| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com |
| * Written by Alex Tomas <alex@clusterfs.com> |
| */ |
| |
| #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 { |
| __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; |
| }; |
| |
| /* |
| * 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)) \ |
| : 0) |
| #define EXT_MAX_INDEX(__hdr__) \ |
| ((le16_to_cpu((__hdr__)->eh_max)) ? \ |
| ((EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)) : 0) |
| |
| 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); |
| } |
| |
| #define ext4_ext_dirty(handle, inode, path) \ |
| __ext4_ext_dirty(__func__, __LINE__, (handle), (inode), (path)) |
| int __ext4_ext_dirty(const char *where, unsigned int line, handle_t *handle, |
| struct inode *inode, struct ext4_ext_path *path); |
| |
| #endif /* _EXT4_EXTENTS */ |
| |