// SPDX-License-Identifier: GPL-2.0
/*
 * NVMe Over Fabrics Target File I/O commands implementation.
 * Copyright (c) 2017-2018 Western Digital Corporation or its
 * affiliates.
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/uio.h>
#include <linux/falloc.h>
#include <linux/file.h>
#include <linux/fs.h>
#include "nvmet.h"

#define NVMET_MIN_MPOOL_OBJ             16

void nvmet_file_ns_revalidate(struct nvmet_ns *ns)
{
        ns->size = i_size_read(ns->file->f_mapping->host);
}

void nvmet_file_ns_disable(struct nvmet_ns *ns)
{
        if (ns->file) {
                if (ns->buffered_io)
                        flush_workqueue(buffered_io_wq);
                mempool_destroy(ns->bvec_pool);
                ns->bvec_pool = NULL;
                fput(ns->file);
                ns->file = NULL;
        }
}

int nvmet_file_ns_enable(struct nvmet_ns *ns)
{
        int flags = O_RDWR | O_LARGEFILE;
        int ret = 0;

        if (!ns->buffered_io)
                flags |= O_DIRECT;

        ns->file = filp_open(ns->device_path, flags, 0);
        if (IS_ERR(ns->file)) {
                ret = PTR_ERR(ns->file);
                pr_err("failed to open file %s: (%d)\n",
                        ns->device_path, ret);
                ns->file = NULL;
                return ret;
        }

        nvmet_file_ns_revalidate(ns);

        /*
         * i_blkbits can be greater than the universally accepted upper bound,
         * so make sure we export a sane namespace lba_shift.
         */
        ns->blksize_shift = min_t(u8,
                        file_inode(ns->file)->i_blkbits, 12);

        ns->bvec_pool = mempool_create(NVMET_MIN_MPOOL_OBJ, mempool_alloc_slab,
                        mempool_free_slab, nvmet_bvec_cache);

        if (!ns->bvec_pool) {
                ret = -ENOMEM;
                goto err;
        }

        return ret;
err:
        fput(ns->file);
        ns->file = NULL;
        ns->size = 0;
        ns->blksize_shift = 0;
        return ret;
}

static ssize_t nvmet_file_submit_bvec(struct nvmet_req *req, loff_t pos,
                unsigned long nr_segs, size_t count, int ki_flags)
{
        struct kiocb *iocb = &req->f.iocb;
        ssize_t (*call_iter)(struct kiocb *iocb, struct iov_iter *iter);
        struct iov_iter iter;
        int rw;

        if (req->cmd->rw.opcode == nvme_cmd_write) {
                if (req->cmd->rw.control & cpu_to_le16(NVME_RW_FUA))
                        ki_flags |= IOCB_DSYNC;
                call_iter = req->ns->file->f_op->write_iter;
                rw = ITER_SOURCE;
        } else {
                call_iter = req->ns->file->f_op->read_iter;
                rw = ITER_DEST;
        }

        iov_iter_bvec(&iter, rw, req->f.bvec, nr_segs, count);

        iocb->ki_pos = pos;
        iocb->ki_filp = req->ns->file;
        iocb->ki_flags = ki_flags | iocb->ki_filp->f_iocb_flags;

        return call_iter(iocb, &iter);
}

static void nvmet_file_io_done(struct kiocb *iocb, long ret)
{
        struct nvmet_req *req = container_of(iocb, struct nvmet_req, f.iocb);
        u16 status = NVME_SC_SUCCESS;

        if (req->f.bvec != req->inline_bvec) {
                if (likely(req->f.mpool_alloc == false))
                        kfree(req->f.bvec);
                else
                        mempool_free(req->f.bvec, req->ns->bvec_pool);
        }

        if (unlikely(ret != req->transfer_len))
                status = errno_to_nvme_status(req, ret);
        nvmet_req_complete(req, status);
}

static bool nvmet_file_execute_io(struct nvmet_req *req, int ki_flags)
{
        ssize_t nr_bvec = req->sg_cnt;
        unsigned long bv_cnt = 0;
        bool is_sync = false;
        size_t len = 0, total_len = 0;
        ssize_t ret = 0;
        loff_t pos;
        int i;
        struct scatterlist *sg;

        if (req->f.mpool_alloc && nr_bvec > NVMET_MAX_MPOOL_BVEC)
                is_sync = true;

        pos = le64_to_cpu(req->cmd->rw.slba) << req->ns->blksize_shift;
        if (unlikely(pos + req->transfer_len > req->ns->size)) {
                nvmet_req_complete(req, errno_to_nvme_status(req, -ENOSPC));
                return true;
        }

        memset(&req->f.iocb, 0, sizeof(struct kiocb));
        for_each_sg(req->sg, sg, req->sg_cnt, i) {
                bvec_set_page(&req->f.bvec[bv_cnt], sg_page(sg), sg->length,
                              sg->offset);
                len += req->f.bvec[bv_cnt].bv_len;
                total_len += req->f.bvec[bv_cnt].bv_len;
                bv_cnt++;

                WARN_ON_ONCE((nr_bvec - 1) < 0);

                if (unlikely(is_sync) &&
                    (nr_bvec - 1 == 0 || bv_cnt == NVMET_MAX_MPOOL_BVEC)) {
                        ret = nvmet_file_submit_bvec(req, pos, bv_cnt, len, 0);
                        if (ret < 0)
                                goto complete;

                        pos += len;
                        bv_cnt = 0;
                        len = 0;
                }
                nr_bvec--;
        }

        if (WARN_ON_ONCE(total_len != req->transfer_len)) {
                ret = -EIO;
                goto complete;
        }

        if (unlikely(is_sync)) {
                ret = total_len;
                goto complete;
        }

        /*
         * A NULL ki_complete ask for synchronous execution, which we want
         * for the IOCB_NOWAIT case.
         */
        if (!(ki_flags & IOCB_NOWAIT))
                req->f.iocb.ki_complete = nvmet_file_io_done;

        ret = nvmet_file_submit_bvec(req, pos, bv_cnt, total_len, ki_flags);

        switch (ret) {
        case -EIOCBQUEUED:
                return true;
        case -EAGAIN:
                if (WARN_ON_ONCE(!(ki_flags & IOCB_NOWAIT)))
                        goto complete;
                return false;
        case -EOPNOTSUPP:
                /*
                 * For file systems returning error -EOPNOTSUPP, handle
                 * IOCB_NOWAIT error case separately and retry without
                 * IOCB_NOWAIT.
                 */
                if ((ki_flags & IOCB_NOWAIT))
                        return false;
                break;
        }

complete:
        nvmet_file_io_done(&req->f.iocb, ret);
        return true;
}

static void nvmet_file_buffered_io_work(struct work_struct *w)
{
        struct nvmet_req *req = container_of(w, struct nvmet_req, f.work);

        nvmet_file_execute_io(req, 0);
}

static void nvmet_file_submit_buffered_io(struct nvmet_req *req)
{
        INIT_WORK(&req->f.work, nvmet_file_buffered_io_work);
        queue_work(buffered_io_wq, &req->f.work);
}

static void nvmet_file_execute_rw(struct nvmet_req *req)
{
        ssize_t nr_bvec = req->sg_cnt;

        if (!nvmet_check_transfer_len(req, nvmet_rw_data_len(req)))
                return;

        if (!req->sg_cnt || !nr_bvec) {
                nvmet_req_complete(req, 0);
                return;
        }

        if (nr_bvec > NVMET_MAX_INLINE_BIOVEC)
                req->f.bvec = kmalloc_objs(struct bio_vec, nr_bvec);
        else
                req->f.bvec = req->inline_bvec;

        if (unlikely(!req->f.bvec)) {
                /* fallback under memory pressure */
                req->f.bvec = mempool_alloc(req->ns->bvec_pool, GFP_KERNEL);
                req->f.mpool_alloc = true;
        } else
                req->f.mpool_alloc = false;

        if (req->ns->buffered_io) {
                if (likely(!req->f.mpool_alloc) &&
                    (req->ns->file->f_mode & FMODE_NOWAIT) &&
                    nvmet_file_execute_io(req, IOCB_NOWAIT))
                        return;
                nvmet_file_submit_buffered_io(req);
        } else
                nvmet_file_execute_io(req, 0);
}

u16 nvmet_file_flush(struct nvmet_req *req)
{
        return errno_to_nvme_status(req, vfs_fsync(req->ns->file, 1));
}

static void nvmet_file_flush_work(struct work_struct *w)
{
        struct nvmet_req *req = container_of(w, struct nvmet_req, f.work);

        nvmet_req_complete(req, nvmet_file_flush(req));
}

static void nvmet_file_execute_flush(struct nvmet_req *req)
{
        if (!nvmet_check_transfer_len(req, 0))
                return;
        INIT_WORK(&req->f.work, nvmet_file_flush_work);
        queue_work(nvmet_wq, &req->f.work);
}

static void nvmet_file_execute_discard(struct nvmet_req *req)
{
        int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
        struct nvme_dsm_range range;
        loff_t offset, len;
        u16 status = 0;
        int ret;
        int i;

        for (i = 0; i <= le32_to_cpu(req->cmd->dsm.nr); i++) {
                status = nvmet_copy_from_sgl(req, i * sizeof(range), &range,
                                        sizeof(range));
                if (status)
                        break;

                offset = le64_to_cpu(range.slba) << req->ns->blksize_shift;
                len = le32_to_cpu(range.nlb);
                len <<= req->ns->blksize_shift;
                if (offset + len > req->ns->size) {
                        req->error_slba = le64_to_cpu(range.slba);
                        status = errno_to_nvme_status(req, -ENOSPC);
                        break;
                }

                ret = vfs_fallocate(req->ns->file, mode, offset, len);
                if (ret && ret != -EOPNOTSUPP) {
                        req->error_slba = le64_to_cpu(range.slba);
                        status = errno_to_nvme_status(req, ret);
                        break;
                }
        }

        nvmet_req_complete(req, status);
}

static void nvmet_file_dsm_work(struct work_struct *w)
{
        struct nvmet_req *req = container_of(w, struct nvmet_req, f.work);

        switch (le32_to_cpu(req->cmd->dsm.attributes)) {
        case NVME_DSMGMT_AD:
                nvmet_file_execute_discard(req);
                return;
        case NVME_DSMGMT_IDR:
        case NVME_DSMGMT_IDW:
        default:
                /* Not supported yet */
                nvmet_req_complete(req, 0);
                return;
        }
}

static void nvmet_file_execute_dsm(struct nvmet_req *req)
{
        if (!nvmet_check_data_len_lte(req, nvmet_dsm_len(req)))
                return;
        INIT_WORK(&req->f.work, nvmet_file_dsm_work);
        queue_work(nvmet_wq, &req->f.work);
}

static void nvmet_file_write_zeroes_work(struct work_struct *w)
{
        struct nvmet_req *req = container_of(w, struct nvmet_req, f.work);
        struct nvme_write_zeroes_cmd *write_zeroes = &req->cmd->write_zeroes;
        int mode = FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE;
        loff_t offset;
        loff_t len;
        int ret;

        offset = le64_to_cpu(write_zeroes->slba) << req->ns->blksize_shift;
        len = (((sector_t)le16_to_cpu(write_zeroes->length) + 1) <<
                        req->ns->blksize_shift);

        if (unlikely(offset + len > req->ns->size)) {
                nvmet_req_complete(req, errno_to_nvme_status(req, -ENOSPC));
                return;
        }

        ret = vfs_fallocate(req->ns->file, mode, offset, len);
        nvmet_req_complete(req, ret < 0 ? errno_to_nvme_status(req, ret) : 0);
}

static void nvmet_file_execute_write_zeroes(struct nvmet_req *req)
{
        if (!nvmet_check_transfer_len(req, 0))
                return;
        INIT_WORK(&req->f.work, nvmet_file_write_zeroes_work);
        queue_work(nvmet_wq, &req->f.work);
}

u16 nvmet_file_parse_io_cmd(struct nvmet_req *req)
{
        switch (req->cmd->common.opcode) {
        case nvme_cmd_read:
        case nvme_cmd_write:
                req->execute = nvmet_file_execute_rw;
                return 0;
        case nvme_cmd_flush:
                req->execute = nvmet_file_execute_flush;
                return 0;
        case nvme_cmd_dsm:
                req->execute = nvmet_file_execute_dsm;
                return 0;
        case nvme_cmd_write_zeroes:
                req->execute = nvmet_file_execute_write_zeroes;
                return 0;
        default:
                return nvmet_report_invalid_opcode(req);
        }
}