found - needed to allocate next data block */
iblock = 0;
fblock = 0;
r = ext4_fs_append_inode_dblk(parent, &fblock, &iblock);
if (r != 0)
return r;
/* Load new block */
struct ext4_block b;
r = ext4_trans_block_get_noread(fs->bdev, &b, fblock);
if (r != 0)
return r;
/* Fill block with zeroes */
memset(b.data, 0, block_size);
struct ext4_dir_en *blk_en = (void *)b.data;
/* Save new block */
if (ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_METADATA_CSUM)) {
u16int el = block_size - sizeof(struct ext4_dir_entry_tail);
ext4_dir_write_entry(sb, blk_en, el, child, name, name_len);
ext4_dir_init_entry_tail(EXT4_DIRENT_TAIL(b.data, block_size));
} else {
ext4_dir_write_entry(sb, blk_en, block_size, child, name, name_len);
}
ext4_dir_set_csum(parent, (void *)b.data);
ext4_trans_set_block_dirty(b.buf);
r = ext4_block_set(fs->bdev, &b);
return r;
}
int ext4_dir_find_entry(struct ext4_dir_search_result *result,
struct ext4_inode_ref *parent, const char *name,
u32int name_len)
{
int r;
struct ext4_sblock *sb = &parent->fs->sb;
/* Entry clear */
result->block.lb_id = 0;
result->dentry = nil;
/* Index search */
if ((ext4_sb_feature_com(sb, EXT4_FCOM_DIR_INDEX)) &&
(ext4_inode_has_flag(parent->inode, EXT4_INODE_FLAG_INDEX))) {
r = ext4_dir_dx_find_entry(result, parent, name_len, name);
/* Check if index is corrupted */
if (r == EXT4_ERR_BAD_DX_DIR) {
/* Needed to clear dir index flag if corrupted */
ext4_inode_clear_flag(parent->inode, EXT4_INODE_FLAG_INDEX);
parent->dirty = true;
}
return r;
}
/* Linear algorithm */
u32int iblock;
ext4_fsblk_t fblock;
u32int block_size = ext4_sb_get_block_size(sb);
u64int inode_size = ext4_inode_get_size(sb, parent->inode);
u32int total_blocks = (u32int)(inode_size / block_size);
/* Walk through all data blocks */
for (iblock = 0; iblock < total_blocks; ++iblock) {
/* Load block address */
r = ext4_fs_get_inode_dblk_idx(parent, iblock, &fblock, false);
if (r != 0)
return r;
/* Load data block */
struct ext4_block b;
r = ext4_trans_block_get(parent->fs->bdev, &b, fblock);
if (r != 0){
werrstr("ext4_trans_block_get: %r");
return r;
}
if (!ext4_dir_csum_verify(parent, (void *)b.data)) {
ext4_dbg(DEBUG_DIR,
DBG_WARN "Leaf block checksum failed."
"Inode: %ud, "
"Block: %ud\n",
parent->index,
iblock);
}
/* Try to find entry in block */
struct ext4_dir_en *res_entry;
r = ext4_dir_find_in_block(&b, sb, name_len, name, &res_entry);
if (r == 0) {
result->block = b;
result->dentry = res_entry;
return 0;
}
/* Entry not found - put block and continue to the next block */
r = ext4_block_set(parent->fs->bdev, &b);
if (r != 0)
return r;
}
werrstr(Enotfound);
return EXT4_ERR_NOT_FOUND;
}
int ext4_dir_remove_entry(struct ext4_inode_ref *parent, const char *name,
u32int name_len)
{
struct ext4_sblock *sb = &parent->fs->sb;
/* Check if removing from directory */
if (!ext4_inode_is_type(sb, parent->inode, EXT4_INODE_MODE_DIRECTORY)) {
werrstr("not a directory");
return -1;
}
/* Try to find entry */
struct ext4_dir_search_result result;
int rc = ext4_dir_find_entry(&result, parent, name, name_len);
if (rc != 0)
return rc;
/* Invalidate entry */
ext4_dir_en_set_inode(result.dentry, 0);
/* Store entry position in block */
u32int pos = (u8int *)result.dentry - result.block.data;
/*
* If entry is not the first in block, it must be merged
* with previous entry
*/
if (pos != 0) {
u32int offset = 0;
/* Start from the first entry in block */
struct ext4_dir_en *tmp_de =(void *)result.block.data;
u16int de_len = ext4_dir_en_get_entry_len(tmp_de);
/* Find direct predecessor of removed entry */
while ((offset + de_len) < pos) {
offset += ext4_dir_en_get_entry_len(tmp_de);
tmp_de = (void *)(result.block.data + offset);
de_len = ext4_dir_en_get_entry_len(tmp_de);
}
assert(de_len + offset == pos);
/* Add to removed entry length to predecessor's length */
u16int del_len;
del_len = ext4_dir_en_get_entry_len(result.dentry);
ext4_dir_en_set_entry_len(tmp_de, de_len + del_len);
}
ext4_dir_set_csum(parent,
(struct ext4_dir_en *)result.block.data);
ext4_trans_set_block_dirty(result.block.buf);
return ext4_dir_destroy_result(parent, &result);
}
int ext4_dir_try_insert_entry(struct ext4_sblock *sb,
struct ext4_inode_ref *inode_ref,
struct ext4_block *dst_blk,
struct ext4_inode_ref *child, const char *name,
u32int name_len)
{
/* Compute required length entry and align it to 4 bytes */
u32int block_size = ext4_sb_get_block_size(sb);
u16int required_len = sizeof(struct ext4_fake_dir_entry) + name_len;
if ((required_len % 4) != 0)
required_len += 4 - (required_len % 4);
/* Initialize pointers, stop means to upper bound */
struct ext4_dir_en *start = (void *)dst_blk->data;
struct ext4_dir_en *stop = (void *)(dst_blk->data + block_size);
/*
* Walk through the block and check for invalid entries
* or entries with free space for new entry
*/
while (start < stop) {
u32int inode = ext4_dir_en_get_inode(start);
u16int rec_len = ext4_dir_en_get_entry_len(start);
u8int itype = ext4_dir_en_get_inode_type(sb, start);
/* If invalid and large enough entry, use it */
if ((inode == 0) && (itype != EXT4_DIRENTRY_DIR_CSUM) &&
(rec_len >= required_len)) {
ext4_dir_write_entry(sb, start, rec_len, child, name,
name_len);
ext4_dir_set_csum(inode_ref, (void *)dst_blk->data);
ext4_trans_set_block_dirty(dst_blk->buf);
return 0;
}
/* Valid entry, try to split it */
if (inode != 0) {
u16int used_len;
used_len = ext4_dir_en_get_name_len(sb, start);
u16int sz;
sz = sizeof(struct ext4_fake_dir_entry) + used_len;
if ((used_len % 4) != 0)
sz += 4 - (used_len % 4);
u16int free_space = rec_len - sz;
/* There is free space for new entry */
if (free_space >= required_len) {
/* Cut tail of current entry */
struct ext4_dir_en * new_entry;
new_entry = (void *)((u8int *)start + sz);
ext4_dir_en_set_entry_len(start, sz);
ext4_dir_write_entry(sb, new_entry, free_space,
child, name, name_len);
ext4_dir_set_csum(inode_ref,
(void *)dst_blk->data);
ext4_trans_set_block_dirty(dst_blk->buf);
return 0;
}
}
/* Jump to the next entry */
start = (void *)((u8int *)start + rec_len);
}
/* No free space found for new entry */
werrstr("no space");
return -1;
}
int ext4_dir_find_in_block(struct ext4_block *block, struct ext4_sblock *sb,
usize name_len, const char *name,
struct ext4_dir_en **res_entry)
{
/* Start from the first entry in block */
struct ext4_dir_en *de = (struct ext4_dir_en *)block->data;
/* Set upper bound for cycling */
u8int *addr_limit = block->data + ext4_sb_get_block_size(sb);
/* Walk through the block and check entries */
while ((u8int *)de < addr_limit) {
/* Termination condition */
if ((u8int *)de + name_len > addr_limit)
break;
/* Valid entry - check it */
if (ext4_dir_en_get_inode(de) != 0) {
/* For more efficient compare only lengths firstly*/
int el = ext4_dir_en_get_name_len(sb, de);
if (el == name_len) {
/* Compare names */
if (memcmp(name, de->name, name_len) == 0) {
*res_entry = de;
return 0;
}
}
}
u16int de_len = ext4_dir_en_get_entry_len(de);
if (de_len == 0) {
werrstr("corrupt entry");
return -1;
}
/* Jump to next entry */
de = (struct ext4_dir_en *)((u8int *)de + de_len);
}
/* Entry not found */
werrstr(Enotfound);
return EXT4_ERR_NOT_FOUND;
}
int ext4_dir_destroy_result(struct ext4_inode_ref *parent,
struct ext4_dir_search_result *result)
{
if (result->block.lb_id)
return ext4_block_set(parent->fs->bdev, &result->block);
return 0;
}