--- /dev/null
+/*
+ * 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
Code Review / kvmfornfv.git / blobdiff