// SPDX-License-Identifier: GPL-2.0
#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));
}

static void ceph_fl_copy_lock(struct file_lock *dst, struct file_lock *src)
{
        struct ceph_file_info *fi = dst->fl_file->private_data;
        struct inode *inode = file_inode(dst->fl_file);
        atomic_inc(&ceph_inode(inode)->i_filelock_ref);
        atomic_inc(&fi->num_locks);
}

static void ceph_fl_release_lock(struct file_lock *fl)
{
        struct ceph_file_info *fi = fl->fl_file->private_data;
        struct inode *inode = file_inode(fl->fl_file);
        struct ceph_inode_info *ci = ceph_inode(inode);
        atomic_dec(&fi->num_locks);
        if (atomic_dec_and_test(&ci->i_filelock_ref)) {
                /* clear error when all locks are released */
                spin_lock(&ci->i_ceph_lock);
                ci->i_ceph_flags &= ~CEPH_I_ERROR_FILELOCK;
                spin_unlock(&ci->i_ceph_lock);
        }
}

static const struct file_lock_operations ceph_fl_lock_ops = {
        .fl_copy_lock = ceph_fl_copy_lock,
        .fl_release_private = ceph_fl_release_lock,
};

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

        if (operation == CEPH_MDS_OP_SETFILELOCK) {
                /*
                 * increasing i_filelock_ref closes race window between
                 * handling request reply and adding file_lock struct to
                 * inode. Otherwise, auth caps may get trimmed in the
                 * window. Caller function will decrease the counter.
                 */
                fl->fl_ops = &ceph_fl_lock_ops;
                fl->fl_ops->fl_copy_lock(fl, NULL);
        }

        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\n", (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 (!err && 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\n", (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);

        mutex_lock(&mdsc->mutex);
        if (test_bit(CEPH_MDS_R_GOT_RESULT, &req->r_req_flags)) {
                err = 0;
        } else {
                /*
                 * ensure we aren't running concurrently with
                 * ceph_fill_trace or ceph_readdir_prepopulate, which
                 * rely on locks (dir mutex) held by our caller.
                 */
                mutex_lock(&req->r_fill_mutex);
                req->r_err = err;
                set_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags);
                mutex_unlock(&req->r_fill_mutex);

                if (!req->r_session) {
                        // haven't sent the request
                        err = 0;
                }
        }
        mutex_unlock(&mdsc->mutex);
        if (!err)
                return 0;

        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_killable(&req->r_safe_completion);
        return 0;
}

static int try_unlock_file(struct file *file, struct file_lock *fl)
{
        int err;
        unsigned int orig_flags = fl->fl_flags;
        fl->fl_flags |= FL_EXISTS;
        err = locks_lock_file_wait(file, fl);
        fl->fl_flags = orig_flags;
        if (err == -ENOENT) {
                if (!(orig_flags & FL_EXISTS))
                        err = 0;
                return err;
        }
        return 1;
}

/*
 * 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)
{
        struct inode *inode = file_inode(file);
        struct ceph_inode_info *ci = ceph_inode(inode);
        int err = 0;
        u16 op = CEPH_MDS_OP_SETFILELOCK;
        u8 wait = 0;
        u8 lock_cmd;

        if (!(fl->fl_flags & FL_POSIX))
                return -ENOLCK;

        dout("ceph_lock, fl_owner: %p\n", 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;

        spin_lock(&ci->i_ceph_lock);
        if (ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK) {
                err = -EIO;
        }
        spin_unlock(&ci->i_ceph_lock);
        if (err < 0) {
                if (op == CEPH_MDS_OP_SETFILELOCK && F_UNLCK == fl->fl_type)
                        posix_lock_file(file, fl, NULL);
                return err;
        }

        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;

        if (op == CEPH_MDS_OP_SETFILELOCK && F_UNLCK == fl->fl_type) {
                err = try_unlock_file(file, fl);
                if (err <= 0)
                        return err;
        }

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

int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
{
        struct inode *inode = file_inode(file);
        struct ceph_inode_info *ci = ceph_inode(inode);
        int err = 0;
        u8 wait = 0;
        u8 lock_cmd;

        if (!(fl->fl_flags & FL_FLOCK))
                return -ENOLCK;
        /* No mandatory locks */
        if (fl->fl_type & LOCK_MAND)
                return -EOPNOTSUPP;

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

        spin_lock(&ci->i_ceph_lock);
        if (ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK) {
                err = -EIO;
        }
        spin_unlock(&ci->i_ceph_lock);
        if (err < 0) {
                if (F_UNLCK == fl->fl_type)
                        locks_lock_file_wait(file, fl);
                return err;
        }

        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;

        if (F_UNLCK == fl->fl_type) {
                err = try_unlock_file(file, fl);
                if (err <= 0)
                        return err;
        }

        err = ceph_lock_message(CEPH_LOCK_FLOCK, CEPH_MDS_OP_SETFILELOCK,
                                inode, lock_cmd, wait, fl);
        if (!err && F_UNLCK != fl->fl_type) {
                err = locks_lock_file_wait(file, fl);
                if (err) {
                        ceph_lock_message(CEPH_LOCK_FLOCK,
                                          CEPH_MDS_OP_SETFILELOCK,
                                          inode, CEPH_LOCK_UNLOCK, 0, fl);
                        dout("got %d on locks_lock_file_wait, undid lock\n", 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\n",
             *flock_count, *fcntl_count);
}

/*
 * Given a pointer to a lock, convert it to a ceph filelock
 */
static 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\n", lock->fl_type);
                err = -EINVAL;
        }

        return err;
}

/*
 * 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\n", num_flock_locks,
             num_fcntl_locks);

        if (!ctx)
                return 0;

        spin_lock(&ctx->flc_lock);
        list_for_each_entry(lock, &ctx->flc_posix, 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;

        if (num_fcntl_locks > 0) {
                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;

        if (num_flock_locks > 0) {
                err = ceph_pagelist_append(pagelist, &flocks[num_fcntl_locks],
                                           num_flock_locks * sizeof(*flocks));
        }
out_fail:
        return err;
}