mirror of
https://github.com/nitraiolo/CfgUSBLoader.git
synced 2024-12-03 16:44:16 +01:00
110 lines
3.8 KiB
C
110 lines
3.8 KiB
C
/*
|
|
* Copyright (c) 2003,2004 Cluster File Systems, Inc, info@clusterfs.com
|
|
* Written by Alex Tomas <alex@clusterfs.com>
|
|
*
|
|
* %Begin-Header%
|
|
* This file may be redistributed under the terms of the GNU Library
|
|
* General Public License, version 2.
|
|
* %End-Header%
|
|
*/
|
|
|
|
#ifndef _LINUX_EXT3_EXTENTS
|
|
#define _LINUX_EXT3_EXTENTS
|
|
|
|
/*
|
|
* ext3_inode has i_block array (total 60 bytes)
|
|
* first 4 bytes are used to store:
|
|
* - tree depth (0 mean there is no tree yet. all extents in the inode)
|
|
* - number of alive extents in the inode
|
|
*/
|
|
|
|
/*
|
|
* this is extent on-disk structure
|
|
* it's used at the bottom of the tree
|
|
*/
|
|
struct ext3_extent {
|
|
__u32 ee_block; /* first logical block extent covers */
|
|
__u16 ee_len; /* number of blocks covered by extent */
|
|
__u16 ee_start_hi; /* high 16 bits of physical block */
|
|
__u32 ee_start; /* low 32 bigs of physical block */
|
|
};
|
|
|
|
/*
|
|
* this is index on-disk structure
|
|
* it's used at all the levels, but the bottom
|
|
*/
|
|
struct ext3_extent_idx {
|
|
__u32 ei_block; /* index covers logical blocks from 'block' */
|
|
__u32 ei_leaf; /* pointer to the physical block of the next *
|
|
* level. leaf or next index could bet here */
|
|
__u16 ei_leaf_hi; /* high 16 bits of physical block */
|
|
__u16 ei_unused;
|
|
};
|
|
|
|
/*
|
|
* each block (leaves and indexes), even inode-stored has header
|
|
*/
|
|
struct ext3_extent_header {
|
|
__u16 eh_magic; /* probably will support different formats */
|
|
__u16 eh_entries; /* number of valid entries */
|
|
__u16 eh_max; /* capacity of store in entries */
|
|
__u16 eh_depth; /* has tree real underlaying blocks? */
|
|
__u32 eh_generation; /* generation of the tree */
|
|
};
|
|
|
|
#define EXT3_EXT_MAGIC 0xf30a
|
|
|
|
/*
|
|
* array of ext3_ext_path contains path to some extent
|
|
* creation/lookup routines use it for traversal/splitting/etc
|
|
* truncate uses it to simulate recursive walking
|
|
*/
|
|
struct ext3_ext_path {
|
|
__u32 p_block;
|
|
__u16 p_depth;
|
|
struct ext3_extent *p_ext;
|
|
struct ext3_extent_idx *p_idx;
|
|
struct ext3_extent_header *p_hdr;
|
|
struct buffer_head *p_bh;
|
|
};
|
|
|
|
/*
|
|
* 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 uninitialized (i.e.
|
|
* preallocated).
|
|
* EXT_UNINIT_MAX_LEN is the maximum number of blocks we can have in an
|
|
* uninitialized extent.
|
|
* If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an
|
|
* uninitialized one. In other words, if MSB of ee_len is set, it is an
|
|
* uninitialized extent with only one special scenario when ee_len = 0x8000.
|
|
* In this case we can not have an uninitialized 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 *uninitialized* extent is 2^15-1 (32767).
|
|
*/
|
|
#define EXT_INIT_MAX_LEN (1UL << 15)
|
|
#define EXT_UNINIT_MAX_LEN (EXT_INIT_MAX_LEN - 1)
|
|
|
|
#define EXT_FIRST_EXTENT(__hdr__) \
|
|
((struct ext3_extent *) (((char *) (__hdr__)) + \
|
|
sizeof(struct ext3_extent_header)))
|
|
#define EXT_FIRST_INDEX(__hdr__) \
|
|
((struct ext3_extent_idx *) (((char *) (__hdr__)) + \
|
|
sizeof(struct ext3_extent_header)))
|
|
#define EXT_HAS_FREE_INDEX(__path__) \
|
|
((__path__)->p_hdr->eh_entries < (__path__)->p_hdr->eh_max)
|
|
#define EXT_LAST_EXTENT(__hdr__) \
|
|
(EXT_FIRST_EXTENT((__hdr__)) + (__hdr__)->eh_entries - 1)
|
|
#define EXT_LAST_INDEX(__hdr__) \
|
|
(EXT_FIRST_INDEX((__hdr__)) + (__hdr__)->eh_entries - 1)
|
|
#define EXT_MAX_EXTENT(__hdr__) \
|
|
(EXT_FIRST_EXTENT((__hdr__)) + (__hdr__)->eh_max - 1)
|
|
#define EXT_MAX_INDEX(__hdr__) \
|
|
(EXT_FIRST_INDEX((__hdr__)) + (__hdr__)->eh_max - 1)
|
|
|
|
#endif /* _LINUX_EXT3_EXTENTS */
|
|
|