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 License 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_STATS is defined then stats numbers are collected. 47 * These number will be displayed at umount time. 48 */ 49 #define EXT_STATS_ 50 51 52 /* 53 * ext4_inode has i_block array (60 bytes total). 54 * The first 12 bytes store ext4_extent_header; 55 * the remainder stores an array of ext4_extent. 56 * For non-inode extent blocks, ext4_extent_tail 57 * follows the array. 58 */ 59 60 /* 61 * This is the extent tail on-disk structure. 62 * All other extent structures are 12 bytes long. It turns out that 63 * block_size % 12 >= 4 for at least all powers of 2 greater than 512, which 64 * covers all valid ext4 block sizes. Therefore, this tail structure can be 65 * crammed into the end of the block without having to rebalance the tree. 66 */ 67 struct ext4_extent_tail { 68 __le32 et_checksum; /* crc32c(uuid+inum+extent_block) */ 69 }; 70 71 /* 72 * This is the extent on-disk structure. 73 * It's used at the bottom of the tree. 74 */ 75 struct ext4_extent { 76 __le32 ee_block; /* first logical block extent covers */ 77 __le16 ee_len; /* number of blocks covered by extent */ 78 __le16 ee_start_hi; /* high 16 bits of physical block */ 79 __le32 ee_start_lo; /* low 32 bits of physical block */ 80 }; 81 82 /* 83 * This is index on-disk structure. 84 * It's used at all the levels except the bottom. 85 */ 86 struct ext4_extent_idx { 87 __le32 ei_block; /* index covers logical blocks from 'block' */ 88 __le32 ei_leaf_lo; /* pointer to the physical block of the next * 89 * level. leaf or next index could be there */ 90 __le16 ei_leaf_hi; /* high 16 bits of physical block */ 91 __u16 ei_unused; 92 }; 93 94 /* 95 * Each block (leaves and indexes), even inode-stored has header. 96 */ 97 struct ext4_extent_header { 98 __le16 eh_magic; /* probably will support different formats */ 99 __le16 eh_entries; /* number of valid entries */ 100 __le16 eh_max; /* capacity of store in entries */ 101 __le16 eh_depth; /* has tree real underlying blocks? */ 102 __le32 eh_generation; /* generation of the tree */ 103 }; 104 105 #define EXT4_EXT_MAGIC cpu_to_le16(0xf30a) 106 107 #define EXT4_EXTENT_TAIL_OFFSET(hdr) \ 108 (sizeof(struct ext4_extent_header) + \ 109 (sizeof(struct ext4_extent) * le16_to_cpu((hdr)->eh_max))) 110 111 static inline struct ext4_extent_tail * 112 find_ext4_extent_tail(struct ext4_extent_header *eh) 113 { 114 return (struct ext4_extent_tail *)(((void *)eh) + 115 EXT4_EXTENT_TAIL_OFFSET(eh)); 116 } 117 118 /* 119 * Array of ext4_ext_path contains path to some extent. 120 * Creation/lookup routines use it for traversal/splitting/etc. 121 * Truncate uses it to simulate recursive walking. 122 */ 123 struct ext4_ext_path { 124 ext4_fsblk_t p_block; 125 __u16 p_depth; 126 __u16 p_maxdepth; 127 struct ext4_extent *p_ext; 128 struct ext4_extent_idx *p_idx; 129 struct ext4_extent_header *p_hdr; 130 struct buffer_head *p_bh; 131 }; 132 133 /* 134 * structure for external API 135 */ 136 137 /* 138 * EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an 139 * initialized extent. This is 2^15 and not (2^16 - 1), since we use the 140 * MSB of ee_len field in the extent datastructure to signify if this 141 * particular extent is an initialized extent or an unwritten (i.e. 142 * preallocated). 143 * EXT_UNWRITTEN_MAX_LEN is the maximum number of blocks we can have in an 144 * unwritten extent. 145 * If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an 146 * unwritten one. In other words, if MSB of ee_len is set, it is an 147 * unwritten extent with only one special scenario when ee_len = 0x8000. 148 * In this case we can not have an unwritten extent of zero length and 149 * thus we make it as a special case of initialized extent with 0x8000 length. 150 * This way we get better extent-to-group alignment for initialized extents. 151 * Hence, the maximum number of blocks we can have in an *initialized* 152 * extent is 2^15 (32768) and in an *unwritten* extent is 2^15-1 (32767). 153 */ 154 #define EXT_INIT_MAX_LEN (1UL << 15) 155 #define EXT_UNWRITTEN_MAX_LEN (EXT_INIT_MAX_LEN - 1) 156 157 158 #define EXT_FIRST_EXTENT(__hdr__) \ 159 ((struct ext4_extent *) (((char *) (__hdr__)) + \ 160 sizeof(struct ext4_extent_header))) 161 #define EXT_FIRST_INDEX(__hdr__) \ 162 ((struct ext4_extent_idx *) (((char *) (__hdr__)) + \ 163 sizeof(struct ext4_extent_header))) 164 #define EXT_HAS_FREE_INDEX(__path__) \ 165 (le16_to_cpu((__path__)->p_hdr->eh_entries) \ 166 < le16_to_cpu((__path__)->p_hdr->eh_max)) 167 #define EXT_LAST_EXTENT(__hdr__) \ 168 (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1) 169 #define EXT_LAST_INDEX(__hdr__) \ 170 (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1) 171 #define EXT_MAX_EXTENT(__hdr__) \ 172 (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1) 173 #define EXT_MAX_INDEX(__hdr__) \ 174 (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1) 175 176 static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode) 177 { 178 return (struct ext4_extent_header *) EXT4_I(inode)->i_data; 179 } 180 181 static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh) 182 { 183 return (struct ext4_extent_header *) bh->b_data; 184 } 185 186 static inline unsigned short ext_depth(struct inode *inode) 187 { 188 return le16_to_cpu(ext_inode_hdr(inode)->eh_depth); 189 } 190 191 static inline void ext4_ext_mark_unwritten(struct ext4_extent *ext) 192 { 193 /* We can not have an unwritten extent of zero length! */ 194 BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0); 195 ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN); 196 } 197 198 static inline int ext4_ext_is_unwritten(struct ext4_extent *ext) 199 { 200 /* Extent with ee_len of 0x8000 is treated as an initialized extent */ 201 return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN); 202 } 203 204 static inline int ext4_ext_get_actual_len(struct ext4_extent *ext) 205 { 206 return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ? 207 le16_to_cpu(ext->ee_len) : 208 (le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN)); 209 } 210 211 static inline void ext4_ext_mark_initialized(struct ext4_extent *ext) 212 { 213 ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext)); 214 } 215 216 /* 217 * ext4_ext_pblock: 218 * combine low and high parts of physical block number into ext4_fsblk_t 219 */ 220 static inline ext4_fsblk_t ext4_ext_pblock(struct ext4_extent *ex) 221 { 222 ext4_fsblk_t block; 223 224 block = le32_to_cpu(ex->ee_start_lo); 225 block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1; 226 return block; 227 } 228 229 /* 230 * ext4_idx_pblock: 231 * combine low and high parts of a leaf physical block number into ext4_fsblk_t 232 */ 233 static inline ext4_fsblk_t ext4_idx_pblock(struct ext4_extent_idx *ix) 234 { 235 ext4_fsblk_t block; 236 237 block = le32_to_cpu(ix->ei_leaf_lo); 238 block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1; 239 return block; 240 } 241 242 /* 243 * ext4_ext_store_pblock: 244 * stores a large physical block number into an extent struct, 245 * breaking it into parts 246 */ 247 static inline void ext4_ext_store_pblock(struct ext4_extent *ex, 248 ext4_fsblk_t pb) 249 { 250 ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff)); 251 ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) & 252 0xffff); 253 } 254 255 /* 256 * ext4_idx_store_pblock: 257 * stores a large physical block number into an index struct, 258 * breaking it into parts 259 */ 260 static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix, 261 ext4_fsblk_t pb) 262 { 263 ix->ei_leaf_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff)); 264 ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) & 265 0xffff); 266 } 267 268 #define ext4_ext_dirty(handle, inode, path) \ 269 __ext4_ext_dirty(__func__, __LINE__, (handle), (inode), (path)) 270 int __ext4_ext_dirty(const char *where, unsigned int line, handle_t *handle, 271 struct inode *inode, struct ext4_ext_path *path); 272 273 #endif /* _EXT4_EXTENTS */ 274 275