/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * stack_o2cb.c
 *
 * Code which interfaces ocfs2 with the o2cb stack.
 *
 * Copyright (C) 2007 Oracle.  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, version 2.
 *
 * This program is distributed in the hope that it will 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.
 */

#include <linux/kernel.h>
#include <linux/crc32.h>
#include <linux/module.h>

/* Needed for AOP_TRUNCATED_PAGE in mlog_errno() */
#include <linux/fs.h>

#include "cluster/masklog.h"
#include "cluster/nodemanager.h"
#include "cluster/heartbeat.h"

#include "stackglue.h"

struct o2dlm_private {
        struct dlm_eviction_cb op_eviction_cb;
};

static struct ocfs2_stack_plugin o2cb_stack;

/* These should be identical */
#if (DLM_LOCK_IV != LKM_IVMODE)
# error Lock modes do not match
#endif
#if (DLM_LOCK_NL != LKM_NLMODE)
# error Lock modes do not match
#endif
#if (DLM_LOCK_CR != LKM_CRMODE)
# error Lock modes do not match
#endif
#if (DLM_LOCK_CW != LKM_CWMODE)
# error Lock modes do not match
#endif
#if (DLM_LOCK_PR != LKM_PRMODE)
# error Lock modes do not match
#endif
#if (DLM_LOCK_PW != LKM_PWMODE)
# error Lock modes do not match
#endif
#if (DLM_LOCK_EX != LKM_EXMODE)
# error Lock modes do not match
#endif
static inline int mode_to_o2dlm(int mode)
{
        BUG_ON(mode > LKM_MAXMODE);

        return mode;
}

#define map_flag(_generic, _o2dlm)              \
        if (flags & (_generic)) {               \
                flags &= ~(_generic);           \
                o2dlm_flags |= (_o2dlm);        \
        }
static int flags_to_o2dlm(u32 flags)
{
        int o2dlm_flags = 0;

        map_flag(DLM_LKF_NOQUEUE, LKM_NOQUEUE);
        map_flag(DLM_LKF_CANCEL, LKM_CANCEL);
        map_flag(DLM_LKF_CONVERT, LKM_CONVERT);
        map_flag(DLM_LKF_VALBLK, LKM_VALBLK);
        map_flag(DLM_LKF_IVVALBLK, LKM_INVVALBLK);
        map_flag(DLM_LKF_ORPHAN, LKM_ORPHAN);
        map_flag(DLM_LKF_FORCEUNLOCK, LKM_FORCE);
        map_flag(DLM_LKF_TIMEOUT, LKM_TIMEOUT);
        map_flag(DLM_LKF_LOCAL, LKM_LOCAL);

        /* map_flag() should have cleared every flag passed in */
        BUG_ON(flags != 0);

        return o2dlm_flags;
}
#undef map_flag

/*
 * Map an o2dlm status to standard errno values.
 *
 * o2dlm only uses a handful of these, and returns even fewer to the
 * caller. Still, we try to assign sane values to each error.
 *
 * The following value pairs have special meanings to dlmglue, thus
 * the right hand side needs to stay unique - never duplicate the
 * mapping elsewhere in the table!
 *
 * DLM_NORMAL:          0
 * DLM_NOTQUEUED:       -EAGAIN
 * DLM_CANCELGRANT:     -EBUSY
 * DLM_CANCEL:          -DLM_ECANCEL
 */
/* Keep in sync with dlmapi.h */
static int status_map[] = {
        [DLM_NORMAL]                    = 0,            /* Success */
        [DLM_GRANTED]                   = -EINVAL,
        [DLM_DENIED]                    = -EACCES,
        [DLM_DENIED_NOLOCKS]            = -EACCES,
        [DLM_WORKING]                   = -EACCES,
        [DLM_BLOCKED]                   = -EINVAL,
        [DLM_BLOCKED_ORPHAN]            = -EINVAL,
        [DLM_DENIED_GRACE_PERIOD]       = -EACCES,
        [DLM_SYSERR]                    = -ENOMEM,      /* It is what it is */
        [DLM_NOSUPPORT]                 = -EPROTO,
        [DLM_CANCELGRANT]               = -EBUSY,       /* Cancel after grant */
        [DLM_IVLOCKID]                  = -EINVAL,
        [DLM_SYNC]                      = -EINVAL,
        [DLM_BADTYPE]                   = -EINVAL,
        [DLM_BADRESOURCE]               = -EINVAL,
        [DLM_MAXHANDLES]                = -ENOMEM,
        [DLM_NOCLINFO]                  = -EINVAL,
        [DLM_NOLOCKMGR]                 = -EINVAL,
        [DLM_NOPURGED]                  = -EINVAL,
        [DLM_BADARGS]                   = -EINVAL,
        [DLM_VOID]                      = -EINVAL,
        [DLM_NOTQUEUED]                 = -EAGAIN,      /* Trylock failed */
        [DLM_IVBUFLEN]                  = -EINVAL,
        [DLM_CVTUNGRANT]                = -EPERM,
        [DLM_BADPARAM]                  = -EINVAL,
        [DLM_VALNOTVALID]               = -EINVAL,
        [DLM_REJECTED]                  = -EPERM,
        [DLM_ABORT]                     = -EINVAL,
        [DLM_CANCEL]                    = -DLM_ECANCEL, /* Successful cancel */
        [DLM_IVRESHANDLE]               = -EINVAL,
        [DLM_DEADLOCK]                  = -EDEADLK,
        [DLM_DENIED_NOASTS]             = -EINVAL,
        [DLM_FORWARD]                   = -EINVAL,
        [DLM_TIMEOUT]                   = -ETIMEDOUT,
        [DLM_IVGROUPID]                 = -EINVAL,
        [DLM_VERS_CONFLICT]             = -EOPNOTSUPP,
        [DLM_BAD_DEVICE_PATH]           = -ENOENT,
        [DLM_NO_DEVICE_PERMISSION]      = -EPERM,
        [DLM_NO_CONTROL_DEVICE]         = -ENOENT,
        [DLM_RECOVERING]                = -ENOTCONN,
        [DLM_MIGRATING]                 = -ERESTART,
        [DLM_MAXSTATS]                  = -EINVAL,
};

static int dlm_status_to_errno(enum dlm_status status)
{
        BUG_ON(status < 0 || status >= ARRAY_SIZE(status_map));

        return status_map[status];
}

static void o2dlm_lock_ast_wrapper(void *astarg)
{
        BUG_ON(o2cb_stack.sp_proto == NULL);

        o2cb_stack.sp_proto->lp_lock_ast(astarg);
}

static void o2dlm_blocking_ast_wrapper(void *astarg, int level)
{
        BUG_ON(o2cb_stack.sp_proto == NULL);

        o2cb_stack.sp_proto->lp_blocking_ast(astarg, level);
}

static void o2dlm_unlock_ast_wrapper(void *astarg, enum dlm_status status)
{
        int error = dlm_status_to_errno(status);

        BUG_ON(o2cb_stack.sp_proto == NULL);

        /*
         * In o2dlm, you can get both the lock_ast() for the lock being
         * granted and the unlock_ast() for the CANCEL failing.  A
         * successful cancel sends DLM_NORMAL here.  If the
         * lock grant happened before the cancel arrived, you get
         * DLM_CANCELGRANT.
         *
         * There's no need for the double-ast.  If we see DLM_CANCELGRANT,
         * we just ignore it.  We expect the lock_ast() to handle the
         * granted lock.
         */
        if (status == DLM_CANCELGRANT)
                return;

        o2cb_stack.sp_proto->lp_unlock_ast(astarg, error);
}

static int o2cb_dlm_lock(struct ocfs2_cluster_connection *conn,
                         int mode,
                         union ocfs2_dlm_lksb *lksb,
                         u32 flags,
                         void *name,
                         unsigned int namelen,
                         void *astarg)
{
        enum dlm_status status;
        int o2dlm_mode = mode_to_o2dlm(mode);
        int o2dlm_flags = flags_to_o2dlm(flags);
        int ret;

        status = dlmlock(conn->cc_lockspace, o2dlm_mode, &lksb->lksb_o2dlm,
                         o2dlm_flags, name, namelen,
                         o2dlm_lock_ast_wrapper, astarg,
                         o2dlm_blocking_ast_wrapper);
        ret = dlm_status_to_errno(status);
        return ret;
}

static int o2cb_dlm_unlock(struct ocfs2_cluster_connection *conn,
                           union ocfs2_dlm_lksb *lksb,
                           u32 flags,
                           void *astarg)
{
        enum dlm_status status;
        int o2dlm_flags = flags_to_o2dlm(flags);
        int ret;

        status = dlmunlock(conn->cc_lockspace, &lksb->lksb_o2dlm,
                           o2dlm_flags, o2dlm_unlock_ast_wrapper, astarg);
        ret = dlm_status_to_errno(status);
        return ret;
}

static int o2cb_dlm_lock_status(union ocfs2_dlm_lksb *lksb)
{
        return dlm_status_to_errno(lksb->lksb_o2dlm.status);
}

/*
 * o2dlm aways has a "valid" LVB. If the dlm loses track of the LVB
 * contents, it will zero out the LVB.  Thus the caller can always trust
 * the contents.
 */
static int o2cb_dlm_lvb_valid(union ocfs2_dlm_lksb *lksb)
{
        return 1;
}

static void *o2cb_dlm_lvb(union ocfs2_dlm_lksb *lksb)
{
        return (void *)(lksb->lksb_o2dlm.lvb);
}

static void o2cb_dump_lksb(union ocfs2_dlm_lksb *lksb)
{
        dlm_print_one_lock(lksb->lksb_o2dlm.lockid);
}

/*
 * Called from the dlm when it's about to evict a node. This is how the
 * classic stack signals node death.
 */
static void o2dlm_eviction_cb(int node_num, void *data)
{
        struct ocfs2_cluster_connection *conn = data;

        mlog(ML_NOTICE, "o2dlm has evicted node %d from group %.*s\n",
             node_num, conn->cc_namelen, conn->cc_name);

        conn->cc_recovery_handler(node_num, conn->cc_recovery_data);
}

static int o2cb_cluster_connect(struct ocfs2_cluster_connection *conn)
{
        int rc = 0;
        u32 dlm_key;
        struct dlm_ctxt *dlm;
        struct o2dlm_private *priv;
        struct dlm_protocol_version dlm_version;

        BUG_ON(conn == NULL);
        BUG_ON(o2cb_stack.sp_proto == NULL);

        /* for now we only have one cluster/node, make sure we see it
         * in the heartbeat universe */
        if (!o2hb_check_local_node_heartbeating()) {
                rc = -EINVAL;
                goto out;
        }

        priv = kzalloc(sizeof(struct o2dlm_private), GFP_KERNEL);
        if (!priv) {
                rc = -ENOMEM;
                goto out_free;
        }

        /* This just fills the structure in.  It is safe to pass conn. */
        dlm_setup_eviction_cb(&priv->op_eviction_cb, o2dlm_eviction_cb,
                              conn);

        conn->cc_private = priv;

        /* used by the dlm code to make message headers unique, each
         * node in this domain must agree on this. */
        dlm_key = crc32_le(0, conn->cc_name, conn->cc_namelen);
        dlm_version.pv_major = conn->cc_version.pv_major;
        dlm_version.pv_minor = conn->cc_version.pv_minor;

        dlm = dlm_register_domain(conn->cc_name, dlm_key, &dlm_version);
        if (IS_ERR(dlm)) {
                rc = PTR_ERR(dlm);
                mlog_errno(rc);
                goto out_free;
        }

        conn->cc_version.pv_major = dlm_version.pv_major;
        conn->cc_version.pv_minor = dlm_version.pv_minor;
        conn->cc_lockspace = dlm;

        dlm_register_eviction_cb(dlm, &priv->op_eviction_cb);

out_free:
        if (rc && conn->cc_private)
                kfree(conn->cc_private);

out:
        return rc;
}

static int o2cb_cluster_disconnect(struct ocfs2_cluster_connection *conn)
{
        struct dlm_ctxt *dlm = conn->cc_lockspace;
        struct o2dlm_private *priv = conn->cc_private;

        dlm_unregister_eviction_cb(&priv->op_eviction_cb);
        conn->cc_private = NULL;
        kfree(priv);

        dlm_unregister_domain(dlm);
        conn->cc_lockspace = NULL;

        return 0;
}

static int o2cb_cluster_this_node(unsigned int *node)
{
        int node_num;

        node_num = o2nm_this_node();
        if (node_num == O2NM_INVALID_NODE_NUM)
                return -ENOENT;

        if (node_num >= O2NM_MAX_NODES)
                return -EOVERFLOW;

        *node = node_num;
        return 0;
}

static struct ocfs2_stack_operations o2cb_stack_ops = {
        .connect        = o2cb_cluster_connect,
        .disconnect     = o2cb_cluster_disconnect,
        .this_node      = o2cb_cluster_this_node,
        .dlm_lock       = o2cb_dlm_lock,
        .dlm_unlock     = o2cb_dlm_unlock,
        .lock_status    = o2cb_dlm_lock_status,
        .lvb_valid      = o2cb_dlm_lvb_valid,
        .lock_lvb       = o2cb_dlm_lvb,
        .dump_lksb      = o2cb_dump_lksb,
};

static struct ocfs2_stack_plugin o2cb_stack = {
        .sp_name        = "o2cb",
        .sp_ops         = &o2cb_stack_ops,
        .sp_owner       = THIS_MODULE,
};

static int __init o2cb_stack_init(void)
{
        return ocfs2_stack_glue_register(&o2cb_stack);
}

static void __exit o2cb_stack_exit(void)
{
        ocfs2_stack_glue_unregister(&o2cb_stack);
}

MODULE_AUTHOR("Oracle");
MODULE_DESCRIPTION("ocfs2 driver for the classic o2cb stack");
MODULE_LICENSE("GPL");
module_init(o2cb_stack_init);
module_exit(o2cb_stack_exit);