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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 ext4_extent_header {
86 : : __le16 eh_magic; /* probably will support different formats */
87 : : __le16 eh_entries; /* number of valid entries */
88 : : __le16 eh_max; /* capacity of store in entries */
89 : : __le16 eh_depth; /* has tree real underlying blocks? */
90 : : __le32 eh_generation; /* 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 : 0 : return (struct ext4_extent_tail *)(((void *)eh) +
104 : 0 : 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 : : : 0)
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)) : 0)
180 : :
181 : : static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode)
182 : : {
183 : 1284995 : return (struct ext4_extent_header *) EXT4_I(inode)->i_data;
184 : : }
185 : :
186 : : static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh)
187 : : {
188 : 12581 : return (struct ext4_extent_header *) bh->b_data;
189 : : }
190 : :
191 : : static inline unsigned short ext_depth(struct inode *inode)
192 : : {
193 : 3691943 : return le16_to_cpu(ext_inode_hdr(inode)->eh_depth);
194 : : }
195 : :
196 : 84 : static inline void ext4_ext_mark_unwritten(struct ext4_extent *ext)
197 : : {
198 : : /* We can not have an unwritten extent of zero length! */
199 [ - + ]: 84 : BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0);
200 : 84 : ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN);
201 : 84 : }
202 : :
203 : : static inline int ext4_ext_is_unwritten(struct ext4_extent *ext)
204 : : {
205 : : /* Extent with ee_len of 0x8000 is treated as an initialized extent */
206 : 1098742 : return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN);
207 : : }
208 : :
209 : : static inline int ext4_ext_get_actual_len(struct ext4_extent *ext)
210 : : {
211 [ # # # # : 2592483 : return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ?
# # # # #
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# # # - +
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+ - + - +
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+ - + - #
# # # # #
+ + # # +
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+ + + + +
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+ + + + ]
212 : : le16_to_cpu(ext->ee_len) :
213 : 1113 : (le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN));
214 : : }
215 : :
216 : : static inline void ext4_ext_mark_initialized(struct ext4_extent *ext)
217 : : {
218 : 26 : ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext));
219 : : }
220 : :
221 : : /*
222 : : * ext4_ext_pblock:
223 : : * combine low and high parts of physical block number into ext4_fsblk_t
224 : : */
225 : : static inline ext4_fsblk_t ext4_ext_pblock(struct ext4_extent *ex)
226 : : {
227 : : ext4_fsblk_t block;
228 : :
229 : 2385434 : block = le32_to_cpu(ex->ee_start_lo);
230 : 2385434 : block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1;
231 : : return block;
232 : : }
233 : :
234 : : /*
235 : : * ext4_idx_pblock:
236 : : * combine low and high parts of a leaf physical block number into ext4_fsblk_t
237 : : */
238 : : static inline ext4_fsblk_t ext4_idx_pblock(struct ext4_extent_idx *ix)
239 : : {
240 : : ext4_fsblk_t block;
241 : :
242 : 8127 : block = le32_to_cpu(ix->ei_leaf_lo);
243 : 8127 : block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1;
244 : : return block;
245 : : }
246 : :
247 : : /*
248 : : * ext4_ext_store_pblock:
249 : : * stores a large physical block number into an extent struct,
250 : : * breaking it into parts
251 : : */
252 : : static inline void ext4_ext_store_pblock(struct ext4_extent *ex,
253 : : ext4_fsblk_t pb)
254 : : {
255 : 121001 : ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
256 : 121001 : ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
257 : : 0xffff);
258 : : }
259 : :
260 : : /*
261 : : * ext4_idx_store_pblock:
262 : : * stores a large physical block number into an index struct,
263 : : * breaking it into parts
264 : : */
265 : : static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix,
266 : : ext4_fsblk_t pb)
267 : : {
268 : 7 : ix->ei_leaf_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
269 : 7 : ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
270 : : 0xffff);
271 : : }
272 : :
273 : : #define ext4_ext_dirty(handle, inode, path) \
274 : : __ext4_ext_dirty(__func__, __LINE__, (handle), (inode), (path))
275 : : int __ext4_ext_dirty(const char *where, unsigned int line, handle_t *handle,
276 : : struct inode *inode, struct ext4_ext_path *path);
277 : :
278 : : #endif /* _EXT4_EXTENTS */
279 : :
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