- 根目录:
- fs
- logfs
- logfs_abi.h
/*
* fs/logfs/logfs_abi.h
*
* As should be obvious for Linux kernel code, license is GPLv2
*
* Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
*
* Public header for logfs.
*/
#ifndef FS_LOGFS_LOGFS_ABI_H
#define FS_LOGFS_LOGFS_ABI_H
/* For out-of-kernel compiles */
#ifndef BUILD_BUG_ON
#define BUILD_BUG_ON(condition) /**/
#endif
#define SIZE_CHECK(type, size) \
static inline void check_##type(void) \
{ \
BUILD_BUG_ON(sizeof(struct type) != (size)); \
}
/*
* Throughout the logfs code, we're constantly dealing with blocks at
* various positions or offsets. To remove confusion, we stricly
* distinguish between a "position" - the logical position within a
* file and an "offset" - the physical location within the device.
*
* Any usage of the term offset for a logical location or position for
* a physical one is a bug and should get fixed.
*/
/*
* Block are allocated in one of several segments depending on their
* level. The following levels are used:
* 0 - regular data block
* 1 - i1 indirect blocks
* 2 - i2 indirect blocks
* 3 - i3 indirect blocks
* 4 - i4 indirect blocks
* 5 - i5 indirect blocks
* 6 - ifile data blocks
* 7 - ifile i1 indirect blocks
* 8 - ifile i2 indirect blocks
* 9 - ifile i3 indirect blocks
* 10 - ifile i4 indirect blocks
* 11 - ifile i5 indirect blocks
* Potential levels to be used in the future:
* 12 - gc recycled blocks, long-lived data
* 13 - replacement blocks, short-lived data
*
* Levels 1-11 are necessary for robust gc operations and help separate
* short-lived metadata from longer-lived file data. In the future,
* file data should get separated into several segments based on simple
* heuristics. Old data recycled during gc operation is expected to be
* long-lived. New data is of uncertain life expectancy. New data
* used to replace older blocks in existing files is expected to be
* short-lived.
*/
/* Magic numbers. 64bit for superblock, 32bit for statfs f_type */
#define LOGFS_MAGIC 0x7a3a8e5cb9d5bf67ull
#define LOGFS_MAGIC_U32 0xc97e8168u
/*
* Various blocksize related macros. Blocksize is currently fixed at 4KiB.
* Sooner or later that should become configurable and the macros replaced
* by something superblock-dependent. Pointers in indirect blocks are and
* will remain 64bit.
*
* LOGFS_BLOCKSIZE - self-explaining
* LOGFS_BLOCK_FACTOR - number of pointers per indirect block
* LOGFS_BLOCK_BITS - log2 of LOGFS_BLOCK_FACTOR, used for shifts
*/
#define LOGFS_BLOCKSIZE (4096ull)
#define LOGFS_BLOCK_FACTOR (LOGFS_BLOCKSIZE / sizeof(u64))
#define LOGFS_BLOCK_BITS (9)
/*
* Number of blocks at various levels of indirection. There are 16 direct
* block pointers plus a single indirect pointer.
*/
#define I0_BLOCKS (16)
#define I1_BLOCKS LOGFS_BLOCK_FACTOR
#define I2_BLOCKS (LOGFS_BLOCK_FACTOR * I1_BLOCKS)
#define I3_BLOCKS (LOGFS_BLOCK_FACTOR * I2_BLOCKS)
#define I4_BLOCKS (LOGFS_BLOCK_FACTOR * I3_BLOCKS)
#define I5_BLOCKS (LOGFS_BLOCK_FACTOR * I4_BLOCKS)
#define INDIRECT_INDEX I0_BLOCKS
#define LOGFS_EMBEDDED_FIELDS (I0_BLOCKS + 1)
/*
* Sizes at which files require another level of indirection. Files smaller
* than LOGFS_EMBEDDED_SIZE can be completely stored in the inode itself,
* similar like ext2 fast symlinks.
*
* Data at a position smaller than LOGFS_I0_SIZE is accessed through the
* direct pointers, else through the 1x indirect pointer and so forth.
*/
#define LOGFS_EMBEDDED_SIZE (LOGFS_EMBEDDED_FIELDS * sizeof(u64))
#define LOGFS_I0_SIZE (I0_BLOCKS * LOGFS_BLOCKSIZE)
#define LOGFS_I1_SIZE (I1_BLOCKS * LOGFS_BLOCKSIZE)
#define LOGFS_I2_SIZE (I2_BLOCKS * LOGFS_BLOCKSIZE)
#define LOGFS_I3_SIZE (I3_BLOCKS * LOGFS_BLOCKSIZE)
#define LOGFS_I4_SIZE (I4_BLOCKS * LOGFS_BLOCKSIZE)
#define LOGFS_I5_SIZE (I5_BLOCKS * LOGFS_BLOCKSIZE)
/*
* Each indirect block pointer must have this flag set, if all block pointers
* behind it are set, i.e. there is no hole hidden in the shadow of this
* indirect block pointer.
*/
#define LOGFS_FULLY_POPULATED (1ULL << 63)
#define pure_ofs(ofs) (ofs & ~LOGFS_FULLY_POPULATED)
/*
* LogFS needs to separate data into levels. Each level is defined as the
* maximal possible distance from the master inode (inode of the inode file).
* Data blocks reside on level 0, 1x indirect block on level 1, etc.
* Inodes reside on level 6, indirect blocks for the inode file on levels 7-11.
* This effort is necessary to guarantee garbage collection to always make
* progress.
*
* LOGFS_MAX_INDIRECT is the maximal indirection through indirect blocks,
* LOGFS_MAX_LEVELS is one more for the actual data level of a file. It is
* the maximal number of levels for one file.
* LOGFS_NO_AREAS is twice that, as the inode file and regular files are
* effectively stacked on top of each other.
*/
#define LOGFS_MAX_INDIRECT (5)
#define LOGFS_MAX_LEVELS (LOGFS_MAX_INDIRECT + 1)
#define LOGFS_NO_AREAS (2 * LOGFS_MAX_LEVELS)
/* Maximum size of filenames */
#define LOGFS_MAX_NAMELEN (255)
/* Number of segments in the primary journal. */
#define LOGFS_JOURNAL_SEGS (16)
/* Maximum number of free/erased/etc. segments in journal entries */
#define MAX_CACHED_SEGS (64)
/*
* LOGFS_OBJECT_HEADERSIZE is the size of a single header in the object store,
* LOGFS_MAX_OBJECTSIZE the size of the largest possible object, including
* its header,
* LOGFS_SEGMENT_RESERVE is the amount of space reserved for each segment for
* its segment header and the padded space at the end when no further objects
* fit.
*/
#define LOGFS_OBJECT_HEADERSIZE (0x1c)
#define LOGFS_SEGMENT_HEADERSIZE (0x18)
#define LOGFS_MAX_OBJECTSIZE (LOGFS_OBJECT_HEADERSIZE + LOGFS_BLOCKSIZE)
#define LOGFS_SEGMENT_RESERVE \
(LOGFS_SEGMENT_HEADERSIZE + LOGFS_MAX_OBJECTSIZE - 1)
/*
* Segment types:
* SEG_SUPER - Data or indirect block
* SEG_JOURNAL - Inode
* SEG_OSTORE - Dentry
*/
enum {
SEG_SUPER = 0x01,
SEG_JOURNAL = 0x02,
SEG_OSTORE = 0x03,
};
/**
* struct logfs_segment_header - per-segment header in the ostore
*
* @crc: crc32 of header (there is no data)
* @pad: unused, must be 0
* @type: segment type, see above
* @level: GC level for all objects in this segment
* @segno: segment number
* @ec: erase count for this segment
* @gec: global erase count at time of writing
*/
struct logfs_segment_header {
__be32 crc;
__be16 pad;
__u8 type;
__u8 level;
__be32 segno;
__be32 ec;
__be64 gec;
};
SIZE_CHECK(logfs_segment_header, LOGFS_SEGMENT_HEADERSIZE);
#define LOGFS_FEATURES_INCOMPAT (0ull)
#define LOGFS_FEATURES_RO_COMPAT (0ull)
#define LOGFS_FEATURES_COMPAT (0ull)
/**
* struct logfs_disk_super - on-medium superblock
*
* @ds_magic: magic number, must equal LOGFS_MAGIC
* @ds_crc: crc32 of structure starting with the next field
* @ds_ifile_levels: maximum number of levels for ifile
* @ds_iblock_levels: maximum number of levels for regular files
* @ds_data_levels: number of separate levels for data
* @pad0: reserved, must be 0
* @ds_feature_incompat: incompatible filesystem features
* @ds_feature_ro_compat: read-only compatible filesystem features
* @ds_feature_compat: compatible filesystem features
* @ds_flags: flags
* @ds_segment_shift: log2 of segment size
* @ds_block_shift: log2 of block size
* @ds_write_shift: log2 of write size
* @pad1: reserved, must be 0
* @ds_journal_seg: segments used by primary journal
* @ds_root_reserve: bytes reserved for the superuser
* @ds_speed_reserve: bytes reserved to speed up GC
* @ds_bad_seg_reserve: number of segments reserved to handle bad blocks
* @pad2: reserved, must be 0
* @pad3: reserved, must be 0
*
* Contains only read-only fields. Read-write fields like the amount of used
* space is tracked in the dynamic superblock, which is stored in the journal.
*/
struct logfs_disk_super {
struct logfs_segment_header ds_sh;
__be64 ds_magic;
__be32 ds_crc;
__u8 ds_ifile_levels;
__u8 ds_iblock_levels;
__u8 ds_data_levels;
__u8 ds_segment_shift;
__u8 ds_block_shift;
__u8 ds_write_shift;
__u8 pad0[6];
__be64 ds_filesystem_size;
__be32 ds_segment_size;
__be32 ds_bad_seg_reserve;
__be64 ds_feature_incompat;
__be64 ds_feature_ro_compat;
__be64 ds_feature_compat;
__be64 ds_feature_flags;
__be64 ds_root_reserve;
__be64 ds_speed_reserve;
__be32 ds_journal_seg[LOGFS_JOURNAL_SEGS];
__be64 ds_super_ofs[2];
__be64 pad3[8];
};
SIZE_CHECK(logfs_disk_super, 256);
/*
* Object types:
* OBJ_BLOCK - Data or indirect block
* OBJ_INODE - Inode
* OBJ_DENTRY - Dentry
*/
enum {
OBJ_BLOCK = 0x04,
OBJ_INODE = 0x05,
OBJ_DENTRY = 0x06,
};
/**
* struct logfs_object_header - per-object header in the ostore
*
* @crc: crc32 of header, excluding data_crc
* @len: length of data
* @type: object type, see above
* @compr: compression type
* @ino: inode number
* @bix: block index
* @data_crc: crc32 of payload
*/
struct logfs_object_header {
__be32 crc;
__be16 len;
__u8 type;
__u8 compr;
__be64 ino;
__be64 bix;
__be32 data_crc;
} __attribute__((packed));
SIZE_CHECK(logfs_object_header, LOGFS_OBJECT_HEADERSIZE);
/*
* Reserved inode numbers:
* LOGFS_INO_MASTER - master inode (for inode file)
* LOGFS_INO_ROOT - root directory
* LOGFS_INO_SEGFILE - per-segment used bytes and erase count
*/
enum {
LOGFS_INO_MAPPING = 0x00,
LOGFS_INO_MASTER = 0x01,
LOGFS_INO_ROOT = 0x02,
LOGFS_INO_SEGFILE = 0x03,
LOGFS_RESERVED_INOS = 0x10,
};
/*
* Inode flags. High bits should never be written to the medium. They are
* reserved for in-memory usage.
* Low bits should either remain in sync with the corresponding FS_*_FL or
* reuse slots that obviously don't make sense for logfs.
*
* LOGFS_IF_DIRTY Inode must be written back
* LOGFS_IF_ZOMBIE Inode has been deleted
* LOGFS_IF_STILLBORN -ENOSPC happened when creating inode
*/
#define LOGFS_IF_COMPRESSED 0x00000004 /* == FS_COMPR_FL */
#define LOGFS_IF_DIRTY 0x20000000
#define LOGFS_IF_ZOMBIE 0x40000000
#define LOGFS_IF_STILLBORN 0x80000000
/* Flags available to chattr */
#define LOGFS_FL_USER_VISIBLE (LOGFS_IF_COMPRESSED)
#define LOGFS_FL_USER_MODIFIABLE (LOGFS_IF_COMPRESSED)
/* Flags inherited from parent directory on file/directory creation */
#define LOGFS_FL_INHERITED (LOGFS_IF_COMPRESSED)
/**
* struct logfs_disk_inode - on-medium inode
*
* @di_mode: file mode
* @di_pad: reserved, must be 0
* @di_flags: inode flags, see above
* @di_uid: user id
* @di_gid: group id
* @di_ctime: change time
* @di_mtime: modify time
* @di_refcount: reference count (aka nlink or link count)
* @di_generation: inode generation, for nfs
* @di_used_bytes: number of bytes used
* @di_size: file size
* @di_data: data pointers
*/
struct logfs_disk_inode {
__be16 di_mode;
__u8 di_height;
__u8 di_pad;
__be32 di_flags;
__be32 di_uid;
__be32 di_gid;
__be64 di_ctime;
__be64 di_mtime;
__be64 di_atime;
__be32 di_refcount;
__be32 di_generation;
__be64 di_used_bytes;
__be64 di_size;
__be64 di_data[LOGFS_EMBEDDED_FIELDS];
};
SIZE_CHECK(logfs_disk_inode, 200);
#define INODE_POINTER_OFS \
(offsetof(struct logfs_disk_inode, di_data) / sizeof(__be64))
#define INODE_USED_OFS \
(offsetof(struct logfs_disk_inode, di_used_bytes) / sizeof(__be64))
#define INODE_SIZE_OFS \
(offsetof(struct logfs_disk_inode, di_size) / sizeof(__be64))
#define INODE_HEIGHT_OFS (0)
/**
* struct logfs_disk_dentry - on-medium dentry structure
*
* @ino: inode number
* @namelen: length of file name
* @type: file type, identical to bits 12..15 of mode
* @name: file name
*/
/* FIXME: add 6 bytes of padding to remove the __packed */
struct logfs_disk_dentry {
__be64 ino;
__be16 namelen;
__u8 type;
__u8 name[LOGFS_MAX_NAMELEN];
} __attribute__((packed));
SIZE_CHECK(logfs_disk_dentry, 266);
#define RESERVED 0xffffffff
#define BADSEG 0xffffffff
/**
* struct logfs_segment_entry - segment file entry
*
* @ec_level: erase count and level
* @valid: number of valid bytes
*
* Segment file contains one entry for every segment. ec_level contains the
* erasecount in the upper 28 bits and the level in the lower 4 bits. An
* ec_level of BADSEG (-1) identifies bad segments. valid contains the number
* of valid bytes or RESERVED (-1 again) if the segment is used for either the
* superblock or the journal, or when the segment is bad.
*/
struct logfs_segment_entry {
__be32 ec_level;
__be32 valid;
};
SIZE_CHECK(logfs_segment_entry, 8);
/**
* struct logfs_journal_header - header for journal entries (JEs)
*
* @h_crc: crc32 of journal entry
* @h_len: length of compressed journal entry,
* not including header
* @h_datalen: length of uncompressed data
* @h_type: JE type
* @h_compr: compression type
* @h_pad: reserved
*/
struct logfs_journal_header {
__be32 h_crc;
__be16 h_len;
__be16 h_datalen;
__be16 h_type;
__u8 h_compr;
__u8 h_pad[5];
};
SIZE_CHECK(logfs_journal_header, 16);
/*
* Life expectency of data.
* VIM_DEFAULT - default vim
* VIM_SEGFILE - for segment file only - very short-living
* VIM_GC - GC'd data - likely long-living
*/
enum logfs_vim {
VIM_DEFAULT = 0,
VIM_SEGFILE = 1,
};
/**
* struct logfs_je_area - wbuf header
*
* @segno: segment number of area
* @used_bytes: number of bytes already used
* @gc_level: GC level
* @vim: life expectancy of data
*
* "Areas" are segments currently being used for writing. There is at least
* one area per GC level. Several may be used to separate long-living from
* short-living data. If an area with unknown vim is encountered, it can
* simply be closed.
* The write buffer immediately follow this header.
*/
struct logfs_je_area {
__be32 segno;
__be32 used_bytes;
__u8 gc_level;
__u8 vim;
} __attribute__((packed));
SIZE_CHECK(logfs_je_area, 10);
#define MAX_JOURNAL_HEADER \
(sizeof(struct logfs_journal_header) + sizeof(struct logfs_je_area))
/**
* struct logfs_je_dynsb - dynamic superblock
*
* @ds_gec: global erase count
* @ds_sweeper: current position of GC "sweeper"
* @ds_rename_dir: source directory ino (see dir.c documentation)
* @ds_rename_pos: position of source dd (see dir.c documentation)
* @ds_victim_ino: victims of incomplete dir operation (see dir.c)
* @ds_victim_ino: parent inode of victim (see dir.c)
* @ds_used_bytes: number of used bytes
*/
struct logfs_je_dynsb {
__be64 ds_gec;
__be64 ds_sweeper;
__be64 ds_rename_dir;
__be64 ds_rename_pos;
__be64 ds_victim_ino;
__be64 ds_victim_parent; /* XXX */
__be64 ds_used_bytes;
__be32 ds_generation;
__be32 pad;
};
SIZE_CHECK(logfs_je_dynsb, 64);
/**
* struct logfs_je_anchor - anchor of filesystem tree, aka master inode
*
* @da_size: size of inode file
* @da_last_ino: last created inode
* @da_used_bytes: number of bytes used
* @da_data: data pointers
*/
struct logfs_je_anchor {
__be64 da_size;
__be64 da_last_ino;
__be64 da_used_bytes;
u8 da_height;
u8 pad[7];
__be64 da_data[LOGFS_EMBEDDED_FIELDS];
};
SIZE_CHECK(logfs_je_anchor, 168);
/**
* struct logfs_je_spillout - spillout entry (from 1st to 2nd journal)
*
* @so_segment: segments used for 2nd journal
*
* Length of the array is given by h_len field in the header.
*/
struct logfs_je_spillout {
__be64 so_segment[0];
};
SIZE_CHECK(logfs_je_spillout, 0);
/**
* struct logfs_je_journal_ec - erase counts for all journal segments
*
* @ec: erase count
*
* Length of the array is given by h_len field in the header.
*/
struct logfs_je_journal_ec {
__be32 ec[0];
};
SIZE_CHECK(logfs_je_journal_ec, 0);
/**
* struct logfs_je_free_segments - list of free segmetns with erase count
*/
struct logfs_je_free_segments {
__be32 segno;
__be32 ec;
};
SIZE_CHECK(logfs_je_free_segments, 8);
/**
* struct logfs_seg_alias - list of segment aliases
*/
struct logfs_seg_alias {
__be32 old_segno;
__be32 new_segno;
};
SIZE_CHECK(logfs_seg_alias, 8);
/**
* struct logfs_obj_alias - list of object aliases
*/
struct logfs_obj_alias {
__be64 ino;
__be64 bix;
__be64 val;
u8 level;
u8 pad[5];
__be16 child_no;
};
SIZE_CHECK(logfs_obj_alias, 32);
/**
* Compression types.
*
* COMPR_NONE - uncompressed
* COMPR_ZLIB - compressed with zlib
*/
enum {
COMPR_NONE = 0,
COMPR_ZLIB = 1,
};
/*
* Journal entries come in groups of 16. First group contains unique
* entries, next groups contain one entry per level
*
* JE_FIRST - smallest possible journal entry number
*
* JEG_BASE - base group, containing unique entries
* JE_COMMIT - commit entry, validates all previous entries
* JE_DYNSB - dynamic superblock, anything that ought to be in the
* superblock but cannot because it is read-write data
* JE_ANCHOR - anchor aka master inode aka inode file's inode
* JE_ERASECOUNT erasecounts for all journal segments
* JE_SPILLOUT - unused
* JE_SEG_ALIAS - aliases segments
* JE_AREA - area description
*
* JE_LAST - largest possible journal entry number
*/
enum {
JE_FIRST = 0x01,
JEG_BASE = 0x00,
JE_COMMIT = 0x02,
JE_DYNSB = 0x03,
JE_ANCHOR = 0x04,
JE_ERASECOUNT = 0x05,
JE_SPILLOUT = 0x06,
JE_OBJ_ALIAS = 0x0d,
JE_AREA = 0x0e,
JE_LAST = 0x0e,
};
#endif