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 * Turn on EXT_DEBUG to get lots of info about extents operations.
47 */
48 #define EXT_DEBUG__
49 #ifdef EXT_DEBUG
50 #define ext_debug(a...) printk(a)
51 #else
52 #define ext_debug(a...)
53 #endif
54
55 /*
56 * If EXT_STATS is defined then stats numbers are collected.
57 * These number will be displayed at umount time.
58 */
59 #define EXT_STATS_
60
61
62 /*
63 * ext4_inode has i_block array (60 bytes total).
64 * The first 12 bytes store ext4_extent_header;
65 * the remainder stores an array of ext4_extent.
66 */
67
68 /*
69 * This is the extent on-disk structure.
70 * It's used at the bottom of the tree.
71 */
72 struct ext4_extent {
73 __le32 ee_block; /* first logical block extent covers */
74 __le16 ee_len; /* number of blocks covered by extent */
75 __le16 ee_start_hi; /* high 16 bits of physical block */
76 __le32 ee_start_lo; /* low 32 bits of physical block */
77 };
78
79 /*
80 * This is index on-disk structure.
81 * It's used at all the levels except the bottom.
82 */
83 struct ext4_extent_idx {
84 __le32 ei_block; /* index covers logical blocks from 'block' */
85 __le32 ei_leaf_lo; /* pointer to the physical block of the next *
86 * level. leaf or next index could be there */
87 __le16 ei_leaf_hi; /* high 16 bits of physical block */
88 __u16 ei_unused;
89 };
90
91 /*
92 * Each block (leaves and indexes), even inode-stored has header.
93 */
94 struct ext4_extent_header {
95 __le16 eh_magic; /* probably will support different formats */
96 __le16 eh_entries; /* number of valid entries */
97 __le16 eh_max; /* capacity of store in entries */
98 __le16 eh_depth; /* has tree real underlying blocks? */
99 __le32 eh_generation; /* generation of the tree */
100 };
101
102 #define EXT4_EXT_MAGIC cpu_to_le16(0xf30a)
103
104 /*
105 * Array of ext4_ext_path contains path to some extent.
106 * Creation/lookup routines use it for traversal/splitting/etc.
107 * Truncate uses it to simulate recursive walking.
108 */
109 struct ext4_ext_path {
110 ext4_fsblk_t p_block;
111 __u16 p_depth;
112 struct ext4_extent *p_ext;
113 struct ext4_extent_idx *p_idx;
114 struct ext4_extent_header *p_hdr;
115 struct buffer_head *p_bh;
116 };
117
118 /*
119 * structure for external API
120 */
121
122 /*
123 * to be called by ext4_ext_walk_space()
124 * negative retcode - error
125 * positive retcode - signal for ext4_ext_walk_space(), see below
126 * callback must return valid extent (passed or newly created)
127 */
128 typedef int (*ext_prepare_callback)(struct inode *, struct ext4_ext_path *,
129 struct ext4_ext_cache *,
130 struct ext4_extent *, void *);
131
132 #define EXT_CONTINUE 0
133 #define EXT_BREAK 1
134 #define EXT_REPEAT 2
135
136 /* Maximum logical block in a file; ext4_extent's ee_block is __le32 */
137 #define EXT_MAX_BLOCK 0xffffffff
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 uninitialized (i.e.
144 * preallocated).
145 * EXT_UNINIT_MAX_LEN is the maximum number of blocks we can have in an
146 * uninitialized extent.
147 * If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an
148 * uninitialized one. In other words, if MSB of ee_len is set, it is an
149 * uninitialized extent with only one special scenario when ee_len = 0x8000.
150 * In this case we can not have an uninitialized 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 *uninitialized* extent is 2^15-1 (32767).
155 */
156 #define EXT_INIT_MAX_LEN (1UL << 15)
157 #define EXT_UNINIT_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
ext_inode_hdr(struct inode * inode)178 static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode)
179 {
180 return (struct ext4_extent_header *) EXT4_I(inode)->i_data;
181 }
182
ext_block_hdr(struct buffer_head * bh)183 static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh)
184 {
185 return (struct ext4_extent_header *) bh->b_data;
186 }
187
ext_depth(struct inode * inode)188 static inline unsigned short ext_depth(struct inode *inode)
189 {
190 return le16_to_cpu(ext_inode_hdr(inode)->eh_depth);
191 }
192
193 static inline void
ext4_ext_invalidate_cache(struct inode * inode)194 ext4_ext_invalidate_cache(struct inode *inode)
195 {
196 EXT4_I(inode)->i_cached_extent.ec_len = 0;
197 }
198
ext4_ext_mark_uninitialized(struct ext4_extent * ext)199 static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext)
200 {
201 /* We can not have an uninitialized extent of zero length! */
202 BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0);
203 ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN);
204 }
205
ext4_ext_is_uninitialized(struct ext4_extent * ext)206 static inline int ext4_ext_is_uninitialized(struct ext4_extent *ext)
207 {
208 /* Extent with ee_len of 0x8000 is treated as an initialized extent */
209 return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN);
210 }
211
ext4_ext_get_actual_len(struct ext4_extent * ext)212 static inline int ext4_ext_get_actual_len(struct ext4_extent *ext)
213 {
214 return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ?
215 le16_to_cpu(ext->ee_len) :
216 (le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN));
217 }
218
ext4_ext_mark_initialized(struct ext4_extent * ext)219 static inline void ext4_ext_mark_initialized(struct ext4_extent *ext)
220 {
221 ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext));
222 }
223
224 /*
225 * ext4_ext_pblock:
226 * combine low and high parts of physical block number into ext4_fsblk_t
227 */
ext4_ext_pblock(struct ext4_extent * ex)228 static inline ext4_fsblk_t ext4_ext_pblock(struct ext4_extent *ex)
229 {
230 ext4_fsblk_t block;
231
232 block = le32_to_cpu(ex->ee_start_lo);
233 block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1;
234 return block;
235 }
236
237 /*
238 * ext4_idx_pblock:
239 * combine low and high parts of a leaf physical block number into ext4_fsblk_t
240 */
ext4_idx_pblock(struct ext4_extent_idx * ix)241 static inline ext4_fsblk_t ext4_idx_pblock(struct ext4_extent_idx *ix)
242 {
243 ext4_fsblk_t block;
244
245 block = le32_to_cpu(ix->ei_leaf_lo);
246 block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1;
247 return block;
248 }
249
250 /*
251 * ext4_ext_store_pblock:
252 * stores a large physical block number into an extent struct,
253 * breaking it into parts
254 */
ext4_ext_store_pblock(struct ext4_extent * ex,ext4_fsblk_t pb)255 static inline void ext4_ext_store_pblock(struct ext4_extent *ex,
256 ext4_fsblk_t pb)
257 {
258 ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
259 ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
260 0xffff);
261 }
262
263 /*
264 * ext4_idx_store_pblock:
265 * stores a large physical block number into an index struct,
266 * breaking it into parts
267 */
ext4_idx_store_pblock(struct ext4_extent_idx * ix,ext4_fsblk_t pb)268 static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix,
269 ext4_fsblk_t pb)
270 {
271 ix->ei_leaf_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
272 ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
273 0xffff);
274 }
275
276 extern int ext4_ext_calc_metadata_amount(struct inode *inode,
277 ext4_lblk_t lblocks);
278 extern int ext4_extent_tree_init(handle_t *, struct inode *);
279 extern int ext4_ext_calc_credits_for_single_extent(struct inode *inode,
280 int num,
281 struct ext4_ext_path *path);
282 extern int ext4_can_extents_be_merged(struct inode *inode,
283 struct ext4_extent *ex1,
284 struct ext4_extent *ex2);
285 extern int ext4_ext_insert_extent(handle_t *, struct inode *, struct ext4_ext_path *, struct ext4_extent *, int);
286 extern struct ext4_ext_path *ext4_ext_find_extent(struct inode *, ext4_lblk_t,
287 struct ext4_ext_path *);
288 extern void ext4_ext_drop_refs(struct ext4_ext_path *);
289 extern int ext4_ext_check_inode(struct inode *inode);
290 #endif /* _EXT4_EXTENTS */
291
292