Root/fs/ext4/ext4_extents.h

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_DEBUG is defined you can use the 'extdebug' mount option
47 * to get lots of info about what's going on.
48 */
49#define EXT_DEBUG__
50#ifdef EXT_DEBUG
51#define ext_debug(a...) printk(a)
52#else
53#define ext_debug(a...)
54#endif
55
56/*
57 * If EXT_STATS is defined then stats numbers are collected.
58 * These number will be displayed at umount time.
59 */
60#define EXT_STATS_
61
62
63/*
64 * ext4_inode has i_block array (60 bytes total).
65 * The first 12 bytes store ext4_extent_header;
66 * the remainder stores an array of ext4_extent.
67 */
68
69/*
70 * This is the extent on-disk structure.
71 * It's used at the bottom of the tree.
72 */
73struct ext4_extent {
74    __le32 ee_block; /* first logical block extent covers */
75    __le16 ee_len; /* number of blocks covered by extent */
76    __le16 ee_start_hi; /* high 16 bits of physical block */
77    __le32 ee_start_lo; /* low 32 bits of physical block */
78};
79
80/*
81 * This is index on-disk structure.
82 * It's used at all the levels except the bottom.
83 */
84struct ext4_extent_idx {
85    __le32 ei_block; /* index covers logical blocks from 'block' */
86    __le32 ei_leaf_lo; /* pointer to the physical block of the next *
87                 * level. leaf or next index could be there */
88    __le16 ei_leaf_hi; /* high 16 bits of physical block */
89    __u16 ei_unused;
90};
91
92/*
93 * Each block (leaves and indexes), even inode-stored has header.
94 */
95struct ext4_extent_header {
96    __le16 eh_magic; /* probably will support different formats */
97    __le16 eh_entries; /* number of valid entries */
98    __le16 eh_max; /* capacity of store in entries */
99    __le16 eh_depth; /* has tree real underlying blocks? */
100    __le32 eh_generation; /* generation of the tree */
101};
102
103#define EXT4_EXT_MAGIC cpu_to_le16(0xf30a)
104
105/*
106 * Array of ext4_ext_path contains path to some extent.
107 * Creation/lookup routines use it for traversal/splitting/etc.
108 * Truncate uses it to simulate recursive walking.
109 */
110struct ext4_ext_path {
111    ext4_fsblk_t p_block;
112    __u16 p_depth;
113    struct ext4_extent *p_ext;
114    struct ext4_extent_idx *p_idx;
115    struct ext4_extent_header *p_hdr;
116    struct buffer_head *p_bh;
117};
118
119/*
120 * structure for external API
121 */
122
123#define EXT4_EXT_CACHE_NO 0
124#define EXT4_EXT_CACHE_GAP 1
125#define EXT4_EXT_CACHE_EXTENT 2
126
127/*
128 * to be called by ext4_ext_walk_space()
129 * negative retcode - error
130 * positive retcode - signal for ext4_ext_walk_space(), see below
131 * callback must return valid extent (passed or newly created)
132 */
133typedef int (*ext_prepare_callback)(struct inode *, struct ext4_ext_path *,
134                    struct ext4_ext_cache *,
135                    struct ext4_extent *, void *);
136
137#define EXT_CONTINUE 0
138#define EXT_BREAK 1
139#define EXT_REPEAT 2
140
141#define EXT_MAX_BLOCK 0xffffffff
142
143/*
144 * EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an
145 * initialized extent. This is 2^15 and not (2^16 - 1), since we use the
146 * MSB of ee_len field in the extent datastructure to signify if this
147 * particular extent is an initialized extent or an uninitialized (i.e.
148 * preallocated).
149 * EXT_UNINIT_MAX_LEN is the maximum number of blocks we can have in an
150 * uninitialized extent.
151 * If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an
152 * uninitialized one. In other words, if MSB of ee_len is set, it is an
153 * uninitialized extent with only one special scenario when ee_len = 0x8000.
154 * In this case we can not have an uninitialized extent of zero length and
155 * thus we make it as a special case of initialized extent with 0x8000 length.
156 * This way we get better extent-to-group alignment for initialized extents.
157 * Hence, the maximum number of blocks we can have in an *initialized*
158 * extent is 2^15 (32768) and in an *uninitialized* extent is 2^15-1 (32767).
159 */
160#define EXT_INIT_MAX_LEN (1UL << 15)
161#define EXT_UNINIT_MAX_LEN (EXT_INIT_MAX_LEN - 1)
162
163
164#define EXT_FIRST_EXTENT(__hdr__) \
165    ((struct ext4_extent *) (((char *) (__hdr__)) + \
166                 sizeof(struct ext4_extent_header)))
167#define EXT_FIRST_INDEX(__hdr__) \
168    ((struct ext4_extent_idx *) (((char *) (__hdr__)) + \
169                     sizeof(struct ext4_extent_header)))
170#define EXT_HAS_FREE_INDEX(__path__) \
171    (le16_to_cpu((__path__)->p_hdr->eh_entries) \
172                     < le16_to_cpu((__path__)->p_hdr->eh_max))
173#define EXT_LAST_EXTENT(__hdr__) \
174    (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
175#define EXT_LAST_INDEX(__hdr__) \
176    (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
177#define EXT_MAX_EXTENT(__hdr__) \
178    (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
179#define EXT_MAX_INDEX(__hdr__) \
180    (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
181
182static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode)
183{
184    return (struct ext4_extent_header *) EXT4_I(inode)->i_data;
185}
186
187static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh)
188{
189    return (struct ext4_extent_header *) bh->b_data;
190}
191
192static inline unsigned short ext_depth(struct inode *inode)
193{
194    return le16_to_cpu(ext_inode_hdr(inode)->eh_depth);
195}
196
197static inline void
198ext4_ext_invalidate_cache(struct inode *inode)
199{
200    EXT4_I(inode)->i_cached_extent.ec_type = EXT4_EXT_CACHE_NO;
201}
202
203static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext)
204{
205    /* We can not have an uninitialized extent of zero length! */
206    BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0);
207    ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN);
208}
209
210static inline int ext4_ext_is_uninitialized(struct ext4_extent *ext)
211{
212    /* Extent with ee_len of 0x8000 is treated as an initialized extent */
213    return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN);
214}
215
216static inline int ext4_ext_get_actual_len(struct ext4_extent *ext)
217{
218    return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ?
219        le16_to_cpu(ext->ee_len) :
220        (le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN));
221}
222
223extern int ext4_ext_calc_metadata_amount(struct inode *inode, int blocks);
224extern ext4_fsblk_t ext_pblock(struct ext4_extent *ex);
225extern ext4_fsblk_t idx_pblock(struct ext4_extent_idx *);
226extern void ext4_ext_store_pblock(struct ext4_extent *, ext4_fsblk_t);
227extern int ext4_extent_tree_init(handle_t *, struct inode *);
228extern int ext4_ext_calc_credits_for_single_extent(struct inode *inode,
229                           int num,
230                           struct ext4_ext_path *path);
231extern int ext4_can_extents_be_merged(struct inode *inode,
232                      struct ext4_extent *ex1,
233                      struct ext4_extent *ex2);
234extern int ext4_ext_try_to_merge(struct inode *inode,
235                 struct ext4_ext_path *path,
236                 struct ext4_extent *);
237extern unsigned int ext4_ext_check_overlap(struct inode *, struct ext4_extent *, struct ext4_ext_path *);
238extern int ext4_ext_insert_extent(handle_t *, struct inode *, struct ext4_ext_path *, struct ext4_extent *);
239extern int ext4_ext_walk_space(struct inode *, ext4_lblk_t, ext4_lblk_t,
240                            ext_prepare_callback, void *);
241extern struct ext4_ext_path *ext4_ext_find_extent(struct inode *, ext4_lblk_t,
242                            struct ext4_ext_path *);
243extern int ext4_ext_search_left(struct inode *, struct ext4_ext_path *,
244                        ext4_lblk_t *, ext4_fsblk_t *);
245extern int ext4_ext_search_right(struct inode *, struct ext4_ext_path *,
246                        ext4_lblk_t *, ext4_fsblk_t *);
247extern void ext4_ext_drop_refs(struct ext4_ext_path *);
248extern int ext4_ext_check_inode(struct inode *inode);
249#endif /* _EXT4_EXTENTS */
250
251

Archive Download this file



interactive