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