/**
* recomp_data_node - re-compress a truncated data node.
* @dn: data node to re-compress
* @new_len: new length
*
* This function is used when an inode is truncated and the last data node of
* the inode has to be re-compressed and re-written.
*/
static int recomp_data_node(struct ubifs_data_node *dn, int *new_len)
{
void *buf;
int err, len, compr_type, out_len;
out_len = le32_to_cpu(dn->size);
buf = kmalloc(out_len * WORST_COMPR_FACTOR, GFP_NOFS);
if (!buf)
return -ENOMEM;
len = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ;
compr_type = le16_to_cpu(dn->compr_type);
err = ubifs_decompress(&dn->data, len, buf, &out_len, compr_type);
if (err)
goto out;
ubifs_compress(buf, *new_len, &dn->data, &out_len, &compr_type);
ubifs_assert(out_len <= UBIFS_BLOCK_SIZE);
dn->compr_type = cpu_to_le16(compr_type);
dn->size = cpu_to_le32(*new_len);
*new_len = UBIFS_DATA_NODE_SZ + out_len;
out:
kfree(buf);
return err;
}
static int read_block(struct inode *inode, void *addr, unsigned int block,
struct ubifs_data_node *dn)
{
struct ubifs_info *c = inode->i_sb->s_fs_info;
int err, len, out_len;
union ubifs_key key;
unsigned int dlen;
data_key_init(c, &key, inode->i_ino, block);
err = ubifs_tnc_lookup(c, &key, dn);
if (err) {
if (err == -ENOENT)
/* Not found, so it must be a hole */
memset(addr, 0, UBIFS_BLOCK_SIZE);
return err;
}
ubifs_assert(le64_to_cpu(dn->ch.sqnum) > ubifs_inode(inode)->creat_sqnum);
len = le32_to_cpu(dn->size);
if (len <= 0 || len > UBIFS_BLOCK_SIZE)
goto dump;
dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ;
out_len = UBIFS_BLOCK_SIZE;
err = ubifs_decompress(&dn->data, dlen, addr, &out_len,
le16_to_cpu(dn->compr_type));
if (err || len != out_len)
goto dump;
/*
* Data length can be less than a full block, even for blocks that are
* not the last in the file (e.g., as a result of making a hole and
* appending data). Ensure that the remainder is zeroed out.
*/
if (len < UBIFS_BLOCK_SIZE)
memset(addr + len, 0, UBIFS_BLOCK_SIZE - len);
return 0;
dump:
ubifs_err("bad data node (block %u, inode %lu)",
block, inode->i_ino);
dbg_dump_node(c, dn);
return -EINVAL;
}
