1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com |
4 | * Written by Alex Tomas <alex@clusterfs.com> |
5 | */ |
6 | |
7 | #ifndef _EXT4_EXTENTS |
8 | #define _EXT4_EXTENTS |
9 | |
10 | #include "ext4.h" |
11 | |
12 | /* |
13 | * With AGGRESSIVE_TEST defined, the capacity of index/leaf blocks |
14 | * becomes very small, so index split, in-depth growing and |
15 | * other hard changes happen much more often. |
16 | * This is for debug purposes only. |
17 | */ |
18 | #define AGGRESSIVE_TEST_ |
19 | |
20 | /* |
21 | * With EXTENTS_STATS defined, the number of blocks and extents |
22 | * are collected in the truncate path. They'll be shown at |
23 | * umount time. |
24 | */ |
25 | #define EXTENTS_STATS__ |
26 | |
27 | /* |
28 | * If CHECK_BINSEARCH is defined, then the results of the binary search |
29 | * will also be checked by linear search. |
30 | */ |
31 | #define CHECK_BINSEARCH__ |
32 | |
33 | /* |
34 | * If EXT_STATS is defined then stats numbers are collected. |
35 | * These number will be displayed at umount time. |
36 | */ |
37 | #define EXT_STATS_ |
38 | |
39 | |
40 | /* |
41 | * ext4_inode has i_block array (60 bytes total). |
42 | * The first 12 bytes store ext4_extent_header; |
43 | * the remainder stores an array of ext4_extent. |
44 | * For non-inode extent blocks, ext4_extent_tail |
45 | * follows the array. |
46 | */ |
47 | |
48 | /* |
49 | * This is the extent tail on-disk structure. |
50 | * All other extent structures are 12 bytes long. It turns out that |
51 | * block_size % 12 >= 4 for at least all powers of 2 greater than 512, which |
52 | * covers all valid ext4 block sizes. Therefore, this tail structure can be |
53 | * crammed into the end of the block without having to rebalance the tree. |
54 | */ |
55 | struct ext4_extent_tail { |
56 | __le32 et_checksum; /* crc32c(uuid+inum+extent_block) */ |
57 | }; |
58 | |
59 | /* |
60 | * This is the extent on-disk structure. |
61 | * It's used at the bottom of the tree. |
62 | */ |
63 | struct ext4_extent { |
64 | __le32 ee_block; /* first logical block extent covers */ |
65 | __le16 ee_len; /* number of blocks covered by extent */ |
66 | __le16 ee_start_hi; /* high 16 bits of physical block */ |
67 | __le32 ee_start_lo; /* low 32 bits of physical block */ |
68 | }; |
69 | |
70 | /* |
71 | * This is index on-disk structure. |
72 | * It's used at all the levels except the bottom. |
73 | */ |
74 | struct ext4_extent_idx { |
75 | __le32 ei_block; /* index covers logical blocks from 'block' */ |
76 | __le32 ei_leaf_lo; /* pointer to the physical block of the next * |
77 | * level. leaf or next index could be there */ |
78 | __le16 ei_leaf_hi; /* high 16 bits of physical block */ |
79 | __u16 ei_unused; |
80 | }; |
81 | |
82 | /* |
83 | * Each block (leaves and indexes), even inode-stored has header. |
84 | */ |
85 | struct { |
86 | __le16 ; /* probably will support different formats */ |
87 | __le16 ; /* number of valid entries */ |
88 | __le16 ; /* capacity of store in entries */ |
89 | __le16 ; /* has tree real underlying blocks? */ |
90 | __le32 ; /* generation of the tree */ |
91 | }; |
92 | |
93 | #define EXT4_EXT_MAGIC cpu_to_le16(0xf30a) |
94 | #define EXT4_MAX_EXTENT_DEPTH 5 |
95 | |
96 | #define EXT4_EXTENT_TAIL_OFFSET(hdr) \ |
97 | (sizeof(struct ext4_extent_header) + \ |
98 | (sizeof(struct ext4_extent) * le16_to_cpu((hdr)->eh_max))) |
99 | |
100 | static inline struct ext4_extent_tail * |
101 | find_ext4_extent_tail(struct ext4_extent_header *eh) |
102 | { |
103 | return (struct ext4_extent_tail *)(((void *)eh) + |
104 | EXT4_EXTENT_TAIL_OFFSET(eh)); |
105 | } |
106 | |
107 | /* |
108 | * Array of ext4_ext_path contains path to some extent. |
109 | * Creation/lookup routines use it for traversal/splitting/etc. |
110 | * Truncate uses it to simulate recursive walking. |
111 | */ |
112 | struct ext4_ext_path { |
113 | ext4_fsblk_t p_block; |
114 | __u16 p_depth; |
115 | __u16 p_maxdepth; |
116 | struct ext4_extent *p_ext; |
117 | struct ext4_extent_idx *p_idx; |
118 | struct ext4_extent_header *p_hdr; |
119 | struct buffer_head *p_bh; |
120 | }; |
121 | |
122 | /* |
123 | * Used to record a portion of a cluster found at the beginning or end |
124 | * of an extent while traversing the extent tree during space removal. |
125 | * A partial cluster may be removed if it does not contain blocks shared |
126 | * with extents that aren't being deleted (tofree state). Otherwise, |
127 | * it cannot be removed (nofree state). |
128 | */ |
129 | struct partial_cluster { |
130 | ext4_fsblk_t pclu; /* physical cluster number */ |
131 | ext4_lblk_t lblk; /* logical block number within logical cluster */ |
132 | enum {initial, tofree, nofree} state; |
133 | }; |
134 | |
135 | /* |
136 | * structure for external API |
137 | */ |
138 | |
139 | /* |
140 | * EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an |
141 | * initialized extent. This is 2^15 and not (2^16 - 1), since we use the |
142 | * MSB of ee_len field in the extent datastructure to signify if this |
143 | * particular extent is an initialized extent or an unwritten (i.e. |
144 | * preallocated). |
145 | * EXT_UNWRITTEN_MAX_LEN is the maximum number of blocks we can have in an |
146 | * unwritten extent. |
147 | * If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an |
148 | * unwritten one. In other words, if MSB of ee_len is set, it is an |
149 | * unwritten extent with only one special scenario when ee_len = 0x8000. |
150 | * In this case we can not have an unwritten extent of zero length and |
151 | * thus we make it as a special case of initialized extent with 0x8000 length. |
152 | * This way we get better extent-to-group alignment for initialized extents. |
153 | * Hence, the maximum number of blocks we can have in an *initialized* |
154 | * extent is 2^15 (32768) and in an *unwritten* extent is 2^15-1 (32767). |
155 | */ |
156 | #define EXT_INIT_MAX_LEN (1UL << 15) |
157 | #define EXT_UNWRITTEN_MAX_LEN (EXT_INIT_MAX_LEN - 1) |
158 | |
159 | |
160 | #define EXT_FIRST_EXTENT(__hdr__) \ |
161 | ((struct ext4_extent *) (((char *) (__hdr__)) + \ |
162 | sizeof(struct ext4_extent_header))) |
163 | #define EXT_FIRST_INDEX(__hdr__) \ |
164 | ((struct ext4_extent_idx *) (((char *) (__hdr__)) + \ |
165 | sizeof(struct ext4_extent_header))) |
166 | #define EXT_HAS_FREE_INDEX(__path__) \ |
167 | (le16_to_cpu((__path__)->p_hdr->eh_entries) \ |
168 | < le16_to_cpu((__path__)->p_hdr->eh_max)) |
169 | #define EXT_LAST_EXTENT(__hdr__) \ |
170 | (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1) |
171 | #define EXT_LAST_INDEX(__hdr__) \ |
172 | (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1) |
173 | #define EXT_MAX_EXTENT(__hdr__) \ |
174 | ((le16_to_cpu((__hdr__)->eh_max)) ? \ |
175 | ((EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)) \ |
176 | : NULL) |
177 | #define EXT_MAX_INDEX(__hdr__) \ |
178 | ((le16_to_cpu((__hdr__)->eh_max)) ? \ |
179 | ((EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)) \ |
180 | : NULL) |
181 | |
182 | static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode) |
183 | { |
184 | return (struct ext4_extent_header *) EXT4_I(inode)->i_data; |
185 | } |
186 | |
187 | static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh) |
188 | { |
189 | return (struct ext4_extent_header *) bh->b_data; |
190 | } |
191 | |
192 | static inline unsigned short ext_depth(struct inode *inode) |
193 | { |
194 | return le16_to_cpu(ext_inode_hdr(inode)->eh_depth); |
195 | } |
196 | |
197 | static inline void ext4_ext_mark_unwritten(struct ext4_extent *ext) |
198 | { |
199 | /* We can not have an unwritten extent of zero length! */ |
200 | BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0); |
201 | ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN); |
202 | } |
203 | |
204 | static inline int ext4_ext_is_unwritten(struct ext4_extent *ext) |
205 | { |
206 | /* Extent with ee_len of 0x8000 is treated as an initialized extent */ |
207 | return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN); |
208 | } |
209 | |
210 | static inline int ext4_ext_get_actual_len(struct ext4_extent *ext) |
211 | { |
212 | return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ? |
213 | le16_to_cpu(ext->ee_len) : |
214 | (le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN)); |
215 | } |
216 | |
217 | static inline void ext4_ext_mark_initialized(struct ext4_extent *ext) |
218 | { |
219 | ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext)); |
220 | } |
221 | |
222 | /* |
223 | * ext4_ext_pblock: |
224 | * combine low and high parts of physical block number into ext4_fsblk_t |
225 | */ |
226 | static inline ext4_fsblk_t ext4_ext_pblock(struct ext4_extent *ex) |
227 | { |
228 | ext4_fsblk_t block; |
229 | |
230 | block = le32_to_cpu(ex->ee_start_lo); |
231 | block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1; |
232 | return block; |
233 | } |
234 | |
235 | /* |
236 | * ext4_idx_pblock: |
237 | * combine low and high parts of a leaf physical block number into ext4_fsblk_t |
238 | */ |
239 | static inline ext4_fsblk_t ext4_idx_pblock(struct ext4_extent_idx *ix) |
240 | { |
241 | ext4_fsblk_t block; |
242 | |
243 | block = le32_to_cpu(ix->ei_leaf_lo); |
244 | block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1; |
245 | return block; |
246 | } |
247 | |
248 | /* |
249 | * ext4_ext_store_pblock: |
250 | * stores a large physical block number into an extent struct, |
251 | * breaking it into parts |
252 | */ |
253 | static inline void ext4_ext_store_pblock(struct ext4_extent *ex, |
254 | ext4_fsblk_t pb) |
255 | { |
256 | ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff)); |
257 | ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) & |
258 | 0xffff); |
259 | } |
260 | |
261 | /* |
262 | * ext4_idx_store_pblock: |
263 | * stores a large physical block number into an index struct, |
264 | * breaking it into parts |
265 | */ |
266 | static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix, |
267 | ext4_fsblk_t pb) |
268 | { |
269 | ix->ei_leaf_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff)); |
270 | ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) & |
271 | 0xffff); |
272 | } |
273 | |
274 | #endif /* _EXT4_EXTENTS */ |
275 | |
276 | |