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(fmt, ...) printk(fmt, ##__VA_ARGS__) 51 #else 52 #define ext_debug(fmt, ...) no_printk(fmt, ##__VA_ARGS__) 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 * For non-inode extent blocks, ext4_extent_tail 67 * follows the array. 68 */ 69 70 /* 71 * This is the extent tail on-disk structure. 72 * All other extent structures are 12 bytes long. It turns out that 73 * block_size % 12 >= 4 for at least all powers of 2 greater than 512, which 74 * covers all valid ext4 block sizes. Therefore, this tail structure can be 75 * crammed into the end of the block without having to rebalance the tree. 76 */ 77 struct ext4_extent_tail { 78 __le32 et_checksum; /* crc32c(uuid+inum+extent_block) */ 79 }; 80 81 /* 82 * This is the extent on-disk structure. 83 * It's used at the bottom of the tree. 84 */ 85 struct ext4_extent { 86 __le32 ee_block; /* first logical block extent covers */ 87 __le16 ee_len; /* number of blocks covered by extent */ 88 __le16 ee_start_hi; /* high 16 bits of physical block */ 89 __le32 ee_start_lo; /* low 32 bits of physical block */ 90 }; 91 92 /* 93 * This is index on-disk structure. 94 * It's used at all the levels except the bottom. 95 */ 96 struct ext4_extent_idx { 97 __le32 ei_block; /* index covers logical blocks from 'block' */ 98 __le32 ei_leaf_lo; /* pointer to the physical block of the next * 99 * level. leaf or next index could be there */ 100 __le16 ei_leaf_hi; /* high 16 bits of physical block */ 101 __u16 ei_unused; 102 }; 103 104 /* 105 * Each block (leaves and indexes), even inode-stored has header. 106 */ 107 struct ext4_extent_header { 108 __le16 eh_magic; /* probably will support different formats */ 109 __le16 eh_entries; /* number of valid entries */ 110 __le16 eh_max; /* capacity of store in entries */ 111 __le16 eh_depth; /* has tree real underlying blocks? */ 112 __le32 eh_generation; /* generation of the tree */ 113 }; 114 115 #define EXT4_EXT_MAGIC cpu_to_le16(0xf30a) 116 117 #define EXT4_EXTENT_TAIL_OFFSET(hdr) \ 118 (sizeof(struct ext4_extent_header) + \ 119 (sizeof(struct ext4_extent) * le16_to_cpu((hdr)->eh_max))) 120 121 static inline struct ext4_extent_tail * 122 find_ext4_extent_tail(struct ext4_extent_header *eh) 123 { 124 return (struct ext4_extent_tail *)(((void *)eh) + 125 EXT4_EXTENT_TAIL_OFFSET(eh)); 126 } 127 128 /* 129 * Array of ext4_ext_path contains path to some extent. 130 * Creation/lookup routines use it for traversal/splitting/etc. 131 * Truncate uses it to simulate recursive walking. 132 */ 133 struct ext4_ext_path { 134 ext4_fsblk_t p_block; 135 __u16 p_depth; 136 struct ext4_extent *p_ext; 137 struct ext4_extent_idx *p_idx; 138 struct ext4_extent_header *p_hdr; 139 struct buffer_head *p_bh; 140 }; 141 142 /* 143 * structure for external API 144 */ 145 146 /* 147 * Maximum number of logical blocks in a file; ext4_extent's ee_block is 148 * __le32. 149 */ 150 #define EXT_MAX_BLOCKS 0xffffffff 151 152 /* 153 * EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an 154 * initialized extent. This is 2^15 and not (2^16 - 1), since we use the 155 * MSB of ee_len field in the extent datastructure to signify if this 156 * particular extent is an initialized extent or an uninitialized (i.e. 157 * preallocated). 158 * EXT_UNINIT_MAX_LEN is the maximum number of blocks we can have in an 159 * uninitialized extent. 160 * If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an 161 * uninitialized one. In other words, if MSB of ee_len is set, it is an 162 * uninitialized extent with only one special scenario when ee_len = 0x8000. 163 * In this case we can not have an uninitialized extent of zero length and 164 * thus we make it as a special case of initialized extent with 0x8000 length. 165 * This way we get better extent-to-group alignment for initialized extents. 166 * Hence, the maximum number of blocks we can have in an *initialized* 167 * extent is 2^15 (32768) and in an *uninitialized* extent is 2^15-1 (32767). 168 */ 169 #define EXT_INIT_MAX_LEN (1UL << 15) 170 #define EXT_UNINIT_MAX_LEN (EXT_INIT_MAX_LEN - 1) 171 172 173 #define EXT_FIRST_EXTENT(__hdr__) \ 174 ((struct ext4_extent *) (((char *) (__hdr__)) + \ 175 sizeof(struct ext4_extent_header))) 176 #define EXT_FIRST_INDEX(__hdr__) \ 177 ((struct ext4_extent_idx *) (((char *) (__hdr__)) + \ 178 sizeof(struct ext4_extent_header))) 179 #define EXT_HAS_FREE_INDEX(__path__) \ 180 (le16_to_cpu((__path__)->p_hdr->eh_entries) \ 181 < le16_to_cpu((__path__)->p_hdr->eh_max)) 182 #define EXT_LAST_EXTENT(__hdr__) \ 183 (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1) 184 #define EXT_LAST_INDEX(__hdr__) \ 185 (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1) 186 #define EXT_MAX_EXTENT(__hdr__) \ 187 (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1) 188 #define EXT_MAX_INDEX(__hdr__) \ 189 (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1) 190 191 static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode) 192 { 193 return (struct ext4_extent_header *) EXT4_I(inode)->i_data; 194 } 195 196 static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh) 197 { 198 return (struct ext4_extent_header *) bh->b_data; 199 } 200 201 static inline unsigned short ext_depth(struct inode *inode) 202 { 203 return le16_to_cpu(ext_inode_hdr(inode)->eh_depth); 204 } 205 206 static inline void 207 ext4_ext_invalidate_cache(struct inode *inode) 208 { 209 EXT4_I(inode)->i_cached_extent.ec_len = 0; 210 } 211 212 static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext) 213 { 214 /* We can not have an uninitialized extent of zero length! */ 215 BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0); 216 ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN); 217 } 218 219 static inline int ext4_ext_is_uninitialized(struct ext4_extent *ext) 220 { 221 /* Extent with ee_len of 0x8000 is treated as an initialized extent */ 222 return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN); 223 } 224 225 static inline int ext4_ext_get_actual_len(struct ext4_extent *ext) 226 { 227 return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ? 228 le16_to_cpu(ext->ee_len) : 229 (le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN)); 230 } 231 232 static inline void ext4_ext_mark_initialized(struct ext4_extent *ext) 233 { 234 ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext)); 235 } 236 237 /* 238 * ext4_ext_pblock: 239 * combine low and high parts of physical block number into ext4_fsblk_t 240 */ 241 static inline ext4_fsblk_t ext4_ext_pblock(struct ext4_extent *ex) 242 { 243 ext4_fsblk_t block; 244 245 block = le32_to_cpu(ex->ee_start_lo); 246 block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1; 247 return block; 248 } 249 250 /* 251 * ext4_idx_pblock: 252 * combine low and high parts of a leaf physical block number into ext4_fsblk_t 253 */ 254 static inline ext4_fsblk_t ext4_idx_pblock(struct ext4_extent_idx *ix) 255 { 256 ext4_fsblk_t block; 257 258 block = le32_to_cpu(ix->ei_leaf_lo); 259 block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1; 260 return block; 261 } 262 263 /* 264 * ext4_ext_store_pblock: 265 * stores a large physical block number into an extent struct, 266 * breaking it into parts 267 */ 268 static inline void ext4_ext_store_pblock(struct ext4_extent *ex, 269 ext4_fsblk_t pb) 270 { 271 ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff)); 272 ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) & 273 0xffff); 274 } 275 276 /* 277 * ext4_idx_store_pblock: 278 * stores a large physical block number into an index struct, 279 * breaking it into parts 280 */ 281 static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix, 282 ext4_fsblk_t pb) 283 { 284 ix->ei_leaf_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff)); 285 ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) & 286 0xffff); 287 } 288 289 extern int ext4_ext_calc_metadata_amount(struct inode *inode, 290 ext4_lblk_t lblocks); 291 extern int ext4_extent_tree_init(handle_t *, struct inode *); 292 extern int ext4_ext_calc_credits_for_single_extent(struct inode *inode, 293 int num, 294 struct ext4_ext_path *path); 295 extern int ext4_can_extents_be_merged(struct inode *inode, 296 struct ext4_extent *ex1, 297 struct ext4_extent *ex2); 298 extern int ext4_ext_insert_extent(handle_t *, struct inode *, struct ext4_ext_path *, struct ext4_extent *, int); 299 extern struct ext4_ext_path *ext4_ext_find_extent(struct inode *, ext4_lblk_t, 300 struct ext4_ext_path *); 301 extern void ext4_ext_drop_refs(struct ext4_ext_path *); 302 extern int ext4_ext_check_inode(struct inode *inode); 303 extern int ext4_find_delalloc_cluster(struct inode *inode, ext4_lblk_t lblk); 304 #endif /* _EXT4_EXTENTS */ 305 306