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1// SPDX-License-Identifier: GPL-2.02/*3 * Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com4 * Written by Alex Tomas <alex@clusterfs.com>5 */6 7#ifndef _EXT4_EXTENTS8#define _EXT4_EXTENTS9 10#include "ext4.h"11 12/*13 * With AGGRESSIVE_TEST defined, the capacity of index/leaf blocks14 * becomes very small, so index split, in-depth growing and15 * other hard changes happen much more often.16 * This is for debug purposes only.17 */18#define AGGRESSIVE_TEST_19 20/*21 * With EXTENTS_STATS defined, the number of blocks and extents22 * are collected in the truncate path. They'll be shown at23 * umount time.24 */25#define EXTENTS_STATS__26 27/*28 * If CHECK_BINSEARCH is defined, then the results of the binary search29 * will also be checked by linear search.30 */31#define CHECK_BINSEARCH__32 33/*34 * If EXT_STATS is defined then stats numbers are collected.35 * These number will be displayed at umount time.36 */37#define EXT_STATS_38 39 40/*41 * ext4_inode has i_block array (60 bytes total).42 * The first 12 bytes store ext4_extent_header;43 * the remainder stores an array of ext4_extent.44 * For non-inode extent blocks, ext4_extent_tail45 * follows the array.46 */47 48/*49 * This is the extent tail on-disk structure.50 * All other extent structures are 12 bytes long. It turns out that51 * block_size % 12 >= 4 for at least all powers of 2 greater than 512, which52 * covers all valid ext4 block sizes. Therefore, this tail structure can be53 * crammed into the end of the block without having to rebalance the tree.54 */55struct ext4_extent_tail {56 __le32 et_checksum; /* crc32c(uuid+inum+extent_block) */57};58 59/*60 * This is the extent on-disk structure.61 * It's used at the bottom of the tree.62 */63struct ext4_extent {64 __le32 ee_block; /* first logical block extent covers */65 __le16 ee_len; /* number of blocks covered by extent */66 __le16 ee_start_hi; /* high 16 bits of physical block */67 __le32 ee_start_lo; /* low 32 bits of physical block */68};69 70/*71 * This is index on-disk structure.72 * It's used at all the levels except the bottom.73 */74struct ext4_extent_idx {75 __le32 ei_block; /* index covers logical blocks from 'block' */76 __le32 ei_leaf_lo; /* pointer to the physical block of the next *77 * level. leaf or next index could be there */78 __le16 ei_leaf_hi; /* high 16 bits of physical block */79 __u16 ei_unused;80};81 82/*83 * Each block (leaves and indexes), even inode-stored has header.84 */85struct ext4_extent_header {86 __le16 eh_magic; /* probably will support different formats */87 __le16 eh_entries; /* number of valid entries */88 __le16 eh_max; /* capacity of store in entries */89 __le16 eh_depth; /* has tree real underlying blocks? */90 __le32 eh_generation; /* generation of the tree */91};92 93#define EXT4_EXT_MAGIC cpu_to_le16(0xf30a)94#define EXT4_MAX_EXTENT_DEPTH 595 96#define EXT4_EXTENT_TAIL_OFFSET(hdr) \97 (sizeof(struct ext4_extent_header) + \98 (sizeof(struct ext4_extent) * le16_to_cpu((hdr)->eh_max)))99 100static inline struct ext4_extent_tail *101find_ext4_extent_tail(struct ext4_extent_header *eh)102{103 return (struct ext4_extent_tail *)(((void *)eh) +104 EXT4_EXTENT_TAIL_OFFSET(eh));105}106 107/*108 * Array of ext4_ext_path contains path to some extent.109 * Creation/lookup routines use it for traversal/splitting/etc.110 * Truncate uses it to simulate recursive walking.111 */112struct ext4_ext_path {113 ext4_fsblk_t p_block;114 __u16 p_depth;115 __u16 p_maxdepth;116 struct ext4_extent *p_ext;117 struct ext4_extent_idx *p_idx;118 struct ext4_extent_header *p_hdr;119 struct buffer_head *p_bh;120};121 122/*123 * Used to record a portion of a cluster found at the beginning or end124 * of an extent while traversing the extent tree during space removal.125 * A partial cluster may be removed if it does not contain blocks shared126 * with extents that aren't being deleted (tofree state). Otherwise,127 * it cannot be removed (nofree state).128 */129struct partial_cluster {130 ext4_fsblk_t pclu; /* physical cluster number */131 ext4_lblk_t lblk; /* logical block number within logical cluster */132 enum {initial, tofree, nofree} state;133};134 135/*136 * structure for external API137 */138 139/*140 * EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an141 * initialized extent. This is 2^15 and not (2^16 - 1), since we use the142 * MSB of ee_len field in the extent datastructure to signify if this143 * particular extent is an initialized extent or an unwritten (i.e.144 * preallocated).145 * EXT_UNWRITTEN_MAX_LEN is the maximum number of blocks we can have in an146 * unwritten extent.147 * If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an148 * unwritten one. In other words, if MSB of ee_len is set, it is an149 * unwritten extent with only one special scenario when ee_len = 0x8000.150 * In this case we can not have an unwritten extent of zero length and151 * thus we make it as a special case of initialized extent with 0x8000 length.152 * This way we get better extent-to-group alignment for initialized extents.153 * Hence, the maximum number of blocks we can have in an *initialized*154 * extent is 2^15 (32768) and in an *unwritten* extent is 2^15-1 (32767).155 */156#define EXT_INIT_MAX_LEN (1UL << 15)157#define EXT_UNWRITTEN_MAX_LEN (EXT_INIT_MAX_LEN - 1)158 159 160#define EXT_FIRST_EXTENT(__hdr__) \161 ((struct ext4_extent *) (((char *) (__hdr__)) + \162 sizeof(struct ext4_extent_header)))163#define EXT_FIRST_INDEX(__hdr__) \164 ((struct ext4_extent_idx *) (((char *) (__hdr__)) + \165 sizeof(struct ext4_extent_header)))166#define EXT_HAS_FREE_INDEX(__path__) \167 (le16_to_cpu((__path__)->p_hdr->eh_entries) \168 < le16_to_cpu((__path__)->p_hdr->eh_max))169#define EXT_LAST_EXTENT(__hdr__) \170 (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)171#define EXT_LAST_INDEX(__hdr__) \172 (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)173#define EXT_MAX_EXTENT(__hdr__) \174 ((le16_to_cpu((__hdr__)->eh_max)) ? \175 ((EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)) \176 : NULL)177#define EXT_MAX_INDEX(__hdr__) \178 ((le16_to_cpu((__hdr__)->eh_max)) ? \179 ((EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)) \180 : NULL)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 ext4_ext_mark_unwritten(struct ext4_extent *ext)198{199 /* We can not have an unwritten extent of zero length! */200 BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0);201 ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN);202}203 204static inline int ext4_ext_is_unwritten(struct ext4_extent *ext)205{206 /* Extent with ee_len of 0x8000 is treated as an initialized extent */207 return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN);208}209 210static inline int ext4_ext_get_actual_len(struct ext4_extent *ext)211{212 return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ?213 le16_to_cpu(ext->ee_len) :214 (le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN));215}216 217static inline void ext4_ext_mark_initialized(struct ext4_extent *ext)218{219 ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext));220}221 222/*223 * ext4_ext_pblock:224 * combine low and high parts of physical block number into ext4_fsblk_t225 */226static inline ext4_fsblk_t ext4_ext_pblock(struct ext4_extent *ex)227{228 ext4_fsblk_t block;229 230 block = le32_to_cpu(ex->ee_start_lo);231 block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1;232 return block;233}234 235/*236 * ext4_idx_pblock:237 * combine low and high parts of a leaf physical block number into ext4_fsblk_t238 */239static inline ext4_fsblk_t ext4_idx_pblock(struct ext4_extent_idx *ix)240{241 ext4_fsblk_t block;242 243 block = le32_to_cpu(ix->ei_leaf_lo);244 block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1;245 return block;246}247 248/*249 * ext4_ext_store_pblock:250 * stores a large physical block number into an extent struct,251 * breaking it into parts252 */253static inline void ext4_ext_store_pblock(struct ext4_extent *ex,254 ext4_fsblk_t pb)255{256 ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));257 ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &258 0xffff);259}260 261/*262 * ext4_idx_store_pblock:263 * stores a large physical block number into an index struct,264 * breaking it into parts265 */266static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix,267 ext4_fsblk_t pb)268{269 ix->ei_leaf_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));270 ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &271 0xffff);272}273 274#endif /* _EXT4_EXTENTS */275 276