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 _LINUX_EXT4_EXTENTS
20#define _LINUX_EXT4_EXTENTS
21
22#include <linux/ext4_fs.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;	/* 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;	/* 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					void *);
136
137#define EXT_CONTINUE	0
138#define EXT_BREAK	1
139#define EXT_REPEAT	2
140
141
142#define EXT_MAX_BLOCK	0xffffffff
143
144#define EXT_MAX_LEN	((1UL << 15) - 1)
145
146
147#define EXT_FIRST_EXTENT(__hdr__) \
148	((struct ext4_extent *) (((char *) (__hdr__)) +		\
149				 sizeof(struct ext4_extent_header)))
150#define EXT_FIRST_INDEX(__hdr__) \
151	((struct ext4_extent_idx *) (((char *) (__hdr__)) +	\
152				     sizeof(struct ext4_extent_header)))
153#define EXT_HAS_FREE_INDEX(__path__) \
154	(le16_to_cpu((__path__)->p_hdr->eh_entries) \
155				     < le16_to_cpu((__path__)->p_hdr->eh_max))
156#define EXT_LAST_EXTENT(__hdr__) \
157	(EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
158#define EXT_LAST_INDEX(__hdr__) \
159	(EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
160#define EXT_MAX_EXTENT(__hdr__) \
161	(EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
162#define EXT_MAX_INDEX(__hdr__) \
163	(EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
164
165static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode)
166{
167	return (struct ext4_extent_header *) EXT4_I(inode)->i_data;
168}
169
170static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh)
171{
172	return (struct ext4_extent_header *) bh->b_data;
173}
174
175static inline unsigned short ext_depth(struct inode *inode)
176{
177	return le16_to_cpu(ext_inode_hdr(inode)->eh_depth);
178}
179
180static inline void ext4_ext_tree_changed(struct inode *inode)
181{
182	EXT4_I(inode)->i_ext_generation++;
183}
184
185static inline void
186ext4_ext_invalidate_cache(struct inode *inode)
187{
188	EXT4_I(inode)->i_cached_extent.ec_type = EXT4_EXT_CACHE_NO;
189}
190
191extern int ext4_extent_tree_init(handle_t *, struct inode *);
192extern int ext4_ext_calc_credits_for_insert(struct inode *, struct ext4_ext_path *);
193extern unsigned int ext4_ext_check_overlap(struct inode *, struct ext4_extent *, struct ext4_ext_path *);
194extern int ext4_ext_insert_extent(handle_t *, struct inode *, struct ext4_ext_path *, struct ext4_extent *);
195extern int ext4_ext_walk_space(struct inode *, unsigned long, unsigned long, ext_prepare_callback, void *);
196extern struct ext4_ext_path * ext4_ext_find_extent(struct inode *, int, struct ext4_ext_path *);
197
198#endif /* _LINUX_EXT4_EXTENTS */
199