/**
* Indicates whether the specified data block is superseded by the just-read
* disk data block. A data block supersedes another if its ID is equal and its
* sequence number is greater than that of the other block.
*
* @param out_should_replace On success, 0 or 1 gets written here, to
* indicate whether replacement should occur.
* @param old_block The data block which has already been read and
* converted to its RAM representation. This
* is the block that may be superseded.
* @param disk_block The disk data block that was just read from
* flash. This is the block which may
* supersede the other.
*
* @return 0 on success; nonzero on failure.
*/
static int
nffs_restore_block_gets_replaced(const struct nffs_block *old_block,
const struct nffs_disk_block *disk_block,
int *out_should_replace)
{
assert(old_block->nb_hash_entry->nhe_id == disk_block->ndb_id);
if (nffs_block_is_dummy(old_block->nb_hash_entry)) {
assert(0);
*out_should_replace = 1;
return 0;
}
if (old_block->nb_seq < disk_block->ndb_seq) {
*out_should_replace = 2;
return 0;
}
if (old_block->nb_seq == disk_block->ndb_seq) {
/* This is a duplicate of an previously-read block. This should never
* happen.
*/
return FS_EEXIST;
}
*out_should_replace = 0;
return 0;
}
/**
* Constructs a block representation from a minimal block hash entry. If the
* hash entry references other objects (inode or previous data block), the
* resulting block object is populated with pointers to the referenced objects.
* If the any referenced objects are not present in the NFFS RAM
* representation, this indicates file system corruption. In this case, the
* resulting block is populated with all valid references, and an FS_ECORRUPT
* code is returned.
*
* @param out_block On success, this gets populated with the data
* block information.
* @param block_entry The source block entry to convert.
*
* @return 0 on success;
* FS_ECORRUPT if one or more pointers could not
* be filled in due to file system corruption;
* FS_EOFFSET on an attempt to read an invalid
* address range;
* FS_EHW on flash error;
* FS_EUNEXP if the specified disk location does
* not contain a block.
*/
int
nffs_block_from_hash_entry(struct nffs_block *out_block,
struct nffs_hash_entry *block_entry)
{
struct nffs_disk_block disk_block;
uint32_t area_offset;
uint8_t area_idx;
int rc;
assert(nffs_hash_id_is_block(block_entry->nhe_id));
if (nffs_block_is_dummy(block_entry)) {
out_block->nb_hash_entry = block_entry;
out_block->nb_inode_entry = NULL;
out_block->nb_prev = NULL;
/*
* Dummy block added when inode was read in before real block
* (see nffs_restore_inode()). Return success (because there's
* too many places that ned to check for this,
* but it's the responsibility fo the upstream code to check
* whether this is still a dummy entry. XXX
*/
return 0;
/*return FS_ENOENT;*/
}
nffs_flash_loc_expand(block_entry->nhe_flash_loc, &area_idx, &area_offset);
rc = nffs_block_read_disk(area_idx, area_offset, &disk_block);
if (rc != 0) {
return rc;
}
out_block->nb_hash_entry = block_entry;
rc = nffs_block_from_disk(out_block, &disk_block);
if (rc != 0) {
return rc;
}
return 0;
}
/**
* Populates the nffs RAM state with the memory representation of the specified
* disk data block.
*
* @param disk_block The source disk block to insert.
* @param area_idx The ID of the area containing the block.
* @param area_offset The area_offset within the area of the block.
*
* @return 0 on success; nonzero on failure.
*/
static int
nffs_restore_block(const struct nffs_disk_block *disk_block, uint8_t area_idx,
uint32_t area_offset)
{
struct nffs_inode_entry *inode_entry;
struct nffs_hash_entry *entry;
struct nffs_block block;
int do_replace;
int new_block;
int rc;
new_block = 0;
/* Check the block's CRC. If the block is corrupt, discard it. If this
* block would have superseded another, the old block becomes current.
*/
rc = nffs_crc_disk_block_validate(disk_block, area_idx, area_offset);
if (rc != 0) {
goto err;
}
entry = nffs_hash_find_block(disk_block->ndb_id);
if (entry != NULL) {
rc = nffs_block_from_hash_entry_no_ptrs(&block, entry);
if (rc != 0 && rc != FS_ENOENT) {
goto err;
}
/*
* If the old block reference is for a 'dummy' block, it was added
* because the owning inode's lastblock was not yet restored.
* Update the block hash entry and inode to reference the entry.
*/
if (nffs_block_is_dummy(entry)) {
assert(entry->nhe_id == disk_block->ndb_id);
/*
* Entry is no longer dummy as it references the correct location
*/
entry->nhe_flash_loc = nffs_flash_loc(area_idx, area_offset);
inode_entry = nffs_hash_find_inode(disk_block->ndb_inode_id);
/*
* Turn off flags in previously restored inode recording the
* allocation of a dummy block
*/
if (inode_entry) {
nffs_inode_unsetflags(inode_entry, NFFS_INODE_FLAG_DUMMYLSTBLK);
}
}
rc = nffs_restore_block_gets_replaced(&block, disk_block,
&do_replace);
if (rc != 0) {
goto err;
}
if (!do_replace) {
/* The new block is superseded by the old; nothing to do. */
return 0;
}
/*
* update the existing hash entry to reference the new flash location
*/
entry->nhe_flash_loc = nffs_flash_loc(area_idx, area_offset);
} else {
entry = nffs_block_entry_alloc();
if (entry == NULL) {
rc = FS_ENOMEM;
goto err;
}
new_block = 1;
entry->nhe_id = disk_block->ndb_id;
entry->nhe_flash_loc = nffs_flash_loc(area_idx, area_offset);
/* The block is ready to be inserted into the hash. */
nffs_hash_insert(entry);
if (disk_block->ndb_id >= nffs_hash_next_block_id) {
nffs_hash_next_block_id = disk_block->ndb_id + 1;
}
}
/* Make sure the maximum block data size is not set lower than the size of
* an existing block.
*/
if (disk_block->ndb_data_len > nffs_restore_largest_block_data_len) {
nffs_restore_largest_block_data_len = disk_block->ndb_data_len;
}
NFFS_LOG(DEBUG, "restoring block; id=0x%08x seq=%u inode_id=%u prev_id=%u "
"data_len=%u\n",
(unsigned int)disk_block->ndb_id,
(unsigned int)disk_block->ndb_seq,
(unsigned int)disk_block->ndb_inode_id,
(unsigned int)disk_block->ndb_prev_id,
disk_block->ndb_data_len);
inode_entry = nffs_hash_find_inode(disk_block->ndb_inode_id);
if (inode_entry == NULL) {
/*
* Owning inode not yet restored.
* Allocate a dummy inode which temporarily owns this block.
* It is not yet linked to a parent.
*/
rc = nffs_restore_dummy_inode(disk_block->ndb_inode_id, &inode_entry);
if (rc != 0) {
goto err;
}
/*
* Record that this inode was created because a block was restored
* before the inode
*/
nffs_inode_setflags(inode_entry, NFFS_INODE_FLAG_DUMMYINOBLK);
inode_entry->nie_last_block_entry = entry;
} else {
if (nffs_inode_getflags(inode_entry, NFFS_INODE_FLAG_DELETED)) {
/*
* don't restore blocks for deleted inodes
*/
rc = FS_ENOENT;
goto err;
}
}
return 0;
err:
if (new_block) {
nffs_hash_remove(entry);
nffs_block_entry_free(entry);
}
return rc;
}
