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 */ 72struct 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 */ 83struct 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 */ 94struct 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 */ 109struct 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#define EXT4_EXT_CACHE_NO 0 123#define EXT4_EXT_CACHE_GAP 1 124#define EXT4_EXT_CACHE_EXTENT 2 125 126/* 127 * to be called by ext4_ext_walk_space() 128 * negative retcode - error 129 * positive retcode - signal for ext4_ext_walk_space(), see below 130 * callback must return valid extent (passed or newly created) 131 */ 132typedef int (*ext_prepare_callback)(struct inode *, struct ext4_ext_path *, 133 struct ext4_ext_cache *, 134 struct ext4_extent *, void *); 135 136#define EXT_CONTINUE 0 137#define EXT_BREAK 1 138#define EXT_REPEAT 2 139 140/* Maximum logical block in a file; ext4_extent's ee_block is __le32 */ 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 223static inline void ext4_ext_mark_initialized(struct ext4_extent *ext) 224{ 225 ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext)); 226} 227 228extern int ext4_ext_calc_metadata_amount(struct inode *inode, 229 sector_t lblocks); 230extern ext4_fsblk_t ext_pblock(struct ext4_extent *ex); 231extern ext4_fsblk_t idx_pblock(struct ext4_extent_idx *); 232extern void ext4_ext_store_pblock(struct ext4_extent *, ext4_fsblk_t); 233extern int ext4_extent_tree_init(handle_t *, struct inode *); 234extern int ext4_ext_calc_credits_for_single_extent(struct inode *inode, 235 int num, 236 struct ext4_ext_path *path); 237extern int ext4_can_extents_be_merged(struct inode *inode, 238 struct ext4_extent *ex1, 239 struct ext4_extent *ex2); 240extern int ext4_ext_try_to_merge(struct inode *inode, 241 struct ext4_ext_path *path, 242 struct ext4_extent *); 243extern unsigned int ext4_ext_check_overlap(struct inode *, struct ext4_extent *, struct ext4_ext_path *); 244extern int ext4_ext_insert_extent(handle_t *, struct inode *, struct ext4_ext_path *, struct ext4_extent *, int); 245extern int ext4_ext_walk_space(struct inode *, ext4_lblk_t, ext4_lblk_t, 246 ext_prepare_callback, void *); 247extern struct ext4_ext_path *ext4_ext_find_extent(struct inode *, ext4_lblk_t, 248 struct ext4_ext_path *); 249extern int ext4_ext_search_left(struct inode *, struct ext4_ext_path *, 250 ext4_lblk_t *, ext4_fsblk_t *); 251extern int ext4_ext_search_right(struct inode *, struct ext4_ext_path *, 252 ext4_lblk_t *, ext4_fsblk_t *); 253extern void ext4_ext_drop_refs(struct ext4_ext_path *); 254extern int ext4_ext_check_inode(struct inode *inode); 255#endif /* _EXT4_EXTENTS */ 256