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 */ 73 struct 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 */ 84 struct 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 */ 95 struct 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 */ 110 struct 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 #define EXT_MAX_BLOCK 0xffffffff 129 130 /* 131 * EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an 132 * initialized extent. This is 2^15 and not (2^16 - 1), since we use the 133 * MSB of ee_len field in the extent datastructure to signify if this 134 * particular extent is an initialized extent or an uninitialized (i.e. 135 * preallocated). 136 * EXT_UNINIT_MAX_LEN is the maximum number of blocks we can have in an 137 * uninitialized extent. 138 * If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an 139 * uninitialized one. In other words, if MSB of ee_len is set, it is an 140 * uninitialized extent with only one special scenario when ee_len = 0x8000. 141 * In this case we can not have an uninitialized extent of zero length and 142 * thus we make it as a special case of initialized extent with 0x8000 length. 143 * This way we get better extent-to-group alignment for initialized extents. 144 * Hence, the maximum number of blocks we can have in an *initialized* 145 * extent is 2^15 (32768) and in an *uninitialized* extent is 2^15-1 (32767). 146 */ 147 #define EXT_INIT_MAX_LEN (1UL << 15) 148 #define EXT_UNINIT_MAX_LEN (EXT_INIT_MAX_LEN - 1) 149 150 151 #define EXT_FIRST_EXTENT(__hdr__) \ 152 ((struct ext4_extent *) (((char *) (__hdr__)) + \ 153 sizeof(struct ext4_extent_header))) 154 #define EXT_FIRST_INDEX(__hdr__) \ 155 ((struct ext4_extent_idx *) (((char *) (__hdr__)) + \ 156 sizeof(struct ext4_extent_header))) 157 #define EXT_HAS_FREE_INDEX(__path__) \ 158 (le16_to_cpu((__path__)->p_hdr->eh_entries) \ 159 < le16_to_cpu((__path__)->p_hdr->eh_max)) 160 #define EXT_LAST_EXTENT(__hdr__) \ 161 (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1) 162 #define EXT_LAST_INDEX(__hdr__) \ 163 (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1) 164 #define EXT_MAX_EXTENT(__hdr__) \ 165 (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1) 166 #define EXT_MAX_INDEX(__hdr__) \ 167 (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1) 168 169 static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode) 170 { 171 return (struct ext4_extent_header *) EXT4_I(inode)->i_data; 172 } 173 174 static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh) 175 { 176 return (struct ext4_extent_header *) bh->b_data; 177 } 178 179 static inline unsigned short ext_depth(struct inode *inode) 180 { 181 return le16_to_cpu(ext_inode_hdr(inode)->eh_depth); 182 } 183 184 static inline void ext4_ext_tree_changed(struct inode *inode) 185 { 186 EXT4_I(inode)->i_ext_generation++; 187 } 188 189 static inline void 190 ext4_ext_invalidate_cache(struct inode *inode) 191 { 192 EXT4_I(inode)->i_cached_extent.ec_type = EXT4_EXT_CACHE_NO; 193 } 194 195 static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext) 196 { 197 /* We can not have an uninitialized extent of zero length! */ 198 BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0); 199 ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN); 200 } 201 202 static inline int ext4_ext_is_uninitialized(struct ext4_extent *ext) 203 { 204 /* Extent with ee_len of 0x8000 is treated as an initialized extent */ 205 return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN); 206 } 207 208 static inline int ext4_ext_get_actual_len(struct ext4_extent *ext) 209 { 210 return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ? 211 le16_to_cpu(ext->ee_len) : 212 (le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN)); 213 } 214 215 extern int ext4_ext_calc_metadata_amount(struct inode *inode, int blocks); 216 extern ext4_fsblk_t idx_pblock(struct ext4_extent_idx *); 217 extern void ext4_ext_store_pblock(struct ext4_extent *, ext4_fsblk_t); 218 extern int ext4_extent_tree_init(handle_t *, struct inode *); 219 extern int ext4_ext_calc_credits_for_single_extent(struct inode *inode, 220 int num, 221 struct ext4_ext_path *path); 222 extern int ext4_ext_try_to_merge(struct inode *inode, 223 struct ext4_ext_path *path, 224 struct ext4_extent *); 225 extern unsigned int ext4_ext_check_overlap(struct inode *, struct ext4_extent *, struct ext4_ext_path *); 226 extern int ext4_ext_insert_extent(handle_t *, struct inode *, struct ext4_ext_path *, struct ext4_extent *); 227 extern struct ext4_ext_path *ext4_ext_find_extent(struct inode *, ext4_lblk_t, 228 struct ext4_ext_path *); 229 extern int ext4_ext_search_left(struct inode *, struct ext4_ext_path *, 230 ext4_lblk_t *, ext4_fsblk_t *); 231 extern int ext4_ext_search_right(struct inode *, struct ext4_ext_path *, 232 ext4_lblk_t *, ext4_fsblk_t *); 233 extern void ext4_ext_drop_refs(struct ext4_ext_path *); 234 #endif /* _EXT4_EXTENTS */ 235 236