xref: /aosp_15_r20/external/e2fsprogs/lib/ext2fs/ext3_extents.h (revision 6a54128f25917bfc36a8a6e9d722c04a0b4641b6)
1*6a54128fSAndroid Build Coastguard Worker /*
2*6a54128fSAndroid Build Coastguard Worker  * Copyright (c) 2003,2004 Cluster File Systems, Inc, [email protected]
3*6a54128fSAndroid Build Coastguard Worker  * Written by Alex Tomas <[email protected]>
4*6a54128fSAndroid Build Coastguard Worker  *
5*6a54128fSAndroid Build Coastguard Worker  * %Begin-Header%
6*6a54128fSAndroid Build Coastguard Worker  * This file may be redistributed under the terms of the GNU Library
7*6a54128fSAndroid Build Coastguard Worker  * General Public License, version 2.
8*6a54128fSAndroid Build Coastguard Worker  * %End-Header%
9*6a54128fSAndroid Build Coastguard Worker  */
10*6a54128fSAndroid Build Coastguard Worker 
11*6a54128fSAndroid Build Coastguard Worker #ifndef _LINUX_EXT3_EXTENTS
12*6a54128fSAndroid Build Coastguard Worker #define _LINUX_EXT3_EXTENTS
13*6a54128fSAndroid Build Coastguard Worker 
14*6a54128fSAndroid Build Coastguard Worker /*
15*6a54128fSAndroid Build Coastguard Worker  * ext3_inode has i_block array (total 60 bytes)
16*6a54128fSAndroid Build Coastguard Worker  * first 4 bytes are used to store:
17*6a54128fSAndroid Build Coastguard Worker  *  - tree depth (0 mean there is no tree yet. all extents in the inode)
18*6a54128fSAndroid Build Coastguard Worker  *  - number of alive extents in the inode
19*6a54128fSAndroid Build Coastguard Worker  */
20*6a54128fSAndroid Build Coastguard Worker 
21*6a54128fSAndroid Build Coastguard Worker /*
22*6a54128fSAndroid Build Coastguard Worker  * This is extent tail on-disk structure.
23*6a54128fSAndroid Build Coastguard Worker  * All other extent structures are 12 bytes long.  It turns out that
24*6a54128fSAndroid Build Coastguard Worker  * block_size % 12 >= 4 for at least all powers of 2 greater than 512, which
25*6a54128fSAndroid Build Coastguard Worker  * covers all valid ext4 block sizes.  Therefore, this tail structure can be
26*6a54128fSAndroid Build Coastguard Worker  * crammed into the end of the block without having to rebalance the tree.
27*6a54128fSAndroid Build Coastguard Worker  */
28*6a54128fSAndroid Build Coastguard Worker struct ext3_extent_tail {
29*6a54128fSAndroid Build Coastguard Worker 	__le32	et_checksum;	/* crc32c(uuid+inum+extent_block) */
30*6a54128fSAndroid Build Coastguard Worker };
31*6a54128fSAndroid Build Coastguard Worker 
32*6a54128fSAndroid Build Coastguard Worker /*
33*6a54128fSAndroid Build Coastguard Worker  * this is extent on-disk structure
34*6a54128fSAndroid Build Coastguard Worker  * it's used at the bottom of the tree
35*6a54128fSAndroid Build Coastguard Worker  */
36*6a54128fSAndroid Build Coastguard Worker struct ext3_extent {
37*6a54128fSAndroid Build Coastguard Worker 	__le32	ee_block;	/* first logical block extent covers */
38*6a54128fSAndroid Build Coastguard Worker 	__le16	ee_len;		/* number of blocks covered by extent */
39*6a54128fSAndroid Build Coastguard Worker 	__le16	ee_start_hi;	/* high 16 bits of physical block */
40*6a54128fSAndroid Build Coastguard Worker 	__le32	ee_start;	/* low 32 bigs of physical block */
41*6a54128fSAndroid Build Coastguard Worker };
42*6a54128fSAndroid Build Coastguard Worker 
43*6a54128fSAndroid Build Coastguard Worker /*
44*6a54128fSAndroid Build Coastguard Worker  * this is index on-disk structure
45*6a54128fSAndroid Build Coastguard Worker  * it's used at all the levels, but the bottom
46*6a54128fSAndroid Build Coastguard Worker  */
47*6a54128fSAndroid Build Coastguard Worker struct ext3_extent_idx {
48*6a54128fSAndroid Build Coastguard Worker 	__le32	ei_block;	/* index covers logical blocks from 'block' */
49*6a54128fSAndroid Build Coastguard Worker 	__le32	ei_leaf;	/* pointer to the physical block of the next *
50*6a54128fSAndroid Build Coastguard Worker 				 * level. leaf or next index could bet here */
51*6a54128fSAndroid Build Coastguard Worker 	__le16	ei_leaf_hi;	/* high 16 bits of physical block */
52*6a54128fSAndroid Build Coastguard Worker 	__le16	ei_unused;
53*6a54128fSAndroid Build Coastguard Worker };
54*6a54128fSAndroid Build Coastguard Worker 
55*6a54128fSAndroid Build Coastguard Worker /*
56*6a54128fSAndroid Build Coastguard Worker  * each block (leaves and indexes), even inode-stored has header
57*6a54128fSAndroid Build Coastguard Worker  */
58*6a54128fSAndroid Build Coastguard Worker struct ext3_extent_header {
59*6a54128fSAndroid Build Coastguard Worker 	__le16	eh_magic;	/* probably will support different formats */
60*6a54128fSAndroid Build Coastguard Worker 	__le16	eh_entries;	/* number of valid entries */
61*6a54128fSAndroid Build Coastguard Worker 	__le16	eh_max;		/* capacity of store in entries */
62*6a54128fSAndroid Build Coastguard Worker 	__le16	eh_depth;	/* has tree real underlying blocks? */
63*6a54128fSAndroid Build Coastguard Worker 	__le32	eh_generation;	/* generation of the tree */
64*6a54128fSAndroid Build Coastguard Worker };
65*6a54128fSAndroid Build Coastguard Worker 
66*6a54128fSAndroid Build Coastguard Worker #define EXT3_EXT_MAGIC		0xf30a
67*6a54128fSAndroid Build Coastguard Worker 
68*6a54128fSAndroid Build Coastguard Worker /*
69*6a54128fSAndroid Build Coastguard Worker  * array of ext3_ext_path contains path to some extent
70*6a54128fSAndroid Build Coastguard Worker  * creation/lookup routines use it for traversal/splitting/etc
71*6a54128fSAndroid Build Coastguard Worker  * truncate uses it to simulate recursive walking
72*6a54128fSAndroid Build Coastguard Worker  */
73*6a54128fSAndroid Build Coastguard Worker struct ext3_ext_path {
74*6a54128fSAndroid Build Coastguard Worker 	__u32				p_block;
75*6a54128fSAndroid Build Coastguard Worker 	__u16				p_depth;
76*6a54128fSAndroid Build Coastguard Worker 	struct ext3_extent		*p_ext;
77*6a54128fSAndroid Build Coastguard Worker 	struct ext3_extent_idx		*p_idx;
78*6a54128fSAndroid Build Coastguard Worker 	struct ext3_extent_header	*p_hdr;
79*6a54128fSAndroid Build Coastguard Worker 	struct buffer_head		*p_bh;
80*6a54128fSAndroid Build Coastguard Worker };
81*6a54128fSAndroid Build Coastguard Worker 
82*6a54128fSAndroid Build Coastguard Worker /*
83*6a54128fSAndroid Build Coastguard Worker  * EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an
84*6a54128fSAndroid Build Coastguard Worker  * initialized extent. This is 2^15 and not (2^16 - 1), since we use the
85*6a54128fSAndroid Build Coastguard Worker  * MSB of ee_len field in the extent datastructure to signify if this
86*6a54128fSAndroid Build Coastguard Worker  * particular extent is an initialized extent or an uninitialized (i.e.
87*6a54128fSAndroid Build Coastguard Worker  * preallocated).
88*6a54128fSAndroid Build Coastguard Worker  * EXT_UNINIT_MAX_LEN is the maximum number of blocks we can have in an
89*6a54128fSAndroid Build Coastguard Worker  * uninitialized extent.
90*6a54128fSAndroid Build Coastguard Worker  * If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an
91*6a54128fSAndroid Build Coastguard Worker  * uninitialized one. In other words, if MSB of ee_len is set, it is an
92*6a54128fSAndroid Build Coastguard Worker  * uninitialized extent with only one special scenario when ee_len = 0x8000.
93*6a54128fSAndroid Build Coastguard Worker  * In this case we can not have an uninitialized extent of zero length and
94*6a54128fSAndroid Build Coastguard Worker  * thus we make it as a special case of initialized extent with 0x8000 length.
95*6a54128fSAndroid Build Coastguard Worker  * This way we get better extent-to-group alignment for initialized extents.
96*6a54128fSAndroid Build Coastguard Worker  * Hence, the maximum number of blocks we can have in an *initialized*
97*6a54128fSAndroid Build Coastguard Worker  * extent is 2^15 (32768) and in an *uninitialized* extent is 2^15-1 (32767).
98*6a54128fSAndroid Build Coastguard Worker  */
99*6a54128fSAndroid Build Coastguard Worker #define EXT_INIT_MAX_LEN	(1UL << 15)
100*6a54128fSAndroid Build Coastguard Worker #define EXT_UNINIT_MAX_LEN	(EXT_INIT_MAX_LEN - 1)
101*6a54128fSAndroid Build Coastguard Worker #define EXT_MAX_EXTENT_LBLK	(((__u64) 1 << 32) - 1)
102*6a54128fSAndroid Build Coastguard Worker #define EXT_MAX_EXTENT_PBLK	(((__u64) 1 << 48) - 1)
103*6a54128fSAndroid Build Coastguard Worker 
104*6a54128fSAndroid Build Coastguard Worker #define EXT_FIRST_EXTENT(__hdr__) \
105*6a54128fSAndroid Build Coastguard Worker 	((struct ext3_extent *) (((char *) (__hdr__)) +		\
106*6a54128fSAndroid Build Coastguard Worker 				 sizeof(struct ext3_extent_header)))
107*6a54128fSAndroid Build Coastguard Worker #define EXT_FIRST_INDEX(__hdr__) \
108*6a54128fSAndroid Build Coastguard Worker 	((struct ext3_extent_idx *) (((char *) (__hdr__)) +	\
109*6a54128fSAndroid Build Coastguard Worker 				     sizeof(struct ext3_extent_header)))
110*6a54128fSAndroid Build Coastguard Worker #define EXT_HAS_FREE_INDEX(__path__) \
111*6a54128fSAndroid Build Coastguard Worker 	(ext2fs_le16_to_cpu((__path__)->p_hdr->eh_entries) < \
112*6a54128fSAndroid Build Coastguard Worker 	 ext2fs_le16_to_cpu((__path__)->p_hdr->eh_max))
113*6a54128fSAndroid Build Coastguard Worker #define EXT_LAST_EXTENT(__hdr__) \
114*6a54128fSAndroid Build Coastguard Worker 	(EXT_FIRST_EXTENT((__hdr__)) + \
115*6a54128fSAndroid Build Coastguard Worker 	ext2fs_le16_to_cpu((__hdr__)->eh_entries) - 1)
116*6a54128fSAndroid Build Coastguard Worker #define EXT_LAST_INDEX(__hdr__) \
117*6a54128fSAndroid Build Coastguard Worker 	(EXT_FIRST_INDEX((__hdr__)) + \
118*6a54128fSAndroid Build Coastguard Worker 	ext2fs_le16_to_cpu((__hdr__)->eh_entries) - 1)
119*6a54128fSAndroid Build Coastguard Worker #define EXT_MAX_EXTENT(__hdr__) \
120*6a54128fSAndroid Build Coastguard Worker 	(EXT_FIRST_EXTENT((__hdr__)) + \
121*6a54128fSAndroid Build Coastguard Worker 	ext2fs_le16_to_cpu((__hdr__)->eh_max) - 1)
122*6a54128fSAndroid Build Coastguard Worker #define EXT_MAX_INDEX(__hdr__) \
123*6a54128fSAndroid Build Coastguard Worker 	(EXT_FIRST_INDEX((__hdr__)) + \
124*6a54128fSAndroid Build Coastguard Worker 	ext2fs_le16_to_cpu((__hdr__)->eh_max) - 1)
125*6a54128fSAndroid Build Coastguard Worker 
126*6a54128fSAndroid Build Coastguard Worker #endif /* _LINUX_EXT3_EXTENTS */
127*6a54128fSAndroid Build Coastguard Worker 
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