xfs_log_priv.h

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/*
 * Copyright (c) 2000-2003,2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#ifndef __XFS_LOG_PRIV_H__
#define __XFS_LOG_PRIV_H__

struct xfs_buf;
struct xlog;
struct xlog_ticket;
struct xfs_mount;

/*
 * Macros, structures, prototypes for internal log manager use.
 */

#define XLOG_MIN_ICLOGS     2
#define XLOG_MAX_ICLOGS     8
#define XLOG_HEADER_MAGIC_NUM   0xFEEDbabe  /* Invalid cycle number */
#define XLOG_VERSION_1      1
#define XLOG_VERSION_2      2       /* Large IClogs, Log sunit */
#define XLOG_VERSION_OKBITS (XLOG_VERSION_1 | XLOG_VERSION_2)
#define XLOG_MIN_RECORD_BSIZE   (16*1024)   /* eventually 32k */
#define XLOG_BIG_RECORD_BSIZE   (32*1024)   /* 32k buffers */
#define XLOG_MAX_RECORD_BSIZE   (256*1024)
#define XLOG_HEADER_CYCLE_SIZE  (32*1024)   /* cycle data in header */
#define XLOG_MIN_RECORD_BSHIFT  14      /* 16384 == 1 << 14 */
#define XLOG_BIG_RECORD_BSHIFT  15      /* 32k == 1 << 15 */
#define XLOG_MAX_RECORD_BSHIFT  18      /* 256k == 1 << 18 */
#define XLOG_BTOLSUNIT(log, b)  (((b)+(log)->l_mp->m_sb.sb_logsunit-1) / \
                                 (log)->l_mp->m_sb.sb_logsunit)
#define XLOG_LSUNITTOB(log, su) ((su) * (log)->l_mp->m_sb.sb_logsunit)

#define XLOG_HEADER_SIZE    512

#define XLOG_REC_SHIFT(log) \
    BTOBB(1 << (xfs_sb_version_haslogv2(&log->l_mp->m_sb) ? \
     XLOG_MAX_RECORD_BSHIFT : XLOG_BIG_RECORD_BSHIFT))
#define XLOG_TOTAL_REC_SHIFT(log) \
    BTOBB(XLOG_MAX_ICLOGS << (xfs_sb_version_haslogv2(&log->l_mp->m_sb) ? \
     XLOG_MAX_RECORD_BSHIFT : XLOG_BIG_RECORD_BSHIFT))

static inline xfs_lsn_t xlog_assign_lsn(uint cycle, uint block)
{
    return ((xfs_lsn_t)cycle << 32) | block;
}

static inline uint xlog_get_cycle(char *ptr)
{
    if (be32_to_cpu(*(__be32 *)ptr) == XLOG_HEADER_MAGIC_NUM)
        return be32_to_cpu(*((__be32 *)ptr + 1));
    else
        return be32_to_cpu(*(__be32 *)ptr);
}

#define BLK_AVG(blk1, blk2) ((blk1+blk2) >> 1)

#ifdef __KERNEL__

/*
 * get client id from packed copy.
 *
 * this hack is here because the xlog_pack code copies four bytes
 * of xlog_op_header containing the fields oh_clientid, oh_flags
 * and oh_res2 into the packed copy.
 *
 * later on this four byte chunk is treated as an int and the
 * client id is pulled out.
 *
 * this has endian issues, of course.
 */
static inline uint xlog_get_client_id(__be32 i)
{
    return be32_to_cpu(i) >> 24;
}

/*
 * In core log state
 */
#define XLOG_STATE_ACTIVE    0x0001 /* Current IC log being written to */
#define XLOG_STATE_WANT_SYNC 0x0002 /* Want to sync this iclog; no more writes */
#define XLOG_STATE_SYNCING   0x0004 /* This IC log is syncing */
#define XLOG_STATE_DONE_SYNC 0x0008 /* Done syncing to disk */
#define XLOG_STATE_DO_CALLBACK \
                 0x0010 /* Process callback functions */
#define XLOG_STATE_CALLBACK  0x0020 /* Callback functions now */
#define XLOG_STATE_DIRTY     0x0040 /* Dirty IC log, not ready for ACTIVE status*/
#define XLOG_STATE_IOERROR   0x0080 /* IO error happened in sync'ing log */
#define XLOG_STATE_ALL       0x7FFF /* All possible valid flags */
#define XLOG_STATE_NOTUSED   0x8000 /* This IC log not being used */
#endif  /* __KERNEL__ */

/*
 * Flags to log operation header
 *
 * The first write of a new transaction will be preceded with a start
 * record, XLOG_START_TRANS.  Once a transaction is committed, a commit
 * record is written, XLOG_COMMIT_TRANS.  If a single region can not fit into
 * the remainder of the current active in-core log, it is split up into
 * multiple regions.  Each partial region will be marked with a
 * XLOG_CONTINUE_TRANS until the last one, which gets marked with XLOG_END_TRANS.
 *
 */
#define XLOG_START_TRANS    0x01    /* Start a new transaction */
#define XLOG_COMMIT_TRANS   0x02    /* Commit this transaction */
#define XLOG_CONTINUE_TRANS 0x04    /* Cont this trans into new region */
#define XLOG_WAS_CONT_TRANS 0x08    /* Cont this trans into new region */
#define XLOG_END_TRANS      0x10    /* End a continued transaction */
#define XLOG_UNMOUNT_TRANS  0x20    /* Unmount a filesystem transaction */

#ifdef __KERNEL__
/*
 * Flags to log ticket
 */
#define XLOG_TIC_INITED     0x1 /* has been initialized */
#define XLOG_TIC_PERM_RESERV    0x2 /* permanent reservation */

#define XLOG_TIC_FLAGS \
    { XLOG_TIC_INITED,  "XLOG_TIC_INITED" }, \
    { XLOG_TIC_PERM_RESERV, "XLOG_TIC_PERM_RESERV" }

#endif  /* __KERNEL__ */

#define XLOG_UNMOUNT_TYPE   0x556e  /* Un for Unmount */

/*
 * Flags for log structure
 */
#define XLOG_CHKSUM_MISMATCH    0x1 /* used only during recovery */
#define XLOG_ACTIVE_RECOVERY    0x2 /* in the middle of recovery */
#define XLOG_RECOVERY_NEEDED    0x4 /* log was recovered */
#define XLOG_IO_ERROR       0x8 /* log hit an I/O error, and being
                       shutdown */
#define XLOG_TAIL_WARN      0x10    /* log tail verify warning issued */

typedef __uint32_t xlog_tid_t;

#ifdef __KERNEL__
/*
 * Below are states for covering allocation transactions.
 * By covering, we mean changing the h_tail_lsn in the last on-disk
 * log write such that no allocation transactions will be re-done during
 * recovery after a system crash. Recovery starts at the last on-disk
 * log write.
 *
 * These states are used to insert dummy log entries to cover
 * space allocation transactions which can undo non-transactional changes
 * after a crash. Writes to a file with space
 * already allocated do not result in any transactions. Allocations
 * might include space beyond the EOF. So if we just push the EOF a
 * little, the last transaction for the file could contain the wrong
 * size. If there is no file system activity, after an allocation
 * transaction, and the system crashes, the allocation transaction
 * will get replayed and the file will be truncated. This could
 * be hours/days/... after the allocation occurred.
 *
 * The fix for this is to do two dummy transactions when the
 * system is idle. We need two dummy transaction because the h_tail_lsn
 * in the log record header needs to point beyond the last possible
 * non-dummy transaction. The first dummy changes the h_tail_lsn to
 * the first transaction before the dummy. The second dummy causes
 * h_tail_lsn to point to the first dummy. Recovery starts at h_tail_lsn.
 *
 * These dummy transactions get committed when everything
 * is idle (after there has been some activity).
 *
 * There are 5 states used to control this.
 *
 *  IDLE -- no logging has been done on the file system or
 *      we are done covering previous transactions.
 *  NEED -- logging has occurred and we need a dummy transaction
 *      when the log becomes idle.
 *  DONE -- we were in the NEED state and have committed a dummy
 *      transaction.
 *  NEED2 -- we detected that a dummy transaction has gone to the
 *      on disk log with no other transactions.
 *  DONE2 -- we committed a dummy transaction when in the NEED2 state.
 *
 * There are two places where we switch states:
 *
 * 1.) In xfs_sync, when we detect an idle log and are in NEED or NEED2.
 *  We commit the dummy transaction and switch to DONE or DONE2,
 *  respectively. In all other states, we don't do anything.
 *
 * 2.) When we finish writing the on-disk log (xlog_state_clean_log).
 *
 *  No matter what state we are in, if this isn't the dummy
 *  transaction going out, the next state is NEED.
 *  So, if we aren't in the DONE or DONE2 states, the next state
 *  is NEED. We can't be finishing a write of the dummy record
 *  unless it was committed and the state switched to DONE or DONE2.
 *
 *  If we are in the DONE state and this was a write of the
 *      dummy transaction, we move to NEED2.
 *
 *  If we are in the DONE2 state and this was a write of the
 *      dummy transaction, we move to IDLE.
 *
 *
 * Writing only one dummy transaction can get appended to
 * one file space allocation. When this happens, the log recovery
 * code replays the space allocation and a file could be truncated.
 * This is why we have the NEED2 and DONE2 states before going idle.
 */

#define XLOG_STATE_COVER_IDLE   0
#define XLOG_STATE_COVER_NEED   1
#define XLOG_STATE_COVER_DONE   2
#define XLOG_STATE_COVER_NEED2  3
#define XLOG_STATE_COVER_DONE2  4

#define XLOG_COVER_OPS      5


/* Ticket reservation region accounting */ 
#define XLOG_TIC_LEN_MAX    15

/*
 * Reservation region
 * As would be stored in xfs_log_iovec but without the i_addr which
 * we don't care about.
 */
typedef struct xlog_res {
    uint    r_len;  /* region length        :4 */
    uint    r_type; /* region's transaction type    :4 */
} xlog_res_t;

typedef struct xlog_ticket {
    struct list_head   t_queue;  /* reserve/write queue */
    struct task_struct *t_task;  /* task that owns this ticket */
    xlog_tid_t     t_tid;    /* transaction identifier   : 4  */
    atomic_t       t_ref;    /* ticket reference count       : 4  */
    int        t_curr_res;   /* current reservation in bytes : 4  */
    int        t_unit_res;   /* unit reservation in bytes    : 4  */
    char           t_ocnt;   /* original count       : 1  */
    char           t_cnt;    /* current count        : 1  */
    char           t_clientid;   /* who does this belong to;     : 1  */
    char           t_flags;  /* properties of reservation    : 1  */
    uint           t_trans_type; /* transaction type             : 4  */

        /* reservation array fields */
    uint           t_res_num;                    /* num in array : 4 */
    uint           t_res_num_ophdrs;         /* num op hdrs  : 4 */
    uint           t_res_arr_sum;        /* array sum    : 4 */
    uint           t_res_o_flow;         /* sum overflow : 4 */
    xlog_res_t     t_res_arr[XLOG_TIC_LEN_MAX];  /* array of res : 8 * 15 */ 
} xlog_ticket_t;

#endif


typedef struct xlog_op_header {
    __be32     oh_tid;  /* transaction id of operation  :  4 b */
    __be32     oh_len;  /* bytes in data region     :  4 b */
    __u8       oh_clientid; /* who sent me this     :  1 b */
    __u8       oh_flags;    /*              :  1 b */
    __u16      oh_res2; /* 32 bit align         :  2 b */
} xlog_op_header_t;


/* valid values for h_fmt */
#define XLOG_FMT_UNKNOWN  0
#define XLOG_FMT_LINUX_LE 1
#define XLOG_FMT_LINUX_BE 2
#define XLOG_FMT_IRIX_BE  3

/* our fmt */
#ifdef XFS_NATIVE_HOST
#define XLOG_FMT XLOG_FMT_LINUX_BE
#else
#define XLOG_FMT XLOG_FMT_LINUX_LE
#endif

typedef struct xlog_rec_header {
    __be32    h_magicno;    /* log record (LR) identifier       :  4 */
    __be32    h_cycle;  /* write cycle of log           :  4 */
    __be32    h_version;    /* LR version               :  4 */
    __be32    h_len;    /* len in bytes; should be 64-bit aligned: 4 */
    __be64    h_lsn;    /* lsn of this LR           :  8 */
    __be64    h_tail_lsn;   /* lsn of 1st LR w/ buffers not committed: 8 */
    __be32    h_chksum; /* may not be used; non-zero if used    :  4 */
    __be32    h_prev_block; /* block number to previous LR      :  4 */
    __be32    h_num_logops; /* number of log operations in this LR  :  4 */
    __be32    h_cycle_data[XLOG_HEADER_CYCLE_SIZE / BBSIZE];
    /* new fields */
    __be32    h_fmt;        /* format of log record                 :  4 */
    uuid_t    h_fs_uuid;    /* uuid of FS                           : 16 */
    __be32    h_size;   /* iclog size               :  4 */
} xlog_rec_header_t;

typedef struct xlog_rec_ext_header {
    __be32    xh_cycle; /* write cycle of log           : 4 */
    __be32    xh_cycle_data[XLOG_HEADER_CYCLE_SIZE / BBSIZE]; /*    : 256 */
} xlog_rec_ext_header_t;

#ifdef __KERNEL__

/*
 * Quite misnamed, because this union lays out the actual on-disk log buffer.
 */
typedef union xlog_in_core2 {
    xlog_rec_header_t   hic_header;
    xlog_rec_ext_header_t   hic_xheader;
    char            hic_sector[XLOG_HEADER_SIZE];
} xlog_in_core_2_t;

/*
 * - A log record header is 512 bytes.  There is plenty of room to grow the
 *  xlog_rec_header_t into the reserved space.
 * - ic_data follows, so a write to disk can start at the beginning of
 *  the iclog.
 * - ic_forcewait is used to implement synchronous forcing of the iclog to disk.
 * - ic_next is the pointer to the next iclog in the ring.
 * - ic_bp is a pointer to the buffer used to write this incore log to disk.
 * - ic_log is a pointer back to the global log structure.
 * - ic_callback is a linked list of callback function/argument pairs to be
 *  called after an iclog finishes writing.
 * - ic_size is the full size of the header plus data.
 * - ic_offset is the current number of bytes written to in this iclog.
 * - ic_refcnt is bumped when someone is writing to the log.
 * - ic_state is the state of the iclog.
 *
 * Because of cacheline contention on large machines, we need to separate
 * various resources onto different cachelines. To start with, make the
 * structure cacheline aligned. The following fields can be contended on
 * by independent processes:
 *
 *  - ic_callback_*
 *  - ic_refcnt
 *  - fields protected by the global l_icloglock
 *
 * so we need to ensure that these fields are located in separate cachelines.
 * We'll put all the read-only and l_icloglock fields in the first cacheline,
 * and move everything else out to subsequent cachelines.
 */
typedef struct xlog_in_core {
    wait_queue_head_t   ic_force_wait;
    wait_queue_head_t   ic_write_wait;
    struct xlog_in_core *ic_next;
    struct xlog_in_core *ic_prev;
    struct xfs_buf      *ic_bp;
    struct xlog     *ic_log;
    int         ic_size;
    int         ic_offset;
    int         ic_bwritecnt;
    unsigned short      ic_state;
    char            *ic_datap;  /* pointer to iclog data */

    /* Callback structures need their own cacheline */
    spinlock_t      ic_callback_lock ____cacheline_aligned_in_smp;
    xfs_log_callback_t  *ic_callback;
    xfs_log_callback_t  **ic_callback_tail;

    /* reference counts need their own cacheline */
    atomic_t        ic_refcnt ____cacheline_aligned_in_smp;
    xlog_in_core_2_t    *ic_data;
#define ic_header   ic_data->hic_header
} xlog_in_core_t;

/*
 * The CIL context is used to aggregate per-transaction details as well be
 * passed to the iclog for checkpoint post-commit processing.  After being
 * passed to the iclog, another context needs to be allocated for tracking the
 * next set of transactions to be aggregated into a checkpoint.
 */
struct xfs_cil;

struct xfs_cil_ctx {
    struct xfs_cil      *cil;
    xfs_lsn_t       sequence;   /* chkpt sequence # */
    xfs_lsn_t       start_lsn;  /* first LSN of chkpt commit */
    xfs_lsn_t       commit_lsn; /* chkpt commit record lsn */
    struct xlog_ticket  *ticket;    /* chkpt ticket */
    int         nvecs;      /* number of regions */
    int         space_used; /* aggregate size of regions */
    struct list_head    busy_extents;   /* busy extents in chkpt */
    struct xfs_log_vec  *lv_chain;  /* logvecs being pushed */
    xfs_log_callback_t  log_cb;     /* completion callback hook. */
    struct list_head    committing; /* ctx committing list */
};

/*
 * Committed Item List structure
 *
 * This structure is used to track log items that have been committed but not
 * yet written into the log. It is used only when the delayed logging mount
 * option is enabled.
 *
 * This structure tracks the list of committing checkpoint contexts so
 * we can avoid the problem of having to hold out new transactions during a
 * flush until we have a the commit record LSN of the checkpoint. We can
 * traverse the list of committing contexts in xlog_cil_push_lsn() to find a
 * sequence match and extract the commit LSN directly from there. If the
 * checkpoint is still in the process of committing, we can block waiting for
 * the commit LSN to be determined as well. This should make synchronous
 * operations almost as efficient as the old logging methods.
 */
struct xfs_cil {
    struct xlog     *xc_log;
    struct list_head    xc_cil;
    spinlock_t      xc_cil_lock;
    struct xfs_cil_ctx  *xc_ctx;
    struct rw_semaphore xc_ctx_lock;
    struct list_head    xc_committing;
    wait_queue_head_t   xc_commit_wait;
    xfs_lsn_t       xc_current_sequence;
    struct work_struct  xc_push_work;
    xfs_lsn_t       xc_push_seq;
};

/*
 * The amount of log space we allow the CIL to aggregate is difficult to size.
 * Whatever we choose, we have to make sure we can get a reservation for the
 * log space effectively, that it is large enough to capture sufficient
 * relogging to reduce log buffer IO significantly, but it is not too large for
 * the log or induces too much latency when writing out through the iclogs. We
 * track both space consumed and the number of vectors in the checkpoint
 * context, so we need to decide which to use for limiting.
 *
 * Every log buffer we write out during a push needs a header reserved, which
 * is at least one sector and more for v2 logs. Hence we need a reservation of
 * at least 512 bytes per 32k of log space just for the LR headers. That means
 * 16KB of reservation per megabyte of delayed logging space we will consume,
 * plus various headers.  The number of headers will vary based on the num of
 * io vectors, so limiting on a specific number of vectors is going to result
 * in transactions of varying size. IOWs, it is more consistent to track and
 * limit space consumed in the log rather than by the number of objects being
 * logged in order to prevent checkpoint ticket overruns.
 *
 * Further, use of static reservations through the log grant mechanism is
 * problematic. It introduces a lot of complexity (e.g. reserve grant vs write
 * grant) and a significant deadlock potential because regranting write space
 * can block on log pushes. Hence if we have to regrant log space during a log
 * push, we can deadlock.
 *
 * However, we can avoid this by use of a dynamic "reservation stealing"
 * technique during transaction commit whereby unused reservation space in the
 * transaction ticket is transferred to the CIL ctx commit ticket to cover the
 * space needed by the checkpoint transaction. This means that we never need to
 * specifically reserve space for the CIL checkpoint transaction, nor do we
 * need to regrant space once the checkpoint completes. This also means the
 * checkpoint transaction ticket is specific to the checkpoint context, rather
 * than the CIL itself.
 *
 * With dynamic reservations, we can effectively make up arbitrary limits for
 * the checkpoint size so long as they don't violate any other size rules.
 * Recovery imposes a rule that no transaction exceed half the log, so we are
 * limited by that.  Furthermore, the log transaction reservation subsystem
 * tries to keep 25% of the log free, so we need to keep below that limit or we
 * risk running out of free log space to start any new transactions.
 *
 * In order to keep background CIL push efficient, we will set a lower
 * threshold at which background pushing is attempted without blocking current
 * transaction commits.  A separate, higher bound defines when CIL pushes are
 * enforced to ensure we stay within our maximum checkpoint size bounds.
 * threshold, yet give us plenty of space for aggregation on large logs.
 */
#define XLOG_CIL_SPACE_LIMIT(log)   (log->l_logsize >> 3)
#define XLOG_CIL_HARD_SPACE_LIMIT(log)  (3 * (log->l_logsize >> 4))

/*
 * ticket grant locks, queues and accounting have their own cachlines
 * as these are quite hot and can be operated on concurrently.
 */
struct xlog_grant_head {
    spinlock_t      lock ____cacheline_aligned_in_smp;
    struct list_head    waiters;
    atomic64_t      grant;
};

/*
 * The reservation head lsn is not made up of a cycle number and block number.
 * Instead, it uses a cycle number and byte number.  Logs don't expect to
 * overflow 31 bits worth of byte offset, so using a byte number will mean
 * that round off problems won't occur when releasing partial reservations.
 */
struct xlog {
    /* The following fields don't need locking */
    struct xfs_mount    *l_mp;          /* mount point */
    struct xfs_ail      *l_ailp;    /* AIL log is working with */
    struct xfs_cil      *l_cilp;    /* CIL log is working with */
    struct xfs_buf      *l_xbuf;        /* extra buffer for log
                         * wrapping */
    struct xfs_buftarg  *l_targ;        /* buftarg of log */
    uint            l_flags;
    uint            l_quotaoffs_flag; /* XFS_DQ_*, for QUOTAOFFs */
    struct list_head    *l_buf_cancel_table;
    int         l_iclog_hsize;  /* size of iclog header */
    int         l_iclog_heads;  /* # of iclog header sectors */
    uint            l_sectBBsize;   /* sector size in BBs (2^n) */
    int         l_iclog_size;   /* size of log in bytes */
    int         l_iclog_size_log; /* log power size of log */
    int         l_iclog_bufs;   /* number of iclog buffers */
    xfs_daddr_t     l_logBBstart;   /* start block of log */
    int         l_logsize;      /* size of log in bytes */
    int         l_logBBsize;    /* size of log in BB chunks */

    /* The following block of fields are changed while holding icloglock */
    wait_queue_head_t   l_flush_wait ____cacheline_aligned_in_smp;
                        /* waiting for iclog flush */
    int         l_covered_state;/* state of "covering disk
                         * log entries" */
    xlog_in_core_t      *l_iclog;       /* head log queue   */
    spinlock_t      l_icloglock;    /* grab to change iclog state */
    int         l_curr_cycle;   /* Cycle number of log writes */
    int         l_prev_cycle;   /* Cycle number before last
                         * block increment */
    int         l_curr_block;   /* current logical log block */
    int         l_prev_block;   /* previous logical log block */

    /*
     * l_last_sync_lsn and l_tail_lsn are atomics so they can be set and
     * read without needing to hold specific locks. To avoid operations
     * contending with other hot objects, place each of them on a separate
     * cacheline.
     */
    /* lsn of last LR on disk */
    atomic64_t      l_last_sync_lsn ____cacheline_aligned_in_smp;
    /* lsn of 1st LR with unflushed * buffers */
    atomic64_t      l_tail_lsn ____cacheline_aligned_in_smp;

    struct xlog_grant_head  l_reserve_head;
    struct xlog_grant_head  l_write_head;

    /* The following field are used for debugging; need to hold icloglock */
#ifdef DEBUG
    char            *l_iclog_bak[XLOG_MAX_ICLOGS];
#endif

};

#define XLOG_BUF_CANCEL_BUCKET(log, blkno) \
    ((log)->l_buf_cancel_table + ((__uint64_t)blkno % XLOG_BC_TABLE_SIZE))

#define XLOG_FORCED_SHUTDOWN(log)   ((log)->l_flags & XLOG_IO_ERROR)

/* common routines */
extern int
xlog_recover(
    struct xlog     *log);
extern int
xlog_recover_finish(
    struct xlog     *log);
extern void
xlog_pack_data(
    struct xlog     *log,
    struct xlog_in_core *iclog,
    int);

extern kmem_zone_t *xfs_log_ticket_zone;
struct xlog_ticket *
xlog_ticket_alloc(
    struct xlog *log,
    int     unit_bytes,
    int     count,
    char        client,
    bool        permanent,
    xfs_km_flags_t  alloc_flags);


static inline void
xlog_write_adv_cnt(void **ptr, int *len, int *off, size_t bytes)
{
    *ptr += bytes;
    *len -= bytes;
    *off += bytes;
}

void    xlog_print_tic_res(struct xfs_mount *mp, struct xlog_ticket *ticket);
int
xlog_write(
    struct xlog     *log,
    struct xfs_log_vec  *log_vector,
    struct xlog_ticket  *tic,
    xfs_lsn_t       *start_lsn,
    struct xlog_in_core **commit_iclog,
    uint            flags);

/*
 * When we crack an atomic LSN, we sample it first so that the value will not
 * change while we are cracking it into the component values. This means we
 * will always get consistent component values to work from. This should always
 * be used to sample and crack LSNs that are stored and updated in atomic
 * variables.
 */
static inline void
xlog_crack_atomic_lsn(atomic64_t *lsn, uint *cycle, uint *block)
{
    xfs_lsn_t val = atomic64_read(lsn);

    *cycle = CYCLE_LSN(val);
    *block = BLOCK_LSN(val);
}

/*
 * Calculate and assign a value to an atomic LSN variable from component pieces.
 */
static inline void
xlog_assign_atomic_lsn(atomic64_t *lsn, uint cycle, uint block)
{
    atomic64_set(lsn, xlog_assign_lsn(cycle, block));
}

/*
 * When we crack the grant head, we sample it first so that the value will not
 * change while we are cracking it into the component values. This means we
 * will always get consistent component values to work from.
 */
static inline void
xlog_crack_grant_head_val(int64_t val, int *cycle, int *space)
{
    *cycle = val >> 32;
    *space = val & 0xffffffff;
}

static inline void
xlog_crack_grant_head(atomic64_t *head, int *cycle, int *space)
{
    xlog_crack_grant_head_val(atomic64_read(head), cycle, space);
}

static inline int64_t
xlog_assign_grant_head_val(int cycle, int space)
{
    return ((int64_t)cycle << 32) | space;
}

static inline void
xlog_assign_grant_head(atomic64_t *head, int cycle, int space)
{
    atomic64_set(head, xlog_assign_grant_head_val(cycle, space));
}

/*
 * Committed Item List interfaces
 */
int
xlog_cil_init(struct xlog *log);
void
xlog_cil_init_post_recovery(struct xlog *log);
void
xlog_cil_destroy(struct xlog *log);

/*
 * CIL force routines
 */
xfs_lsn_t
xlog_cil_force_lsn(
    struct xlog *log,
    xfs_lsn_t sequence);

static inline void
xlog_cil_force(struct xlog *log)
{
    xlog_cil_force_lsn(log, log->l_cilp->xc_current_sequence);
}

/*
 * Unmount record type is used as a pseudo transaction type for the ticket.
 * It's value must be outside the range of XFS_TRANS_* values.
 */
#define XLOG_UNMOUNT_REC_TYPE   (-1U)

/*
 * Wrapper function for waiting on a wait queue serialised against wakeups
 * by a spinlock. This matches the semantics of all the wait queues used in the
 * log code.
 */
static inline void xlog_wait(wait_queue_head_t *wq, spinlock_t *lock)
{
    DECLARE_WAITQUEUE(wait, current);

    add_wait_queue_exclusive(wq, &wait);
    __set_current_state(TASK_UNINTERRUPTIBLE);
    spin_unlock(lock);
    schedule();
    remove_wait_queue(wq, &wait);
}
#endif  /* __KERNEL__ */

#endif  /* __XFS_LOG_PRIV_H__ */