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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 : 0 : 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 : : (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
175 : : #define EXT_MAX_INDEX(__hdr__) \
176 : : (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
177 : :
178 : 20499 : static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode)
179 : : {
180 [ - - - + ]: 6186 : return (struct ext4_extent_header *) EXT4_I(inode)->i_data;
181 : : }
182 : :
183 : 0 : static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh)
184 : : {
185 [ # # # # : 0 : return (struct ext4_extent_header *) bh->b_data;
# # ]
186 : : }
187 : :
188 : 18396 : static inline unsigned short ext_depth(struct inode *inode)
189 : : {
190 [ - - - - : 18396 : return le16_to_cpu(ext_inode_hdr(inode)->eh_depth);
- - + + -
- - - - -
- + - - -
- - - - -
- + - + +
- - - + +
- - - + +
- - + - +
- + - - -
- - - - -
- + - + -
+ ]
191 : : }
192 : :
193 : 24 : static inline void ext4_ext_mark_unwritten(struct ext4_extent *ext)
194 : : {
195 : : /* We can not have an unwritten extent of zero length! */
196 [ - - - - : 24 : BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0);
- + - - -
- - - - -
- - - - -
- - - - -
- - ]
197 : 24 : ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN);
198 : 0 : }
199 : :
200 : 3912 : static inline int ext4_ext_is_unwritten(struct ext4_extent *ext)
201 : : {
202 : : /* Extent with ee_len of 0x8000 is treated as an initialized extent */
203 [ - - - - : 3888 : return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN);
+ + + + -
- - - - -
- - + - -
- - - - -
- - + + -
- ]
204 : : }
205 : :
206 : 5664 : static inline int ext4_ext_get_actual_len(struct ext4_extent *ext)
207 : : {
208 [ - - ]: 3 : return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ?
209 [ - - - - : 5637 : le16_to_cpu(ext->ee_len) :
- - - - -
- - - - -
+ + - - +
+ - - - -
- - - + -
- - - - -
- - - - -
- - - - -
- - - - -
- + - - -
+ - + - +
- - - - -
+ + - - -
- - - - -
- - - - -
- - - - -
+ + + - ]
210 : 144 : (le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN));
211 : : }
212 : :
213 : 24 : static inline void ext4_ext_mark_initialized(struct ext4_extent *ext)
214 : : {
215 [ - + - - ]: 48 : ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext));
216 : 0 : }
217 : :
218 : : /*
219 : : * ext4_ext_pblock:
220 : : * combine low and high parts of physical block number into ext4_fsblk_t
221 : : */
222 : 5484 : static inline ext4_fsblk_t ext4_ext_pblock(struct ext4_extent *ex)
223 : : {
224 : 5484 : ext4_fsblk_t block;
225 : :
226 : 5484 : block = le32_to_cpu(ex->ee_start_lo);
227 : 5484 : block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1;
228 [ + + + + : 4686 : return block;
- - - - -
- - - - -
- - - + -
- - - -
- ]
229 : : }
230 : :
231 : : /*
232 : : * ext4_idx_pblock:
233 : : * combine low and high parts of a leaf physical block number into ext4_fsblk_t
234 : : */
235 : 0 : static inline ext4_fsblk_t ext4_idx_pblock(struct ext4_extent_idx *ix)
236 : : {
237 : 0 : ext4_fsblk_t block;
238 : :
239 : 0 : block = le32_to_cpu(ix->ei_leaf_lo);
240 : 0 : block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1;
241 [ # # # # ]: 0 : return block;
242 : : }
243 : :
244 : : /*
245 : : * ext4_ext_store_pblock:
246 : : * stores a large physical block number into an extent struct,
247 : : * breaking it into parts
248 : : */
249 : 1566 : static inline void ext4_ext_store_pblock(struct ext4_extent *ex,
250 : : ext4_fsblk_t pb)
251 : : {
252 : 1566 : ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
253 [ - - + + : 1536 : ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
- - - - -
- - - ]
254 : : 0xffff);
255 : 30 : }
256 : :
257 : : /*
258 : : * ext4_idx_store_pblock:
259 : : * stores a large physical block number into an index struct,
260 : : * breaking it into parts
261 : : */
262 : 0 : static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix,
263 : : ext4_fsblk_t pb)
264 : : {
265 : 0 : ix->ei_leaf_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
266 [ # # # # : 0 : ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
# # ]
267 : : 0xffff);
268 : : }
269 : :
270 : : #endif /* _EXT4_EXTENTS */
271 : :
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