1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2007 Oracle.  All rights reserved.
  4 */
  5
  6#include <asm/unaligned.h>
  7
  8#include "ctree.h"
  9
 10static bool check_setget_bounds(const struct extent_buffer *eb,
 11				const void *ptr, unsigned off, int size)
 12{
 13	const unsigned long member_offset = (unsigned long)ptr + off;
 14
 15	if (member_offset > eb->len) {
 16		btrfs_warn(eb->fs_info,
 17	"bad eb member start: ptr 0x%lx start %llu member offset %lu size %d",
 18			(unsigned long)ptr, eb->start, member_offset, size);
 19		return false;
 20	}
 21	if (member_offset + size > eb->len) {
 22		btrfs_warn(eb->fs_info,
 23	"bad eb member end: ptr 0x%lx start %llu member offset %lu size %d",
 24			(unsigned long)ptr, eb->start, member_offset, size);
 25		return false;
 26	}
 27
 28	return true;
 29}
 30
 31/*
 32 * Macro templates that define helpers to read/write extent buffer data of a
 33 * given size, that are also used via ctree.h for access to item members by
 34 * specialized helpers.
 35 *
 36 * Generic helpers:
 37 * - btrfs_set_8 (for 8/16/32/64)
 38 * - btrfs_get_8 (for 8/16/32/64)
 39 *
 40 * Generic helpers with a token (cached address of the most recently accessed
 41 * page):
 42 * - btrfs_set_token_8 (for 8/16/32/64)
 43 * - btrfs_get_token_8 (for 8/16/32/64)
 44 *
 45 * The set/get functions handle data spanning two pages transparently, in case
 46 * metadata block size is larger than page.  Every pointer to metadata items is
 47 * an offset into the extent buffer page array, cast to a specific type.  This
 48 * gives us all the type checking.
 49 *
 50 * The extent buffer pages stored in the array pages do not form a contiguous
 51 * phyusical range, but the API functions assume the linear offset to the range
 52 * from 0 to metadata node size.
 53 */
 54
 55#define DEFINE_BTRFS_SETGET_BITS(bits)					\
 56u##bits btrfs_get_token_##bits(struct btrfs_map_token *token,		\
 57			       const void *ptr, unsigned long off)	\
 58{									\
 59	const unsigned long member_offset = (unsigned long)ptr + off;	\
 60	const unsigned long idx = get_eb_page_index(member_offset);	\
 61	const unsigned long oip = get_eb_offset_in_page(token->eb,	\
 62							member_offset);	\
 63	const int size = sizeof(u##bits);				\
 64	u8 lebytes[sizeof(u##bits)];					\
 65	const int part = PAGE_SIZE - oip;				\
 66									\
 67	ASSERT(token);							\
 68	ASSERT(token->kaddr);						\
 69	ASSERT(check_setget_bounds(token->eb, ptr, off, size));		\
 70	if (token->offset <= member_offset &&				\
 71	    member_offset + size <= token->offset + PAGE_SIZE) {	\
 72		return get_unaligned_le##bits(token->kaddr + oip);	\
 73	}								\
 74	token->kaddr = page_address(token->eb->pages[idx]);		\
 75	token->offset = idx << PAGE_SHIFT;				\
 76	if (oip + size <= PAGE_SIZE)					\
 77		return get_unaligned_le##bits(token->kaddr + oip);	\
 78									\
 79	memcpy(lebytes, token->kaddr + oip, part);			\
 80	token->kaddr = page_address(token->eb->pages[idx + 1]);		\
 81	token->offset = (idx + 1) << PAGE_SHIFT;			\
 82	memcpy(lebytes + part, token->kaddr, size - part);		\
 83	return get_unaligned_le##bits(lebytes);				\
 84}									\
 85u##bits btrfs_get_##bits(const struct extent_buffer *eb,		\
 86			 const void *ptr, unsigned long off)		\
 87{									\
 88	const unsigned long member_offset = (unsigned long)ptr + off;	\
 89	const unsigned long oip = get_eb_offset_in_page(eb, member_offset); \
 90	const unsigned long idx = get_eb_page_index(member_offset);	\
 91	char *kaddr = page_address(eb->pages[idx]);			\
 92	const int size = sizeof(u##bits);				\
 93	const int part = PAGE_SIZE - oip;				\
 94	u8 lebytes[sizeof(u##bits)];					\
 95									\
 96	ASSERT(check_setget_bounds(eb, ptr, off, size));		\
 97	if (oip + size <= PAGE_SIZE)					\
 98		return get_unaligned_le##bits(kaddr + oip);		\
 99									\
100	memcpy(lebytes, kaddr + oip, part);				\
101	kaddr = page_address(eb->pages[idx + 1]);			\
102	memcpy(lebytes + part, kaddr, size - part);			\
103	return get_unaligned_le##bits(lebytes);				\
104}									\
105void btrfs_set_token_##bits(struct btrfs_map_token *token,		\
106			    const void *ptr, unsigned long off,		\
107			    u##bits val)				\
108{									\
109	const unsigned long member_offset = (unsigned long)ptr + off;	\
110	const unsigned long idx = get_eb_page_index(member_offset);	\
111	const unsigned long oip = get_eb_offset_in_page(token->eb,	\
112							member_offset);	\
113	const int size = sizeof(u##bits);				\
114	u8 lebytes[sizeof(u##bits)];					\
115	const int part = PAGE_SIZE - oip;				\
116									\
117	ASSERT(token);							\
118	ASSERT(token->kaddr);						\
119	ASSERT(check_setget_bounds(token->eb, ptr, off, size));		\
120	if (token->offset <= member_offset &&				\
121	    member_offset + size <= token->offset + PAGE_SIZE) {	\
122		put_unaligned_le##bits(val, token->kaddr + oip);	\
123		return;							\
124	}								\
125	token->kaddr = page_address(token->eb->pages[idx]);		\
126	token->offset = idx << PAGE_SHIFT;				\
127	if (oip + size <= PAGE_SIZE) {					\
128		put_unaligned_le##bits(val, token->kaddr + oip);	\
129		return;							\
130	}								\
131	put_unaligned_le##bits(val, lebytes);				\
132	memcpy(token->kaddr + oip, lebytes, part);			\
133	token->kaddr = page_address(token->eb->pages[idx + 1]);		\
134	token->offset = (idx + 1) << PAGE_SHIFT;			\
135	memcpy(token->kaddr, lebytes + part, size - part);		\
136}									\
137void btrfs_set_##bits(const struct extent_buffer *eb, void *ptr,	\
138		      unsigned long off, u##bits val)			\
139{									\
140	const unsigned long member_offset = (unsigned long)ptr + off;	\
141	const unsigned long oip = get_eb_offset_in_page(eb, member_offset); \
142	const unsigned long idx = get_eb_page_index(member_offset);	\
143	char *kaddr = page_address(eb->pages[idx]);			\
144	const int size = sizeof(u##bits);				\
145	const int part = PAGE_SIZE - oip;				\
146	u8 lebytes[sizeof(u##bits)];					\
147									\
148	ASSERT(check_setget_bounds(eb, ptr, off, size));		\
149	if (oip + size <= PAGE_SIZE) {					\
150		put_unaligned_le##bits(val, kaddr + oip);		\
151		return;							\
152	}								\
153									\
154	put_unaligned_le##bits(val, lebytes);				\
155	memcpy(kaddr + oip, lebytes, part);				\
156	kaddr = page_address(eb->pages[idx + 1]);			\
157	memcpy(kaddr, lebytes + part, size - part);			\
158}
159
160DEFINE_BTRFS_SETGET_BITS(8)
161DEFINE_BTRFS_SETGET_BITS(16)
162DEFINE_BTRFS_SETGET_BITS(32)
163DEFINE_BTRFS_SETGET_BITS(64)
164
165void btrfs_node_key(const struct extent_buffer *eb,
166		    struct btrfs_disk_key *disk_key, int nr)
167{
168	unsigned long ptr = btrfs_node_key_ptr_offset(nr);
169	read_eb_member(eb, (struct btrfs_key_ptr *)ptr,
170		       struct btrfs_key_ptr, key, disk_key);
171}