fs: rename AT_* to VATTR_*

[unleashed/lotheac.git] / kernel / fs / nfs / nfs_log.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
 */

#include <sys/cred.h>
#include <sys/cmn_err.h>
#include <sys/debug.h>
#include <sys/systm.h>
#include <sys/kmem.h>
#include <sys/disp.h>
#include <sys/atomic.h>
#include <rpc/types.h>
#include <nfs/nfs.h>
#include <nfs/nfssys.h>
#include <nfs/export.h>
#include <nfs/rnode.h>
#include <rpc/auth.h>
#include <rpc/svc.h>
#include <rpc/xdr.h>
#include <rpc/clnt.h>
#include <nfs/nfs_log.h>

#define NUM_RECORDS_TO_WRITE 256
#define NUM_BYTES_TO_WRITE 65536

extern krwlock_t exported_lock;

static int nfslog_num_records_to_write = NUM_RECORDS_TO_WRITE;
static int nfslog_num_bytes_to_write = NUM_BYTES_TO_WRITE;

/*
 * This struct is used to 'hide' the details of managing the log
 * records internally to the logging code.  Allocation routines
 * are used to obtain pieces of memory for XDR encoding.  This struct
 * is a 'header' to those areas and a opaque cookie is used to pass
 * this data structure between the allocating function and the put
 * function.
 */
struct lr_alloc {
        struct lr_alloc         *next;          /* links for write queuing */
        struct lr_alloc         *prev;
#define LR_ALLOC_NOFREE 0x1                     /* not present, call free */
        int                     lr_flags;
        caddr_t                 log_record;     /* address to XDR encoding */
        size_t                  size;           /* final size of encoding */
        struct kmem_cache       *alloc_cache;   /* keep track of cache ptr */
        struct exportinfo       *exi;           /* who are we related to? */
        struct log_buffer       *lb;
};

struct flush_thread_params {
        struct nfsl_flush_args tp_args;
        int tp_error;
};

static int log_file_create(caddr_t, struct log_file **);
static void log_file_rele(struct log_file *);
static struct log_buffer *log_buffer_create(caddr_t);
static void log_buffer_rele(struct log_buffer *);
static int nfslog_record_append2all(struct lr_alloc *);
static int nfslog_logbuffer_rename(struct log_buffer *);
static void nfslog_logfile_wait(struct log_file *);
static int nfslog_logfile_rename(char *, char *);
static void nfslog_do_flush(struct flush_thread_params *);
static void create_buffer_header(caddr_t *, size_t *, size_t *);

static int nfslog_write_logrecords(struct log_file *, struct lr_alloc *, int);
static void nfslog_free_logrecords(struct lr_alloc *);
static int nfslog_records_flush_to_disk(struct log_buffer *);
static int nfslog_records_flush_to_disk_nolock(struct log_buffer *);

/*
 * Read/Write lock that protects 'nfslog_buffer_list'.
 * This lock must be held when searching or modifying 'nfslog_buffer_list'.
 */
static krwlock_t nfslog_buffer_list_lock;

/*
 * The list of "log_buffer" structures.
 */
struct log_buffer *nfslog_buffer_list = NULL;


#define LOG_BUFFER_HOLD(lbp)    { \
        mutex_enter(&(lbp)->lb_lock); \
        (lbp)->lb_refcnt++; \
        mutex_exit(&(lbp)->lb_lock); \
}

#define LOG_FILE_HOLD(lfp)      { \
        mutex_enter(&(lfp)->lf_lock); \
        (lfp)->lf_refcnt++; \
        mutex_exit(&(lfp)->lf_lock); \
}

#define LOG_FILE_RELE(lfp)      { \
        log_file_rele(lfp); \
}

/*
 * These two macros are used to prep a logfile data structure and
 * associated file for writing data.  Note that the lf_lock is
 * held as a result of the call to the first macro.  This is used
 * for serialization correctness between the logbuffer struct and
 * the logfile struct.
 */
#define LOG_FILE_LOCK_TO_WRITE(lfp)     { \
        mutex_enter(&(lfp)->lf_lock); \
        (lfp)->lf_refcnt++; \
        (lfp)->lf_writers++; \
}

#define LOG_FILE_UNLOCK_FROM_WRITE(lfp) { \
        (lfp)->lf_writers--; \
        if ((lfp)->lf_writers == 0 && ((lfp)->lf_flags & L_WAITING)) { \
                (lfp)->lf_flags &= ~L_WAITING; \
                cv_broadcast(&(lfp)->lf_cv_waiters); \
        } \
        mutex_exit(&(lfp)->lf_lock); \
        log_file_rele(lfp); \
}

int rfsl_log_buffer = 0;
static int rfsl_log_file = 0;

/* This array is used for memory allocation of record encoding spaces */
static struct {
        int     size;
        struct kmem_cache *mem_cache;
        char    *cache_name;
} nfslog_mem_alloc[] = {
#define SMALL_INDX 0
        { NFSLOG_SMALL_RECORD_SIZE - sizeof (struct lr_alloc),
        NULL, NFSLOG_SMALL_REC_NAME },
#define MEDIUM_INDX 1
        { NFSLOG_MEDIUM_RECORD_SIZE - sizeof (struct lr_alloc),
        NULL, NFSLOG_MEDIUM_REC_NAME },
#define LARGE_INDX 2
        { NFSLOG_LARGE_RECORD_SIZE - sizeof (struct lr_alloc),
        NULL, NFSLOG_LARGE_REC_NAME },
        { (-1), NULL }
};

/* Used to calculate the 'real' allocation size */
#define ALLOC_SIZE(index) \
        (nfslog_mem_alloc[index].size + sizeof (struct lr_alloc))

/*
 * Initialize logging data buffer cache
 */
void
nfslog_init()
{
        int indx;

        rw_init(&nfslog_buffer_list_lock, NULL, RW_DEFAULT, NULL);

        /*
         * Initialize the kmem caches for encoding
         */
        for (indx = 0; nfslog_mem_alloc[indx].size != (-1); indx++) {
                nfslog_mem_alloc[indx].mem_cache =
                    kmem_cache_create(nfslog_mem_alloc[indx].cache_name,
                    ALLOC_SIZE(indx), 0, NULL, NULL, NULL, NULL, NULL, 0);
        }
}

/*
 * Sets up the necessary log file and related buffers to enable logging
 * on the given export point.
 * Returns 0 on success, non-zero on failure.
 */
int
nfslog_setup(struct exportinfo *exi)
{
        struct exportdata *kex;
        struct log_buffer *lbp;
        struct log_buffer *nlbp;

        kex = &exi->exi_export;
        ASSERT(kex->ex_flags & EX_LOG);

        /*
         * Logging is enabled for the new export point, check
         * the existing log_buffer structures to see if the
         * desired buffer has already been opened. If so, point
         * the new exportinfo's exi_logbuffer to the existing
         * one.
         */
        rw_enter(&nfslog_buffer_list_lock, RW_READER);
        for (lbp = nfslog_buffer_list; lbp != NULL; lbp = lbp->lb_next) {
                LOGGING_DPRINT((10,
                    "searching for buffer... found log_buffer '%s'\n",
                    lbp->lb_path));
                if (strcmp(lbp->lb_path, kex->ex_log_buffer) == 0) {
                        /* Found our match. Ref it and return */
                        LOG_BUFFER_HOLD(lbp);
                        exi->exi_logbuffer = lbp;
                        LOGGING_DPRINT((10,  "\tfound log_buffer for '%s'\n",
                            kex->ex_log_buffer));
                        rw_exit(&nfslog_buffer_list_lock);
                        return (0);
                }
        }
        rw_exit(&nfslog_buffer_list_lock);

        /*
         * New buffer needed, allocate it.
         * The buffer list lock has been dropped so we will need to search
         * the list again to ensure that another thread has not added
         * a matching buffer.
         */
        if ((nlbp = log_buffer_create(kex->ex_log_buffer)) == NULL) {
                /*
                 * Failed the buffer creation for some reason so we
                 * will need to return.
                 */
                return (EIO);
        }

        rw_enter(&nfslog_buffer_list_lock, RW_WRITER);
        for (lbp = nfslog_buffer_list; lbp != NULL;
            lbp = lbp->lb_next) {
                if (strcmp(lbp->lb_path, kex->ex_log_buffer) == 0) {
                                /*
                                 * A log_buffer already exists for the
                                 * indicated buffer, use it instead.
                                 */
                        LOG_BUFFER_HOLD(lbp);

                        exi->exi_logbuffer = lbp;

                        LOGGING_DPRINT((10, "found log_buffer for '%s' "
                            "after allocation\n", kex->ex_log_buffer));

                        rw_exit(&nfslog_buffer_list_lock);

                        log_buffer_rele(nlbp);

                        return (0);
                }
        }
        /*
         * Didn't find an existing log_buffer for this buffer,
         * use the the newly created one, and add to list.  We
         * increment the reference count because the node is
         * entered into the global list.
         */
        LOGGING_DPRINT((10, "exportfs: adding nlbp=%p to list\n",
            (void *)nlbp));

        nlbp->lb_next = nfslog_buffer_list;
        nfslog_buffer_list = nlbp;

        LOG_BUFFER_HOLD(nlbp);  /* hold is for export entry */
        exi->exi_logbuffer = nlbp;

        rw_exit(&nfslog_buffer_list_lock);

        return (0);
}

/*
 * Disables logging for the given export point.
 */
void
nfslog_disable(struct exportinfo *exi)
{
        log_buffer_rele(exi->exi_logbuffer);
}

/*
 * Creates the corresponding log_buffer and log_file structures
 * for the the buffer named 'name'.
 * Returns a pointer to the log_buffer structure with reference one.
 */
static struct log_buffer *
log_buffer_create(caddr_t name)
{
        struct log_buffer *buffer;
        struct log_file *logfile;
        int namelen = strlen(name);

        LOGGING_DPRINT((10,  "log_buffer_create: %s\n", name));
        if (log_file_create(name, &logfile))
                return (NULL);

        buffer = kmem_alloc(sizeof (*buffer), KM_SLEEP);
        buffer->lb_refcnt = 1;
        buffer->lb_rec_id = 0;
        buffer->lb_path = kmem_alloc(namelen + 1, KM_SLEEP);
        bcopy(name, buffer->lb_path, namelen + 1);
        buffer->lb_logfile = logfile;
        buffer->lb_records = NULL;
        buffer->lb_num_recs = 0;
        buffer->lb_size_queued = 0;
        mutex_init(&buffer->lb_lock, NULL, MUTEX_DEFAULT, NULL);
        rfsl_log_buffer++;

        return (buffer);
}

/*
 * Release a log_buffer structure
 */
static void
log_buffer_rele(struct log_buffer *lbp)
{
        int len;

        mutex_enter(&lbp->lb_lock);
        if (--lbp->lb_refcnt > 1) {
                mutex_exit(&lbp->lb_lock);
                return;
        }

        if (lbp->lb_refcnt < 0) {
                panic("log_rele: log_buffer refcnt < 0");
                /*NOTREACHED*/
        }

        /*
         * Need to drop the lb_lock before acquiring the
         * nfslog_buffer_list_lock. To avoid double free we need
         * to hold an additional reference to the log buffer.
         * This will ensure that no two threads will simultaneously
         * be trying to free the same log buffer.
         */

        if (lbp->lb_refcnt == 1) {

                /*
                 * If the ref count is 1, then the last
                 * unshare/reference has been given up and we need to
                 * clean up the buffer and remove it from the buffer
                 * list.
                 */
                LOGGING_DPRINT((10,
                    "log_buffer_rele lbp=%p disconnecting\n", (void *)lbp));
                /*
                 * Hold additional reference before dropping the lb_lock
                 */

                lbp->lb_refcnt++;
                mutex_exit(&lbp->lb_lock);

                /*
                 * Make sure that all of the buffered records are written.
                 * Don't bother checking the write return value since there
                 * isn't much we can do at this point.
                 */
                (void) nfslog_records_flush_to_disk(lbp);

                rw_enter(&nfslog_buffer_list_lock, RW_WRITER);
                mutex_enter(&lbp->lb_lock);
                /*
                 * Drop the reference count held above.
                 * If the ref count is still > 1 then someone has
                 * stepped in to use this log buffer.  unlock and return.
                 */
                if (--lbp->lb_refcnt > 1) {
                        mutex_exit(&lbp->lb_lock);
                        rw_exit(&nfslog_buffer_list_lock);
                        return;
                }

                if (lbp == nfslog_buffer_list) {
                        nfslog_buffer_list = lbp->lb_next;
                } else {
                        struct log_buffer *tlbp;

                        /* Drop the log_buffer from the master list */
                        for (tlbp = nfslog_buffer_list; tlbp->lb_next != NULL;
                            tlbp = tlbp->lb_next) {
                                if (tlbp->lb_next == lbp) {
                                        tlbp->lb_next = lbp->lb_next;
                                        break;
                                }
                        }
                }

                mutex_exit(&lbp->lb_lock);
                rw_exit(&nfslog_buffer_list_lock);
        }
        /*
         * ref count zero; finish clean up.
         */
        LOGGING_DPRINT((10, "log_buffer_rele lbp=%p freeing\n", (void *)lbp));

        log_file_rele(lbp->lb_logfile);
        len = strlen(lbp->lb_path) + 1;
        kmem_free(lbp->lb_path, len);
        kmem_free(lbp, sizeof (*lbp));
        rfsl_log_buffer--;
}

/*
 * Creates the corresponding log_file structure for the buffer
 * named 'log_file_name'.
 * 'log_file_name' is created by concatenating 'origname' and LOG_INPROG_STRING.
 * 'logfile' is set to be the log_file structure with reference one.
 */
static int
log_file_create(caddr_t origname, struct log_file **lfpp)
{
        vnode_t *vp = NULL;
        char *name;
        int namelen;
        int error;
        struct log_file *logfile = NULL;
        vattr_t va;
        caddr_t loghdr = NULL;
        size_t loghdr_len = 0;
        size_t loghdr_free = 0;

        namelen = strlen(origname) + strlen(LOG_INPROG_STRING);
        name = kmem_alloc(namelen + 1, KM_SLEEP);
        (void) sprintf(name, "%s%s", origname, LOG_INPROG_STRING);

        LOGGING_DPRINT((3, "log_file_create: %s\n", name));
        if (error = vn_open(name, UIO_SYSSPACE, FCREAT|FWRITE|FOFFMAX,
            LOG_MODE, &vp, CRCREAT, 0)) {
                nfs_cmn_err(error, CE_WARN,
                    "log_file_create: Can not open %s - error %m", name);
                goto out;
        }
        LOGGING_DPRINT((3, "log_file_create: %s vp=%p v_count=%d\n",
            name, (void *)vp, vp->v_count));

        logfile = kmem_zalloc(sizeof (*logfile), KM_SLEEP);
        logfile->lf_path = name;
        /*
         * No need to bump the vnode reference count since it is set
         * to one by vn_open().
         */
        logfile->lf_vp = vp;
        logfile->lf_refcnt = 1;
        mutex_init(&logfile->lf_lock, NULL, MUTEX_DEFAULT, NULL);
        rfsl_log_file++;

        va.va_mask = VATTR_SIZE;
        error = fop_getattr(vp, &va, 0, CRED(), NULL);
        if (error) {
                nfs_cmn_err(error, CE_WARN,
                    "log_file_create: Can not stat %s - error = %m",  name);
                goto out;
        }

        if (va.va_size == 0) {
                struct lr_alloc lr;

                /*
                 * Write Header.
                 */
                create_buffer_header(&loghdr, &loghdr_len, &loghdr_free);
                /*
                 * Dummy up a lr_alloc struct for the write
                 */
                lr.next = lr.prev = &lr;
                lr.lr_flags = 0;
                lr.log_record = loghdr;
                lr.size = loghdr_len;
                lr.alloc_cache = NULL;
                lr.exi = NULL;
                lr.lb = NULL;

                mutex_enter(&logfile->lf_lock);

                error = nfslog_write_logrecords(logfile, &lr, 1);

                mutex_exit(&logfile->lf_lock);

                if (error != 0) {
                        nfs_cmn_err(error, CE_WARN,
                            "log_file_create: Can not write header "
                            "on %s - error = %m", name);
                        goto out;
                }
        }
        *lfpp = logfile;

        if (loghdr != NULL)
                kmem_free(loghdr, loghdr_free);

        return (0);

out:
        if (vp != NULL) {
                int error1;
                error1 = fop_close(vp, FCREAT|FWRITE|FOFFMAX, 1, 0,
                    CRED(), NULL);
                if (error1) {
                        nfs_cmn_err(error1, CE_WARN,
                            "log_file_create: Can not close %s - "
                            "error = %m", name);
                }
                VN_RELE(vp);
        }

        kmem_free(name, namelen + 1);
        if (logfile != NULL) {
                mutex_destroy(&logfile->lf_lock);
                kmem_free(logfile, sizeof (*logfile));
                rfsl_log_file--;
        }
        if (loghdr != NULL)
                kmem_free(loghdr, loghdr_free);

        return (error);
}

/*
 * Release a log_file structure
 */
static void
log_file_rele(struct log_file *lfp)
{
        int len;
        int error;

        mutex_enter(&lfp->lf_lock);
        if (--lfp->lf_refcnt > 0) {
                LOGGING_DPRINT((10,
                    "log_file_rele lfp=%p decremented refcnt to %d\n",
                    (void *)lfp, lfp->lf_refcnt));
                mutex_exit(&lfp->lf_lock);
                return;
        }
        if (lfp->lf_refcnt < 0) {
                panic("log_file_rele: log_file refcnt < 0");
                /*NOTREACHED*/
        }

        LOGGING_DPRINT((10, "log_file_rele lfp=%p freeing node\n",
            (void *)lfp));

        lfp->lf_flags &= ~(L_PRINTED | L_ERROR);

        ASSERT(lfp->lf_flags == 0);
        ASSERT(lfp->lf_writers == 0);

        if (error = fop_close(lfp->lf_vp, FCREAT|FWRITE|FOFFMAX, 1, 0,
            CRED(), NULL)) {
                nfs_cmn_err(error, CE_WARN,
                    "NFS: Could not close log buffer %s - error = %m",
                    lfp->lf_path);
#ifdef DEBUG
        } else {
                LOGGING_DPRINT((3,
                    "log_file_rele: %s has been closed vp=%p v_count=%d\n",
                    lfp->lf_path, (void *)lfp->lf_vp, lfp->lf_vp->v_count));
#endif
        }
        VN_RELE(lfp->lf_vp);

        len = strlen(lfp->lf_path) + 1;
        kmem_free(lfp->lf_path, len);
        kmem_free(lfp, sizeof (*lfp));
        rfsl_log_file--;
}

/*
 * Allocates a record of the size specified.
 * 'exi' identifies the exportinfo structure being logged.
 * 'size' indicates how much memory should be allocated
 * 'cookie' is used to store an opaque value for the caller for later use
 * 'flags' currently ignored.
 *
 * Returns a pointer to the beginning of the allocated memory.
 * 'cookie' is a pointer to the 'lr_alloc' struct; this will be used
 * to keep track of the encoded record and contains all the info
 * for enqueuing the record on the log buffer for later writing.
 *
 * nfslog_record_put() must be used to 'free' this record or allocation.
 */
/* ARGSUSED */
void *
nfslog_record_alloc(
        struct exportinfo *exi,
        int alloc_indx,
        void **cookie,
        int flags)
{
        struct lr_alloc *lrp;

        lrp = (struct lr_alloc *)
            kmem_cache_alloc(nfslog_mem_alloc[alloc_indx].mem_cache,
            KM_NOSLEEP);

        if (lrp == NULL) {
                *cookie = NULL;
                return (NULL);
        }

        lrp->next = lrp;
        lrp->prev = lrp;
        lrp->lr_flags = 0;

        lrp->log_record = (caddr_t)((uintptr_t)lrp +
            (uintptr_t)sizeof (struct lr_alloc));
        lrp->size = nfslog_mem_alloc[alloc_indx].size;
        lrp->alloc_cache = nfslog_mem_alloc[alloc_indx].mem_cache;
        lrp->exi = exi;

        if (exi->exi_export.ex_flags & EX_LOG) {
                LOG_BUFFER_HOLD(exi->exi_logbuffer);
                lrp->lb = exi->exi_logbuffer;
        } else {
                lrp->lb = NULL;
        }

        *cookie = (void *)lrp;

        LOGGING_DPRINT((3,
            "nfslog_record_alloc(log_buffer=%p mem=%p size=%lu)\n",
            (void *)exi->exi_logbuffer, (void *)lrp->log_record, lrp->size));
        return (lrp->log_record);
}

/*
 * After the above nfslog_record_alloc() has been called and a record
 * encoded into the buffer that was returned, this function is called
 * to handle appropriate disposition of the newly created record.
 * The cookie value is the one that was returned from nfslog_record_alloc().
 * Size is the actual size of the record that was encoded.  This is
 * passed in because the size used for the alloc was just an approximation.
 * The sync parameter is used to tell us if we need to force this record
 * to disk and if not it will be queued for later writing.
 *
 * Note that if the size parameter has a value of 0, then the record is
 * not written to the log and the associated data structures are released.
 */
void
nfslog_record_put(void *cookie, size_t size, bool_t sync,
        unsigned int which_buffers)
{
        struct lr_alloc *lrp = (struct lr_alloc *)cookie;
        struct log_buffer *lbp = lrp->lb;

        /*
         * If the caller has nothing to write or if there is
         * an apparent error, rele the buffer and free.
         */
        if (size == 0 || size > lrp->size) {
                nfslog_free_logrecords(lrp);
                return;
        }

        /*
         * Reset the size to what actually needs to be written
         * This is used later on when the iovec is built for
         * writing the records to the log file.
         */
        lrp->size = size;

        /* append to all if public exi */
        if (which_buffers == NFSLOG_ALL_BUFFERS) {
                (void) nfslog_record_append2all(lrp);
                nfslog_free_logrecords(lrp);
                return;
        }

        /* Insert the record on the list to be written */
        mutex_enter(&lbp->lb_lock);
        if (lbp->lb_records == NULL) {
                lbp->lb_records = (caddr_t)lrp;
                lbp->lb_num_recs = 1;
                lbp->lb_size_queued = lrp->size;
        } else {
                insque(lrp, ((struct lr_alloc *)lbp->lb_records)->prev);
                lbp->lb_num_recs++;
                lbp->lb_size_queued += lrp->size;
        }

        /*
         * Determine if the queue for this log buffer should be flushed.
         * This is done by either the number of records queued, the total
         * size of all records queued or by the request of the caller
         * via the sync parameter.
         */
        if (lbp->lb_size_queued >= nfslog_num_bytes_to_write ||
            lbp->lb_num_recs > nfslog_num_records_to_write || sync == TRUE) {
                mutex_exit(&lbp->lb_lock);
                (void) nfslog_records_flush_to_disk(lbp);
        } else {
                mutex_exit(&lbp->lb_lock);
        }

}

/*
 * Examine the log_buffer struct to see if there are queue log records
 * that need to be written to disk.  If some exist, pull them off of
 * the log buffer and write them to the log file.
 */
static int
nfslog_records_flush_to_disk(struct log_buffer *lbp)
{

        mutex_enter(&lbp->lb_lock);

        if (lbp->lb_records == NULL) {
                mutex_exit(&lbp->lb_lock);
                return (0);
        }
        return  (nfslog_records_flush_to_disk_nolock(lbp));
}

/*
 * Function requires that the caller holds lb_lock.
 * Function flushes any records in the log buffer to the disk.
 * Function drops the lb_lock on return.
 */

static int
nfslog_records_flush_to_disk_nolock(struct log_buffer *lbp)
{
        struct log_file *lfp = NULL;
        struct lr_alloc *lrp_writers;
        int num_recs;
        int error = 0;

        ASSERT(MUTEX_HELD(&lbp->lb_lock));

        lfp = lbp->lb_logfile;

        LOG_FILE_LOCK_TO_WRITE(lfp);
        ASSERT(lbp->lb_records != NULL);

        lrp_writers = (struct lr_alloc *)lbp->lb_records;
        lbp->lb_records = NULL;
        num_recs = lbp->lb_num_recs;
        lbp->lb_num_recs = 0;
        lbp->lb_size_queued = 0;
        mutex_exit(&lbp->lb_lock);
        error = nfslog_write_logrecords(lfp, lrp_writers, num_recs);

        LOG_FILE_UNLOCK_FROM_WRITE(lfp);

        nfslog_free_logrecords(lrp_writers);
        return (error);
}


/*
 * Take care of writing the provided log record(s) to the log file.
 * We group the log records with an iovec and use fop_write to append
 * them to the end of the log file.
 */
static int
nfslog_write_logrecords(struct log_file *lfp,
        struct lr_alloc *lrp_writers, int num_recs)
{
        struct uio uio;
        struct iovec *iovp;
        int size_iovecs;
        vnode_t *vp;
        struct vattr va;
        struct lr_alloc *lrp;
        int i;
        ssize_t len;
        int ioflag = FAPPEND;
        int error = 0;

        ASSERT(MUTEX_HELD(&lfp->lf_lock));

        vp = lfp->lf_vp;

        size_iovecs = sizeof (struct iovec) * num_recs;
        iovp = kmem_alloc(size_iovecs, KM_NOSLEEP);

        if (iovp == NULL) {
                error = ENOMEM;
                goto out;
        }

        /* Build the iovec based on the list of log records */
        i = 0;
        len = 0;
        lrp = lrp_writers;
        do {
                iovp[i].iov_base = lrp->log_record;
                iovp[i].iov_len = lrp->size;
                len += lrp->size;
                lrp = lrp->next;
                i++;
        } while (lrp != lrp_writers);

        ASSERT(i == num_recs);

        uio.uio_iov = iovp;
        uio.uio_iovcnt = num_recs;
        uio.uio_loffset = 0;
        uio.uio_segflg = (short)UIO_SYSSPACE;
        uio.uio_resid = len;
        uio.uio_llimit = (rlim64_t)MAXOFFSET_T;
        uio.uio_fmode = FWRITE;
        uio.uio_extflg = UIO_COPY_DEFAULT;

        /*
         * Save the size. If the write fails, reset the size to avoid
         * corrupted log buffer files.
         */
        va.va_mask = VATTR_SIZE;

        (void) fop_rwlock(vp, V_WRITELOCK_TRUE, NULL);  /* UIO_WRITE */
        if ((error = fop_getattr(vp, &va, 0, CRED(), NULL)) == 0) {
                if ((len + va.va_size) < (MAXOFF32_T)) {
                        error = fop_write(vp, &uio, ioflag, CRED(), NULL);
                        fop_rwunlock(vp, V_WRITELOCK_TRUE, NULL);
                        if (uio.uio_resid)
                                error = ENOSPC;
                        if (error)
                                (void) fop_setattr(vp, &va, 0, CRED(), NULL);
                } else {
                        fop_rwunlock(vp, V_WRITELOCK_TRUE, NULL);
                        if (!(lfp->lf_flags & L_PRINTED)) {
                                cmn_err(CE_WARN,
                                    "NFS Logging: buffer file %s exceeds 2GB; "
                                    "stopped writing buffer \n", lfp->lf_path);
                        }
                        error = ENOSPC;
                }
        } else {
                fop_rwunlock(vp, V_WRITELOCK_TRUE, NULL);
        }

        kmem_free(iovp, size_iovecs);

out:
        if (error) {
                if (!(lfp->lf_flags & L_PRINTED)) {
                        nfs_cmn_err(error, CE_WARN,
                            "NFS Logging disabled for buffer %s - "
                            "write error = %m\n", lfp->lf_path);
                        lfp->lf_flags |= L_PRINTED;
                }
        } else if (lfp->lf_flags & (L_ERROR | L_PRINTED)) {
                lfp->lf_flags &= ~(L_ERROR | L_PRINTED);
                cmn_err(CE_WARN,
                    "NFS Logging re-enabled for buffer %s\n", lfp->lf_path);
        }

        return (error);
}

static void
nfslog_free_logrecords(struct lr_alloc *lrp_writers)
{
        struct lr_alloc *lrp = lrp_writers;
        struct lr_alloc *lrp_free;

        do {
                lrp_free = lrp;

                lrp = lrp->next;

                /*
                 * Check to see if we are supposed to free this structure
                 * and relese the log_buffer ref count.
                 * It may be the case that the caller does not want this
                 * structure and its record contents freed just yet.
                 */
                if ((lrp_free->lr_flags & LR_ALLOC_NOFREE) == 0) {
                        if (lrp_free->lb != NULL)
                                log_buffer_rele(lrp_free->lb);
                        if (lrp_free->alloc_cache) /* double check */
                                kmem_cache_free(lrp_free->alloc_cache,
                                    (void *)lrp_free);
                } else {
                        /*
                         * after being pulled from the list the
                         * pointers need to be reinitialized.
                         */
                        lrp_free->next = lrp_free;
                        lrp_free->prev = lrp_free;
                }

        } while (lrp != lrp_writers);
}

/*
 * Rename lbp->lb_logfile to reflect the true name requested by 'share'
 */
static int
nfslog_logbuffer_rename(struct log_buffer *lbp)
{
        struct log_file *lf;
        int error;
        struct log_file *logfile;

        /*
         * Try our best to get the cache records into the log file
         * before the rename occurs.
         */
        (void) nfslog_records_flush_to_disk(lbp);

        /*
         * Hold lb_lock before retrieving
         * lb_logfile.
         * Hold a reference to the
         * "lf" structure. this is
         * same as LOG_FILE_HOLD()
         */
        mutex_enter(&(lbp)->lb_lock);
        lf = lbp->lb_logfile;
        mutex_enter(&(lf)->lf_lock);
        mutex_exit(&(lbp)->lb_lock);
        lf->lf_refcnt++;
        mutex_exit(&(lf)->lf_lock);

        LOGGING_DPRINT((10, "nfslog_logbuffer_rename: renaming %s to %s\n",
            lf->lf_path, lbp->lb_path));

        /*
         * rename the current buffer to what the daemon expects
         */
        if (error = nfslog_logfile_rename(lf->lf_path, lbp->lb_path))
                goto out;

        /*
         * Create a new working buffer file and have all new data sent there.
         */
        if (error = log_file_create(lbp->lb_path, &logfile)) {
                /* Attempt to rename to original */
                (void) nfslog_logfile_rename(lbp->lb_path, lf->lf_path);
                goto out;
        }

        /*
         * Hold the lb_lock here, this will make
         * all the threads trying to access lb->logfile block
         * and get a new logfile structure instead of old one.
         */
        mutex_enter(&(lbp)->lb_lock);
        lbp->lb_logfile = logfile;
        mutex_exit(&(lbp)->lb_lock);

        LOG_FILE_RELE(lf);      /* release log_buffer's reference */

        /*
         * Wait for log_file to be in a quiescent state before we
         * return to our caller to let it proceed with the reading of
         * this file.
         */
        nfslog_logfile_wait(lf);

out:
        /*
         * Release our reference on "lf" in two different cases.
         * 1. Error condition, release only the reference
         *    that we held at the begining of this
         *    routine on "lf" structure.
         * 2. Fall through condition, no errors but the old
         *    logfile structure "lf" has been replaced with
         *    the new "logfile" structure, so release the
         *    reference that was part of the creation of
         *    "lf" structure to free up the resources.
         */

        LOG_FILE_RELE(lf);

        return (error);
}

/*
 * Renames the 'from' file to 'new'.
 */
static int
nfslog_logfile_rename(char *from, char *new)
{
        int error;

        if (error = vn_rename(from, new, UIO_SYSSPACE)) {
                cmn_err(CE_WARN,
                    "nfslog_logfile_rename: couldn't rename %s to %s\n",
                    from, new);
        }
        return (error);
}

/*
 * Wait for the log_file writers to finish before returning
 */
static void
nfslog_logfile_wait(struct log_file *lf)
{
        mutex_enter(&lf->lf_lock);
        while (lf->lf_writers > 0) {
                lf->lf_flags |= L_WAITING;
                (void) cv_wait_sig(&lf->lf_cv_waiters, &lf->lf_lock);
        }
        mutex_exit(&lf->lf_lock);
}

static int
nfslog_record_append2all(struct lr_alloc *lrp)
{
        struct log_buffer *lbp, *nlbp;
        int error, ret_error = 0;
        int lr_flags = lrp->lr_flags;

        rw_enter(&nfslog_buffer_list_lock, RW_READER);
        if ((lbp = nfslog_buffer_list) != NULL)
                LOG_BUFFER_HOLD(lbp);
        for (nlbp = NULL; lbp != NULL; lbp = nlbp) {
                if ((nlbp = lbp->lb_next) != NULL) {
                        /*
                         * Remember next element in the list
                         */
                        LOG_BUFFER_HOLD(nlbp);
                }
                rw_exit(&nfslog_buffer_list_lock);

                /*
                 * Insert the record on the buffer's list to be written
                 * and then flush the records to the log file.
                 * Make sure to set the no free flag so that the
                 * record can be used for the next write
                 */
                lrp->lr_flags = LR_ALLOC_NOFREE;

                ASSERT(lbp != NULL);
                mutex_enter(&lbp->lb_lock);
                if (lbp->lb_records == NULL) {
                        lbp->lb_records = (caddr_t)lrp;
                        lbp->lb_num_recs = 1;
                        lbp->lb_size_queued = lrp->size;
                } else {
                        insque(lrp, ((struct lr_alloc *)lbp->lb_records)->prev);
                        lbp->lb_num_recs++;
                        lbp->lb_size_queued += lrp->size;
                }

                /*
                 * Flush log records to disk.
                 * Function is called with lb_lock held.
                 * Function drops the lb_lock on return.
                 */
                error = nfslog_records_flush_to_disk_nolock(lbp);

                if (error) {
                        ret_error = -1;
                        nfs_cmn_err(error, CE_WARN,
                            "rfsl_log_pubfh: could not append record to "
                            "\"%s\" error = %m\n", lbp->lb_path);
                }
                log_buffer_rele(lbp);
                rw_enter(&nfslog_buffer_list_lock, RW_READER);
        }
        rw_exit(&nfslog_buffer_list_lock);

        lrp->lr_flags = lr_flags;

        return (ret_error);
}

#ifdef DEBUG
static int logging_debug = 0;

/*
 * 0) no debugging
 * 3) current test software
 * 10) random stuff
 */
void
nfslog_dprint(const int level, const char *fmt, ...)
{
        va_list args;

        if (logging_debug == level ||
            (logging_debug > 10 && (logging_debug - 10) >= level)) {
                va_start(args, fmt);
                (void) vprintf(fmt, args);
                va_end(args);
        }
}

#endif /* DEBUG */

/*
 * NFS Log Flush system call
 * Caller must check privileges.
 */
/* ARGSUSED */
int
nfsl_flush(struct nfsl_flush_args *args, model_t model)
{
        struct flush_thread_params *tparams;
        struct nfsl_flush_args *nfsl_args;
        int error = 0;
        ulong_t buffer_len;
        STRUCT_HANDLE(nfsl_flush_args, uap);

        STRUCT_SET_HANDLE(uap, model, args);

        tparams = (struct flush_thread_params *)
            kmem_zalloc(sizeof (*tparams), KM_SLEEP);

        nfsl_args = &tparams->tp_args;
        nfsl_args->version =  STRUCT_FGET(uap, version);
        if (nfsl_args->version != NFSL_FLUSH_ARGS_VERS) {
                cmn_err(CE_WARN, "nfsl_flush: exected version %d, got %d",
                    NFSL_FLUSH_ARGS_VERS, nfsl_args->version);
                return (EIO);
        }

        nfsl_args->directive = STRUCT_FGET(uap, directive);
        if ((nfsl_args->directive & NFSL_ALL) == 0) {
                /*
                 * Process a specific buffer
                 */
                nfsl_args->buff_len = STRUCT_FGET(uap, buff_len);

                nfsl_args->buff = (char *)
                    kmem_alloc(nfsl_args->buff_len, KM_NOSLEEP);
                if (nfsl_args->buff == NULL)
                        return (ENOMEM);

                error = copyinstr((const char *)STRUCT_FGETP(uap, buff),
                    nfsl_args->buff, nfsl_args->buff_len, &buffer_len);
                if (error)
                        return (EFAULT);

                if (nfsl_args->buff_len != buffer_len)
                        return (EFAULT);
        }

        LOGGING_DPRINT((10, "nfsl_flush: Flushing %s buffer(s)\n",
            nfsl_args->directive & NFSL_ALL ? "all" : nfsl_args->buff));

        if (nfsl_args->directive & NFSL_SYNC) {
                /*
                 * Do the work synchronously
                 */
                nfslog_do_flush(tparams);
                error = tparams->tp_error;
                kmem_free(nfsl_args->buff, nfsl_args->buff_len);
                kmem_free(tparams, sizeof (*tparams));
        } else {
                /*
                 * Do the work asynchronously
                 */
                (void) thread_create(NULL, 0, nfslog_do_flush,
                    tparams, 0, &p0, TS_RUN, minclsyspri);
        }

        return (error);
}

/*
 * This is where buffer flushing would occur, but there is no buffering
 * at this time.
 * Possibly rename the log buffer for processing.
 * Sets tparams->ta_error equal to the value of the error that occurred,
 * 0 otherwise.
 * Returns ENOENT if the buffer is not found.
 */
static void
nfslog_do_flush(struct flush_thread_params *tparams)
{
        struct nfsl_flush_args *args;
        struct log_buffer *lbp, *nlbp;
        int error = ENOENT;
        int found = 0;
        char *buf_inprog;       /* name of buff in progress */
        int buf_inprog_len;

        /*
         * Sanity check on the arguments.
         */
        if (!tparams)
                return;
        args = &tparams->tp_args;
        if (!args)
                return;

        rw_enter(&nfslog_buffer_list_lock, RW_READER);
        if ((lbp = nfslog_buffer_list) != NULL) {
                LOG_BUFFER_HOLD(lbp);
        }
        for (nlbp = NULL; lbp != NULL; lbp = nlbp) {
                if ((nlbp = lbp->lb_next) != NULL) {
                        LOG_BUFFER_HOLD(nlbp);
                }
                rw_exit(&nfslog_buffer_list_lock);
                if (args->directive & NFSL_ALL) {
                        (void) nfslog_records_flush_to_disk(lbp);
                } else {
                        if ((strcmp(lbp->lb_path, args->buff) == 0) &&
                            (args->directive & NFSL_RENAME)) {
                                error = nfslog_logbuffer_rename(lbp);
                                found++;
                                if (nlbp != NULL)
                                        log_buffer_rele(nlbp);
                                log_buffer_rele(lbp);
                                break;
                        }
                }
                log_buffer_rele(lbp);
                rw_enter(&nfslog_buffer_list_lock, RW_READER);
        }
        if (!found)
                rw_exit(&nfslog_buffer_list_lock);

        if (!found && ((args->directive & NFSL_ALL) == 0) &&
            (args->directive & NFSL_RENAME)) {
                /*
                 * The specified buffer is not currently in use,
                 * simply rename the file indicated.
                 */
                buf_inprog_len = strlen(args->buff) +
                    strlen(LOG_INPROG_STRING) + 1;
                buf_inprog = kmem_alloc(buf_inprog_len, KM_SLEEP);
                (void) sprintf(buf_inprog, "%s%s",
                    args->buff, LOG_INPROG_STRING);

                error = nfslog_logfile_rename(buf_inprog, args->buff);

                kmem_free(buf_inprog, buf_inprog_len);
        }

out:
        if ((args->directive & NFSL_SYNC) == 0) {
                /*
                 * Work was performed asynchronously, the caller is
                 * no longer waiting for us.
                 * Free the thread arguments and exit.
                 */
                kmem_free(args->buff, args->buff_len);
                kmem_free(tparams, sizeof (*tparams));
                thread_exit();
                /* NOTREACHED */
        }

        tparams->tp_error = error;
}

/*
 * Generate buffer_header.
 * 'loghdr' points the the buffer_header, and *reclen
 * contains the length of the buffer.
 */
static void
create_buffer_header(caddr_t *loghdr, size_t *reclen, size_t *freesize)
{
        timestruc_t             now;
        nfslog_buffer_header    lh;
        XDR                     xdrs;
        unsigned int            final_size;


        /* pick some size that will hold the buffer_header */
        *freesize = NFSLOG_SMALL_RECORD_SIZE;

        /*
         * Fill header
         */
        lh.bh_length = 0;       /* don't know yet how large it will be */
        lh.bh_version = NFSLOG_BUF_VERSION;
        lh.bh_flags = 0;
        lh.bh_offset = 0;
        gethrestime(&now);
        TIMESPEC_TO_TIMESPEC32(&lh.bh_timestamp, &now);

        /*
         * Encode the header
         */
        *loghdr = kmem_alloc(*freesize, KM_SLEEP);
        xdrmem_create(&xdrs, *loghdr, *freesize, XDR_ENCODE);

        (void) xdr_nfslog_buffer_header(&xdrs, &lh);

        /*
         * Reset with final size of the encoded data
         */
        final_size = xdr_getpos(&xdrs);
        xdr_setpos(&xdrs, 0);
        (void) xdr_u_int(&xdrs, &final_size);

        *reclen = (size_t)final_size;
}

/*
 * ****************************************************************
 * RPC dispatch table for logging
 * Indexed by program, version, proc
 * Based on NFS dispatch table.
 */
struct nfslog_proc_disp {
        bool_t  (*xdrargs)();
        bool_t  (*xdrres)();
        bool_t  affects_transactions;   /* Operation affects transaction */
                                        /* processing */
};

struct nfslog_vers_disp {
        int     nfslog_dis_nprocs;                      /* number of procs */
        struct nfslog_proc_disp *nfslog_dis_proc_table; /* proc array */
};

struct nfslog_prog_disp {
        int     nfslog_dis_prog;                /* program number */
        int     nfslog_dis_versmin;             /* Minimum version value */
        int     nfslog_dis_nvers;               /* Number of version values */
        struct nfslog_vers_disp *nfslog_dis_vers_table; /* versions array */
};

static int rfs_log_bad = 0;     /* incremented on bad log attempts */
static int rfs_log_good = 0;    /* incremented on successful log attempts */

/*
 * Define the actions taken per prog/vers/proc:
 *
 * In some cases, the nl types are the same as the nfs types and a simple
 * bcopy should suffice. Rather that define tens of identical procedures,
 * simply define these to bcopy. Similarly this takes care of different
 * procs that use same parameter struct.
 */

static struct nfslog_proc_disp nfslog_proc_v2[] = {
        /*
         * NFS VERSION 2
         */

        /* RFS_NULL = 0 */
        {xdr_void, xdr_void, FALSE},

        /* RFS_GETATTR = 1 */
        {xdr_fhandle, xdr_nfslog_getattrres, FALSE},

        /* RFS_SETATTR = 2 */
        {xdr_nfslog_setattrargs, xdr_nfsstat, TRUE},

        /* RFS_ROOT = 3 *** NO LONGER SUPPORTED *** */
        {xdr_void, xdr_void, FALSE},

        /* RFS_LOOKUP = 4 */
        {xdr_nfslog_diropargs, xdr_nfslog_diropres, TRUE},

        /* RFS_READLINK = 5 */
        {xdr_fhandle, xdr_nfslog_rdlnres, FALSE},

        /* RFS_READ = 6 */
        {xdr_nfslog_nfsreadargs, xdr_nfslog_rdresult, TRUE},

        /* RFS_WRITECACHE = 7 *** NO LONGER SUPPORTED *** */
        {xdr_void, xdr_void, FALSE},

        /* RFS_WRITE = 8 */
        {xdr_nfslog_writeargs, xdr_nfslog_writeresult, TRUE},

        /* RFS_CREATE = 9 */
        {xdr_nfslog_createargs, xdr_nfslog_diropres, TRUE},

        /* RFS_REMOVE = 10 */
        {xdr_nfslog_diropargs, xdr_nfsstat, TRUE},

        /* RFS_RENAME = 11 */
        {xdr_nfslog_rnmargs, xdr_nfsstat, TRUE},

        /* RFS_LINK = 12 */
        {xdr_nfslog_linkargs, xdr_nfsstat, TRUE},

        /* RFS_SYMLINK = 13 */
        {xdr_nfslog_symlinkargs, xdr_nfsstat, TRUE},

        /* RFS_MKDIR = 14 */
        {xdr_nfslog_createargs, xdr_nfslog_diropres, TRUE},

        /* RFS_RMDIR = 15 */
        {xdr_nfslog_diropargs, xdr_nfsstat, TRUE},

        /* RFS_READDIR = 16 */
        {xdr_nfslog_rddirargs, xdr_nfslog_rddirres, TRUE},

        /* RFS_STATFS = 17 */
        {xdr_fhandle, xdr_nfslog_statfs, FALSE},
};


/*
 * NFS VERSION 3
 */

static struct nfslog_proc_disp nfslog_proc_v3[] = {

        /* NFSPROC3_NULL = 0 */
        {xdr_void, xdr_void, FALSE},

        /* NFSPROC3_GETATTR = 1 */
        {xdr_nfslog_nfs_fh3, xdr_nfslog_GETATTR3res, FALSE},

        /* NFSPROC3_SETATTR = 2 */
        {xdr_nfslog_SETATTR3args, xdr_nfslog_SETATTR3res, TRUE},

        /* NFSPROC3_LOOKUP = 3 */
        {xdr_nfslog_diropargs3, xdr_nfslog_LOOKUP3res, TRUE},

        /* NFSPROC3_ACCESS = 4 */
        {xdr_nfslog_ACCESS3args, xdr_nfslog_ACCESS3res, FALSE},

        /* NFSPROC3_READLINK = 5 */
        {xdr_nfslog_nfs_fh3, xdr_nfslog_READLINK3res, FALSE},

        /* NFSPROC3_READ = 6 */
        {xdr_nfslog_READ3args, xdr_nfslog_READ3res, TRUE},

        /* NFSPROC3_WRITE = 7 */
        {xdr_nfslog_WRITE3args, xdr_nfslog_WRITE3res, TRUE},

        /* NFSPROC3_CREATE = 8 */
        {xdr_nfslog_CREATE3args, xdr_nfslog_CREATE3res, TRUE},

        /* NFSPROC3_MKDIR = 9 */
        {xdr_nfslog_MKDIR3args, xdr_nfslog_MKDIR3res, TRUE},

        /* NFSPROC3_SYMLINK = 10 */
        {xdr_nfslog_SYMLINK3args, xdr_nfslog_SYMLINK3res, TRUE},

        /* NFSPROC3_MKNOD = 11 */
        {xdr_nfslog_MKNOD3args, xdr_nfslog_MKNOD3res, TRUE},

        /* NFSPROC3_REMOVE = 12 */
        {xdr_nfslog_REMOVE3args, xdr_nfslog_REMOVE3res, TRUE},

        /* NFSPROC3_RMDIR = 13 */
        {xdr_nfslog_RMDIR3args, xdr_nfslog_RMDIR3res, TRUE},

        /* NFSPROC3_RENAME = 14 */
        {xdr_nfslog_RENAME3args, xdr_nfslog_RENAME3res, TRUE},

        /* NFSPROC3_LINK = 15 */
        {xdr_nfslog_LINK3args, xdr_nfslog_LINK3res, TRUE},

        /* NFSPROC3_READDIR = 16 */
        {xdr_nfslog_READDIR3args, xdr_nfslog_READDIR3res, TRUE},

        /* NFSPROC3_READDIRPLUS = 17 */
        {xdr_nfslog_READDIRPLUS3args, xdr_nfslog_READDIRPLUS3res, TRUE},

        /* NFSPROC3_FSSTAT = 18 */
        {xdr_nfslog_FSSTAT3args, xdr_nfslog_FSSTAT3res, FALSE},

        /* NFSPROC3_FSINFO = 19 */
        {xdr_nfslog_FSINFO3args, xdr_nfslog_FSINFO3res, FALSE},

        /* NFSPROC3_PATHCONF = 20 */
        {xdr_nfslog_PATHCONF3args, xdr_nfslog_PATHCONF3res, FALSE},

        /* NFSPROC3_COMMIT = 21 */
        {xdr_nfslog_COMMIT3args, xdr_nfslog_COMMIT3res, FALSE},
};

static struct nfslog_proc_disp nfslog_proc_v1[] = {
        /*
         * NFSLOG VERSION 1
         */

        /* NFSLOG_NULL = 0 */
        {xdr_void, xdr_void, TRUE},

        /* NFSLOG_SHARE = 1 */
        {xdr_nfslog_sharefsargs, xdr_nfslog_sharefsres, TRUE},

        /* NFSLOG_UNSHARE = 2 */
        {xdr_nfslog_sharefsargs, xdr_nfslog_sharefsres, TRUE},

        /* NFSLOG_LOOKUP = 3 */
        {xdr_nfslog_diropargs3, xdr_nfslog_LOOKUP3res, TRUE},

        /* NFSLOG_GETFH = 4 */
        {xdr_nfslog_getfhargs, xdr_nfsstat, TRUE},
};

static struct nfslog_vers_disp nfslog_vers_disptable[] = {
        {sizeof (nfslog_proc_v2) / sizeof (nfslog_proc_v2[0]),
            nfslog_proc_v2},
        {sizeof (nfslog_proc_v3) / sizeof (nfslog_proc_v3[0]),
            nfslog_proc_v3},
};

static struct nfslog_vers_disp nfslog_nfslog_vers_disptable[] = {
        {sizeof (nfslog_proc_v1) / sizeof (nfslog_proc_v1[0]),
            nfslog_proc_v1},
};

static struct nfslog_prog_disp nfslog_dispatch_table[] = {
        {NFS_PROGRAM, NFS_VERSMIN,
                (sizeof (nfslog_vers_disptable) /
                sizeof (nfslog_vers_disptable[0])),
                nfslog_vers_disptable},

        {NFSLOG_PROGRAM, NFSLOG_VERSMIN,
                (sizeof (nfslog_nfslog_vers_disptable) /
                sizeof (nfslog_nfslog_vers_disptable[0])),
                nfslog_nfslog_vers_disptable},
};

static int      nfslog_dispatch_table_arglen = sizeof (nfslog_dispatch_table) /
                                        sizeof (nfslog_dispatch_table[0]);

/*
 * This function will determine the appropriate export info struct to use
 * and allocate a record id to be used in the written log buffer.
 * Usually this is a straightforward operation but the existence of the
 * multicomponent lookup and its semantics of crossing file system
 * boundaries add to the complexity.  See the comments below...
 */
struct exportinfo *
nfslog_get_exi(
        struct exportinfo *exi,
        struct svc_req *req,
        caddr_t res,
        unsigned int *nfslog_rec_id)
{
        struct log_buffer *lb;
        struct exportinfo *exi_ret = NULL;
        fhandle_t               *fh;
        nfs_fh3                 *fh3;

        if (exi == NULL)
                return (NULL);

        /*
         * If the exi is marked for logging, allocate a record id and return
         */
        if (exi->exi_export.ex_flags & EX_LOG) {
                lb = exi->exi_logbuffer;

                /* obtain the unique record id for the caller */
                *nfslog_rec_id = atomic_add_32_nv(&lb->lb_rec_id, (int32_t)1);

                /*
                 * The caller will expect to be able to exi_rele() it,
                 * so exi->exi_count must be incremented before it can
                 * be returned, to make it uniform with exi_ret->exi_count
                 */
                exi_hold(exi);
                return (exi);
        }

        if (exi != exi_public)
                return (NULL);

        /*
         * Here we have an exi that is not marked for logging.
         * It is possible that this request is a multicomponent lookup
         * that was done from the public file handle (not logged) and
         * the resulting file handle being returned to the client exists
         * in a file system that is being logged.  If this is the case
         * we need to log this multicomponent lookup to the appropriate
         * log buffer.  This will allow for the appropriate path name
         * mapping to occur at user level.
         */
        if (req->rq_prog == NFS_PROGRAM) {
                switch (req->rq_vers) {
                case NFS_V3:
                        if ((req->rq_proc == NFSPROC3_LOOKUP) &&
                            (((LOOKUP3res *)res)->status == NFS3_OK)) {
                                fh3 = &((LOOKUP3res *)res)->res_u.ok.object;
                                exi_ret = checkexport(&fh3->fh3_fsid,
                                    FH3TOXFIDP(fh3));
                        }
                        break;

                case NFS_VERSION:
                        if ((req->rq_proc == RFS_LOOKUP) &&
                            (((struct nfsdiropres *)
                            res)->dr_status == NFS_OK)) {
                                fh =  &((struct nfsdiropres *)res)->
                                    dr_u.dr_drok_u.drok_fhandle;
                                exi_ret = checkexport(&fh->fh_fsid,
                                    (fid_t *)&fh->fh_xlen);
                        }
                        break;
                default:
                        break;
                }
        }

        if (exi_ret != NULL && exi_ret->exi_export.ex_flags & EX_LOG) {
                lb = exi_ret->exi_logbuffer;
                /* obtain the unique record id for the caller */
                *nfslog_rec_id = atomic_add_32_nv(&lb->lb_rec_id, (int32_t)1);

                return (exi_ret);
        }
        return (NULL);
}

#ifdef DEBUG
static long long rfslog_records_ignored = 0;
#endif

/*
 * nfslog_write_record - Fill in the record buffer for writing out.
 * If logrecp is null, log it, otherwise, malloc the record and return it.
 *
 * It is the responsibility of the caller to check whether this exportinfo
 * has logging enabled.
 * Note that nfslog_share_public_record() only needs to check for the
 * existence of at least one logbuffer to which the public filehandle record
 * needs to be logged.
 */
void
nfslog_write_record(struct exportinfo *exi, struct svc_req *req,
        caddr_t args, caddr_t res, cred_t *cr, struct netbuf *pnb,
        unsigned int record_id, unsigned int which_buffers)
{
        struct nfslog_prog_disp *progtable;     /* prog struct */
        struct nfslog_vers_disp *verstable;     /* version struct */
        struct nfslog_proc_disp *disp = NULL;   /* proc struct */
        int                     i, vers;
        void                    *log_cookie;    /* for logrecord if */
        caddr_t                 buffer;
        XDR                     xdrs;
        unsigned int            final_size;
        int                     encode_ok;
        int                     alloc_indx;

        ASSERT(exi != NULL); ASSERT(req != NULL); ASSERT(args != NULL);
        ASSERT(res != NULL); ASSERT(cr != NULL);

        /*
         * Find program element
         * Search the list since program can not be used as index
         */
        for (i = 0; (i < nfslog_dispatch_table_arglen); i++) {
                if (req->rq_prog == nfslog_dispatch_table[i].nfslog_dis_prog)
                        break;
        }
        if (i >= nfslog_dispatch_table_arglen) {        /* program not logged */
                /* not an error */
                return;
        }

        /*
         * Extract the dispatch functions based on program/version
         */
        progtable = &nfslog_dispatch_table[i];
        vers = req->rq_vers - progtable->nfslog_dis_versmin;
        verstable = &progtable->nfslog_dis_vers_table[vers];
        disp = &verstable->nfslog_dis_proc_table[req->rq_proc];

        if (!(exi->exi_export.ex_flags & EX_LOG_ALLOPS) &&
            !disp->affects_transactions) {
                /*
                 * Only interested in logging operations affecting
                 * transaction generation. This is not one of them.
                 */
#ifdef DEBUG
                rfslog_records_ignored++;
#endif
                return;
        }

        switch (req->rq_prog) {
        case NFS_PROGRAM:
                switch (req->rq_vers) {
                case NFS_V3:
                        switch (req->rq_proc) {
                        case NFSPROC3_READDIRPLUS:
                                alloc_indx = MEDIUM_INDX;
                                break;
                        default:
                                alloc_indx = SMALL_INDX;
                                break;
                        }
                        break;
                default:
                        alloc_indx = SMALL_INDX;
                        break;
                }
                break;
        case NFSLOG_PROGRAM:
                alloc_indx = MEDIUM_INDX;
                break;
        default:
                alloc_indx = SMALL_INDX;
                break;
        }

        do {
                encode_ok = FALSE;

                /* Pick the size to alloc; end of the road - return */
                if (nfslog_mem_alloc[alloc_indx].size == (-1)) {
                        cmn_err(CE_WARN,
                            "NFSLOG: unable to encode record - prog=%d "
                            "proc = %d", req->rq_prog, req->rq_proc);
                        return;
                }

                buffer = nfslog_record_alloc(exi, alloc_indx, &log_cookie, 0);
                if (buffer == NULL) {
                        /* Error processing - no space alloced */
                        rfs_log_bad++;
                        cmn_err(CE_WARN, "NFSLOG: can't get record");
                        return;
                }

                xdrmem_create(&xdrs, buffer,
                    nfslog_mem_alloc[alloc_indx].size, XDR_ENCODE);

                /*
                 * Encode the header, args and results of the record
                 */
                if (xdr_nfslog_request_record(&xdrs, exi, req, cr, pnb,
                    nfslog_mem_alloc[alloc_indx].size, record_id) &&
                    (*disp->xdrargs)(&xdrs, args) &&
                    (*disp->xdrres)(&xdrs, res)) {
                                encode_ok = TRUE;

                                rfs_log_good++;
                                /*
                                 * Get the final size of the encoded
                                 * data and insert that length at the
                                 * beginning.
                                 */
                                final_size = xdr_getpos(&xdrs);
                                xdr_setpos(&xdrs, 0);
                                (void) xdr_u_int(&xdrs, &final_size);
                } else {
                        /* Oops, the encode failed so we need to free memory */
                        nfslog_record_put(log_cookie, 0, FALSE, which_buffers);
                        alloc_indx++;
                }

        } while (encode_ok == FALSE);


        /*
         * Take the final log record and put it in the log file.
         * This may be queued to the file internally and written
         * later unless the last parameter is TRUE.
         * If the record_id is 0 then this is most likely a share/unshare
         * request and it should be written synchronously to the log file.
         */
        nfslog_record_put(log_cookie,
            final_size, (record_id == 0), which_buffers);
}

static char *
get_publicfh_path(int *alloc_length)
{
        extern struct exportinfo *exi_public;
        char *pubpath;

        rw_enter(&exported_lock, RW_READER);

        *alloc_length = exi_public->exi_export.ex_pathlen + 1;
        pubpath = kmem_alloc(*alloc_length, KM_SLEEP);

        (void) strcpy(pubpath, exi_public->exi_export.ex_path);

        rw_exit(&exported_lock);

        return (pubpath);
}

static void
log_public_record(struct exportinfo *exi, cred_t *cr)
{
        struct svc_req  req;
        struct netbuf   nb = {0, 0, NULL};
        int free_length = 0;
        diropargs3 args;
        LOOKUP3res res;

        bzero(&req, sizeof (req));
        req.rq_prog = NFSLOG_PROGRAM;
        req.rq_vers = NFSLOG_VERSION;
        req.rq_proc = NFSLOG_LOOKUP;
        req.rq_cred.oa_flavor = AUTH_NONE;

        bzero(&args, sizeof (diropargs3));
        bzero(&res, sizeof (LOOKUP3res));

        args.dir.fh3_length = 0;
        if ((args.name = get_publicfh_path(&free_length)) == NULL)
                return;
        args.dirp = &args.dir;

        res.status = NFS3_OK;
        res.res_u.ok.object.fh3_length = 0;

        /*
         * Calling this function with the exi_public
         * will have the effect of appending the record
         * to each of the open log buffers
         */
        nfslog_write_record(exi, &req,
            (caddr_t)&args, (caddr_t)&res, cr, &nb, 0, NFSLOG_ALL_BUFFERS);

        kmem_free(args.name, free_length);
}

/*
 * nfslog_share_record - logs a share request.
 * This is not an NFS request, but we pretend here...
 */
void
nfslog_share_record(struct exportinfo *exi, cred_t *cr)
{
        struct svc_req  req;
        int             res = 0;
        struct netbuf   nb = {0, 0, NULL};

        ASSERT(exi != NULL);

        if (nfslog_buffer_list == NULL)
                return;

        if (exi->exi_export.ex_flags & EX_LOG) {
                bzero(&req, sizeof (req));
                req.rq_prog = NFSLOG_PROGRAM;
                req.rq_vers = NFSLOG_VERSION;
                req.rq_proc = NFSLOG_SHARE;
                req.rq_cred.oa_flavor = AUTH_NONE;
                nfslog_write_record(exi, &req, (caddr_t)exi, (caddr_t)&res, cr,
                    &nb, 0, NFSLOG_ONE_BUFFER);
        }

        log_public_record(exi, cr);
}

/*
 * nfslog_unshare_record - logs an unshare request.
 * This is not an NFS request, but we pretend here...
 */
void
nfslog_unshare_record(struct exportinfo *exi, cred_t *cr)
{
        struct svc_req  req;
        int             res = 0;
        struct netbuf   nb = {0, 0, NULL};

        ASSERT(exi != NULL);
        ASSERT(exi->exi_export.ex_flags & EX_LOG);

        bzero(&req, sizeof (req));
        req.rq_prog = NFSLOG_PROGRAM;
        req.rq_vers = NFSLOG_VERSION;
        req.rq_proc = NFSLOG_UNSHARE;
        req.rq_cred.oa_flavor = AUTH_NONE;
        nfslog_write_record(exi, &req,
            (caddr_t)exi, (caddr_t)&res, cr, &nb, 0, NFSLOG_ONE_BUFFER);
}


void
nfslog_getfh(struct exportinfo *exi,
        fhandle *fh,
        char *fname,
        enum uio_seg seg,
        cred_t *cr)
{
        struct svc_req  req;
        int             res = 0;
        struct netbuf   nb = {0, 0, NULL};
        int             error = 0;
        char            *namebuf;
        size_t          len;
        nfslog_getfhargs gfh;

        ASSERT(exi != NULL);
        ASSERT(exi->exi_export.ex_flags & EX_LOG);

        bzero(&req, sizeof (req));
        req.rq_prog = NFSLOG_PROGRAM;
        req.rq_vers = NFSLOG_VERSION;
        req.rq_proc = NFSLOG_GETFH;
        req.rq_cred.oa_flavor = AUTH_NONE;

        namebuf = kmem_alloc(MAXPATHLEN + 4, KM_SLEEP);
        if (seg == UIO_USERSPACE) {
                error = copyinstr(fname, namebuf, MAXPATHLEN, &len);
        } else {
                error = copystr(fname, namebuf, MAXPATHLEN, &len);
        }

        if (!error) {
                gfh.gfh_fh_buf = *fh;
                gfh.gfh_path = namebuf;

                nfslog_write_record(exi, &req, (caddr_t)&gfh, (caddr_t)&res,
                    cr, &nb, 0, NFSLOG_ONE_BUFFER);
        }
        kmem_free(namebuf, MAXPATHLEN + 4);
}