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Diffstat (limited to 'fs/logfs/logfs_abi.h')
| -rw-r--r-- | fs/logfs/logfs_abi.h | 629 |
1 files changed, 629 insertions, 0 deletions
diff --git a/fs/logfs/logfs_abi.h b/fs/logfs/logfs_abi.h new file mode 100644 index 000000000..ae960519c --- /dev/null +++ b/fs/logfs/logfs_abi.h @@ -0,0 +1,629 @@ +/* + * 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 |