1 /* 2 * Copyright (c) 2000-2003,2005 Silicon Graphics, Inc. 3 * All Rights Reserved. 4 * 5 * This program is free software; you can redistribute it and/or 6 * modify it under the terms of the GNU General Public License as 7 * published by the Free Software Foundation. 8 * 9 * This program is distributed in the hope that it would be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, write the Free Software Foundation, 16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 17 */ 18 #ifndef __XFS_LOG_PRIV_H__ 19 #define __XFS_LOG_PRIV_H__ 20 21 struct xfs_buf; 22 struct xlog; 23 struct xlog_ticket; 24 struct xfs_mount; 25 struct xfs_log_callback; 26 27 /* 28 * Flags for log structure 29 */ 30 #define XLOG_ACTIVE_RECOVERY 0x2 /* in the middle of recovery */ 31 #define XLOG_RECOVERY_NEEDED 0x4 /* log was recovered */ 32 #define XLOG_IO_ERROR 0x8 /* log hit an I/O error, and being 33 shutdown */ 34 #define XLOG_TAIL_WARN 0x10 /* log tail verify warning issued */ 35 36 /* 37 * get client id from packed copy. 38 * 39 * this hack is here because the xlog_pack code copies four bytes 40 * of xlog_op_header containing the fields oh_clientid, oh_flags 41 * and oh_res2 into the packed copy. 42 * 43 * later on this four byte chunk is treated as an int and the 44 * client id is pulled out. 45 * 46 * this has endian issues, of course. 47 */ 48 static inline uint xlog_get_client_id(__be32 i) 49 { 50 return be32_to_cpu(i) >> 24; 51 } 52 53 /* 54 * In core log state 55 */ 56 #define XLOG_STATE_ACTIVE 0x0001 /* Current IC log being written to */ 57 #define XLOG_STATE_WANT_SYNC 0x0002 /* Want to sync this iclog; no more writes */ 58 #define XLOG_STATE_SYNCING 0x0004 /* This IC log is syncing */ 59 #define XLOG_STATE_DONE_SYNC 0x0008 /* Done syncing to disk */ 60 #define XLOG_STATE_DO_CALLBACK \ 61 0x0010 /* Process callback functions */ 62 #define XLOG_STATE_CALLBACK 0x0020 /* Callback functions now */ 63 #define XLOG_STATE_DIRTY 0x0040 /* Dirty IC log, not ready for ACTIVE status*/ 64 #define XLOG_STATE_IOERROR 0x0080 /* IO error happened in sync'ing log */ 65 #define XLOG_STATE_ALL 0x7FFF /* All possible valid flags */ 66 #define XLOG_STATE_NOTUSED 0x8000 /* This IC log not being used */ 67 68 /* 69 * Flags to log ticket 70 */ 71 #define XLOG_TIC_INITED 0x1 /* has been initialized */ 72 #define XLOG_TIC_PERM_RESERV 0x2 /* permanent reservation */ 73 74 #define XLOG_TIC_FLAGS \ 75 { XLOG_TIC_INITED, "XLOG_TIC_INITED" }, \ 76 { XLOG_TIC_PERM_RESERV, "XLOG_TIC_PERM_RESERV" } 77 78 /* 79 * Below are states for covering allocation transactions. 80 * By covering, we mean changing the h_tail_lsn in the last on-disk 81 * log write such that no allocation transactions will be re-done during 82 * recovery after a system crash. Recovery starts at the last on-disk 83 * log write. 84 * 85 * These states are used to insert dummy log entries to cover 86 * space allocation transactions which can undo non-transactional changes 87 * after a crash. Writes to a file with space 88 * already allocated do not result in any transactions. Allocations 89 * might include space beyond the EOF. So if we just push the EOF a 90 * little, the last transaction for the file could contain the wrong 91 * size. If there is no file system activity, after an allocation 92 * transaction, and the system crashes, the allocation transaction 93 * will get replayed and the file will be truncated. This could 94 * be hours/days/... after the allocation occurred. 95 * 96 * The fix for this is to do two dummy transactions when the 97 * system is idle. We need two dummy transaction because the h_tail_lsn 98 * in the log record header needs to point beyond the last possible 99 * non-dummy transaction. The first dummy changes the h_tail_lsn to 100 * the first transaction before the dummy. The second dummy causes 101 * h_tail_lsn to point to the first dummy. Recovery starts at h_tail_lsn. 102 * 103 * These dummy transactions get committed when everything 104 * is idle (after there has been some activity). 105 * 106 * There are 5 states used to control this. 107 * 108 * IDLE -- no logging has been done on the file system or 109 * we are done covering previous transactions. 110 * NEED -- logging has occurred and we need a dummy transaction 111 * when the log becomes idle. 112 * DONE -- we were in the NEED state and have committed a dummy 113 * transaction. 114 * NEED2 -- we detected that a dummy transaction has gone to the 115 * on disk log with no other transactions. 116 * DONE2 -- we committed a dummy transaction when in the NEED2 state. 117 * 118 * There are two places where we switch states: 119 * 120 * 1.) In xfs_sync, when we detect an idle log and are in NEED or NEED2. 121 * We commit the dummy transaction and switch to DONE or DONE2, 122 * respectively. In all other states, we don't do anything. 123 * 124 * 2.) When we finish writing the on-disk log (xlog_state_clean_log). 125 * 126 * No matter what state we are in, if this isn't the dummy 127 * transaction going out, the next state is NEED. 128 * So, if we aren't in the DONE or DONE2 states, the next state 129 * is NEED. We can't be finishing a write of the dummy record 130 * unless it was committed and the state switched to DONE or DONE2. 131 * 132 * If we are in the DONE state and this was a write of the 133 * dummy transaction, we move to NEED2. 134 * 135 * If we are in the DONE2 state and this was a write of the 136 * dummy transaction, we move to IDLE. 137 * 138 * 139 * Writing only one dummy transaction can get appended to 140 * one file space allocation. When this happens, the log recovery 141 * code replays the space allocation and a file could be truncated. 142 * This is why we have the NEED2 and DONE2 states before going idle. 143 */ 144 145 #define XLOG_STATE_COVER_IDLE 0 146 #define XLOG_STATE_COVER_NEED 1 147 #define XLOG_STATE_COVER_DONE 2 148 #define XLOG_STATE_COVER_NEED2 3 149 #define XLOG_STATE_COVER_DONE2 4 150 151 #define XLOG_COVER_OPS 5 152 153 /* Ticket reservation region accounting */ 154 #define XLOG_TIC_LEN_MAX 15 155 156 /* 157 * Reservation region 158 * As would be stored in xfs_log_iovec but without the i_addr which 159 * we don't care about. 160 */ 161 typedef struct xlog_res { 162 uint r_len; /* region length :4 */ 163 uint r_type; /* region's transaction type :4 */ 164 } xlog_res_t; 165 166 typedef struct xlog_ticket { 167 struct list_head t_queue; /* reserve/write queue */ 168 struct task_struct *t_task; /* task that owns this ticket */ 169 xlog_tid_t t_tid; /* transaction identifier : 4 */ 170 atomic_t t_ref; /* ticket reference count : 4 */ 171 int t_curr_res; /* current reservation in bytes : 4 */ 172 int t_unit_res; /* unit reservation in bytes : 4 */ 173 char t_ocnt; /* original count : 1 */ 174 char t_cnt; /* current count : 1 */ 175 char t_clientid; /* who does this belong to; : 1 */ 176 char t_flags; /* properties of reservation : 1 */ 177 uint t_trans_type; /* transaction type : 4 */ 178 179 /* reservation array fields */ 180 uint t_res_num; /* num in array : 4 */ 181 uint t_res_num_ophdrs; /* num op hdrs : 4 */ 182 uint t_res_arr_sum; /* array sum : 4 */ 183 uint t_res_o_flow; /* sum overflow : 4 */ 184 xlog_res_t t_res_arr[XLOG_TIC_LEN_MAX]; /* array of res : 8 * 15 */ 185 } xlog_ticket_t; 186 187 /* 188 * - A log record header is 512 bytes. There is plenty of room to grow the 189 * xlog_rec_header_t into the reserved space. 190 * - ic_data follows, so a write to disk can start at the beginning of 191 * the iclog. 192 * - ic_forcewait is used to implement synchronous forcing of the iclog to disk. 193 * - ic_next is the pointer to the next iclog in the ring. 194 * - ic_bp is a pointer to the buffer used to write this incore log to disk. 195 * - ic_log is a pointer back to the global log structure. 196 * - ic_callback is a linked list of callback function/argument pairs to be 197 * called after an iclog finishes writing. 198 * - ic_size is the full size of the header plus data. 199 * - ic_offset is the current number of bytes written to in this iclog. 200 * - ic_refcnt is bumped when someone is writing to the log. 201 * - ic_state is the state of the iclog. 202 * 203 * Because of cacheline contention on large machines, we need to separate 204 * various resources onto different cachelines. To start with, make the 205 * structure cacheline aligned. The following fields can be contended on 206 * by independent processes: 207 * 208 * - ic_callback_* 209 * - ic_refcnt 210 * - fields protected by the global l_icloglock 211 * 212 * so we need to ensure that these fields are located in separate cachelines. 213 * We'll put all the read-only and l_icloglock fields in the first cacheline, 214 * and move everything else out to subsequent cachelines. 215 */ 216 typedef struct xlog_in_core { 217 wait_queue_head_t ic_force_wait; 218 wait_queue_head_t ic_write_wait; 219 struct xlog_in_core *ic_next; 220 struct xlog_in_core *ic_prev; 221 struct xfs_buf *ic_bp; 222 struct xlog *ic_log; 223 int ic_size; 224 int ic_offset; 225 int ic_bwritecnt; 226 unsigned short ic_state; 227 char *ic_datap; /* pointer to iclog data */ 228 229 /* Callback structures need their own cacheline */ 230 spinlock_t ic_callback_lock ____cacheline_aligned_in_smp; 231 struct xfs_log_callback *ic_callback; 232 struct xfs_log_callback **ic_callback_tail; 233 234 /* reference counts need their own cacheline */ 235 atomic_t ic_refcnt ____cacheline_aligned_in_smp; 236 xlog_in_core_2_t *ic_data; 237 #define ic_header ic_data->hic_header 238 } xlog_in_core_t; 239 240 /* 241 * The CIL context is used to aggregate per-transaction details as well be 242 * passed to the iclog for checkpoint post-commit processing. After being 243 * passed to the iclog, another context needs to be allocated for tracking the 244 * next set of transactions to be aggregated into a checkpoint. 245 */ 246 struct xfs_cil; 247 248 struct xfs_cil_ctx { 249 struct xfs_cil *cil; 250 xfs_lsn_t sequence; /* chkpt sequence # */ 251 xfs_lsn_t start_lsn; /* first LSN of chkpt commit */ 252 xfs_lsn_t commit_lsn; /* chkpt commit record lsn */ 253 struct xlog_ticket *ticket; /* chkpt ticket */ 254 int nvecs; /* number of regions */ 255 int space_used; /* aggregate size of regions */ 256 struct list_head busy_extents; /* busy extents in chkpt */ 257 struct xfs_log_vec *lv_chain; /* logvecs being pushed */ 258 struct xfs_log_callback log_cb; /* completion callback hook. */ 259 struct list_head committing; /* ctx committing list */ 260 }; 261 262 /* 263 * Committed Item List structure 264 * 265 * This structure is used to track log items that have been committed but not 266 * yet written into the log. It is used only when the delayed logging mount 267 * option is enabled. 268 * 269 * This structure tracks the list of committing checkpoint contexts so 270 * we can avoid the problem of having to hold out new transactions during a 271 * flush until we have a the commit record LSN of the checkpoint. We can 272 * traverse the list of committing contexts in xlog_cil_push_lsn() to find a 273 * sequence match and extract the commit LSN directly from there. If the 274 * checkpoint is still in the process of committing, we can block waiting for 275 * the commit LSN to be determined as well. This should make synchronous 276 * operations almost as efficient as the old logging methods. 277 */ 278 struct xfs_cil { 279 struct xlog *xc_log; 280 struct list_head xc_cil; 281 spinlock_t xc_cil_lock; 282 283 struct rw_semaphore xc_ctx_lock ____cacheline_aligned_in_smp; 284 struct xfs_cil_ctx *xc_ctx; 285 286 spinlock_t xc_push_lock ____cacheline_aligned_in_smp; 287 xfs_lsn_t xc_push_seq; 288 struct list_head xc_committing; 289 wait_queue_head_t xc_commit_wait; 290 xfs_lsn_t xc_current_sequence; 291 struct work_struct xc_push_work; 292 } ____cacheline_aligned_in_smp; 293 294 /* 295 * The amount of log space we allow the CIL to aggregate is difficult to size. 296 * Whatever we choose, we have to make sure we can get a reservation for the 297 * log space effectively, that it is large enough to capture sufficient 298 * relogging to reduce log buffer IO significantly, but it is not too large for 299 * the log or induces too much latency when writing out through the iclogs. We 300 * track both space consumed and the number of vectors in the checkpoint 301 * context, so we need to decide which to use for limiting. 302 * 303 * Every log buffer we write out during a push needs a header reserved, which 304 * is at least one sector and more for v2 logs. Hence we need a reservation of 305 * at least 512 bytes per 32k of log space just for the LR headers. That means 306 * 16KB of reservation per megabyte of delayed logging space we will consume, 307 * plus various headers. The number of headers will vary based on the num of 308 * io vectors, so limiting on a specific number of vectors is going to result 309 * in transactions of varying size. IOWs, it is more consistent to track and 310 * limit space consumed in the log rather than by the number of objects being 311 * logged in order to prevent checkpoint ticket overruns. 312 * 313 * Further, use of static reservations through the log grant mechanism is 314 * problematic. It introduces a lot of complexity (e.g. reserve grant vs write 315 * grant) and a significant deadlock potential because regranting write space 316 * can block on log pushes. Hence if we have to regrant log space during a log 317 * push, we can deadlock. 318 * 319 * However, we can avoid this by use of a dynamic "reservation stealing" 320 * technique during transaction commit whereby unused reservation space in the 321 * transaction ticket is transferred to the CIL ctx commit ticket to cover the 322 * space needed by the checkpoint transaction. This means that we never need to 323 * specifically reserve space for the CIL checkpoint transaction, nor do we 324 * need to regrant space once the checkpoint completes. This also means the 325 * checkpoint transaction ticket is specific to the checkpoint context, rather 326 * than the CIL itself. 327 * 328 * With dynamic reservations, we can effectively make up arbitrary limits for 329 * the checkpoint size so long as they don't violate any other size rules. 330 * Recovery imposes a rule that no transaction exceed half the log, so we are 331 * limited by that. Furthermore, the log transaction reservation subsystem 332 * tries to keep 25% of the log free, so we need to keep below that limit or we 333 * risk running out of free log space to start any new transactions. 334 * 335 * In order to keep background CIL push efficient, we will set a lower 336 * threshold at which background pushing is attempted without blocking current 337 * transaction commits. A separate, higher bound defines when CIL pushes are 338 * enforced to ensure we stay within our maximum checkpoint size bounds. 339 * threshold, yet give us plenty of space for aggregation on large logs. 340 */ 341 #define XLOG_CIL_SPACE_LIMIT(log) (log->l_logsize >> 3) 342 343 /* 344 * ticket grant locks, queues and accounting have their own cachlines 345 * as these are quite hot and can be operated on concurrently. 346 */ 347 struct xlog_grant_head { 348 spinlock_t lock ____cacheline_aligned_in_smp; 349 struct list_head waiters; 350 atomic64_t grant; 351 }; 352 353 /* 354 * The reservation head lsn is not made up of a cycle number and block number. 355 * Instead, it uses a cycle number and byte number. Logs don't expect to 356 * overflow 31 bits worth of byte offset, so using a byte number will mean 357 * that round off problems won't occur when releasing partial reservations. 358 */ 359 struct xlog { 360 /* The following fields don't need locking */ 361 struct xfs_mount *l_mp; /* mount point */ 362 struct xfs_ail *l_ailp; /* AIL log is working with */ 363 struct xfs_cil *l_cilp; /* CIL log is working with */ 364 struct xfs_buf *l_xbuf; /* extra buffer for log 365 * wrapping */ 366 struct xfs_buftarg *l_targ; /* buftarg of log */ 367 struct delayed_work l_work; /* background flush work */ 368 uint l_flags; 369 uint l_quotaoffs_flag; /* XFS_DQ_*, for QUOTAOFFs */ 370 struct list_head *l_buf_cancel_table; 371 int l_iclog_hsize; /* size of iclog header */ 372 int l_iclog_heads; /* # of iclog header sectors */ 373 uint l_sectBBsize; /* sector size in BBs (2^n) */ 374 int l_iclog_size; /* size of log in bytes */ 375 int l_iclog_size_log; /* log power size of log */ 376 int l_iclog_bufs; /* number of iclog buffers */ 377 xfs_daddr_t l_logBBstart; /* start block of log */ 378 int l_logsize; /* size of log in bytes */ 379 int l_logBBsize; /* size of log in BB chunks */ 380 381 /* The following block of fields are changed while holding icloglock */ 382 wait_queue_head_t l_flush_wait ____cacheline_aligned_in_smp; 383 /* waiting for iclog flush */ 384 int l_covered_state;/* state of "covering disk 385 * log entries" */ 386 xlog_in_core_t *l_iclog; /* head log queue */ 387 spinlock_t l_icloglock; /* grab to change iclog state */ 388 int l_curr_cycle; /* Cycle number of log writes */ 389 int l_prev_cycle; /* Cycle number before last 390 * block increment */ 391 int l_curr_block; /* current logical log block */ 392 int l_prev_block; /* previous logical log block */ 393 394 /* 395 * l_last_sync_lsn and l_tail_lsn are atomics so they can be set and 396 * read without needing to hold specific locks. To avoid operations 397 * contending with other hot objects, place each of them on a separate 398 * cacheline. 399 */ 400 /* lsn of last LR on disk */ 401 atomic64_t l_last_sync_lsn ____cacheline_aligned_in_smp; 402 /* lsn of 1st LR with unflushed * buffers */ 403 atomic64_t l_tail_lsn ____cacheline_aligned_in_smp; 404 405 struct xlog_grant_head l_reserve_head; 406 struct xlog_grant_head l_write_head; 407 408 struct xfs_kobj l_kobj; 409 410 /* The following field are used for debugging; need to hold icloglock */ 411 #ifdef DEBUG 412 char *l_iclog_bak[XLOG_MAX_ICLOGS]; 413 #endif 414 415 }; 416 417 #define XLOG_BUF_CANCEL_BUCKET(log, blkno) \ 418 ((log)->l_buf_cancel_table + ((__uint64_t)blkno % XLOG_BC_TABLE_SIZE)) 419 420 #define XLOG_FORCED_SHUTDOWN(log) ((log)->l_flags & XLOG_IO_ERROR) 421 422 /* common routines */ 423 extern int 424 xlog_recover( 425 struct xlog *log); 426 extern int 427 xlog_recover_finish( 428 struct xlog *log); 429 430 extern __le32 xlog_cksum(struct xlog *log, struct xlog_rec_header *rhead, 431 char *dp, int size); 432 433 extern kmem_zone_t *xfs_log_ticket_zone; 434 struct xlog_ticket * 435 xlog_ticket_alloc( 436 struct xlog *log, 437 int unit_bytes, 438 int count, 439 char client, 440 bool permanent, 441 xfs_km_flags_t alloc_flags); 442 443 444 static inline void 445 xlog_write_adv_cnt(void **ptr, int *len, int *off, size_t bytes) 446 { 447 *ptr += bytes; 448 *len -= bytes; 449 *off += bytes; 450 } 451 452 void xlog_print_tic_res(struct xfs_mount *mp, struct xlog_ticket *ticket); 453 int 454 xlog_write( 455 struct xlog *log, 456 struct xfs_log_vec *log_vector, 457 struct xlog_ticket *tic, 458 xfs_lsn_t *start_lsn, 459 struct xlog_in_core **commit_iclog, 460 uint flags); 461 462 /* 463 * When we crack an atomic LSN, we sample it first so that the value will not 464 * change while we are cracking it into the component values. This means we 465 * will always get consistent component values to work from. This should always 466 * be used to sample and crack LSNs that are stored and updated in atomic 467 * variables. 468 */ 469 static inline void 470 xlog_crack_atomic_lsn(atomic64_t *lsn, uint *cycle, uint *block) 471 { 472 xfs_lsn_t val = atomic64_read(lsn); 473 474 *cycle = CYCLE_LSN(val); 475 *block = BLOCK_LSN(val); 476 } 477 478 /* 479 * Calculate and assign a value to an atomic LSN variable from component pieces. 480 */ 481 static inline void 482 xlog_assign_atomic_lsn(atomic64_t *lsn, uint cycle, uint block) 483 { 484 atomic64_set(lsn, xlog_assign_lsn(cycle, block)); 485 } 486 487 /* 488 * When we crack the grant head, we sample it first so that the value will not 489 * change while we are cracking it into the component values. This means we 490 * will always get consistent component values to work from. 491 */ 492 static inline void 493 xlog_crack_grant_head_val(int64_t val, int *cycle, int *space) 494 { 495 *cycle = val >> 32; 496 *space = val & 0xffffffff; 497 } 498 499 static inline void 500 xlog_crack_grant_head(atomic64_t *head, int *cycle, int *space) 501 { 502 xlog_crack_grant_head_val(atomic64_read(head), cycle, space); 503 } 504 505 static inline int64_t 506 xlog_assign_grant_head_val(int cycle, int space) 507 { 508 return ((int64_t)cycle << 32) | space; 509 } 510 511 static inline void 512 xlog_assign_grant_head(atomic64_t *head, int cycle, int space) 513 { 514 atomic64_set(head, xlog_assign_grant_head_val(cycle, space)); 515 } 516 517 /* 518 * Committed Item List interfaces 519 */ 520 int xlog_cil_init(struct xlog *log); 521 void xlog_cil_init_post_recovery(struct xlog *log); 522 void xlog_cil_destroy(struct xlog *log); 523 bool xlog_cil_empty(struct xlog *log); 524 525 /* 526 * CIL force routines 527 */ 528 xfs_lsn_t 529 xlog_cil_force_lsn( 530 struct xlog *log, 531 xfs_lsn_t sequence); 532 533 static inline void 534 xlog_cil_force(struct xlog *log) 535 { 536 xlog_cil_force_lsn(log, log->l_cilp->xc_current_sequence); 537 } 538 539 /* 540 * Unmount record type is used as a pseudo transaction type for the ticket. 541 * It's value must be outside the range of XFS_TRANS_* values. 542 */ 543 #define XLOG_UNMOUNT_REC_TYPE (-1U) 544 545 /* 546 * Wrapper function for waiting on a wait queue serialised against wakeups 547 * by a spinlock. This matches the semantics of all the wait queues used in the 548 * log code. 549 */ 550 static inline void xlog_wait(wait_queue_head_t *wq, spinlock_t *lock) 551 { 552 DECLARE_WAITQUEUE(wait, current); 553 554 add_wait_queue_exclusive(wq, &wait); 555 __set_current_state(TASK_UNINTERRUPTIBLE); 556 spin_unlock(lock); 557 schedule(); 558 remove_wait_queue(wq, &wait); 559 } 560 561 #endif /* __XFS_LOG_PRIV_H__ */ 562