128 lines
4.5 KiB
C
128 lines
4.5 KiB
C
/*
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* Copyright (c) 2003,2004 Cluster File Systems, Inc, info@clusterfs.com
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* Written by Alex Tomas <alex@clusterfs.com>
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*
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* %Begin-Header%
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* This file may be redistributed under the terms of the GNU Library
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* General Public License, version 2.
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* %End-Header%
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*/
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#ifndef _LINUX_EXT3_EXTENTS
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#define _LINUX_EXT3_EXTENTS
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/*
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* ext3_inode has i_block array (total 60 bytes)
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* first 4 bytes are used to store:
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* - tree depth (0 mean there is no tree yet. all extents in the inode)
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* - number of alive extents in the inode
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*/
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/*
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* This is 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 ext3_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 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 ext3_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; /* low 32 bigs 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, but the bottom
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*/
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struct ext3_extent_idx {
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__le32 ei_block; /* index covers logical blocks from 'block' */
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__le32 ei_leaf; /* pointer to the physical block of the next *
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* level. leaf or next index could bet here */
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__le16 ei_leaf_hi; /* high 16 bits of physical block */
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__le16 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 ext3_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 EXT3_EXT_MAGIC 0xf30a
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/*
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* array of ext3_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 ext3_ext_path {
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__u32 p_block;
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__u16 p_depth;
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struct ext3_extent *p_ext;
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struct ext3_extent_idx *p_idx;
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struct ext3_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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* 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_UNINIT_MAX_LEN (EXT_INIT_MAX_LEN - 1)
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#define EXT_MAX_EXTENT_LBLK (((__u64) 1 << 32) - 1)
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#define EXT_MAX_EXTENT_PBLK (((__u64) 1 << 48) - 1)
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#define EXT_FIRST_EXTENT(__hdr__) \
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((struct ext3_extent *) (((char *) (__hdr__)) + \
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sizeof(struct ext3_extent_header)))
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#define EXT_FIRST_INDEX(__hdr__) \
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((struct ext3_extent_idx *) (((char *) (__hdr__)) + \
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sizeof(struct ext3_extent_header)))
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#define EXT_HAS_FREE_INDEX(__path__) \
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(ext2fs_le16_to_cpu((__path__)->p_hdr->eh_entries) < \
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ext2fs_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__)) + \
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ext2fs_le16_to_cpu((__hdr__)->eh_entries) - 1)
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#define EXT_LAST_INDEX(__hdr__) \
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(EXT_FIRST_INDEX((__hdr__)) + \
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ext2fs_le16_to_cpu((__hdr__)->eh_entries) - 1)
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#define EXT_MAX_EXTENT(__hdr__) \
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(EXT_FIRST_EXTENT((__hdr__)) + \
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ext2fs_le16_to_cpu((__hdr__)->eh_max) - 1)
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#define EXT_MAX_INDEX(__hdr__) \
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(EXT_FIRST_INDEX((__hdr__)) + \
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ext2fs_le16_to_cpu((__hdr__)->eh_max) - 1)
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#endif /* _LINUX_EXT3_EXTENTS */
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