blocklayoutdev.c

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/*
 *  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 <[email protected]>
 *  Fred Isaman <[email protected]>
 *
 * 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;
}