1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2007 Oracle.  All rights reserved.
4  */
5 
6 #include <linux/unaligned.h>
7 #include "messages.h"
8 #include "extent_io.h"
9 #include "fs.h"
10 #include "accessors.h"
11 
check_setget_bounds(const struct extent_buffer * eb,const void * ptr,unsigned off,int size)12 static bool check_setget_bounds(const struct extent_buffer *eb,
13 				const void *ptr, unsigned off, int size)
14 {
15 	const unsigned long member_offset = (unsigned long)ptr + off;
16 
17 	if (unlikely(member_offset + size > eb->len)) {
18 		btrfs_warn(eb->fs_info,
19 		"bad eb member %s: ptr 0x%lx start %llu member offset %lu size %d",
20 			(member_offset > eb->len ? "start" : "end"),
21 			(unsigned long)ptr, eb->start, member_offset, size);
22 		return false;
23 	}
24 
25 	return true;
26 }
27 
btrfs_init_map_token(struct btrfs_map_token * token,struct extent_buffer * eb)28 void btrfs_init_map_token(struct btrfs_map_token *token, struct extent_buffer *eb)
29 {
30 	token->eb = eb;
31 	token->kaddr = folio_address(eb->folios[0]);
32 	token->offset = 0;
33 }
34 
35 /*
36  * Macro templates that define helpers to read/write extent buffer data of a
37  * given size, that are also used via ctree.h for access to item members by
38  * specialized helpers.
39  *
40  * Generic helpers:
41  * - btrfs_set_8 (for 8/16/32/64)
42  * - btrfs_get_8 (for 8/16/32/64)
43  *
44  * Generic helpers with a token (cached address of the most recently accessed
45  * page):
46  * - btrfs_set_token_8 (for 8/16/32/64)
47  * - btrfs_get_token_8 (for 8/16/32/64)
48  *
49  * The set/get functions handle data spanning two pages transparently, in case
50  * metadata block size is larger than page.  Every pointer to metadata items is
51  * an offset into the extent buffer page array, cast to a specific type.  This
52  * gives us all the type checking.
53  *
54  * The extent buffer pages stored in the array folios may not form a contiguous
55  * phyusical range, but the API functions assume the linear offset to the range
56  * from 0 to metadata node size.
57  */
58 
59 #define DEFINE_BTRFS_SETGET_BITS(bits)					\
60 u##bits btrfs_get_token_##bits(struct btrfs_map_token *token,		\
61 			       const void *ptr, unsigned long off)	\
62 {									\
63 	const unsigned long member_offset = (unsigned long)ptr + off;	\
64 	const unsigned long idx = get_eb_folio_index(token->eb, member_offset); \
65 	const unsigned long oil = get_eb_offset_in_folio(token->eb,	\
66 							 member_offset);\
67 	const int unit_size = token->eb->folio_size;			\
68 	const int unit_shift = token->eb->folio_shift;			\
69 	const int size = sizeof(u##bits);				\
70 	u8 lebytes[sizeof(u##bits)];					\
71 	const int part = unit_size - oil;				\
72 									\
73 	ASSERT(token);							\
74 	ASSERT(token->kaddr);						\
75 	ASSERT(check_setget_bounds(token->eb, ptr, off, size));		\
76 	if (token->offset <= member_offset &&				\
77 	    member_offset + size <= token->offset + unit_size) {	\
78 		return get_unaligned_le##bits(token->kaddr + oil);	\
79 	}								\
80 	token->kaddr = folio_address(token->eb->folios[idx]);		\
81 	token->offset = idx << unit_shift;				\
82 	if (INLINE_EXTENT_BUFFER_PAGES == 1 || oil + size <= unit_size) \
83 		return get_unaligned_le##bits(token->kaddr + oil);	\
84 									\
85 	memcpy(lebytes, token->kaddr + oil, part);			\
86 	token->kaddr = folio_address(token->eb->folios[idx + 1]);	\
87 	token->offset = (idx + 1) << unit_shift;			\
88 	memcpy(lebytes + part, token->kaddr, size - part);		\
89 	return get_unaligned_le##bits(lebytes);				\
90 }									\
91 u##bits btrfs_get_##bits(const struct extent_buffer *eb,		\
92 			 const void *ptr, unsigned long off)		\
93 {									\
94 	const unsigned long member_offset = (unsigned long)ptr + off;	\
95 	const unsigned long idx = get_eb_folio_index(eb, member_offset);\
96 	const unsigned long oil = get_eb_offset_in_folio(eb,		\
97 							 member_offset);\
98 	const int unit_size = eb->folio_size;				\
99 	char *kaddr = folio_address(eb->folios[idx]);			\
100 	const int size = sizeof(u##bits);				\
101 	const int part = unit_size - oil;				\
102 	u8 lebytes[sizeof(u##bits)];					\
103 									\
104 	ASSERT(check_setget_bounds(eb, ptr, off, size));		\
105 	if (INLINE_EXTENT_BUFFER_PAGES == 1 || oil + size <= unit_size)	\
106 		return get_unaligned_le##bits(kaddr + oil);		\
107 									\
108 	memcpy(lebytes, kaddr + oil, part);				\
109 	kaddr = folio_address(eb->folios[idx + 1]);			\
110 	memcpy(lebytes + part, kaddr, size - part);			\
111 	return get_unaligned_le##bits(lebytes);				\
112 }									\
113 void btrfs_set_token_##bits(struct btrfs_map_token *token,		\
114 			    const void *ptr, unsigned long off,		\
115 			    u##bits val)				\
116 {									\
117 	const unsigned long member_offset = (unsigned long)ptr + off;	\
118 	const unsigned long idx = get_eb_folio_index(token->eb, member_offset); \
119 	const unsigned long oil = get_eb_offset_in_folio(token->eb,	\
120 							 member_offset);\
121 	const int unit_size = token->eb->folio_size;			\
122 	const int unit_shift = token->eb->folio_shift;			\
123 	const int size = sizeof(u##bits);				\
124 	u8 lebytes[sizeof(u##bits)];					\
125 	const int part = unit_size - oil;				\
126 									\
127 	ASSERT(token);							\
128 	ASSERT(token->kaddr);						\
129 	ASSERT(check_setget_bounds(token->eb, ptr, off, size));		\
130 	if (token->offset <= member_offset &&				\
131 	    member_offset + size <= token->offset + unit_size) {	\
132 		put_unaligned_le##bits(val, token->kaddr + oil);	\
133 		return;							\
134 	}								\
135 	token->kaddr = folio_address(token->eb->folios[idx]);		\
136 	token->offset = idx << unit_shift;				\
137 	if (INLINE_EXTENT_BUFFER_PAGES == 1 ||				\
138 	    oil + size <= unit_size) {					\
139 		put_unaligned_le##bits(val, token->kaddr + oil);	\
140 		return;							\
141 	}								\
142 	put_unaligned_le##bits(val, lebytes);				\
143 	memcpy(token->kaddr + oil, lebytes, part);			\
144 	token->kaddr = folio_address(token->eb->folios[idx + 1]);	\
145 	token->offset = (idx + 1) << unit_shift;			\
146 	memcpy(token->kaddr, lebytes + part, size - part);		\
147 }									\
148 void btrfs_set_##bits(const struct extent_buffer *eb, void *ptr,	\
149 		      unsigned long off, u##bits val)			\
150 {									\
151 	const unsigned long member_offset = (unsigned long)ptr + off;	\
152 	const unsigned long idx = get_eb_folio_index(eb, member_offset);\
153 	const unsigned long oil = get_eb_offset_in_folio(eb,		\
154 							 member_offset);\
155 	const int unit_size = eb->folio_size;				\
156 	char *kaddr = folio_address(eb->folios[idx]);			\
157 	const int size = sizeof(u##bits);				\
158 	const int part = unit_size - oil;				\
159 	u8 lebytes[sizeof(u##bits)];					\
160 									\
161 	ASSERT(check_setget_bounds(eb, ptr, off, size));		\
162 	if (INLINE_EXTENT_BUFFER_PAGES == 1 ||				\
163 	    oil + size <= unit_size) {					\
164 		put_unaligned_le##bits(val, kaddr + oil);		\
165 		return;							\
166 	}								\
167 									\
168 	put_unaligned_le##bits(val, lebytes);				\
169 	memcpy(kaddr + oil, lebytes, part);				\
170 	kaddr = folio_address(eb->folios[idx + 1]);			\
171 	memcpy(kaddr, lebytes + part, size - part);			\
172 }
173 
174 DEFINE_BTRFS_SETGET_BITS(8)
175 DEFINE_BTRFS_SETGET_BITS(16)
176 DEFINE_BTRFS_SETGET_BITS(32)
177 DEFINE_BTRFS_SETGET_BITS(64)
178 
btrfs_node_key(const struct extent_buffer * eb,struct btrfs_disk_key * disk_key,int nr)179 void btrfs_node_key(const struct extent_buffer *eb,
180 		    struct btrfs_disk_key *disk_key, int nr)
181 {
182 	unsigned long ptr = btrfs_node_key_ptr_offset(eb, nr);
183 	read_eb_member(eb, (struct btrfs_key_ptr *)ptr,
184 		       struct btrfs_key_ptr, key, disk_key);
185 }
186