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(fmt, ...) printk(fmt, ##__VA_ARGS__)
51 #else
52 #define ext_debug(fmt, ...) no_printk(fmt, ##__VA_ARGS__)
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 *, ext4_lblk_t,
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 /*
137 * Maximum number of logical blocks in a file; ext4_extent's ee_block is
138 * __le32.
139 */
140 #define EXT_MAX_BLOCKS 0xffffffff
141
142 /*
143 * EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an
144 * initialized extent. This is 2^15 and not (2^16 - 1), since we use the
145 * MSB of ee_len field in the extent datastructure to signify if this
146 * particular extent is an initialized extent or an uninitialized (i.e.
147 * preallocated).
148 * EXT_UNINIT_MAX_LEN is the maximum number of blocks we can have in an
149 * uninitialized extent.
150 * If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an
151 * uninitialized one. In other words, if MSB of ee_len is set, it is an
152 * uninitialized extent with only one special scenario when ee_len = 0x8000.
153 * In this case we can not have an uninitialized extent of zero length and
154 * thus we make it as a special case of initialized extent with 0x8000 length.
155 * This way we get better extent-to-group alignment for initialized extents.
156 * Hence, the maximum number of blocks we can have in an *initialized*
157 * extent is 2^15 (32768) and in an *uninitialized* extent is 2^15-1 (32767).
158 */
159 #define EXT_INIT_MAX_LEN (1UL << 15)
160 #define EXT_UNINIT_MAX_LEN (EXT_INIT_MAX_LEN - 1)
161
162
163 #define EXT_FIRST_EXTENT(__hdr__) \
164 ((struct ext4_extent *) (((char *) (__hdr__)) + \
165 sizeof(struct ext4_extent_header)))
166 #define EXT_FIRST_INDEX(__hdr__) \
167 ((struct ext4_extent_idx *) (((char *) (__hdr__)) + \
168 sizeof(struct ext4_extent_header)))
169 #define EXT_HAS_FREE_INDEX(__path__) \
170 (le16_to_cpu((__path__)->p_hdr->eh_entries) \
171 < le16_to_cpu((__path__)->p_hdr->eh_max))
172 #define EXT_LAST_EXTENT(__hdr__) \
173 (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
174 #define EXT_LAST_INDEX(__hdr__) \
175 (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
176 #define EXT_MAX_EXTENT(__hdr__) \
177 (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
178 #define EXT_MAX_INDEX(__hdr__) \
179 (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
180
ext_inode_hdr(struct inode * inode)181 static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode)
182 {
183 return (struct ext4_extent_header *) EXT4_I(inode)->i_data;
184 }
185
ext_block_hdr(struct buffer_head * bh)186 static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh)
187 {
188 return (struct ext4_extent_header *) bh->b_data;
189 }
190
ext_depth(struct inode * inode)191 static inline unsigned short ext_depth(struct inode *inode)
192 {
193 return le16_to_cpu(ext_inode_hdr(inode)->eh_depth);
194 }
195
196 static inline void
ext4_ext_invalidate_cache(struct inode * inode)197 ext4_ext_invalidate_cache(struct inode *inode)
198 {
199 EXT4_I(inode)->i_cached_extent.ec_len = 0;
200 }
201
ext4_ext_mark_uninitialized(struct ext4_extent * ext)202 static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext)
203 {
204 /* We can not have an uninitialized extent of zero length! */
205 BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0);
206 ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN);
207 }
208
ext4_ext_is_uninitialized(struct ext4_extent * ext)209 static inline int ext4_ext_is_uninitialized(struct ext4_extent *ext)
210 {
211 /* Extent with ee_len of 0x8000 is treated as an initialized extent */
212 return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN);
213 }
214
ext4_ext_get_actual_len(struct ext4_extent * ext)215 static inline int ext4_ext_get_actual_len(struct ext4_extent *ext)
216 {
217 return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ?
218 le16_to_cpu(ext->ee_len) :
219 (le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN));
220 }
221
ext4_ext_mark_initialized(struct ext4_extent * ext)222 static inline void ext4_ext_mark_initialized(struct ext4_extent *ext)
223 {
224 ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext));
225 }
226
227 /*
228 * ext4_ext_pblock:
229 * combine low and high parts of physical block number into ext4_fsblk_t
230 */
ext4_ext_pblock(struct ext4_extent * ex)231 static inline ext4_fsblk_t ext4_ext_pblock(struct ext4_extent *ex)
232 {
233 ext4_fsblk_t block;
234
235 block = le32_to_cpu(ex->ee_start_lo);
236 block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1;
237 return block;
238 }
239
240 /*
241 * ext4_idx_pblock:
242 * combine low and high parts of a leaf physical block number into ext4_fsblk_t
243 */
ext4_idx_pblock(struct ext4_extent_idx * ix)244 static inline ext4_fsblk_t ext4_idx_pblock(struct ext4_extent_idx *ix)
245 {
246 ext4_fsblk_t block;
247
248 block = le32_to_cpu(ix->ei_leaf_lo);
249 block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1;
250 return block;
251 }
252
253 /*
254 * ext4_ext_store_pblock:
255 * stores a large physical block number into an extent struct,
256 * breaking it into parts
257 */
ext4_ext_store_pblock(struct ext4_extent * ex,ext4_fsblk_t pb)258 static inline void ext4_ext_store_pblock(struct ext4_extent *ex,
259 ext4_fsblk_t pb)
260 {
261 ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
262 ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
263 0xffff);
264 }
265
266 /*
267 * ext4_idx_store_pblock:
268 * stores a large physical block number into an index struct,
269 * breaking it into parts
270 */
ext4_idx_store_pblock(struct ext4_extent_idx * ix,ext4_fsblk_t pb)271 static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix,
272 ext4_fsblk_t pb)
273 {
274 ix->ei_leaf_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
275 ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
276 0xffff);
277 }
278
279 extern int ext4_ext_calc_metadata_amount(struct inode *inode,
280 ext4_lblk_t lblocks);
281 extern int ext4_extent_tree_init(handle_t *, struct inode *);
282 extern int ext4_ext_calc_credits_for_single_extent(struct inode *inode,
283 int num,
284 struct ext4_ext_path *path);
285 extern int ext4_can_extents_be_merged(struct inode *inode,
286 struct ext4_extent *ex1,
287 struct ext4_extent *ex2);
288 extern int ext4_ext_insert_extent(handle_t *, struct inode *, struct ext4_ext_path *, struct ext4_extent *, int);
289 extern struct ext4_ext_path *ext4_ext_find_extent(struct inode *, ext4_lblk_t,
290 struct ext4_ext_path *);
291 extern void ext4_ext_drop_refs(struct ext4_ext_path *);
292 extern int ext4_ext_check_inode(struct inode *inode);
293 extern int ext4_find_delalloc_cluster(struct inode *inode, ext4_lblk_t lblk,
294 int search_hint_reverse);
295 #endif /* _EXT4_EXTENTS */
296
297