#include <linux/ceph/ceph_debug.h>

#include <linux/file.h>
#include <linux/namei.h>
#include <linux/random.h>

#include "super.h"
#include "mds_client.h"
#include <linux/ceph/pagelist.h>

static u64 lock_secret;
static int ceph_lock_wait_for_completion(struct ceph_mds_client *mdsc,
                                         struct ceph_mds_request *req);

static inline u64 secure_addr(void *addr)
{
        u64 v = lock_secret ^ (u64)(unsigned long)addr;
        /*
         * Set the most significant bit, so that MDS knows the 'owner'
         * is sufficient to identify the owner of lock. (old code uses
         * both 'owner' and 'pid')
         */
        v |= (1ULL << 63);
        return v;
}

void __init ceph_flock_init(void)
{
        get_random_bytes(&lock_secret, sizeof(lock_secret));
}

/**
 * Implement fcntl and flock locking functions.
 */
static int ceph_lock_message(u8 lock_type, u16 operation, struct file *file,
                             int cmd, u8 wait, struct file_lock *fl)
{
        struct inode *inode = file_inode(file);
        struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
        struct ceph_mds_request *req;
        int err;
        u64 length = 0;
        u64 owner;

        if (operation != CEPH_MDS_OP_SETFILELOCK || cmd == CEPH_LOCK_UNLOCK)
                wait = 0;

        req = ceph_mdsc_create_request(mdsc, operation, USE_AUTH_MDS);
        if (IS_ERR(req))
                return PTR_ERR(req);
        req->r_inode = inode;
        ihold(inode);
        req->r_num_caps = 1;

        /* mds requires start and length rather than start and end */
        if (LLONG_MAX == fl->fl_end)
                length = 0;
        else
                length = fl->fl_end - fl->fl_start + 1;

        owner = secure_addr(fl->fl_owner);

        dout("ceph_lock_message: rule: %d, op: %d, owner: %llx, pid: %llu, "
             "start: %llu, length: %llu, wait: %d, type: %d", (int)lock_type,
             (int)operation, owner, (u64)fl->fl_pid, fl->fl_start, length,
             wait, fl->fl_type);

        req->r_args.filelock_change.rule = lock_type;
        req->r_args.filelock_change.type = cmd;
        req->r_args.filelock_change.owner = cpu_to_le64(owner);
        req->r_args.filelock_change.pid = cpu_to_le64((u64)fl->fl_pid);
        req->r_args.filelock_change.start = cpu_to_le64(fl->fl_start);
        req->r_args.filelock_change.length = cpu_to_le64(length);
        req->r_args.filelock_change.wait = wait;

        if (wait)
                req->r_wait_for_completion = ceph_lock_wait_for_completion;

        err = ceph_mdsc_do_request(mdsc, inode, req);

        if (operation == CEPH_MDS_OP_GETFILELOCK) {
                fl->fl_pid = le64_to_cpu(req->r_reply_info.filelock_reply->pid);
                if (CEPH_LOCK_SHARED == req->r_reply_info.filelock_reply->type)
                        fl->fl_type = F_RDLCK;
                else if (CEPH_LOCK_EXCL == req->r_reply_info.filelock_reply->type)
                        fl->fl_type = F_WRLCK;
                else
                        fl->fl_type = F_UNLCK;

                fl->fl_start = le64_to_cpu(req->r_reply_info.filelock_reply->start);
                length = le64_to_cpu(req->r_reply_info.filelock_reply->start) +
                                                 le64_to_cpu(req->r_reply_info.filelock_reply->length);
                if (length >= 1)
                        fl->fl_end = length -1;
                else
                        fl->fl_end = 0;

        }
        ceph_mdsc_put_request(req);
        dout("ceph_lock_message: rule: %d, op: %d, pid: %llu, start: %llu, "
             "length: %llu, wait: %d, type: %d, err code %d", (int)lock_type,
             (int)operation, (u64)fl->fl_pid, fl->fl_start,
             length, wait, fl->fl_type, err);
        return err;
}

static int ceph_lock_wait_for_completion(struct ceph_mds_client *mdsc,
                                         struct ceph_mds_request *req)
{
        struct ceph_mds_request *intr_req;
        struct inode *inode = req->r_inode;
        int err, lock_type;

        BUG_ON(req->r_op != CEPH_MDS_OP_SETFILELOCK);
        if (req->r_args.filelock_change.rule == CEPH_LOCK_FCNTL)
                lock_type = CEPH_LOCK_FCNTL_INTR;
        else if (req->r_args.filelock_change.rule == CEPH_LOCK_FLOCK)
                lock_type = CEPH_LOCK_FLOCK_INTR;
        else
                BUG_ON(1);
        BUG_ON(req->r_args.filelock_change.type == CEPH_LOCK_UNLOCK);

        err = wait_for_completion_interruptible(&req->r_completion);
        if (!err)
                return 0;

        dout("ceph_lock_wait_for_completion: request %llu was interrupted\n",
             req->r_tid);

        intr_req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_SETFILELOCK,
                                            USE_AUTH_MDS);
        if (IS_ERR(intr_req))
                return PTR_ERR(intr_req);

        intr_req->r_inode = inode;
        ihold(inode);
        intr_req->r_num_caps = 1;

        intr_req->r_args.filelock_change = req->r_args.filelock_change;
        intr_req->r_args.filelock_change.rule = lock_type;
        intr_req->r_args.filelock_change.type = CEPH_LOCK_UNLOCK;

        err = ceph_mdsc_do_request(mdsc, inode, intr_req);
        ceph_mdsc_put_request(intr_req);

        if (err && err != -ERESTARTSYS)
                return err;

        wait_for_completion(&req->r_completion);
        return 0;
}

/**
 * Attempt to set an fcntl lock.
 * For now, this just goes away to the server. Later it may be more awesome.
 */
int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
{
        u8 lock_cmd;
        int err;
        u8 wait = 0;
        u16 op = CEPH_MDS_OP_SETFILELOCK;

        if (!(fl->fl_flags & FL_POSIX))
                return -ENOLCK;
        /* No mandatory locks */
        if (__mandatory_lock(file->f_mapping->host) && fl->fl_type != F_UNLCK)
                return -ENOLCK;

        dout("ceph_lock, fl_owner: %p", fl->fl_owner);

        /* set wait bit as appropriate, then make command as Ceph expects it*/
        if (IS_GETLK(cmd))
                op = CEPH_MDS_OP_GETFILELOCK;
        else if (IS_SETLKW(cmd))
                wait = 1;

        if (F_RDLCK == fl->fl_type)
                lock_cmd = CEPH_LOCK_SHARED;
        else if (F_WRLCK == fl->fl_type)
                lock_cmd = CEPH_LOCK_EXCL;
        else
                lock_cmd = CEPH_LOCK_UNLOCK;

        err = ceph_lock_message(CEPH_LOCK_FCNTL, op, file, lock_cmd, wait, fl);
        if (!err) {
                if (op != CEPH_MDS_OP_GETFILELOCK) {
                        dout("mds locked, locking locally");
                        err = posix_lock_file(file, fl, NULL);
                        if (err && (CEPH_MDS_OP_SETFILELOCK == op)) {
                                /* undo! This should only happen if
                                 * the kernel detects local
                                 * deadlock. */
                                ceph_lock_message(CEPH_LOCK_FCNTL, op, file,
                                                  CEPH_LOCK_UNLOCK, 0, fl);
                                dout("got %d on posix_lock_file, undid lock",
                                     err);
                        }
                }
        }
        return err;
}

int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
{
        u8 lock_cmd;
        int err;
        u8 wait = 0;

        if (!(fl->fl_flags & FL_FLOCK))
                return -ENOLCK;
        /* No mandatory locks */
        if (__mandatory_lock(file->f_mapping->host) && fl->fl_type != F_UNLCK)
                return -ENOLCK;

        dout("ceph_flock, fl_file: %p", fl->fl_file);

        if (IS_SETLKW(cmd))
                wait = 1;

        if (F_RDLCK == fl->fl_type)
                lock_cmd = CEPH_LOCK_SHARED;
        else if (F_WRLCK == fl->fl_type)
                lock_cmd = CEPH_LOCK_EXCL;
        else
                lock_cmd = CEPH_LOCK_UNLOCK;

        err = ceph_lock_message(CEPH_LOCK_FLOCK, CEPH_MDS_OP_SETFILELOCK,
                                file, lock_cmd, wait, fl);
        if (!err) {
                err = flock_lock_file_wait(file, fl);
                if (err) {
                        ceph_lock_message(CEPH_LOCK_FLOCK,
                                          CEPH_MDS_OP_SETFILELOCK,
                                          file, CEPH_LOCK_UNLOCK, 0, fl);
                        dout("got %d on flock_lock_file_wait, undid lock", err);
                }
        }
        return err;
}

/*
 * Fills in the passed counter variables, so you can prepare pagelist metadata
 * before calling ceph_encode_locks.
 */
void ceph_count_locks(struct inode *inode, int *fcntl_count, int *flock_count)
{
        struct file_lock *lock;
        struct file_lock_context *ctx;

        *fcntl_count = 0;
        *flock_count = 0;

        ctx = inode->i_flctx;
        if (ctx) {
                spin_lock(&ctx->flc_lock);
                list_for_each_entry(lock, &ctx->flc_posix, fl_list)
                        ++(*fcntl_count);
                list_for_each_entry(lock, &ctx->flc_flock, fl_list)
                        ++(*flock_count);
                spin_unlock(&ctx->flc_lock);
        }
        dout("counted %d flock locks and %d fcntl locks",
             *flock_count, *fcntl_count);
}

/**
 * Encode the flock and fcntl locks for the given inode into the ceph_filelock
 * array. Must be called with inode->i_lock already held.
 * If we encounter more of a specific lock type than expected, return -ENOSPC.
 */
int ceph_encode_locks_to_buffer(struct inode *inode,
                                struct ceph_filelock *flocks,
                                int num_fcntl_locks, int num_flock_locks)
{
        struct file_lock *lock;
        struct file_lock_context *ctx = inode->i_flctx;
        int err = 0;
        int seen_fcntl = 0;
        int seen_flock = 0;
        int l = 0;

        dout("encoding %d flock and %d fcntl locks", num_flock_locks,
             num_fcntl_locks);

        if (!ctx)
                return 0;

        spin_lock(&ctx->flc_lock);
        list_for_each_entry(lock, &ctx->flc_flock, fl_list) {
                ++seen_fcntl;
                if (seen_fcntl > num_fcntl_locks) {
                        err = -ENOSPC;
                        goto fail;
                }
                err = lock_to_ceph_filelock(lock, &flocks[l]);
                if (err)
                        goto fail;
                ++l;
        }
        list_for_each_entry(lock, &ctx->flc_flock, fl_list) {
                ++seen_flock;
                if (seen_flock > num_flock_locks) {
                        err = -ENOSPC;
                        goto fail;
                }
                err = lock_to_ceph_filelock(lock, &flocks[l]);
                if (err)
                        goto fail;
                ++l;
        }
fail:
        spin_unlock(&ctx->flc_lock);
        return err;
}

/**
 * Copy the encoded flock and fcntl locks into the pagelist.
 * Format is: #fcntl locks, sequential fcntl locks, #flock locks,
 * sequential flock locks.
 * Returns zero on success.
 */
int ceph_locks_to_pagelist(struct ceph_filelock *flocks,
                           struct ceph_pagelist *pagelist,
                           int num_fcntl_locks, int num_flock_locks)
{
        int err = 0;
        __le32 nlocks;

        nlocks = cpu_to_le32(num_fcntl_locks);
        err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
        if (err)
                goto out_fail;

        err = ceph_pagelist_append(pagelist, flocks,
                                   num_fcntl_locks * sizeof(*flocks));
        if (err)
                goto out_fail;

        nlocks = cpu_to_le32(num_flock_locks);
        err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
        if (err)
                goto out_fail;

        err = ceph_pagelist_append(pagelist,
                                   &flocks[num_fcntl_locks],
                                   num_flock_locks * sizeof(*flocks));
out_fail:
        return err;
}

/*
 * Given a pointer to a lock, convert it to a ceph filelock
 */
int lock_to_ceph_filelock(struct file_lock *lock,
                          struct ceph_filelock *cephlock)
{
        int err = 0;
        cephlock->start = cpu_to_le64(lock->fl_start);
        cephlock->length = cpu_to_le64(lock->fl_end - lock->fl_start + 1);
        cephlock->client = cpu_to_le64(0);
        cephlock->pid = cpu_to_le64((u64)lock->fl_pid);
        cephlock->owner = cpu_to_le64(secure_addr(lock->fl_owner));

        switch (lock->fl_type) {
        case F_RDLCK:
                cephlock->type = CEPH_LOCK_SHARED;
                break;
        case F_WRLCK:
                cephlock->type = CEPH_LOCK_EXCL;
                break;
        case F_UNLCK:
                cephlock->type = CEPH_LOCK_UNLOCK;
                break;
        default:
                dout("Have unknown lock type %d", lock->fl_type);
                err = -EINVAL;
        }

        return err;
}