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258 lines
8.5 KiB
C
258 lines
8.5 KiB
C
#ifndef _LINUX_EXT4_EXT
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#define _LINUX_EXT4_EXT
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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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uint32_t 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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typedef struct ext4_extent {
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uint32_t ee_block; /* first logical block extent covers */
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uint16_t ee_len; /* number of blocks covered by extent */
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uint16_t ee_start_hi; /* high 16 bits of physical block */
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uint32_t ee_start_lo; /* low 32 bits of physical block */
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} __attribute__ ((__packed__)) EXT4_EXTENT;
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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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typedef struct ext4_extent_idx {
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uint32_t ei_block; /* index covers logical blocks from 'block' */
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uint32_t 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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uint16_t ei_leaf_hi; /* high 16 bits of physical block */
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uint16_t ei_unused;
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}__attribute__ ((__packed__)) EXT4_EXTENT_IDX;
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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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typedef struct ext4_extent_header {
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uint16_t eh_magic; /* probably will support different formats */
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uint16_t eh_entries; /* number of valid entries */
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uint16_t eh_max; /* capacity of store in entries */
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uint16_t eh_depth; /* has tree real underlying blocks? */
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uint32_t eh_generation; /* generation of the tree */
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}__attribute__ ((__packed__)) EXT4_EXTENT_HEADER;
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#define EXT4_EXT_MAGIC 0xf30a
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#define get_ext4_header(i) ((struct ext4_extent_header *) (i)->i_block)
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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) * (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 *)(((char *)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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{
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ext4_fsblk_t p_block;
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int p_depth;
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int 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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* 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 uninitialized (i.e.
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* preallocated).
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* EXT_UNINIT_MAX_LEN is the maximum number of blocks we can have in an
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* uninitialized extent.
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* If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an
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* uninitialized one. In other words, if MSB of ee_len is set, it is an
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* uninitialized extent with only one special scenario when ee_len = 0x8000.
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* In this case we can not have an uninitialized 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 *uninitialized* 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_EXTENT_SIZE sizeof(struct ext4_extent)
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#define EXT_INDEX_SIZE sizeof(struct ext4_extent_idx)
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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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((__path__)->p_hdr->eh_entries < (__path__)->p_hdr->eh_max)
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#define EXT_LAST_EXTENT(__hdr__) \
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(EXT_FIRST_EXTENT((__hdr__)) + (__hdr__)->eh_entries - 1)
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#define EXT_LAST_INDEX(__hdr__) \
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(EXT_FIRST_INDEX((__hdr__)) + (__hdr__)->eh_entries - 1)
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#define EXT_MAX_EXTENT(__hdr__) \
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(EXT_FIRST_EXTENT((__hdr__)) + (__hdr__)->eh_max - 1)
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#define EXT_MAX_INDEX(__hdr__) \
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(EXT_FIRST_INDEX((__hdr__)) + (__hdr__)->eh_max - 1)
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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 get_ext4_header(inode);
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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 ext_inode_hdr(inode)->eh_depth;
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}
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static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext)
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{
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/* We can not have an uninitialized extent of zero length! */
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ext->ee_len |= EXT_INIT_MAX_LEN;
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}
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static inline int ext4_ext_is_uninitialized(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 (ext->ee_len > EXT_INIT_MAX_LEN);
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}
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static inline uint16_t ext4_ext_get_actual_len(struct ext4_extent *ext)
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{
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return (ext->ee_len <= EXT_INIT_MAX_LEN
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? ext->ee_len
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: (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 = ext4_ext_get_actual_len(ext);
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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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ext->ee_len |= 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 (ext->ee_len > EXT_INIT_MAX_LEN);
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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 = ex->ee_start_lo;
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block |= ((ext4_fsblk_t)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 = ix->ei_leaf_lo;
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block |= ((ext4_fsblk_t)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 = (uint32_t)(pb & 0xffffffff);
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ex->ee_start_hi = (uint16_t)((pb >> 31) >> 1) & 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 = (uint32_t)(pb & 0xffffffff);
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ix->ei_leaf_hi = (uint16_t)((pb >> 31) >> 1) & 0xffff;
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}
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#define ext4_ext_dirty(icb, handle, inode, path) \
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__ext4_ext_dirty("", __LINE__, (icb), (handle), (inode), (path))
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#define INODE_HAS_EXTENT(i) ((i)->i_flags & EXT2_EXTENTS_FL)
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static inline uint64_t ext_to_block(EXT4_EXTENT *extent)
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{
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uint64_t block;
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block = (uint64_t)extent->ee_start_lo;
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block |= ((uint64_t) extent->ee_start_hi << 31) << 1;
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return block;
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}
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static inline uint64_t idx_to_block(EXT4_EXTENT_IDX *idx)
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{
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uint64_t block;
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block = (uint64_t)idx->ei_leaf_lo;
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block |= ((uint64_t) idx->ei_leaf_hi << 31) << 1;
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return block;
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}
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int ext4_ext_get_blocks(void *icb, handle_t *handle, struct inode *inode, ext4_fsblk_t iblock,
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unsigned long max_blocks, struct buffer_head *bh_result,
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int create, int flags);
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int ext4_ext_tree_init(void *icb, handle_t *handle, struct inode *inode);
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int ext4_ext_truncate(void *icb, struct inode *inode, unsigned long start);
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#endif /* _LINUX_EXT4_EXT */
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