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 */ 72 struct 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 */ 83 struct 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 */ 94 struct 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 */ 109 struct 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 /* 123 * to be called by ext4_ext_walk_space() 124 * negative retcode - error 125 * positive retcode - signal for ext4_ext_walk_space(), see below 126 * callback must return valid extent (passed or newly created) 127 */ 128 typedef int (*ext_prepare_callback)(struct inode *, ext4_lblk_t, 129 struct ext4_ext_cache *, 130 struct ext4_extent *, void *); 131 132 #define EXT_CONTINUE 0 133 #define EXT_BREAK 1 134 #define EXT_REPEAT 2 135 136 /* 137 * Maximum number of logical blocks in a file; ext4_extent's ee_block is 138 * __le32. 139 */ 140 #define EXT_MAX_BLOCKS 0xffffffff 141 142 /* 143 * EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an 144 * initialized extent. This is 2^15 and not (2^16 - 1), since we use the 145 * MSB of ee_len field in the extent datastructure to signify if this 146 * particular extent is an initialized extent or an uninitialized (i.e. 147 * preallocated). 148 * EXT_UNINIT_MAX_LEN is the maximum number of blocks we can have in an 149 * uninitialized extent. 150 * If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an 151 * uninitialized one. In other words, if MSB of ee_len is set, it is an 152 * uninitialized extent with only one special scenario when ee_len = 0x8000. 153 * In this case we can not have an uninitialized extent of zero length and 154 * thus we make it as a special case of initialized extent with 0x8000 length. 155 * This way we get better extent-to-group alignment for initialized extents. 156 * Hence, the maximum number of blocks we can have in an *initialized* 157 * extent is 2^15 (32768) and in an *uninitialized* extent is 2^15-1 (32767). 158 */ 159 #define EXT_INIT_MAX_LEN (1UL << 15) 160 #define EXT_UNINIT_MAX_LEN (EXT_INIT_MAX_LEN - 1) 161 162 163 #define EXT_FIRST_EXTENT(__hdr__) \ 164 ((struct ext4_extent *) (((char *) (__hdr__)) + \ 165 sizeof(struct ext4_extent_header))) 166 #define EXT_FIRST_INDEX(__hdr__) \ 167 ((struct ext4_extent_idx *) (((char *) (__hdr__)) + \ 168 sizeof(struct ext4_extent_header))) 169 #define EXT_HAS_FREE_INDEX(__path__) \ 170 (le16_to_cpu((__path__)->p_hdr->eh_entries) \ 171 < le16_to_cpu((__path__)->p_hdr->eh_max)) 172 #define EXT_LAST_EXTENT(__hdr__) \ 173 (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1) 174 #define EXT_LAST_INDEX(__hdr__) \ 175 (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1) 176 #define EXT_MAX_EXTENT(__hdr__) \ 177 (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1) 178 #define EXT_MAX_INDEX(__hdr__) \ 179 (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1) 180 181 static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode) 182 { 183 return (struct ext4_extent_header *) EXT4_I(inode)->i_data; 184 } 185 186 static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh) 187 { 188 return (struct ext4_extent_header *) bh->b_data; 189 } 190 191 static inline unsigned short ext_depth(struct inode *inode) 192 { 193 return le16_to_cpu(ext_inode_hdr(inode)->eh_depth); 194 } 195 196 static inline void 197 ext4_ext_invalidate_cache(struct inode *inode) 198 { 199 EXT4_I(inode)->i_cached_extent.ec_len = 0; 200 } 201 202 static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext) 203 { 204 /* We can not have an uninitialized extent of zero length! */ 205 BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0); 206 ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN); 207 } 208 209 static inline int ext4_ext_is_uninitialized(struct ext4_extent *ext) 210 { 211 /* Extent with ee_len of 0x8000 is treated as an initialized extent */ 212 return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN); 213 } 214 215 static inline int ext4_ext_get_actual_len(struct ext4_extent *ext) 216 { 217 return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ? 218 le16_to_cpu(ext->ee_len) : 219 (le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN)); 220 } 221 222 static inline void ext4_ext_mark_initialized(struct ext4_extent *ext) 223 { 224 ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext)); 225 } 226 227 /* 228 * ext4_ext_pblock: 229 * combine low and high parts of physical block number into ext4_fsblk_t 230 */ 231 static inline ext4_fsblk_t ext4_ext_pblock(struct ext4_extent *ex) 232 { 233 ext4_fsblk_t block; 234 235 block = le32_to_cpu(ex->ee_start_lo); 236 block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1; 237 return block; 238 } 239 240 /* 241 * ext4_idx_pblock: 242 * combine low and high parts of a leaf physical block number into ext4_fsblk_t 243 */ 244 static inline ext4_fsblk_t ext4_idx_pblock(struct ext4_extent_idx *ix) 245 { 246 ext4_fsblk_t block; 247 248 block = le32_to_cpu(ix->ei_leaf_lo); 249 block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1; 250 return block; 251 } 252 253 /* 254 * ext4_ext_store_pblock: 255 * stores a large physical block number into an extent struct, 256 * breaking it into parts 257 */ 258 static inline void ext4_ext_store_pblock(struct ext4_extent *ex, 259 ext4_fsblk_t pb) 260 { 261 ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff)); 262 ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) & 263 0xffff); 264 } 265 266 /* 267 * ext4_idx_store_pblock: 268 * stores a large physical block number into an index struct, 269 * breaking it into parts 270 */ 271 static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix, 272 ext4_fsblk_t pb) 273 { 274 ix->ei_leaf_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff)); 275 ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) & 276 0xffff); 277 } 278 279 extern int ext4_ext_calc_metadata_amount(struct inode *inode, 280 ext4_lblk_t lblocks); 281 extern int ext4_extent_tree_init(handle_t *, struct inode *); 282 extern int ext4_ext_calc_credits_for_single_extent(struct inode *inode, 283 int num, 284 struct ext4_ext_path *path); 285 extern int ext4_can_extents_be_merged(struct inode *inode, 286 struct ext4_extent *ex1, 287 struct ext4_extent *ex2); 288 extern int ext4_ext_insert_extent(handle_t *, struct inode *, struct ext4_ext_path *, struct ext4_extent *, int); 289 extern struct ext4_ext_path *ext4_ext_find_extent(struct inode *, ext4_lblk_t, 290 struct ext4_ext_path *); 291 extern void ext4_ext_drop_refs(struct ext4_ext_path *); 292 extern int ext4_ext_check_inode(struct inode *inode); 293 #endif /* _EXT4_EXTENTS */ 294 295