// SPDX-License-Identifier: GPL-2.0 /* * Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com * Written by Alex Tomas */ #ifndef _EXT4_EXTENTS #define _EXT4_EXTENTS #include "ext4.h" /* * With AGGRESSIVE_TEST defined, the capacity of index/leaf blocks * becomes very small, so index split, in-depth growing and * other hard changes happen much more often. * This is for debug purposes only. */ #define AGGRESSIVE_TEST_ /* * With EXTENTS_STATS defined, the number of blocks and extents * are collected in the truncate path. They'll be shown at * umount time. */ #define EXTENTS_STATS__ /* * If CHECK_BINSEARCH is defined, then the results of the binary search * will also be checked by linear search. */ #define CHECK_BINSEARCH__ /* * ext4_inode has i_block array (60 bytes total). * The first 12 bytes store ext4_extent_header; * the remainder stores an array of ext4_extent. * For non-inode extent blocks, ext4_extent_tail * follows the array. */ /* * This is the extent tail on-disk structure. * All other extent structures are 12 bytes long. It turns out that * block_size % 12 >= 4 for at least all powers of 2 greater than 512, which * covers all valid ext4 block sizes. Therefore, this tail structure can be * crammed into the end of the block without having to rebalance the tree. */ struct ext4_extent_tail { __le32 et_checksum; /* crc32c(uuid+inum+extent_block) */ }; /* * This is the extent on-disk structure. * It's used at the bottom of the tree. */ struct ext4_extent { __le32 ee_block; /* first logical block extent covers */ __le16 ee_len; /* number of blocks covered by extent */ __le16 ee_start_hi; /* high 16 bits of physical block */ __le32 ee_start_lo; /* low 32 bits of physical block */ }; /* * This is index on-disk structure. * It's used at all the levels except the bottom. */ struct ext4_extent_idx { __le32 ei_block; /* index covers logical blocks from 'block' */ __le32 ei_leaf_lo; /* pointer to the physical block of the next * * level. leaf or next index could be there */ __le16 ei_leaf_hi; /* high 16 bits of physical block */ __u16 ei_unused; }; /* * Each block (leaves and indexes), even inode-stored has header. */ struct ext4_extent_header { __le16 eh_magic; /* probably will support different formats */ __le16 eh_entries; /* number of valid entries */ __le16 eh_max; /* capacity of store in entries */ __le16 eh_depth; /* has tree real underlying blocks? */ __le32 eh_generation; /* generation of the tree */ }; #define EXT4_EXT_MAGIC cpu_to_le16(0xf30a) #define EXT4_MAX_EXTENT_DEPTH 5 #define EXT4_EXTENT_TAIL_OFFSET(hdr) \ (sizeof(struct ext4_extent_header) + \ (sizeof(struct ext4_extent) * le16_to_cpu((hdr)->eh_max))) static inline struct ext4_extent_tail * find_ext4_extent_tail(struct ext4_extent_header *eh) { return (struct ext4_extent_tail *)(((void *)eh) + EXT4_EXTENT_TAIL_OFFSET(eh)); } /* * Array of ext4_ext_path contains path to some extent. * Creation/lookup routines use it for traversal/splitting/etc. * Truncate uses it to simulate recursive walking. */ struct ext4_ext_path { ext4_fsblk_t p_block; __u16 p_depth; __u16 p_maxdepth; struct ext4_extent *p_ext; struct ext4_extent_idx *p_idx; struct ext4_extent_header *p_hdr; struct buffer_head *p_bh; }; /* * Used to record a portion of a cluster found at the beginning or end * of an extent while traversing the extent tree during space removal. * A partial cluster may be removed if it does not contain blocks shared * with extents that aren't being deleted (tofree state). Otherwise, * it cannot be removed (nofree state). */ struct partial_cluster { ext4_fsblk_t pclu; /* physical cluster number */ ext4_lblk_t lblk; /* logical block number within logical cluster */ enum {initial, tofree, nofree} state; }; /* * structure for external API */ /* * EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an * initialized extent. This is 2^15 and not (2^16 - 1), since we use the * MSB of ee_len field in the extent datastructure to signify if this * particular extent is an initialized extent or an unwritten (i.e. * preallocated). * EXT_UNWRITTEN_MAX_LEN is the maximum number of blocks we can have in an * unwritten extent. * If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an * unwritten one. In other words, if MSB of ee_len is set, it is an * unwritten extent with only one special scenario when ee_len = 0x8000. * In this case we can not have an unwritten extent of zero length and * thus we make it as a special case of initialized extent with 0x8000 length. * This way we get better extent-to-group alignment for initialized extents. * Hence, the maximum number of blocks we can have in an *initialized* * extent is 2^15 (32768) and in an *unwritten* extent is 2^15-1 (32767). */ #define EXT_INIT_MAX_LEN (1UL << 15) #define EXT_UNWRITTEN_MAX_LEN (EXT_INIT_MAX_LEN - 1) #define EXT_FIRST_EXTENT(__hdr__) \ ((struct ext4_extent *) (((char *) (__hdr__)) + \ sizeof(struct ext4_extent_header))) #define EXT_FIRST_INDEX(__hdr__) \ ((struct ext4_extent_idx *) (((char *) (__hdr__)) + \ sizeof(struct ext4_extent_header))) #define EXT_HAS_FREE_INDEX(__path__) \ (le16_to_cpu((__path__)->p_hdr->eh_entries) \ < le16_to_cpu((__path__)->p_hdr->eh_max)) #define EXT_LAST_EXTENT(__hdr__) \ (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1) #define EXT_LAST_INDEX(__hdr__) \ (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1) #define EXT_MAX_EXTENT(__hdr__) \ ((le16_to_cpu((__hdr__)->eh_max)) ? \ ((EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)) \ : NULL) #define EXT_MAX_INDEX(__hdr__) \ ((le16_to_cpu((__hdr__)->eh_max)) ? \ ((EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)) \ : NULL) static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode) { return (struct ext4_extent_header *) EXT4_I(inode)->i_data; } static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh) { return (struct ext4_extent_header *) bh->b_data; } static inline unsigned short ext_depth(struct inode *inode) { return le16_to_cpu(ext_inode_hdr(inode)->eh_depth); } static inline void ext4_ext_mark_unwritten(struct ext4_extent *ext) { /* We can not have an unwritten extent of zero length! */ BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0); ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN); } static inline int ext4_ext_is_unwritten(struct ext4_extent *ext) { /* Extent with ee_len of 0x8000 is treated as an initialized extent */ return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN); } static inline int ext4_ext_get_actual_len(struct ext4_extent *ext) { return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ? le16_to_cpu(ext->ee_len) : (le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN)); } static inline void ext4_ext_mark_initialized(struct ext4_extent *ext) { ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext)); } /* * ext4_ext_pblock: * combine low and high parts of physical block number into ext4_fsblk_t */ static inline ext4_fsblk_t ext4_ext_pblock(struct ext4_extent *ex) { ext4_fsblk_t block; block = le32_to_cpu(ex->ee_start_lo); block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1; return block; } /* * ext4_idx_pblock: * combine low and high parts of a leaf physical block number into ext4_fsblk_t */ static inline ext4_fsblk_t ext4_idx_pblock(struct ext4_extent_idx *ix) { ext4_fsblk_t block; block = le32_to_cpu(ix->ei_leaf_lo); block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1; return block; } /* * ext4_ext_store_pblock: * stores a large physical block number into an extent struct, * breaking it into parts */ static inline void ext4_ext_store_pblock(struct ext4_extent *ex, ext4_fsblk_t pb) { ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff)); ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) & 0xffff); } /* * ext4_idx_store_pblock: * stores a large physical block number into an index struct, * breaking it into parts */ static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix, ext4_fsblk_t pb) { ix->ei_leaf_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff)); ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) & 0xffff); } #endif /* _EXT4_EXTENTS */