OpenCloudOS-Kernel/drivers/md/persistent-data/dm-btree-internal.h

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/*
* Copyright (C) 2011 Red Hat, Inc.
*
* This file is released under the GPL.
*/
#ifndef DM_BTREE_INTERNAL_H
#define DM_BTREE_INTERNAL_H
#include "dm-btree.h"
/*----------------------------------------------------------------*/
/*
* We'll need 2 accessor functions for n->csum and n->blocknr
* to support dm-btree-spine.c in that case.
*/
enum node_flags {
INTERNAL_NODE = 1,
LEAF_NODE = 1 << 1
};
/*
* Every btree node begins with this structure. Make sure it's a multiple
* of 8-bytes in size, otherwise the 64bit keys will be mis-aligned.
*/
struct node_header {
__le32 csum;
__le32 flags;
__le64 blocknr; /* Block this node is supposed to live in. */
__le32 nr_entries;
__le32 max_entries;
__le32 value_size;
__le32 padding;
} __attribute__((packed, aligned(8)));
struct btree_node {
struct node_header header;
dm: replace zero-length array with flexible-array The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-05-08 02:51:58 +08:00
__le64 keys[];
} __attribute__((packed, aligned(8)));
/*
* Locks a block using the btree node validator.
*/
int bn_read_lock(struct dm_btree_info *info, dm_block_t b,
struct dm_block **result);
void inc_children(struct dm_transaction_manager *tm, struct btree_node *n,
struct dm_btree_value_type *vt);
int new_block(struct dm_btree_info *info, struct dm_block **result);
void unlock_block(struct dm_btree_info *info, struct dm_block *b);
/*
* Spines keep track of the rolling locks. There are 2 variants, read-only
* and one that uses shadowing. These are separate structs to allow the
* type checker to spot misuse, for example accidentally calling read_lock
* on a shadow spine.
*/
struct ro_spine {
struct dm_btree_info *info;
int count;
struct dm_block *nodes[2];
};
void init_ro_spine(struct ro_spine *s, struct dm_btree_info *info);
void exit_ro_spine(struct ro_spine *s);
int ro_step(struct ro_spine *s, dm_block_t new_child);
void ro_pop(struct ro_spine *s);
struct btree_node *ro_node(struct ro_spine *s);
struct shadow_spine {
struct dm_btree_info *info;
int count;
struct dm_block *nodes[2];
dm_block_t root;
};
void init_shadow_spine(struct shadow_spine *s, struct dm_btree_info *info);
void exit_shadow_spine(struct shadow_spine *s);
int shadow_step(struct shadow_spine *s, dm_block_t b,
struct dm_btree_value_type *vt);
/*
* The spine must have at least one entry before calling this.
*/
struct dm_block *shadow_current(struct shadow_spine *s);
/*
* The spine must have at least two entries before calling this.
*/
struct dm_block *shadow_parent(struct shadow_spine *s);
int shadow_has_parent(struct shadow_spine *s);
dm_block_t shadow_root(struct shadow_spine *s);
/*
* Some inlines.
*/
static inline __le64 *key_ptr(struct btree_node *n, uint32_t index)
{
return n->keys + index;
}
static inline void *value_base(struct btree_node *n)
{
return &n->keys[le32_to_cpu(n->header.max_entries)];
}
static inline void *value_ptr(struct btree_node *n, uint32_t index)
{
uint32_t value_size = le32_to_cpu(n->header.value_size);
return value_base(n) + (value_size * index);
}
/*
* Assumes the values are suitably-aligned and converts to core format.
*/
static inline uint64_t value64(struct btree_node *n, uint32_t index)
{
__le64 *values_le = value_base(n);
return le64_to_cpu(values_le[index]);
}
/*
* Searching for a key within a single node.
*/
int lower_bound(struct btree_node *n, uint64_t key);
extern struct dm_block_validator btree_node_validator;
/*
* Value type for upper levels of multi-level btrees.
*/
extern void init_le64_type(struct dm_transaction_manager *tm,
struct dm_btree_value_type *vt);
/*
* This returns a shadowed btree leaf that you may modify. In practise
* this means overwrites only, since an insert could cause a node to
* be split. Useful if you need access to the old value to calculate the
* new one.
*
* This only works with single level btrees. The given key must be present in
* the tree, otherwise -EINVAL will be returned.
*/
int btree_get_overwrite_leaf(struct dm_btree_info *info, dm_block_t root,
uint64_t key, int *index,
dm_block_t *new_root, struct dm_block **leaf);
#endif /* DM_BTREE_INTERNAL_H */