/*
 *  linux/fs/nfs/blocklayout/blocklayoutdev.c
 *
 *  Device operations for the pnfs nfs4 file layout driver.
 *
 *  Copyright (c) 2006 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  Andy Adamson <andros@citi.umich.edu>
 *  Fred Isaman <iisaman@umich.edu>
 *
 * permission is granted to use, copy, create derivative works and
 * redistribute this software and such derivative works for any purpose,
 * so long as the name of the university of michigan is not used in
 * any advertising or publicity pertaining to the use or distribution
 * of this software without specific, written prior authorization.  if
 * the above copyright notice or any other identification of the
 * university of michigan is included in any copy of any portion of
 * this software, then the disclaimer below must also be included.
 *
 * this software is provided as is, without representation from the
 * university of michigan as to its fitness for any purpose, and without
 * warranty by the university of michigan of any kind, either express
 * or implied, including without limitation the implied warranties of
 * merchantability and fitness for a particular purpose.  the regents
 * of the university of michigan shall not be liable for any damages,
 * including special, indirect, incidental, or consequential damages,
 * with respect to any claim arising out or in connection with the use
 * of the software, even if it has been or is hereafter advised of the
 * possibility of such damages.
 */
#include <linux/module.h>
#include <linux/buffer_head.h> /* __bread */

#include <linux/genhd.h>
#include <linux/blkdev.h>
#include <linux/hash.h>

#include "blocklayout.h"

#define NFSDBG_FACILITY         NFSDBG_PNFS_LD

static int decode_sector_number(__be32 **rp, sector_t *sp)
{
        uint64_t s;

        *rp = xdr_decode_hyper(*rp, &s);
        if (s & 0x1ff) {
                printk(KERN_WARNING "NFS: %s: sector not aligned\n", __func__);
                return -1;
        }
        *sp = s >> SECTOR_SHIFT;
        return 0;
}

/*
 * Release the block device
 */
int nfs4_blkdev_put(struct block_device *bdev)
{
        dprintk("%s for device %d:%d\n", __func__, MAJOR(bdev->bd_dev),
                        MINOR(bdev->bd_dev));
        return blkdev_put(bdev, FMODE_READ);
}

ssize_t bl_pipe_downcall(struct file *filp, const char __user *src,
                         size_t mlen)
{
        struct nfs_net *nn = net_generic(filp->f_dentry->d_sb->s_fs_info,
                                         nfs_net_id);

        if (mlen != sizeof (struct bl_dev_msg))
                return -EINVAL;

        if (copy_from_user(&nn->bl_mount_reply, src, mlen) != 0)
                return -EFAULT;

        wake_up(&nn->bl_wq);

        return mlen;
}

void bl_pipe_destroy_msg(struct rpc_pipe_msg *msg)
{
        struct bl_pipe_msg *bl_pipe_msg = container_of(msg, struct bl_pipe_msg, msg);

        if (msg->errno >= 0)
                return;
        wake_up(bl_pipe_msg->bl_wq);
}

/*
 * Decodes pnfs_block_deviceaddr4 which is XDR encoded in dev->dev_addr_buf.
 */
struct pnfs_block_dev *
nfs4_blk_decode_device(struct nfs_server *server,
                       struct pnfs_device *dev)
{
        struct pnfs_block_dev *rv;
        struct block_device *bd = NULL;
        struct bl_pipe_msg bl_pipe_msg;
        struct rpc_pipe_msg *msg = &bl_pipe_msg.msg;
        struct bl_msg_hdr bl_msg = {
                .type = BL_DEVICE_MOUNT,
                .totallen = dev->mincount,
        };
        uint8_t *dataptr;
        DECLARE_WAITQUEUE(wq, current);
        int offset, len, i, rc;
        struct net *net = server->nfs_client->cl_net;
        struct nfs_net *nn = net_generic(net, nfs_net_id);
        struct bl_dev_msg *reply = &nn->bl_mount_reply;

        dprintk("%s CREATING PIPEFS MESSAGE\n", __func__);
        dprintk("%s: deviceid: %s, mincount: %d\n", __func__, dev->dev_id.data,
                dev->mincount);

        bl_pipe_msg.bl_wq = &nn->bl_wq;
        memset(msg, 0, sizeof(*msg));
        msg->data = kzalloc(sizeof(bl_msg) + dev->mincount, GFP_NOFS);
        if (!msg->data) {
                rv = ERR_PTR(-ENOMEM);
                goto out;
        }

        memcpy(msg->data, &bl_msg, sizeof(bl_msg));
        dataptr = (uint8_t *) msg->data;
        len = dev->mincount;
        offset = sizeof(bl_msg);
        for (i = 0; len > 0; i++) {
                memcpy(&dataptr[offset], page_address(dev->pages[i]),
                                len < PAGE_CACHE_SIZE ? len : PAGE_CACHE_SIZE);
                len -= PAGE_CACHE_SIZE;
                offset += PAGE_CACHE_SIZE;
        }
        msg->len = sizeof(bl_msg) + dev->mincount;

        dprintk("%s CALLING USERSPACE DAEMON\n", __func__);
        add_wait_queue(&nn->bl_wq, &wq);
        rc = rpc_queue_upcall(nn->bl_device_pipe, msg);
        if (rc < 0) {
                remove_wait_queue(&nn->bl_wq, &wq);
                rv = ERR_PTR(rc);
                goto out;
        }

        set_current_state(TASK_UNINTERRUPTIBLE);
        schedule();
        __set_current_state(TASK_RUNNING);
        remove_wait_queue(&nn->bl_wq, &wq);

        if (reply->status != BL_DEVICE_REQUEST_PROC) {
                dprintk("%s failed to open device: %d\n",
                        __func__, reply->status);
                rv = ERR_PTR(-EINVAL);
                goto out;
        }

        bd = blkdev_get_by_dev(MKDEV(reply->major, reply->minor),
                               FMODE_READ, NULL);
        if (IS_ERR(bd)) {
                dprintk("%s failed to open device : %ld\n", __func__,
                        PTR_ERR(bd));
                rv = ERR_CAST(bd);
                goto out;
        }

        rv = kzalloc(sizeof(*rv), GFP_NOFS);
        if (!rv) {
                rv = ERR_PTR(-ENOMEM);
                goto out;
        }

        rv->bm_mdev = bd;
        memcpy(&rv->bm_mdevid, &dev->dev_id, sizeof(struct nfs4_deviceid));
        rv->net = net;
        dprintk("%s Created device %s with bd_block_size %u\n",
                __func__,
                bd->bd_disk->disk_name,
                bd->bd_block_size);

out:
        kfree(msg->data);
        return rv;
}

/* Map deviceid returned by the server to constructed block_device */
static struct block_device *translate_devid(struct pnfs_layout_hdr *lo,
                                            struct nfs4_deviceid *id)
{
        struct block_device *rv = NULL;
        struct block_mount_id *mid;
        struct pnfs_block_dev *dev;

        dprintk("%s enter, lo=%p, id=%p\n", __func__, lo, id);
        mid = BLK_ID(lo);
        spin_lock(&mid->bm_lock);
        list_for_each_entry(dev, &mid->bm_devlist, bm_node) {
                if (memcmp(id->data, dev->bm_mdevid.data,
                           NFS4_DEVICEID4_SIZE) == 0) {
                        rv = dev->bm_mdev;
                        goto out;
                }
        }
 out:
        spin_unlock(&mid->bm_lock);
        dprintk("%s returning %p\n", __func__, rv);
        return rv;
}

/* Tracks info needed to ensure extents in layout obey constraints of spec */
struct layout_verification {
        u32 mode;       /* R or RW */
        u64 start;      /* Expected start of next non-COW extent */
        u64 inval;      /* Start of INVAL coverage */
        u64 cowread;    /* End of COW read coverage */
};

/* Verify the extent meets the layout requirements of the pnfs-block draft,
 * section 2.3.1.
 */
static int verify_extent(struct pnfs_block_extent *be,
                         struct layout_verification *lv)
{
        if (lv->mode == IOMODE_READ) {
                if (be->be_state == PNFS_BLOCK_READWRITE_DATA ||
                    be->be_state == PNFS_BLOCK_INVALID_DATA)
                        return -EIO;
                if (be->be_f_offset != lv->start)
                        return -EIO;
                lv->start += be->be_length;
                return 0;
        }
        /* lv->mode == IOMODE_RW */
        if (be->be_state == PNFS_BLOCK_READWRITE_DATA) {
                if (be->be_f_offset != lv->start)
                        return -EIO;
                if (lv->cowread > lv->start)
                        return -EIO;
                lv->start += be->be_length;
                lv->inval = lv->start;
                return 0;
        } else if (be->be_state == PNFS_BLOCK_INVALID_DATA) {
                if (be->be_f_offset != lv->start)
                        return -EIO;
                lv->start += be->be_length;
                return 0;
        } else if (be->be_state == PNFS_BLOCK_READ_DATA) {
                if (be->be_f_offset > lv->start)
                        return -EIO;
                if (be->be_f_offset < lv->inval)
                        return -EIO;
                if (be->be_f_offset < lv->cowread)
                        return -EIO;
                /* It looks like you might want to min this with lv->start,
                 * but you really don't.
                 */
                lv->inval = lv->inval + be->be_length;
                lv->cowread = be->be_f_offset + be->be_length;
                return 0;
        } else
                return -EIO;
}

/* XDR decode pnfs_block_layout4 structure */
int
nfs4_blk_process_layoutget(struct pnfs_layout_hdr *lo,
                           struct nfs4_layoutget_res *lgr, gfp_t gfp_flags)
{
        struct pnfs_block_layout *bl = BLK_LO2EXT(lo);
        int i, status = -EIO;
        uint32_t count;
        struct pnfs_block_extent *be = NULL, *save;
        struct xdr_stream stream;
        struct xdr_buf buf;
        struct page *scratch;
        __be32 *p;
        struct layout_verification lv = {
                .mode = lgr->range.iomode,
                .start = lgr->range.offset >> SECTOR_SHIFT,
                .inval = lgr->range.offset >> SECTOR_SHIFT,
                .cowread = lgr->range.offset >> SECTOR_SHIFT,
        };
        LIST_HEAD(extents);

        dprintk("---> %s\n", __func__);

        scratch = alloc_page(gfp_flags);
        if (!scratch)
                return -ENOMEM;

        xdr_init_decode_pages(&stream, &buf, lgr->layoutp->pages, lgr->layoutp->len);
        xdr_set_scratch_buffer(&stream, page_address(scratch), PAGE_SIZE);

        p = xdr_inline_decode(&stream, 4);
        if (unlikely(!p))
                goto out_err;

        count = be32_to_cpup(p++);

        dprintk("%s enter, number of extents %i\n", __func__, count);
        p = xdr_inline_decode(&stream, (28 + NFS4_DEVICEID4_SIZE) * count);
        if (unlikely(!p))
                goto out_err;

        /* Decode individual extents, putting them in temporary
         * staging area until whole layout is decoded to make error
         * recovery easier.
         */
        for (i = 0; i < count; i++) {
                be = bl_alloc_extent();
                if (!be) {
                        status = -ENOMEM;
                        goto out_err;
                }
                memcpy(&be->be_devid, p, NFS4_DEVICEID4_SIZE);
                p += XDR_QUADLEN(NFS4_DEVICEID4_SIZE);
                be->be_mdev = translate_devid(lo, &be->be_devid);
                if (!be->be_mdev)
                        goto out_err;

                /* The next three values are read in as bytes,
                 * but stored as 512-byte sector lengths
                 */
                if (decode_sector_number(&p, &be->be_f_offset) < 0)
                        goto out_err;
                if (decode_sector_number(&p, &be->be_length) < 0)
                        goto out_err;
                if (decode_sector_number(&p, &be->be_v_offset) < 0)
                        goto out_err;
                be->be_state = be32_to_cpup(p++);
                if (be->be_state == PNFS_BLOCK_INVALID_DATA)
                        be->be_inval = &bl->bl_inval;
                if (verify_extent(be, &lv)) {
                        dprintk("%s verify failed\n", __func__);
                        goto out_err;
                }
                list_add_tail(&be->be_node, &extents);
        }
        if (lgr->range.offset + lgr->range.length !=
                        lv.start << SECTOR_SHIFT) {
                dprintk("%s Final length mismatch\n", __func__);
                be = NULL;
                goto out_err;
        }
        if (lv.start < lv.cowread) {
                dprintk("%s Final uncovered COW extent\n", __func__);
                be = NULL;
                goto out_err;
        }
        /* Extents decoded properly, now try to merge them in to
         * existing layout extents.
         */
        spin_lock(&bl->bl_ext_lock);
        list_for_each_entry_safe(be, save, &extents, be_node) {
                list_del(&be->be_node);
                status = bl_add_merge_extent(bl, be);
                if (status) {
                        spin_unlock(&bl->bl_ext_lock);
                        /* This is a fairly catastrophic error, as the
                         * entire layout extent lists are now corrupted.
                         * We should have some way to distinguish this.
                         */
                        be = NULL;
                        goto out_err;
                }
        }
        spin_unlock(&bl->bl_ext_lock);
        status = 0;
 out:
        __free_page(scratch);
        dprintk("%s returns %i\n", __func__, status);
        return status;

 out_err:
        bl_put_extent(be);
        while (!list_empty(&extents)) {
                be = list_first_entry(&extents, struct pnfs_block_extent,
                                      be_node);
                list_del(&be->be_node);
                bl_put_extent(be);
        }
        goto out;
}