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node.c
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node.c
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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2018 Ernesto A. Fernández <[email protected]>
*/
#include <linux/slab.h>
#include <linux/buffer_head.h>
#include "apfs.h"
/**
* apfs_node_is_valid - Check basic sanity of the node index
* @sb: filesystem superblock
* @node: node to check
*
* Verifies that the node index fits in a single block, and that the number
* of records fits in the index. Without this check a crafted filesystem could
* pretend to have too many records, and calls to apfs_node_locate_key() and
* apfs_node_locate_data() would read beyond the limits of the node.
*/
static bool apfs_node_is_valid(struct super_block *sb,
struct apfs_node *node)
{
u32 records = node->records;
int index_size = node->key - sizeof(struct apfs_btree_node_phys);
int entry_size;
if (node->key > sb->s_blocksize)
return false;
entry_size = (apfs_node_has_fixed_kv_size(node)) ?
sizeof(struct apfs_kvoff) : sizeof(struct apfs_kvloc);
/* Coarse bound to prevent multiplication overflow in final check */
if (records > 1 << 16)
return false;
return records * entry_size <= index_size;
}
void apfs_node_free(struct apfs_node *node)
{
struct apfs_object *obj = NULL;
if (!node)
return;
obj = &node->object;
if (obj->o_bh) {
brelse(obj->o_bh);
obj->o_bh = NULL;
} else if (!obj->ephemeral) {
/* Ephemeral data always remains in memory */
kfree(obj->data);
}
obj->data = NULL;
kfree(node);
}
/**
* apfs_read_node - Read a node header from disk
* @sb: filesystem superblock
* @oid: object id for the node
* @storage: storage type for the node object
* @write: request write access?
*
* Returns ERR_PTR in case of failure, otherwise return a pointer to the
* resulting apfs_node structure with the initial reference taken.
*
* For now we assume the node has not been read before.
*/
struct apfs_node *apfs_read_node(struct super_block *sb, u64 oid, u32 storage,
bool write)
{
struct apfs_sb_info *sbi = APFS_SB(sb);
struct apfs_nxsb_info *nxi = APFS_NXI(sb);
struct buffer_head *bh = NULL;
struct apfs_ephemeral_object_info *eph_info = NULL;
struct apfs_btree_node_phys *raw = NULL;
struct apfs_node *node = NULL;
struct apfs_nloc *free_head = NULL;
u64 bno;
int err;
switch (storage) {
case APFS_OBJ_VIRTUAL:
/* All virtual nodes are inside a volume, at least for now */
err = apfs_omap_lookup_block(sb, sbi->s_omap, oid, &bno, write);
if (err) {
apfs_err(sb, "omap lookup failed for oid 0x%llx", oid);
return ERR_PTR(err);
}
/* CoW has already been done, don't worry about snapshots */
bh = apfs_read_object_block(sb, bno, write, false /* preserve */);
if (IS_ERR(bh)) {
apfs_err(sb, "object read failed for bno 0x%llx", bno);
return (void *)bh;
}
bno = bh->b_blocknr;
raw = (struct apfs_btree_node_phys *)bh->b_data;
break;
case APFS_OBJ_PHYSICAL:
bh = apfs_read_object_block(sb, oid, write, false /* preserve */);
if (IS_ERR(bh)) {
apfs_err(sb, "object read failed for bno 0x%llx", oid);
return (void *)bh;
}
bno = oid = bh->b_blocknr;
raw = (struct apfs_btree_node_phys *)bh->b_data;
break;
case APFS_OBJ_EPHEMERAL:
/* Ephemeral objects are already in memory */
eph_info = apfs_ephemeral_object_lookup(sb, oid);
if (IS_ERR(eph_info)) {
apfs_err(sb, "no ephemeral node for oid 0x%llx", oid);
return (void *)eph_info;
}
if (eph_info->size != sb->s_blocksize) {
apfs_err(sb, "unsupported size for ephemeral node (%u)", eph_info->size);
return ERR_PTR(-EOPNOTSUPP);
}
bno = 0; /* In memory, so meaningless */
raw = eph_info->object;
/* Only for consistency, will happen again on commit */
if (write)
raw->btn_o.o_xid = cpu_to_le64(nxi->nx_xid);
break;
default:
apfs_alert(sb, "invalid storage type %u - bug!", storage);
return ERR_PTR(-EINVAL);
}
node = kmalloc(sizeof(*node), GFP_KERNEL);
if (!node) {
brelse(bh);
return ERR_PTR(-ENOMEM);
}
node->tree_type = le32_to_cpu(raw->btn_o.o_subtype);
node->flags = le16_to_cpu(raw->btn_flags);
node->records = le32_to_cpu(raw->btn_nkeys);
node->key = sizeof(*raw) + le16_to_cpu(raw->btn_table_space.off)
+ le16_to_cpu(raw->btn_table_space.len);
node->free = node->key + le16_to_cpu(raw->btn_free_space.off);
node->data = node->free + le16_to_cpu(raw->btn_free_space.len);
free_head = &raw->btn_key_free_list;
node->key_free_list_len = le16_to_cpu(free_head->len);
free_head = &raw->btn_val_free_list;
node->val_free_list_len = le16_to_cpu(free_head->len);
node->object.sb = sb;
node->object.block_nr = bno;
node->object.oid = oid;
node->object.o_bh = bh;
node->object.data = (char *)raw;
node->object.ephemeral = !bh;
/* Ephemeral objects already got checked on mount */
if (!node->object.ephemeral && nxi->nx_flags & APFS_CHECK_NODES && !apfs_obj_verify_csum(sb, bh)) {
/* TODO: don't check this twice for virtual/physical objects */
apfs_err(sb, "bad checksum for node in block 0x%llx", (unsigned long long)bno);
apfs_node_free(node);
return ERR_PTR(-EFSBADCRC);
}
if (!apfs_node_is_valid(sb, node)) {
apfs_err(sb, "bad node in block 0x%llx", (unsigned long long)bno);
apfs_node_free(node);
return ERR_PTR(-EFSCORRUPTED);
}
return node;
}
/**
* apfs_node_min_table_size - Return the minimum size for a node's toc
* @sb: superblock structure
* @type: tree type for the node
* @flags: flags for the node
*/
static int apfs_node_min_table_size(struct super_block *sb, u32 type, u16 flags)
{
bool leaf = flags & APFS_BTNODE_LEAF;
int key_size, val_size, toc_size;
int space, count;
/* Preallocate the whole table for trees with fixed key/value sizes */
switch (type) {
case APFS_OBJECT_TYPE_OMAP:
key_size = sizeof(struct apfs_omap_key);
val_size = leaf ? sizeof(struct apfs_omap_val) : sizeof(__le64);
toc_size = sizeof(struct apfs_kvoff);
break;
case APFS_OBJECT_TYPE_SPACEMAN_FREE_QUEUE:
key_size = sizeof(struct apfs_spaceman_free_queue_key);
val_size = sizeof(__le64); /* We assume no ghosts here */
toc_size = sizeof(struct apfs_kvoff);
break;
case APFS_OBJECT_TYPE_OMAP_SNAPSHOT:
key_size = sizeof(__le64);
val_size = leaf ? sizeof(struct apfs_omap_snapshot) : sizeof(__le64);
toc_size = sizeof(struct apfs_kvoff);
break;
case APFS_OBJECT_TYPE_FEXT_TREE:
key_size = sizeof(struct apfs_fext_tree_key);
val_size = leaf ? sizeof(struct apfs_fext_tree_val) : sizeof(__le64);
toc_size = sizeof(struct apfs_kvoff);
break;
default:
/* Make room for one record at least */
toc_size = sizeof(struct apfs_kvloc);
return APFS_BTREE_TOC_ENTRY_INCREMENT * toc_size;
}
/* The footer of root nodes is ignored for some reason */
space = sb->s_blocksize - sizeof(struct apfs_btree_node_phys);
count = space / (key_size + val_size + toc_size);
return count * toc_size;
}
/**
* apfs_set_empty_btree_info - Set the info footer for an empty b-tree node
* @sb: filesystem superblock
* @info: pointer to the on-disk info footer
* @subtype: subtype of the root node, i.e., tree type
*
* For now only supports the extent reference tree.
*/
static void apfs_set_empty_btree_info(struct super_block *sb, struct apfs_btree_info *info, u32 subtype)
{
u32 flags;
ASSERT(subtype == APFS_OBJECT_TYPE_BLOCKREFTREE || subtype == APFS_OBJECT_TYPE_OMAP_SNAPSHOT);
memset(info, 0, sizeof(*info));
flags = APFS_BTREE_PHYSICAL;
if (subtype == APFS_OBJECT_TYPE_BLOCKREFTREE)
flags |= APFS_BTREE_KV_NONALIGNED;
info->bt_fixed.bt_flags = cpu_to_le32(flags);
info->bt_fixed.bt_node_size = cpu_to_le32(sb->s_blocksize);
info->bt_key_count = 0;
info->bt_node_count = cpu_to_le64(1); /* Only one node: the root */
if (subtype == APFS_OBJECT_TYPE_BLOCKREFTREE)
return;
info->bt_fixed.bt_key_size = cpu_to_le32(8);
info->bt_longest_key = info->bt_fixed.bt_key_size;
info->bt_fixed.bt_val_size = cpu_to_le32(sizeof(struct apfs_omap_snapshot));
info->bt_longest_val = info->bt_fixed.bt_val_size;
}
/**
* apfs_make_empty_btree_root - Make an empty root for a b-tree
* @sb: filesystem superblock
* @subtype: subtype of the root node, i.e., tree type
* @oid: on return, the root's object id
*
* For now only supports the extent reference tree and an omap's snapshot tree.
* Returns 0 on success or a negative error code in case of failure.
*/
int apfs_make_empty_btree_root(struct super_block *sb, u32 subtype, u64 *oid)
{
struct apfs_superblock *vsb_raw = APFS_SB(sb)->s_vsb_raw;
struct apfs_btree_node_phys *root = NULL;
struct buffer_head *bh = NULL;
u64 bno;
u16 flags;
int toc_len, free_len, head_len, info_len;
int err;
ASSERT(subtype == APFS_OBJECT_TYPE_BLOCKREFTREE || subtype == APFS_OBJECT_TYPE_OMAP_SNAPSHOT);
err = apfs_spaceman_allocate_block(sb, &bno, true /* backwards */);
if (err) {
apfs_err(sb, "block allocation failed");
return err;
}
apfs_assert_in_transaction(sb, &vsb_raw->apfs_o);
le64_add_cpu(&vsb_raw->apfs_fs_alloc_count, 1);
le64_add_cpu(&vsb_raw->apfs_total_blocks_alloced, 1);
bh = apfs_getblk(sb, bno);
if (!bh)
return -EIO;
root = (void *)bh->b_data;
err = apfs_transaction_join(sb, bh);
if (err)
goto fail;
set_buffer_csum(bh);
flags = APFS_BTNODE_ROOT | APFS_BTNODE_LEAF;
if (subtype == APFS_OBJECT_TYPE_OMAP_SNAPSHOT)
flags |= APFS_BTNODE_FIXED_KV_SIZE;
root->btn_flags = cpu_to_le16(flags);
toc_len = apfs_node_min_table_size(sb, subtype, flags);
head_len = sizeof(*root);
info_len = sizeof(struct apfs_btree_info);
free_len = sb->s_blocksize - head_len - toc_len - info_len;
root->btn_level = 0; /* Root */
/* No keys and no values, so this is straightforward */
root->btn_nkeys = 0;
root->btn_table_space.off = 0;
root->btn_table_space.len = cpu_to_le16(toc_len);
root->btn_free_space.off = 0;
root->btn_free_space.len = cpu_to_le16(free_len);
/* No fragmentation */
root->btn_key_free_list.off = cpu_to_le16(APFS_BTOFF_INVALID);
root->btn_key_free_list.len = 0;
root->btn_val_free_list.off = cpu_to_le16(APFS_BTOFF_INVALID);
root->btn_val_free_list.len = 0;
apfs_set_empty_btree_info(sb, (void *)root + sb->s_blocksize - info_len, subtype);
root->btn_o.o_oid = cpu_to_le64(bno);
root->btn_o.o_xid = cpu_to_le64(APFS_NXI(sb)->nx_xid);
root->btn_o.o_type = cpu_to_le32(APFS_OBJECT_TYPE_BTREE | APFS_OBJ_PHYSICAL);
root->btn_o.o_subtype = cpu_to_le32(subtype);
*oid = bno;
err = 0;
fail:
root = NULL;
brelse(bh);
bh = NULL;
return err;
}
/**
* apfs_create_node - Allocates a new nonroot b-tree node on disk
* @sb: filesystem superblock
* @storage: storage type for the node object
*
* On success returns a pointer to the new in-memory node structure; the object
* header is initialized, and the node fields are given reasonable defaults.
* On failure, returns an error pointer.
*/
static struct apfs_node *apfs_create_node(struct super_block *sb, u32 storage)
{
struct apfs_sb_info *sbi = APFS_SB(sb);
struct apfs_nxsb_info *nxi = APFS_NXI(sb);
struct apfs_nx_superblock *msb_raw = nxi->nx_raw;
struct apfs_superblock *vsb_raw = sbi->s_vsb_raw;
struct apfs_ephemeral_object_info *eph_info = NULL;
struct apfs_node *node = NULL;
struct buffer_head *bh = NULL;
struct apfs_btree_node_phys *raw = NULL;
u64 bno, oid;
int err;
switch (storage) {
case APFS_OBJ_VIRTUAL:
err = apfs_spaceman_allocate_block(sb, &bno, true /* backwards */);
if (err) {
apfs_err(sb, "block allocation failed");
return ERR_PTR(err);
}
apfs_assert_in_transaction(sb, &vsb_raw->apfs_o);
le64_add_cpu(&vsb_raw->apfs_fs_alloc_count, 1);
le64_add_cpu(&vsb_raw->apfs_total_blocks_alloced, 1);
oid = le64_to_cpu(msb_raw->nx_next_oid);
le64_add_cpu(&msb_raw->nx_next_oid, 1);
err = apfs_create_omap_rec(sb, oid, bno);
if (err) {
apfs_err(sb, "omap rec creation failed (0x%llx-0x%llx)", oid, bno);
return ERR_PTR(err);
}
break;
case APFS_OBJ_PHYSICAL:
err = apfs_spaceman_allocate_block(sb, &bno, true /* backwards */);
if (err) {
apfs_err(sb, "block allocation failed");
return ERR_PTR(err);
}
/* We don't write to the container's omap */
apfs_assert_in_transaction(sb, &vsb_raw->apfs_o);
le64_add_cpu(&vsb_raw->apfs_fs_alloc_count, 1);
le64_add_cpu(&vsb_raw->apfs_total_blocks_alloced, 1);
oid = bno;
break;
case APFS_OBJ_EPHEMERAL:
if (nxi->nx_eph_count >= APFS_EPHEMERAL_LIST_LIMIT) {
apfs_err(sb, "creating too many ephemeral objects?");
return ERR_PTR(-EOPNOTSUPP);
}
eph_info = &nxi->nx_eph_list[nxi->nx_eph_count++];
eph_info->object = kzalloc(sb->s_blocksize, GFP_KERNEL);
if (!eph_info->object)
return ERR_PTR(-ENOMEM);
eph_info->size = sb->s_blocksize;
oid = eph_info->oid = le64_to_cpu(msb_raw->nx_next_oid);
le64_add_cpu(&msb_raw->nx_next_oid, 1);
break;
default:
apfs_alert(sb, "invalid storage type %u - bug!", storage);
return ERR_PTR(-EINVAL);
}
if (storage == APFS_OBJ_EPHEMERAL) {
bh = NULL;
bno = 0;
raw = eph_info->object;
} else {
bh = apfs_getblk(sb, bno);
if (!bh)
return ERR_PTR(-EIO);
bno = bh->b_blocknr;
raw = (void *)bh->b_data;
err = apfs_transaction_join(sb, bh);
if (err)
goto fail;
set_buffer_csum(bh);
}
/* Set most of the object header, but the subtype is up to the caller */
raw->btn_o.o_oid = cpu_to_le64(oid);
raw->btn_o.o_xid = cpu_to_le64(nxi->nx_xid);
raw->btn_o.o_type = cpu_to_le32(storage | APFS_OBJECT_TYPE_BTREE_NODE);
raw->btn_o.o_subtype = 0;
/* The caller is expected to change most node fields */
raw->btn_flags = 0;
raw->btn_level = 0;
raw->btn_nkeys = 0;
raw->btn_table_space.off = 0; /* Put the toc right after the header */
raw->btn_table_space.len = 0;
raw->btn_free_space.off = 0;
raw->btn_free_space.len = cpu_to_le16(sb->s_blocksize - sizeof(*raw));
raw->btn_key_free_list.off = cpu_to_le16(APFS_BTOFF_INVALID);
raw->btn_key_free_list.len = 0;
raw->btn_val_free_list.off = cpu_to_le16(APFS_BTOFF_INVALID);
raw->btn_val_free_list.len = 0;
node = kmalloc(sizeof(*node), GFP_KERNEL);
if (!node) {
err = -ENOMEM;
goto fail;
}
node->object.sb = sb;
node->object.block_nr = bno;
node->object.oid = oid;
node->object.o_bh = bh;
node->object.data = (char *)raw;
node->object.ephemeral = !bh;
return node;
fail:
if (storage == APFS_OBJ_EPHEMERAL)
kfree(raw);
else
brelse(bh);
raw = NULL;
bh = NULL;
return ERR_PTR(err);
}
/**
* apfs_delete_node - Deletes a nonroot node from disk
* @node: node to delete
* @type: tree type for the query that found the node
*
* Does nothing to the in-memory node structure. Returns 0 on success, or a
* negative error code in case of failure.
*/
int apfs_delete_node(struct apfs_node *node, int type)
{
struct super_block *sb = node->object.sb;
struct apfs_nxsb_info *nxi = APFS_NXI(sb);
struct apfs_superblock *vsb_raw;
u64 oid = node->object.oid;
u64 bno = node->object.block_nr;
struct apfs_ephemeral_object_info *eph_info = NULL, *eph_info_end = NULL;
int err;
switch (type) {
case APFS_QUERY_CAT:
err = apfs_free_queue_insert(sb, bno, 1);
if (err) {
apfs_err(sb, "free queue insertion failed for 0x%llx", bno);
return err;
}
err = apfs_delete_omap_rec(sb, oid);
if (err) {
apfs_err(sb, "omap rec deletion failed (0x%llx)", oid);
return err;
}
vsb_raw = APFS_SB(sb)->s_vsb_raw;
apfs_assert_in_transaction(sb, &vsb_raw->apfs_o);
le64_add_cpu(&vsb_raw->apfs_fs_alloc_count, -1);
le64_add_cpu(&vsb_raw->apfs_total_blocks_freed, 1);
return 0;
case APFS_QUERY_OMAP:
case APFS_QUERY_EXTENTREF:
case APFS_QUERY_SNAP_META:
err = apfs_free_queue_insert(sb, bno, 1);
if (err) {
apfs_err(sb, "free queue insertion failed for 0x%llx", bno);
return err;
}
/* We don't write to the container's omap */
vsb_raw = APFS_SB(sb)->s_vsb_raw;
apfs_assert_in_transaction(sb, &vsb_raw->apfs_o);
le64_add_cpu(&vsb_raw->apfs_fs_alloc_count, -1);
le64_add_cpu(&vsb_raw->apfs_total_blocks_freed, 1);
return 0;
case APFS_QUERY_FREE_QUEUE:
eph_info_end = &nxi->nx_eph_list[nxi->nx_eph_count];
eph_info = apfs_ephemeral_object_lookup(sb, node->object.oid);
if (IS_ERR(eph_info)) {
apfs_alert(sb, "can't find ephemeral object to delete");
return PTR_ERR(eph_info);
}
kfree(eph_info->object);
eph_info->object = NULL;
memmove(eph_info, eph_info + 1, (char *)eph_info_end - (char *)(eph_info + 1));
eph_info_end->object = NULL;
--nxi->nx_eph_count;
return 0;
default:
apfs_alert(sb, "new query type must implement node deletion (%d)", type);
return -EOPNOTSUPP;
}
}
/**
* apfs_update_node - Update an existing node header
* @node: the modified in-memory node
*/
void apfs_update_node(struct apfs_node *node)
{
struct super_block *sb = node->object.sb;
struct buffer_head *bh = node->object.o_bh;
struct apfs_btree_node_phys *raw = (void *)node->object.data;
struct apfs_nloc *free_head;
u32 tflags, type;
int toc_off;
apfs_assert_in_transaction(sb, &raw->btn_o);
raw->btn_o.o_oid = cpu_to_le64(node->object.oid);
/* The node may no longer be a root, so update the object type */
tflags = le32_to_cpu(raw->btn_o.o_type) & APFS_OBJECT_TYPE_FLAGS_MASK;
type = (node->flags & APFS_BTNODE_ROOT) ? APFS_OBJECT_TYPE_BTREE :
APFS_OBJECT_TYPE_BTREE_NODE;
raw->btn_o.o_type = cpu_to_le32(type | tflags);
raw->btn_o.o_subtype = cpu_to_le32(node->tree_type);
raw->btn_flags = cpu_to_le16(node->flags);
raw->btn_nkeys = cpu_to_le32(node->records);
toc_off = sizeof(*raw) + le16_to_cpu(raw->btn_table_space.off);
raw->btn_table_space.len = cpu_to_le16(node->key - toc_off);
raw->btn_free_space.off = cpu_to_le16(node->free - node->key);
raw->btn_free_space.len = cpu_to_le16(node->data - node->free);
/* Reset the lists on zero length, a defragmentation is taking place */
free_head = &raw->btn_key_free_list;
free_head->len = cpu_to_le16(node->key_free_list_len);
if (!free_head->len)
free_head->off = cpu_to_le16(APFS_BTOFF_INVALID);
free_head = &raw->btn_val_free_list;
free_head->len = cpu_to_le16(node->val_free_list_len);
if (!free_head->len)
free_head->off = cpu_to_le16(APFS_BTOFF_INVALID);
if (bh) {
ASSERT(buffer_trans(bh));
ASSERT(buffer_csum(bh));
}
}
/**
* apfs_node_locate_key - Locate the key of a node record
* @node: node to be searched
* @index: number of the entry to locate
* @off: on return will hold the offset in the block
*
* Returns the length of the key, or 0 in case of failure. The function checks
* that this length fits within the block; callers must use the returned value
* to make sure they never operate outside its bounds.
*/
int apfs_node_locate_key(struct apfs_node *node, int index, int *off)
{
struct super_block *sb = node->object.sb;
struct apfs_btree_node_phys *raw;
int len;
if (index >= node->records) {
apfs_err(sb, "index out of bounds (%d of %d)", index, node->records);
return 0;
}
raw = (struct apfs_btree_node_phys *)node->object.data;
if (apfs_node_has_fixed_kv_size(node)) {
struct apfs_kvoff *entry;
entry = (struct apfs_kvoff *)raw->btn_data + index;
/* TODO: it would be cleaner to read this stuff from disk */
if (node->tree_type == APFS_OBJECT_TYPE_OMAP_SNAPSHOT)
len = 8;
else
len = 16;
/* Translate offset in key area to offset in block */
*off = node->key + le16_to_cpu(entry->k);
} else {
/* These node types have variable length keys and data */
struct apfs_kvloc *entry;
entry = (struct apfs_kvloc *)raw->btn_data + index;
len = le16_to_cpu(entry->k.len);
/* Translate offset in key area to offset in block */
*off = node->key + le16_to_cpu(entry->k.off);
}
if (*off + len > sb->s_blocksize) {
apfs_err(sb, "key out of bounds (%d-%d)", *off, len);
return 0;
}
return len;
}
/**
* apfs_node_locate_data - Locate the data of a node record
* @node: node to be searched
* @index: number of the entry to locate
* @off: on return will hold the offset in the block
*
* Returns the length of the data, which may be 0 in case of corruption or if
* the record is a ghost. The function checks that this length fits within the
* block; callers must use the returned value to make sure they never operate
* outside its bounds.
*/
static int apfs_node_locate_data(struct apfs_node *node, int index, int *off)
{
struct super_block *sb = node->object.sb;
struct apfs_btree_node_phys *raw;
int len;
if (index >= node->records) {
apfs_err(sb, "index out of bounds (%d of %d)", index, node->records);
return 0;
}
raw = (struct apfs_btree_node_phys *)node->object.data;
if (apfs_node_has_fixed_kv_size(node)) {
/* These node types have fixed length keys and data */
struct apfs_kvoff *entry;
entry = (struct apfs_kvoff *)raw->btn_data + index;
if (node->tree_type == APFS_OBJECT_TYPE_SPACEMAN_FREE_QUEUE) {
/* A free-space queue record may have no value */
if (le16_to_cpu(entry->v) == APFS_BTOFF_INVALID) {
*off = 0;
return 0;
}
len = 8;
} else {
/* This is an omap or omap snapshots node */
len = apfs_node_is_leaf(node) ? 16 : 8;
}
/*
* Data offsets are counted backwards from the end of the
* block, or from the beginning of the footer when it exists
*/
if (apfs_node_is_root(node)) /* has footer */
*off = sb->s_blocksize - sizeof(struct apfs_btree_info)
- le16_to_cpu(entry->v);
else
*off = sb->s_blocksize - le16_to_cpu(entry->v);
} else {
/* These node types have variable length keys and data */
struct apfs_kvloc *entry;
entry = (struct apfs_kvloc *)raw->btn_data + index;
len = le16_to_cpu(entry->v.len);
/*
* Data offsets are counted backwards from the end of the
* block, or from the beginning of the footer when it exists
*/
if (apfs_node_is_root(node)) /* has footer */
*off = sb->s_blocksize - sizeof(struct apfs_btree_info)
- le16_to_cpu(entry->v.off);
else
*off = sb->s_blocksize - le16_to_cpu(entry->v.off);
}
if (*off < 0 || *off + len > sb->s_blocksize) {
apfs_err(sb, "value out of bounds (%d-%d)", *off, len);
return 0;
}
return len;
}
/**
* apfs_create_toc_entry - Create the table-of-contents entry for a record
* @query: query pointing to the record
*
* Creates a toc entry for the record at index @query->index and increases
* @node->records. The caller must ensure enough space in the table.
*/
static void apfs_create_toc_entry(struct apfs_query *query)
{
struct apfs_node *node = query->node;
struct super_block *sb = node->object.sb;
struct apfs_btree_node_phys *raw = (void *)node->object.data;
int value_end;
int recs = node->records;
int index = query->index;
value_end = sb->s_blocksize;
if (apfs_node_is_root(node))
value_end -= sizeof(struct apfs_btree_info);
if (apfs_node_has_fixed_kv_size(node)) {
struct apfs_kvoff *kvoff;
kvoff = (struct apfs_kvoff *)raw->btn_data + query->index;
memmove(kvoff + 1, kvoff, (recs - index) * sizeof(*kvoff));
if (!query->len) /* Ghost record */
kvoff->v = cpu_to_le16(APFS_BTOFF_INVALID);
else
kvoff->v = cpu_to_le16(value_end - query->off);
kvoff->k = cpu_to_le16(query->key_off - node->key);
} else {
struct apfs_kvloc *kvloc;
kvloc = (struct apfs_kvloc *)raw->btn_data + query->index;
memmove(kvloc + 1, kvloc, (recs - index) * sizeof(*kvloc));
kvloc->v.off = cpu_to_le16(value_end - query->off);
kvloc->v.len = cpu_to_le16(query->len);
kvloc->k.off = cpu_to_le16(query->key_off - node->key);
kvloc->k.len = cpu_to_le16(query->key_len);
}
node->records++;
}
/**
* apfs_key_from_query - Read the current key from a query structure
* @query: the query, with @query->key_off and @query->key_len already set
* @key: return parameter for the key
*
* Reads the key into @key and performs some basic sanity checks as a
* protection against crafted filesystems. Returns 0 on success or a
* negative error code otherwise.
*/
static int apfs_key_from_query(struct apfs_query *query, struct apfs_key *key)
{
struct super_block *sb = query->node->object.sb;
char *raw = query->node->object.data;
void *raw_key = (void *)(raw + query->key_off);
bool hashed;
int err = 0;
switch (query->flags & APFS_QUERY_TREE_MASK) {
case APFS_QUERY_CAT:
hashed = apfs_is_normalization_insensitive(sb);
err = apfs_read_cat_key(raw_key, query->key_len, key, hashed);
break;
case APFS_QUERY_OMAP:
err = apfs_read_omap_key(raw_key, query->key_len, key);
break;
case APFS_QUERY_FREE_QUEUE:
err = apfs_read_free_queue_key(raw_key, query->key_len, key);
break;
case APFS_QUERY_EXTENTREF:
err = apfs_read_extentref_key(raw_key, query->key_len, key);
break;
case APFS_QUERY_FEXT:
err = apfs_read_fext_key(raw_key, query->key_len, key);
break;
case APFS_QUERY_SNAP_META:
err = apfs_read_snap_meta_key(raw_key, query->key_len, key);
break;
case APFS_QUERY_OMAP_SNAP:
err = apfs_read_omap_snap_key(raw_key, query->key_len, key);
break;
default:
apfs_alert(sb, "new query type must implement key reads (%d)", query->flags & APFS_QUERY_TREE_MASK);
err = -EOPNOTSUPP;
break;
}
if (err)
apfs_err(sb, "bad node key in block 0x%llx", query->node->object.block_nr);
/* A multiple query must ignore some of these fields */
if (query->flags & APFS_QUERY_ANY_NAME)
key->name = NULL;
if (query->flags & APFS_QUERY_ANY_NUMBER)
key->number = 0;
return err;
}
/**
* apfs_node_prev - Find the previous record in the current node
* @sb: filesystem superblock
* @query: query in execution
*
* Returns 0 on success, -EAGAIN if the previous record is in another node,
* -ENODATA if no more records exist, or another negative error code in case
* of failure.
*
* The meaning of "next" and "previous" is reverted here, because regular
* multiple always start with the final record, and then they go backwards.
* TODO: consider renaming this for clarity.
*/
static int apfs_node_prev(struct super_block *sb, struct apfs_query *query)
{
struct apfs_node *node = query->node;
if (query->index + 1 == node->records) {
/* The next record may be in another node */
return -EAGAIN;
}
++query->index;
query->key_len = apfs_node_locate_key(node, query->index, &query->key_off);
if (query->key_len == 0) {
apfs_err(sb, "bad key for index %d", query->index);
return -EFSCORRUPTED;
}
query->len = apfs_node_locate_data(node, query->index, &query->off);
if (query->len == 0) {
apfs_err(sb, "bad value for index %d", query->index);
return -EFSCORRUPTED;
}
return 0;
}
/**
* apfs_node_next - Find the next matching record in the current node
* @sb: filesystem superblock
* @query: multiple query in execution
*
* Returns 0 on success, -EAGAIN if the next record is in another node,
* -ENODATA if no more matching records exist, or another negative error
* code in case of failure.
*/
static int apfs_node_next(struct super_block *sb, struct apfs_query *query)
{
struct apfs_node *node = query->node;
struct apfs_key curr_key;
int cmp, err;
if (query->flags & APFS_QUERY_DONE)
/* Nothing left to search; the query failed */
return -ENODATA;
if (!query->index) /* The next record may be in another node */
return -EAGAIN;
--query->index;
query->key_len = apfs_node_locate_key(node, query->index,
&query->key_off);
err = apfs_key_from_query(query, &curr_key);
if (err) {
apfs_err(sb, "bad key for index %d", query->index);
return err;
}
cmp = apfs_keycmp(&curr_key, &query->key);
if (cmp > 0) {
apfs_err(sb, "records are out of order");
return -EFSCORRUPTED;
}
if (cmp != 0 && apfs_node_is_leaf(node) &&
query->flags & APFS_QUERY_EXACT)
return -ENODATA;
query->len = apfs_node_locate_data(node, query->index, &query->off);
if (query->len == 0) {
apfs_err(sb, "bad value for index %d", query->index);
return -EFSCORRUPTED;
}
if (cmp != 0) {
/*
* This is the last entry that can be relevant in this node.
* Keep searching the children, but don't return to this level.
*/
query->flags |= APFS_QUERY_DONE;
}
return 0;
}
/**
* apfs_node_query - Execute a query on a single node
* @sb: filesystem superblock
* @query: the query to execute
*
* The search will start at index @query->index, looking for the key that comes
* right before @query->key, according to the order given by apfs_keycmp().
*
* The @query->index will be updated to the last index checked. This is
* important when searching for multiple entries, since the query may need
* to remember where it was on this level. If we are done with this node, the
* query will be flagged as APFS_QUERY_DONE, and the search will end in failure
* as soon as we return to this level. The function may also return -EAGAIN,
* to signal that the search should go on in a different branch.
*
* On success returns 0; the offset of the data within the block will be saved
* in @query->off, and its length in @query->len. The function checks that this
* length fits within the block; callers must use the returned value to make
* sure they never operate outside its bounds.
*
* -ENODATA will be returned if no appropriate entry was found, -EFSCORRUPTED
* in case of corruption.
*/
int apfs_node_query(struct super_block *sb, struct apfs_query *query)
{
struct apfs_node *node = query->node;
int left, right;
int cmp;
int err;
if (query->flags & APFS_QUERY_PREV)
return apfs_node_prev(sb, query);
if (query->flags & APFS_QUERY_NEXT)
return apfs_node_next(sb, query);
/* Search by bisection */
cmp = 1;
left = 0;
do {
struct apfs_key curr_key;
if (cmp > 0) {
right = query->index - 1;
if (right < left) {
query->index = -1;
return -ENODATA;
}
query->index = (left + right) / 2;
} else {
left = query->index;
query->index = DIV_ROUND_UP(left + right, 2);
}
query->key_len = apfs_node_locate_key(node, query->index,
&query->key_off);
err = apfs_key_from_query(query, &curr_key);
if (err) {
apfs_err(sb, "bad key for index %d", query->index);
return err;
}
cmp = apfs_keycmp(&curr_key, &query->key);
if (cmp == 0 && !(query->flags & APFS_QUERY_MULTIPLE))
break;
} while (left != right);
if (cmp > 0) {
query->index = -1;
return -ENODATA;
}
if (cmp != 0 && apfs_node_is_leaf(query->node) &&
query->flags & APFS_QUERY_EXACT)
return -ENODATA;
if (query->flags & APFS_QUERY_MULTIPLE) {
if (cmp != 0) /* Last relevant entry in level */
query->flags |= APFS_QUERY_DONE;
query->flags |= APFS_QUERY_NEXT;
}
query->len = apfs_node_locate_data(node, query->index, &query->off);
return 0;
}
/**
* apfs_node_query_first - Find the first record in a node
* @query: on return this query points to the record
*/
void apfs_node_query_first(struct apfs_query *query)
{
struct apfs_node *node = query->node;
query->index = 0;
query->key_len = apfs_node_locate_key(node, query->index, &query->key_off);
query->len = apfs_node_locate_data(node, query->index, &query->off);
}
/**
* apfs_omap_map_from_query - Read the mapping found by a successful omap query