fs/zfs/vdev_file.c

	vdev_file.c revision 1f7ad2e1275fff503991bf4b43bc5cf1d815669f
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include <sys/zfs_context.h>
#include <sys/spa.h>
#include <sys/vdev_file.h>
#include <sys/vdev_impl.h>
#include <sys/zio.h>
#include <sys/fs/zfs.h>

/*
 * Virtual device vector for files.
 */

static int
vdev_file_open_common(vdev_t *vd)
{
    vdev_file_t *vf;
    vnode_t *vp;
    int error;

    /*
     * We must have a pathname, and it must be absolute.
     */
    if (vd->vdev_path == NULL || vd->vdev_path[0] != '/') {
        vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
        return (EINVAL);
    }

    vf = vd->vdev_tsd = kmem_zalloc(sizeof (vdev_file_t), KM_SLEEP);

    /*
     * We always open the files from the root of the global zone, even if
     * we're in a local zone.  If the user has gotten to this point, the
     * administrator has already decided that the pool should be available
     * to local zone users, so the underlying devices should be as well.
     */
    ASSERT(vd->vdev_path != NULL && vd->vdev_path[0] == '/');
    error = vn_openat(vd->vdev_path + 1, UIO_SYSSPACE,
        spa_mode | FOFFMAX, 0, &vp, 0, 0, rootdir, -1);

    if (error) {
        vd->vdev_stat.vs_aux = VDEV_AUX_OPEN_FAILED;
        return (error);
    }

    vf->vf_vnode = vp;

#ifdef _KERNEL
    /*
     * Make sure it's a regular file.
     */
    if (vp->v_type != VREG) {
        vd->vdev_stat.vs_aux = VDEV_AUX_OPEN_FAILED;
        return (ENODEV);
    }
#endif

    return (0);
}

static int
vdev_file_open(vdev_t *vd, uint64_t *psize, uint64_t *ashift)
{
    vdev_file_t *vf;
    vattr_t vattr;
    int error;

    if ((error = vdev_file_open_common(vd)) != 0)
        return (error);

    vf = vd->vdev_tsd;

    /*
     * Determine the physical size of the file.
     */
    vattr.va_mask = AT_SIZE;
    error = VOP_GETATTR(vf->vf_vnode, &vattr, 0, kcred, NULL);
    if (error) {
        vd->vdev_stat.vs_aux = VDEV_AUX_OPEN_FAILED;
        return (error);
    }

    *psize = vattr.va_size;
    *ashift = SPA_MINBLOCKSHIFT;

    return (0);
}

static void
vdev_file_close(vdev_t *vd)
{
    vdev_file_t *vf = vd->vdev_tsd;

    if (vf == NULL)
        return;

    if (vf->vf_vnode != NULL) {
        (void) VOP_PUTPAGE(vf->vf_vnode, 0, 0, B_INVAL, kcred, NULL);
        (void) VOP_CLOSE(vf->vf_vnode, spa_mode, 1, 0, kcred, NULL);
        VN_RELE(vf->vf_vnode);
    }

    kmem_free(vf, sizeof (vdev_file_t));
    vd->vdev_tsd = NULL;
}

static int
vdev_file_probe_io(vdev_t *vd, caddr_t data, size_t size, uint64_t offset,
    enum uio_rw rw)
{
    vdev_file_t *vf = vd->vdev_tsd;
    ssize_t resid;
    int error = 0;

    if (vd == NULL || vf == NULL || vf->vf_vnode == NULL)
        return (EINVAL);

    ASSERT(rw == UIO_READ || rw ==  UIO_WRITE);

    error = vn_rdwr(rw, vf->vf_vnode, data, size, offset, UIO_SYSSPACE,
        0, RLIM64_INFINITY, kcred, &resid);
    if (error || resid != 0)
        return (EIO);
    return (0);
}

/*
 * Determine if the underlying device is accessible by reading and writing
 * to a known location. We must be able to do this during syncing context
 * and thus we cannot set the vdev state directly.
 */
static int
vdev_file_probe(vdev_t *vd)
{
    vdev_t *nvd;
    char *vl_boot;
    uint64_t offset;
    int l, error = 0, retries = 0;

    if (vd == NULL)
        return (EINVAL);

    /* Hijack the current vdev */
    nvd = vd;

    /*
     * Pick a random label to rewrite.
     */
    l = spa_get_random(VDEV_LABELS);
    ASSERT(l < VDEV_LABELS);

    offset = vdev_label_offset(vd->vdev_psize, l,
        offsetof(vdev_label_t, vl_boot_header));

    vl_boot = kmem_alloc(VDEV_BOOT_HEADER_SIZE, KM_SLEEP);

    while ((error = vdev_file_probe_io(nvd, vl_boot, VDEV_BOOT_HEADER_SIZE,
        offset, UIO_READ)) != 0 && retries == 0) {

        /*
         * If we failed with the vdev that was passed in then
         * try allocating a new one and try again.
         */
        nvd = kmem_zalloc(sizeof (vdev_t), KM_SLEEP);
        if (vd->vdev_path)
            nvd->vdev_path = spa_strdup(vd->vdev_path);
        retries++;

        error = vdev_file_open_common(nvd);
        if (error)
            break;
    }

    if ((spa_mode & FWRITE) && !error) {
        error = vdev_file_probe_io(nvd, vl_boot, VDEV_BOOT_HEADER_SIZE,
            offset, UIO_WRITE);
    }

    if (retries) {
        vdev_file_close(nvd);
        if (nvd->vdev_path)
            spa_strfree(nvd->vdev_path);
        kmem_free(nvd, sizeof (vdev_t));
    }
    kmem_free(vl_boot, VDEV_BOOT_HEADER_SIZE);

    if (!error)
        vd->vdev_is_failing = B_FALSE;

    return (error);
}

static void
vdev_file_io_start(zio_t *zio)
{
    vdev_t *vd = zio->io_vd;
    vdev_file_t *vf = vd->vdev_tsd;
    ssize_t resid;
    int error;

    if (zio->io_type == ZIO_TYPE_IOCTL) {
        zio_vdev_io_bypass(zio);

        /* XXPOLICY */
        if (!vdev_readable(vd)) {
            zio->io_error = ENXIO;
            zio_next_stage_async(zio);
            return;
        }

        switch (zio->io_cmd) {
        case DKIOCFLUSHWRITECACHE:
            zio->io_error = VOP_FSYNC(vf->vf_vnode, FSYNC | FDSYNC,
                kcred, NULL);
            dprintf("fsync(%s) = %d\n", vdev_description(vd),
                zio->io_error);
            break;
        default:
            zio->io_error = ENOTSUP;
        }

        zio_next_stage_async(zio);
        return;
    }

    /*
     * In the kernel, don't bother double-caching, but in userland,
     * we want to test the vdev_cache code.
     */
#ifndef _KERNEL
    if (zio->io_type == ZIO_TYPE_READ && vdev_cache_read(zio) == 0)
        return;
#endif

    if ((zio = vdev_queue_io(zio)) == NULL)
        return;

    /* XXPOLICY */
    if (zio->io_type == ZIO_TYPE_WRITE)
        error = vdev_writeable(vd) ? vdev_error_inject(vd, zio) : ENXIO;
    else
        error = vdev_readable(vd) ? vdev_error_inject(vd, zio) : ENXIO;
    error = (vd->vdev_remove_wanted || vd->vdev_is_failing) ? ENXIO : error;
    if (error) {
        zio->io_error = error;
        zio_next_stage_async(zio);
        return;
    }

    zio->io_error = vn_rdwr(zio->io_type == ZIO_TYPE_READ ?
        UIO_READ : UIO_WRITE, vf->vf_vnode, zio->io_data,
        zio->io_size, zio->io_offset, UIO_SYSSPACE,
        0, RLIM64_INFINITY, kcred, &resid);

    if (resid != 0 && zio->io_error == 0)
        zio->io_error = ENOSPC;

    zio_next_stage_async(zio);
}

static void
vdev_file_io_done(zio_t *zio)
{

    if (zio_injection_enabled && zio->io_error == 0)
        zio->io_error = zio_handle_device_injection(zio->io_vd, EIO);

    /*
     * If an error has been encountered then attempt to probe the device
     * to determine if it's still accessible.
     */
    if (zio->io_error == EIO) {
        vdev_t *vd = zio->io_vd;

        if (vdev_probe(vd) != 0)
            vd->vdev_is_failing = B_TRUE;
    }

    vdev_queue_io_done(zio);

#ifndef _KERNEL
    if (zio->io_type == ZIO_TYPE_WRITE)
        vdev_cache_write(zio);
#endif

    zio_next_stage(zio);
}

vdev_ops_t vdev_file_ops = {
    vdev_file_open,
    vdev_file_close,
    vdev_file_probe,
    vdev_default_asize,
    vdev_file_io_start,
    vdev_file_io_done,
    NULL,
    VDEV_TYPE_FILE,     /* name of this vdev type */
    B_TRUE          /* leaf vdev */
};

/*
 * From userland we access disks just like files.
 */
#ifndef _KERNEL

vdev_ops_t vdev_disk_ops = {
    vdev_file_open,
    vdev_file_close,
    vdev_file_probe,
    vdev_default_asize,
    vdev_file_io_start,
    vdev_file_io_done,
    NULL,
    VDEV_TYPE_DISK,     /* name of this vdev type */
    B_TRUE          /* leaf vdev */
};

#endif