ceph主要数据结构解析2-Rados.h文件
(1)文件系统id结构:16个字符组成
struct ceph_fsid { unsigned char fsid[16]; };
以及对应的比较函数:
static inline int ceph_fsid_compare(const struct ceph_fsid *a, const struct ceph_fsid *b) { return memcmp(a, b, sizeof(*a)); }
(2)定义保留的snap的id宏
typedef __le64 ceph_snapid_t; #define CEPH_SNAPDIR ((__u64)(-1)) /* reserved for hidden .snap dir */ #define CEPH_NOSNAP ((__u64)(-2)) /* "head", "live" revision */ #define CEPH_MAXSNAP ((__u64)(-3)) /* largest valid snapid */ struct ceph_timespec {//自定义的时间描述结构体 __le32 tv_sec; __le32 tv_nsec; } __attribute__ ((packed));
(3)对象布局宏:对象怎样放到放置组PG里面去(placement group)
#define CEPH_OBJECT_LAYOUT_HASH 1 //哈希 #define CEPH_OBJECT_LAYOUT_LINEAR 2 //线性 #define CEPH_OBJECT_LAYOUT_HASHINO 3 //哈希inode struct ceph_object_layout {//对象布局 struct ceph_pg ol_pgid; /* raw pg, with _full_ ps precision. */ __le32 ol_stripe_unit; /* for per-object parity, if any */ } __attribute__ ((packed));
(4)PG布局宏:PG怎样放置到存储设备上去
#define CEPH_PG_LAYOUT_CRUSH 0 //CRUSH算法,伪随机hash #define CEPH_PG_LAYOUT_HASH 1 //hash #define CEPH_PG_LAYOUT_LINEAR 2 //线性 #define CEPH_PG_LAYOUT_HYBRID 3 #define CEPH_PG_MAX_SIZE 16 /* max # osds in a single pg */
(5)PG编码到一个64位
struct ceph_pg { __le16 preferred; /* preferred primary osd */参考主osd __le16 ps; /* placement seed */放置种子 __le32 pool; /* object pool */对象池 } __attribute__ ((packed));
下面是两种对象池的宏定义:
#define CEPH_PG_TYPE_REP 1 //冗余 #define CEPH_PG_TYPE_RAID4 2 //raid
控制PG数量的函数定义:保证b小于bmask并且bmask是2的n次方的最小值
随着时间b的增加产生一个稳定的映射
static inline int ceph_stable_mod(int x, int b, int bmask) { if ((x & bmask) < b) return x & bmask; else return x & (bmask >> 1); }
(6)划时代和版本的组合,被用作存储层的序列化突变
struct ceph_eversion { __le32 epoch; __le64 version; } __attribute__ ((packed));
(7)osd(对象存储设备)映射位的宏定义:
#define CEPH_OSD_EXISTS (1<<0) //osd存在 #define CEPH_OSD_UP (1<<1) // #define CEPH_OSD_AUTOOUT (1<<2) /* osd was automatically marked out */自动标出 #define CEPH_OSD_NEW (1<<3) /* osd is new, never marked in */新的,从未标记 extern const char *ceph_osd_state_name(int s);//得到对应的名字,实现如下: const char *ceph_osd_state_name(int s) { switch (s) { case CEPH_OSD_EXISTS: return "exists"; case CEPH_OSD_UP: return "up"; case CEPH_OSD_AUTOOUT: return "autoout"; case CEPH_OSD_NEW: return "new"; default: return "???"; } } /* osd weights. fixed point value: 0x10000 == 1.0 ("in"), 0 == "out" */ osd的权重值:最大为0x10000相当于1.0,最小为0 #define CEPH_OSD_IN 0x10000 #define CEPH_OSD_OUT 0
(8)osd映射标志位定义:
#define CEPH_OSDMAP_NEARFULL (1<<0) /* sync writes (near ENOSPC) */ #define CEPH_OSDMAP_FULL (1<<1) /* no data writes (ENOSPC) */ #define CEPH_OSDMAP_PAUSERD (1<<2) /* pause all reads */暂停所有读 #define CEPH_OSDMAP_PAUSEWR (1<<3) /* pause all writes */ #define CEPH_OSDMAP_PAUSEREC (1<<4) /* pause recovery */ /* * The error code to return when an OSD can't handle a write * because it is too large. */因为数据太大导致OSD不能处理些时返回的错误代码 #define OSD_WRITETOOBIG EMSGSIZE
(9)osd的操作
#define CEPH_OSD_OP_MODE 0xf000 //操作模式 #define CEPH_OSD_OP_MODE_RD 0x1000 //读 #define CEPH_OSD_OP_MODE_WR 0x2000 //写 #define CEPH_OSD_OP_MODE_RMW 0x3000 //读修改写 #define CEPH_OSD_OP_MODE_SUB 0x4000 //子操作 #define CEPH_OSD_OP_TYPE 0x0f00 //操作类型 #define CEPH_OSD_OP_TYPE_LOCK 0x0100 //锁 #define CEPH_OSD_OP_TYPE_DATA 0x0200 //数据 #define CEPH_OSD_OP_TYPE_ATTR 0x0300 //属性 #define CEPH_OSD_OP_TYPE_EXEC 0x0400 //执行 #define CEPH_OSD_OP_TYPE_PG 0x0500 //PG #define CEPH_OSD_OP_TYPE_MULTI 0x0600 /* multiobject */多对象
下面是定义操作模式与类型组合的枚举:
enum { CEPH_OSD_OP_READ = CEPH_OSD_OP_MODE_RD | CEPH_OSD_OP_TYPE_DATA | 1, 中间省略很多... CEPH_OSD_OP_PGLS_FILTER = CEPH_OSD_OP_MODE_RD | CEPH_OSD_OP_TYPE_PG | 2, };
以及定义了判断操作是否为每一种类型或模式的操作,如判断是否为锁操作类型的函数如下:
static inline int ceph_osd_op_type_lock(int op) { return (op & CEPH_OSD_OP_TYPE) == CEPH_OSD_OP_TYPE_LOCK; }
返回操作名称的函数:
extern const char *ceph_osd_op_name(int op);
(10)osd操作标志定义:有详细的英文注释了
enum { CEPH_OSD_FLAG_ACK = 0x0001, /* want (or is) "ack" ack */ CEPH_OSD_FLAG_ONNVRAM = 0x0002, /* want (or is) "onnvram" ack */ CEPH_OSD_FLAG_ONDISK = 0x0004, /* want (or is) "ondisk" ack */ CEPH_OSD_FLAG_RETRY = 0x0008, /* resend attempt */ CEPH_OSD_FLAG_READ = 0x0010, /* op may read */ CEPH_OSD_FLAG_WRITE = 0x0020, /* op may write */ CEPH_OSD_FLAG_ORDERSNAP = 0x0040, /* EOLDSNAP if snapc is out of order */ CEPH_OSD_FLAG_PEERSTAT_OLD = 0x0080, /* DEPRECATED msg includes osd_peer_stat */ CEPH_OSD_FLAG_BALANCE_READS = 0x0100, CEPH_OSD_FLAG_PARALLELEXEC = 0x0200, /* execute op in parallel */ CEPH_OSD_FLAG_PGOP = 0x0400, /* pg op, no object */ CEPH_OSD_FLAG_EXEC = 0x0800, /* op may exec */ CEPH_OSD_FLAG_EXEC_PUBLIC = 0x1000, /* op may exec (public) */ CEPH_OSD_FLAG_LOCALIZE_READS = 0x2000, /* read from nearby replica, if any */ CEPH_OSD_FLAG_RWORDERED = 0x4000, /* order wrt concurrent reads */ }; enum { CEPH_OSD_OP_FLAG_EXCL = 1, /* EXCL object create */ CEPH_OSD_OP_FLAG_FAILOK = 2, /* continue despite failure */ }; #define EOLDSNAPC 85 /* ORDERSNAP flag set; writer has old snapc*/ #define EBLACKLISTED 108 /* blacklisted */
(11)扩展属性比较操作枚举定义:
enum { CEPH_OSD_CMPXATTR_OP_NOP = 0, CEPH_OSD_CMPXATTR_OP_EQ = 1, CEPH_OSD_CMPXATTR_OP_NE = 2, CEPH_OSD_CMPXATTR_OP_GT = 3, CEPH_OSD_CMPXATTR_OP_GTE = 4, CEPH_OSD_CMPXATTR_OP_LT = 5, CEPH_OSD_CMPXATTR_OP_LTE = 6 }; enum { CEPH_OSD_CMPXATTR_MODE_STRING = 1, CEPH_OSD_CMPXATTR_MODE_U64 = 2 };
(12)osd操作结构体封装定义,可能是来至数据有效负载:
struct ceph_osd_op { __le16 op; /* CEPH_OSD_OP_* */ __le32 flags; /* CEPH_OSD_FLAG_* */ union {//各种数据包格式定义 struct { __le64 offset, length;//偏移量和长度 __le64 truncate_size; __le32 truncate_seq; } __attribute__ ((packed)) extent; struct { __le32 name_len; __le32 value_len; __u8 cmp_op; /* CEPH_OSD_CMPXATTR_OP_* */ __u8 cmp_mode; /* CEPH_OSD_CMPXATTR_MODE_* */ } __attribute__ ((packed)) xattr; struct { __u8 class_len; __u8 method_len; __u8 argc; __le32 indata_len; } __attribute__ ((packed)) cls; struct { __le64 count; __le32 start_epoch; /* for the pgls sequence */ } __attribute__ ((packed)) pgls; struct { __le64 snapid; } __attribute__ ((packed)) snap; struct { __le64 cookie; __le64 ver; __u8 flag; /* 0 = unwatch, 1 = watch */ } __attribute__ ((packed)) watch; struct { __le64 offset, length; __le64 src_offset; } __attribute__ ((packed)) clonerange; }; __le32 payload_len;//数据长度 } __attribute__ ((packed)); struct ceph_osd_reply_head {//回复头部 __le32 client_inc; /* client incarnation */ __le32 flags; struct ceph_object_layout layout; __le32 osdmap_epoch; struct ceph_eversion reassert_version; /* for replaying uncommitted */ __le32 result; /* result code */ __le32 object_len; /* length of object name */ __le32 num_ops; //操作数量 struct ceph_osd_op ops[0]; /* ops[], object */存放所有操作 } __attribute__ ((packed));