// SPDX-License-Identifier: GPL-2.0 /* * Copyright (c) 2003-2006, Cluster File Systems, Inc, [email protected] * Written by Alex Tomas <[email protected]> */ #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__ /* * If EXT_STATS is defined then stats numbers are collected. * These number will be displayed at umount time. */ #define EXT_STATS_ /* * 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 { … }; /* * This is the extent on-disk structure. * It's used at the bottom of the tree. */ struct ext4_extent { … }; /* * This is index on-disk structure. * It's used at all the levels except the bottom. */ struct ext4_extent_idx { … }; /* * Each block (leaves and indexes), even inode-stored has header. */ struct ext4_extent_header { … }; #define EXT4_EXT_MAGIC … #define EXT4_MAX_EXTENT_DEPTH … #define EXT4_EXTENT_TAIL_OFFSET(hdr) … static inline struct ext4_extent_tail * find_ext4_extent_tail(struct ext4_extent_header *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 { … }; /* * 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 { … }; /* * 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 … #define EXT_UNWRITTEN_MAX_LEN … #define EXT_FIRST_EXTENT(__hdr__) … #define EXT_FIRST_INDEX(__hdr__) … #define EXT_HAS_FREE_INDEX(__path__) … #define EXT_LAST_EXTENT(__hdr__) … #define EXT_LAST_INDEX(__hdr__) … #define EXT_MAX_EXTENT(__hdr__) … #define EXT_MAX_INDEX(__hdr__) … static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode) { … } static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh) { … } static inline unsigned short ext_depth(struct inode *inode) { … } static inline void ext4_ext_mark_unwritten(struct ext4_extent *ext) { … } static inline int ext4_ext_is_unwritten(struct ext4_extent *ext) { … } static inline int ext4_ext_get_actual_len(struct ext4_extent *ext) { … } static inline void ext4_ext_mark_initialized(struct ext4_extent *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_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_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) { … } /* * 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) { … } #endif /* _EXT4_EXTENTS */
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