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1 : : /*
2 : : * Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com
3 : : * Written by Alex Tomas <alex@clusterfs.com>
4 : : *
5 : : * This program is free software; you can redistribute it and/or modify
6 : : * it under the terms of the GNU General Public License version 2 as
7 : : * published by the Free Software Foundation.
8 : : *
9 : : * This program is distributed in the hope that it will be useful,
10 : : * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 : : * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 : : * GNU General Public License for more details.
13 : : *
14 : : * You should have received a copy of the GNU General Public Licens
15 : : * along with this program; if not, write to the Free Software
16 : : * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-
17 : : */
18 : :
19 : : #ifndef _EXT4_EXTENTS
20 : : #define _EXT4_EXTENTS
21 : :
22 : : #include "ext4.h"
23 : :
24 : : /*
25 : : * With AGGRESSIVE_TEST defined, the capacity of index/leaf blocks
26 : : * becomes very small, so index split, in-depth growing and
27 : : * other hard changes happen much more often.
28 : : * This is for debug purposes only.
29 : : */
30 : : #define AGGRESSIVE_TEST_
31 : :
32 : : /*
33 : : * With EXTENTS_STATS defined, the number of blocks and extents
34 : : * are collected in the truncate path. They'll be shown at
35 : : * umount time.
36 : : */
37 : : #define EXTENTS_STATS__
38 : :
39 : : /*
40 : : * If CHECK_BINSEARCH is defined, then the results of the binary search
41 : : * will also be checked by linear search.
42 : : */
43 : : #define CHECK_BINSEARCH__
44 : :
45 : : /*
46 : : * If EXT_STATS is defined then stats numbers are collected.
47 : : * These number will be displayed at umount time.
48 : : */
49 : : #define EXT_STATS_
50 : :
51 : :
52 : : /*
53 : : * ext4_inode has i_block array (60 bytes total).
54 : : * The first 12 bytes store ext4_extent_header;
55 : : * the remainder stores an array of ext4_extent.
56 : : * For non-inode extent blocks, ext4_extent_tail
57 : : * follows the array.
58 : : */
59 : :
60 : : /*
61 : : * This is the extent tail on-disk structure.
62 : : * All other extent structures are 12 bytes long. It turns out that
63 : : * block_size % 12 >= 4 for at least all powers of 2 greater than 512, which
64 : : * covers all valid ext4 block sizes. Therefore, this tail structure can be
65 : : * crammed into the end of the block without having to rebalance the tree.
66 : : */
67 : : struct ext4_extent_tail {
68 : : __le32 et_checksum; /* crc32c(uuid+inum+extent_block) */
69 : : };
70 : :
71 : : /*
72 : : * This is the extent on-disk structure.
73 : : * It's used at the bottom of the tree.
74 : : */
75 : : struct ext4_extent {
76 : : __le32 ee_block; /* first logical block extent covers */
77 : : __le16 ee_len; /* number of blocks covered by extent */
78 : : __le16 ee_start_hi; /* high 16 bits of physical block */
79 : : __le32 ee_start_lo; /* low 32 bits of physical block */
80 : : };
81 : :
82 : : /*
83 : : * This is index on-disk structure.
84 : : * It's used at all the levels except the bottom.
85 : : */
86 : : struct ext4_extent_idx {
87 : : __le32 ei_block; /* index covers logical blocks from 'block' */
88 : : __le32 ei_leaf_lo; /* pointer to the physical block of the next *
89 : : * level. leaf or next index could be there */
90 : : __le16 ei_leaf_hi; /* high 16 bits of physical block */
91 : : __u16 ei_unused;
92 : : };
93 : :
94 : : /*
95 : : * Each block (leaves and indexes), even inode-stored has header.
96 : : */
97 : : struct ext4_extent_header {
98 : : __le16 eh_magic; /* probably will support different formats */
99 : : __le16 eh_entries; /* number of valid entries */
100 : : __le16 eh_max; /* capacity of store in entries */
101 : : __le16 eh_depth; /* has tree real underlying blocks? */
102 : : __le32 eh_generation; /* generation of the tree */
103 : : };
104 : :
105 : : #define EXT4_EXT_MAGIC cpu_to_le16(0xf30a)
106 : :
107 : : #define EXT4_EXTENT_TAIL_OFFSET(hdr) \
108 : : (sizeof(struct ext4_extent_header) + \
109 : : (sizeof(struct ext4_extent) * le16_to_cpu((hdr)->eh_max)))
110 : :
111 : : static inline struct ext4_extent_tail *
112 : : find_ext4_extent_tail(struct ext4_extent_header *eh)
113 : : {
114 : 0 : return (struct ext4_extent_tail *)(((void *)eh) +
115 : 0 : EXT4_EXTENT_TAIL_OFFSET(eh));
116 : : }
117 : :
118 : : /*
119 : : * Array of ext4_ext_path contains path to some extent.
120 : : * Creation/lookup routines use it for traversal/splitting/etc.
121 : : * Truncate uses it to simulate recursive walking.
122 : : */
123 : : struct ext4_ext_path {
124 : : ext4_fsblk_t p_block;
125 : : __u16 p_depth;
126 : : struct ext4_extent *p_ext;
127 : : struct ext4_extent_idx *p_idx;
128 : : struct ext4_extent_header *p_hdr;
129 : : struct buffer_head *p_bh;
130 : : };
131 : :
132 : : /*
133 : : * structure for external API
134 : : */
135 : :
136 : : /*
137 : : * EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an
138 : : * initialized extent. This is 2^15 and not (2^16 - 1), since we use the
139 : : * MSB of ee_len field in the extent datastructure to signify if this
140 : : * particular extent is an initialized extent or an uninitialized (i.e.
141 : : * preallocated).
142 : : * EXT_UNINIT_MAX_LEN is the maximum number of blocks we can have in an
143 : : * uninitialized extent.
144 : : * If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an
145 : : * uninitialized one. In other words, if MSB of ee_len is set, it is an
146 : : * uninitialized extent with only one special scenario when ee_len = 0x8000.
147 : : * In this case we can not have an uninitialized extent of zero length and
148 : : * thus we make it as a special case of initialized extent with 0x8000 length.
149 : : * This way we get better extent-to-group alignment for initialized extents.
150 : : * Hence, the maximum number of blocks we can have in an *initialized*
151 : : * extent is 2^15 (32768) and in an *uninitialized* extent is 2^15-1 (32767).
152 : : */
153 : : #define EXT_INIT_MAX_LEN (1UL << 15)
154 : : #define EXT_UNINIT_MAX_LEN (EXT_INIT_MAX_LEN - 1)
155 : :
156 : :
157 : : #define EXT_FIRST_EXTENT(__hdr__) \
158 : : ((struct ext4_extent *) (((char *) (__hdr__)) + \
159 : : sizeof(struct ext4_extent_header)))
160 : : #define EXT_FIRST_INDEX(__hdr__) \
161 : : ((struct ext4_extent_idx *) (((char *) (__hdr__)) + \
162 : : sizeof(struct ext4_extent_header)))
163 : : #define EXT_HAS_FREE_INDEX(__path__) \
164 : : (le16_to_cpu((__path__)->p_hdr->eh_entries) \
165 : : < le16_to_cpu((__path__)->p_hdr->eh_max))
166 : : #define EXT_LAST_EXTENT(__hdr__) \
167 : : (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
168 : : #define EXT_LAST_INDEX(__hdr__) \
169 : : (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
170 : : #define EXT_MAX_EXTENT(__hdr__) \
171 : : (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
172 : : #define EXT_MAX_INDEX(__hdr__) \
173 : : (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
174 : :
175 : : static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode)
176 : : {
177 : : return (struct ext4_extent_header *) EXT4_I(inode)->i_data;
178 : : }
179 : :
180 : : static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh)
181 : : {
182 : : return (struct ext4_extent_header *) bh->b_data;
183 : : }
184 : :
185 : : static inline unsigned short ext_depth(struct inode *inode)
186 : : {
187 : 7060763 : return le16_to_cpu(ext_inode_hdr(inode)->eh_depth);
188 : : }
189 : :
190 : : static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext)
191 : : {
192 : : /* We can not have an uninitialized extent of zero length! */
193 [ - + ][ # # ]: 9 : BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0);
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194 : 0 : ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN);
195 : : }
196 : :
197 : : static inline int ext4_ext_is_uninitialized(struct ext4_extent *ext)
198 : : {
199 : : /* Extent with ee_len of 0x8000 is treated as an initialized extent */
200 : 0 : return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN);
201 : : }
202 : :
203 : : static inline int ext4_ext_get_actual_len(struct ext4_extent *ext)
204 : : {
205 [ # # ][ + + ]: 4704757 : return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ?
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206 : : le16_to_cpu(ext->ee_len) :
207 : 84 : (le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN));
208 : : }
209 : :
210 : 0 : static inline void ext4_ext_mark_initialized(struct ext4_extent *ext)
211 : : {
212 : 0 : ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext));
213 : : }
214 : :
215 : : /*
216 : : * ext4_ext_pblock:
217 : : * combine low and high parts of physical block number into ext4_fsblk_t
218 : : */
219 : : static inline ext4_fsblk_t ext4_ext_pblock(struct ext4_extent *ex)
220 : : {
221 : : ext4_fsblk_t block;
222 : :
223 : 3454777 : block = le32_to_cpu(ex->ee_start_lo);
224 : 3454777 : block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1;
225 : : return block;
226 : : }
227 : :
228 : : /*
229 : : * ext4_idx_pblock:
230 : : * combine low and high parts of a leaf physical block number into ext4_fsblk_t
231 : : */
232 : : static inline ext4_fsblk_t ext4_idx_pblock(struct ext4_extent_idx *ix)
233 : : {
234 : : ext4_fsblk_t block;
235 : :
236 : 352357 : block = le32_to_cpu(ix->ei_leaf_lo);
237 : 352357 : block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1;
238 : : return block;
239 : : }
240 : :
241 : : /*
242 : : * ext4_ext_store_pblock:
243 : : * stores a large physical block number into an extent struct,
244 : : * breaking it into parts
245 : : */
246 : : static inline void ext4_ext_store_pblock(struct ext4_extent *ex,
247 : : ext4_fsblk_t pb)
248 : : {
249 : 481409 : ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
250 : 126850 : ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
251 : : 0xffff);
252 : : }
253 : :
254 : : /*
255 : : * ext4_idx_store_pblock:
256 : : * stores a large physical block number into an index struct,
257 : : * breaking it into parts
258 : : */
259 : : static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix,
260 : : ext4_fsblk_t pb)
261 : : {
262 : 431 : ix->ei_leaf_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
263 : 431 : ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
264 : : 0xffff);
265 : : }
266 : :
267 : : #define ext4_ext_dirty(handle, inode, path) \
268 : : __ext4_ext_dirty(__func__, __LINE__, (handle), (inode), (path))
269 : : int __ext4_ext_dirty(const char *where, unsigned int line, handle_t *handle,
270 : : struct inode *inode, struct ext4_ext_path *path);
271 : :
272 : : #endif /* _EXT4_EXTENTS */
273 : :
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