fs/xfs/xfs_log_priv.h

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