xref: /openbmc/qemu/block/file-posix.c (revision fc59d2d8)

/*
 * Block driver for RAW files (posix)
 *
 * Copyright (c) 2006 Fabrice Bellard
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "qemu/osdep.h"
#include "qemu-common.h"
#include "qapi/error.h"
#include "qemu/cutils.h"
#include "qemu/error-report.h"
#include "block/block_int.h"
#include "qemu/module.h"
#include "qemu/option.h"
#include "trace.h"
#include "block/thread-pool.h"
#include "qemu/iov.h"
#include "block/raw-aio.h"
#include "qapi/qmp/qdict.h"
#include "qapi/qmp/qstring.h"

#include "scsi/pr-manager.h"
#include "scsi/constants.h"

#if defined(__APPLE__) && (__MACH__)
#include <paths.h>
#include <sys/param.h>
#include <IOKit/IOKitLib.h>
#include <IOKit/IOBSD.h>
#include <IOKit/storage/IOMediaBSDClient.h>
#include <IOKit/storage/IOMedia.h>
#include <IOKit/storage/IOCDMedia.h>
//#include <IOKit/storage/IOCDTypes.h>
#include <IOKit/storage/IODVDMedia.h>
#include <CoreFoundation/CoreFoundation.h>
#endif

#ifdef __sun__
#define _POSIX_PTHREAD_SEMANTICS 1
#include <sys/dkio.h>
#endif
#ifdef __linux__
#include <sys/ioctl.h>
#include <sys/param.h>
#include <sys/syscall.h>
#include <linux/cdrom.h>
#include <linux/fd.h>
#include <linux/fs.h>
#include <linux/hdreg.h>
#include <scsi/sg.h>
#ifdef __s390__
#include <asm/dasd.h>
#endif
#ifndef FS_NOCOW_FL
#define FS_NOCOW_FL                     0x00800000 /* Do not cow file */
#endif
#endif
#if defined(CONFIG_FALLOCATE_PUNCH_HOLE) || defined(CONFIG_FALLOCATE_ZERO_RANGE)
#include <linux/falloc.h>
#endif
#if defined (__FreeBSD__) || defined(__FreeBSD_kernel__)
#include <sys/disk.h>
#include <sys/cdio.h>
#endif

#ifdef __OpenBSD__
#include <sys/ioctl.h>
#include <sys/disklabel.h>
#include <sys/dkio.h>
#endif

#ifdef __NetBSD__
#include <sys/ioctl.h>
#include <sys/disklabel.h>
#include <sys/dkio.h>
#include <sys/disk.h>
#endif

#ifdef __DragonFly__
#include <sys/ioctl.h>
#include <sys/diskslice.h>
#endif

#ifdef CONFIG_XFS
#include <xfs/xfs.h>
#endif

#include "trace.h"

/* OS X does not have O_DSYNC */
#ifndef O_DSYNC
#ifdef O_SYNC
#define O_DSYNC O_SYNC
#elif defined(O_FSYNC)
#define O_DSYNC O_FSYNC
#endif
#endif

/* Approximate O_DIRECT with O_DSYNC if O_DIRECT isn't available */
#ifndef O_DIRECT
#define O_DIRECT O_DSYNC
#endif

#define FTYPE_FILE   0
#define FTYPE_CD     1

#define MAX_BLOCKSIZE	4096

/* Posix file locking bytes. Libvirt takes byte 0, we start from higher bytes,
 * leaving a few more bytes for its future use. */
#define RAW_LOCK_PERM_BASE             100
#define RAW_LOCK_SHARED_BASE           200

typedef struct BDRVRawState {
    int fd;
    bool use_lock;
    int type;
    int open_flags;
    size_t buf_align;

    /* The current permissions. */
    uint64_t perm;
    uint64_t shared_perm;

    /* The perms bits whose corresponding bytes are already locked in
     * s->fd. */
    uint64_t locked_perm;
    uint64_t locked_shared_perm;

    int perm_change_fd;
    int perm_change_flags;
    BDRVReopenState *reopen_state;

#ifdef CONFIG_XFS
    bool is_xfs:1;
#endif
    bool has_discard:1;
    bool has_write_zeroes:1;
    bool discard_zeroes:1;
    bool use_linux_aio:1;
    bool page_cache_inconsistent:1;
    bool has_fallocate;
    bool needs_alignment;
    bool drop_cache;
    bool check_cache_dropped;
    struct {
        uint64_t discard_nb_ok;
        uint64_t discard_nb_failed;
        uint64_t discard_bytes_ok;
    } stats;

    PRManager *pr_mgr;
} BDRVRawState;

typedef struct BDRVRawReopenState {
    int fd;
    int open_flags;
    bool drop_cache;
    bool check_cache_dropped;
} BDRVRawReopenState;

static int fd_open(BlockDriverState *bs);
static int64_t raw_getlength(BlockDriverState *bs);

typedef struct RawPosixAIOData {
    BlockDriverState *bs;
    int aio_type;
    int aio_fildes;

    off_t aio_offset;
    uint64_t aio_nbytes;

    union {
        struct {
            struct iovec *iov;
            int niov;
        } io;
        struct {
            uint64_t cmd;
            void *buf;
        } ioctl;
        struct {
            int aio_fd2;
            off_t aio_offset2;
        } copy_range;
        struct {
            PreallocMode prealloc;
            Error **errp;
        } truncate;
    };
} RawPosixAIOData;

#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
static int cdrom_reopen(BlockDriverState *bs);
#endif

#if defined(__NetBSD__)
static int raw_normalize_devicepath(const char **filename, Error **errp)
{
    static char namebuf[PATH_MAX];
    const char *dp, *fname;
    struct stat sb;

    fname = *filename;
    dp = strrchr(fname, '/');
    if (lstat(fname, &sb) < 0) {
        error_setg_file_open(errp, errno, fname);
        return -errno;
    }

    if (!S_ISBLK(sb.st_mode)) {
        return 0;
    }

    if (dp == NULL) {
        snprintf(namebuf, PATH_MAX, "r%s", fname);
    } else {
        snprintf(namebuf, PATH_MAX, "%.*s/r%s",
            (int)(dp - fname), fname, dp + 1);
    }
    *filename = namebuf;
    warn_report("%s is a block device, using %s", fname, *filename);

    return 0;
}
#else
static int raw_normalize_devicepath(const char **filename, Error **errp)
{
    return 0;
}
#endif

/*
 * Get logical block size via ioctl. On success store it in @sector_size_p.
 */
static int probe_logical_blocksize(int fd, unsigned int *sector_size_p)
{
    unsigned int sector_size;
    bool success = false;
    int i;

    errno = ENOTSUP;
    static const unsigned long ioctl_list[] = {
#ifdef BLKSSZGET
        BLKSSZGET,
#endif
#ifdef DKIOCGETBLOCKSIZE
        DKIOCGETBLOCKSIZE,
#endif
#ifdef DIOCGSECTORSIZE
        DIOCGSECTORSIZE,
#endif
    };

    /* Try a few ioctls to get the right size */
    for (i = 0; i < (int)ARRAY_SIZE(ioctl_list); i++) {
        if (ioctl(fd, ioctl_list[i], &sector_size) >= 0) {
            *sector_size_p = sector_size;
            success = true;
        }
    }

    return success ? 0 : -errno;
}

/**
 * Get physical block size of @fd.
 * On success, store it in @blk_size and return 0.
 * On failure, return -errno.
 */
static int probe_physical_blocksize(int fd, unsigned int *blk_size)
{
#ifdef BLKPBSZGET
    if (ioctl(fd, BLKPBSZGET, blk_size) < 0) {
        return -errno;
    }
    return 0;
#else
    return -ENOTSUP;
#endif
}

/* Check if read is allowed with given memory buffer and length.
 *
 * This function is used to check O_DIRECT memory buffer and request alignment.
 */
static bool raw_is_io_aligned(int fd, void *buf, size_t len)
{
    ssize_t ret = pread(fd, buf, len, 0);

    if (ret >= 0) {
        return true;
    }

#ifdef __linux__
    /* The Linux kernel returns EINVAL for misaligned O_DIRECT reads.  Ignore
     * other errors (e.g. real I/O error), which could happen on a failed
     * drive, since we only care about probing alignment.
     */
    if (errno != EINVAL) {
        return true;
    }
#endif

    return false;
}

static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp)
{
    BDRVRawState *s = bs->opaque;
    char *buf;
    size_t max_align = MAX(MAX_BLOCKSIZE, qemu_real_host_page_size);
    size_t alignments[] = {1, 512, 1024, 2048, 4096};

    /* For SCSI generic devices the alignment is not really used.
       With buffered I/O, we don't have any restrictions. */
    if (bdrv_is_sg(bs) || !s->needs_alignment) {
        bs->bl.request_alignment = 1;
        s->buf_align = 1;
        return;
    }

    bs->bl.request_alignment = 0;
    s->buf_align = 0;
    /* Let's try to use the logical blocksize for the alignment. */
    if (probe_logical_blocksize(fd, &bs->bl.request_alignment) < 0) {
        bs->bl.request_alignment = 0;
    }
#ifdef CONFIG_XFS
    if (s->is_xfs) {
        struct dioattr da;
        if (xfsctl(NULL, fd, XFS_IOC_DIOINFO, &da) >= 0) {
            bs->bl.request_alignment = da.d_miniosz;
            /* The kernel returns wrong information for d_mem */
            /* s->buf_align = da.d_mem; */
        }
    }
#endif

    /*
     * If we could not get the sizes so far, we can only guess them. First try
     * to detect request alignment, since it is more likely to succeed. Then
     * try to detect buf_align, which cannot be detected in some cases (e.g.
     * Gluster). If buf_align cannot be detected, we fallback to the value of
     * request_alignment.
     */

    if (!bs->bl.request_alignment) {
        int i;
        size_t align;
        buf = qemu_memalign(max_align, max_align);
        for (i = 0; i < ARRAY_SIZE(alignments); i++) {
            align = alignments[i];
            if (raw_is_io_aligned(fd, buf, align)) {
                /* Fallback to safe value. */
                bs->bl.request_alignment = (align != 1) ? align : max_align;
                break;
            }
        }
        qemu_vfree(buf);
    }

    if (!s->buf_align) {
        int i;
        size_t align;
        buf = qemu_memalign(max_align, 2 * max_align);
        for (i = 0; i < ARRAY_SIZE(alignments); i++) {
            align = alignments[i];
            if (raw_is_io_aligned(fd, buf + align, max_align)) {
                /* Fallback to request_alignment. */
                s->buf_align = (align != 1) ? align : bs->bl.request_alignment;
                break;
            }
        }
        qemu_vfree(buf);
    }

    if (!s->buf_align || !bs->bl.request_alignment) {
        error_setg(errp, "Could not find working O_DIRECT alignment");
        error_append_hint(errp, "Try cache.direct=off\n");
    }
}

static void raw_parse_flags(int bdrv_flags, int *open_flags, bool has_writers)
{
    bool read_write = false;
    assert(open_flags != NULL);

    *open_flags |= O_BINARY;
    *open_flags &= ~O_ACCMODE;

    if (bdrv_flags & BDRV_O_AUTO_RDONLY) {
        read_write = has_writers;
    } else if (bdrv_flags & BDRV_O_RDWR) {
        read_write = true;
    }

    if (read_write) {
        *open_flags |= O_RDWR;
    } else {
        *open_flags |= O_RDONLY;
    }

    /* Use O_DSYNC for write-through caching, no flags for write-back caching,
     * and O_DIRECT for no caching. */
    if ((bdrv_flags & BDRV_O_NOCACHE)) {
        *open_flags |= O_DIRECT;
    }
}

static void raw_parse_filename(const char *filename, QDict *options,
                               Error **errp)
{
    bdrv_parse_filename_strip_prefix(filename, "file:", options);
}

static QemuOptsList raw_runtime_opts = {
    .name = "raw",
    .head = QTAILQ_HEAD_INITIALIZER(raw_runtime_opts.head),
    .desc = {
        {
            .name = "filename",
            .type = QEMU_OPT_STRING,
            .help = "File name of the image",
        },
        {
            .name = "aio",
            .type = QEMU_OPT_STRING,
            .help = "host AIO implementation (threads, native)",
        },
        {
            .name = "locking",
            .type = QEMU_OPT_STRING,
            .help = "file locking mode (on/off/auto, default: auto)",
        },
        {
            .name = "pr-manager",
            .type = QEMU_OPT_STRING,
            .help = "id of persistent reservation manager object (default: none)",
        },
#if defined(__linux__)
        {
            .name = "drop-cache",
            .type = QEMU_OPT_BOOL,
            .help = "invalidate page cache during live migration (default: on)",
        },
#endif
        {
            .name = "x-check-cache-dropped",
            .type = QEMU_OPT_BOOL,
            .help = "check that page cache was dropped on live migration (default: off)"
        },
        { /* end of list */ }
    },
};

static const char *const mutable_opts[] = { "x-check-cache-dropped", NULL };

static int raw_open_common(BlockDriverState *bs, QDict *options,
                           int bdrv_flags, int open_flags,
                           bool device, Error **errp)
{
    BDRVRawState *s = bs->opaque;
    QemuOpts *opts;
    Error *local_err = NULL;
    const char *filename = NULL;
    const char *str;
    BlockdevAioOptions aio, aio_default;
    int fd, ret;
    struct stat st;
    OnOffAuto locking;

    opts = qemu_opts_create(&raw_runtime_opts, NULL, 0, &error_abort);
    qemu_opts_absorb_qdict(opts, options, &local_err);
    if (local_err) {
        error_propagate(errp, local_err);
        ret = -EINVAL;
        goto fail;
    }

    filename = qemu_opt_get(opts, "filename");

    ret = raw_normalize_devicepath(&filename, errp);
    if (ret != 0) {
        goto fail;
    }

    aio_default = (bdrv_flags & BDRV_O_NATIVE_AIO)
                  ? BLOCKDEV_AIO_OPTIONS_NATIVE
                  : BLOCKDEV_AIO_OPTIONS_THREADS;
    aio = qapi_enum_parse(&BlockdevAioOptions_lookup,
                          qemu_opt_get(opts, "aio"),
                          aio_default, &local_err);
    if (local_err) {
        error_propagate(errp, local_err);
        ret = -EINVAL;
        goto fail;
    }
    s->use_linux_aio = (aio == BLOCKDEV_AIO_OPTIONS_NATIVE);

    locking = qapi_enum_parse(&OnOffAuto_lookup,
                              qemu_opt_get(opts, "locking"),
                              ON_OFF_AUTO_AUTO, &local_err);
    if (local_err) {
        error_propagate(errp, local_err);
        ret = -EINVAL;
        goto fail;
    }
    switch (locking) {
    case ON_OFF_AUTO_ON:
        s->use_lock = true;
        if (!qemu_has_ofd_lock()) {
            warn_report("File lock requested but OFD locking syscall is "
                        "unavailable, falling back to POSIX file locks");
            error_printf("Due to the implementation, locks can be lost "
                         "unexpectedly.\n");
        }
        break;
    case ON_OFF_AUTO_OFF:
        s->use_lock = false;
        break;
    case ON_OFF_AUTO_AUTO:
        s->use_lock = qemu_has_ofd_lock();
        break;
    default:
        abort();
    }

    str = qemu_opt_get(opts, "pr-manager");
    if (str) {
        s->pr_mgr = pr_manager_lookup(str, &local_err);
        if (local_err) {
            error_propagate(errp, local_err);
            ret = -EINVAL;
            goto fail;
        }
    }

    s->drop_cache = qemu_opt_get_bool(opts, "drop-cache", true);
    s->check_cache_dropped = qemu_opt_get_bool(opts, "x-check-cache-dropped",
                                               false);

    s->open_flags = open_flags;
    raw_parse_flags(bdrv_flags, &s->open_flags, false);

    s->fd = -1;
    fd = qemu_open(filename, s->open_flags, 0644);
    ret = fd < 0 ? -errno : 0;

    if (ret < 0) {
        error_setg_file_open(errp, -ret, filename);
        if (ret == -EROFS) {
            ret = -EACCES;
        }
        goto fail;
    }
    s->fd = fd;

    s->perm = 0;
    s->shared_perm = BLK_PERM_ALL;

#ifdef CONFIG_LINUX_AIO
     /* Currently Linux does AIO only for files opened with O_DIRECT */
    if (s->use_linux_aio) {
        if (!(s->open_flags & O_DIRECT)) {
            error_setg(errp, "aio=native was specified, but it requires "
                             "cache.direct=on, which was not specified.");
            ret = -EINVAL;
            goto fail;
        }
        if (!aio_setup_linux_aio(bdrv_get_aio_context(bs), errp)) {
            error_prepend(errp, "Unable to use native AIO: ");
            goto fail;
        }
    }
#else
    if (s->use_linux_aio) {
        error_setg(errp, "aio=native was specified, but is not supported "
                         "in this build.");
        ret = -EINVAL;
        goto fail;
    }
#endif /* !defined(CONFIG_LINUX_AIO) */

    s->has_discard = true;
    s->has_write_zeroes = true;
    if ((bs->open_flags & BDRV_O_NOCACHE) != 0) {
        s->needs_alignment = true;
    }

    if (fstat(s->fd, &st) < 0) {
        ret = -errno;
        error_setg_errno(errp, errno, "Could not stat file");
        goto fail;
    }

    if (!device) {
        if (S_ISBLK(st.st_mode)) {
            warn_report("Opening a block device as a file using the '%s' "
                        "driver is deprecated", bs->drv->format_name);
        } else if (S_ISCHR(st.st_mode)) {
            warn_report("Opening a character device as a file using the '%s' "
                        "driver is deprecated", bs->drv->format_name);
        } else if (!S_ISREG(st.st_mode)) {
            error_setg(errp, "A regular file was expected by the '%s' driver, "
                       "but something else was given", bs->drv->format_name);
            ret = -EINVAL;
            goto fail;
        } else {
            s->discard_zeroes = true;
            s->has_fallocate = true;
        }
    } else {
        if (!(S_ISCHR(st.st_mode) || S_ISBLK(st.st_mode))) {
            error_setg(errp, "'%s' driver expects either "
                       "a character or block device", bs->drv->format_name);
            ret = -EINVAL;
            goto fail;
        }
    }

    if (S_ISBLK(st.st_mode)) {
#ifdef BLKDISCARDZEROES
        unsigned int arg;
        if (ioctl(s->fd, BLKDISCARDZEROES, &arg) == 0 && arg) {
            s->discard_zeroes = true;
        }
#endif
#ifdef __linux__
        /* On Linux 3.10, BLKDISCARD leaves stale data in the page cache.  Do
         * not rely on the contents of discarded blocks unless using O_DIRECT.
         * Same for BLKZEROOUT.
         */
        if (!(bs->open_flags & BDRV_O_NOCACHE)) {
            s->discard_zeroes = false;
            s->has_write_zeroes = false;
        }
#endif
    }
#ifdef __FreeBSD__
    if (S_ISCHR(st.st_mode)) {
        /*
         * The file is a char device (disk), which on FreeBSD isn't behind
         * a pager, so force all requests to be aligned. This is needed
         * so QEMU makes sure all IO operations on the device are aligned
         * to sector size, or else FreeBSD will reject them with EINVAL.
         */
        s->needs_alignment = true;
    }
#endif

#ifdef CONFIG_XFS
    if (platform_test_xfs_fd(s->fd)) {
        s->is_xfs = true;
    }
#endif

    bs->supported_zero_flags = BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK;
    ret = 0;
fail:
    if (filename && (bdrv_flags & BDRV_O_TEMPORARY)) {
        unlink(filename);
    }
    qemu_opts_del(opts);
    return ret;
}

static int raw_open(BlockDriverState *bs, QDict *options, int flags,
                    Error **errp)
{
    BDRVRawState *s = bs->opaque;

    s->type = FTYPE_FILE;
    return raw_open_common(bs, options, flags, 0, false, errp);
}

typedef enum {
    RAW_PL_PREPARE,
    RAW_PL_COMMIT,
    RAW_PL_ABORT,
} RawPermLockOp;

#define PERM_FOREACH(i) \
    for ((i) = 0; (1ULL << (i)) <= BLK_PERM_ALL; i++)

/* Lock bytes indicated by @perm_lock_bits and @shared_perm_lock_bits in the
 * file; if @unlock == true, also unlock the unneeded bytes.
 * @shared_perm_lock_bits is the mask of all permissions that are NOT shared.
 */
static int raw_apply_lock_bytes(BDRVRawState *s, int fd,
                                uint64_t perm_lock_bits,
                                uint64_t shared_perm_lock_bits,
                                bool unlock, Error **errp)
{
    int ret;
    int i;
    uint64_t locked_perm, locked_shared_perm;

    if (s) {
        locked_perm = s->locked_perm;
        locked_shared_perm = s->locked_shared_perm;
    } else {
        /*
         * We don't have the previous bits, just lock/unlock for each of the
         * requested bits.
         */
        if (unlock) {
            locked_perm = BLK_PERM_ALL;
            locked_shared_perm = BLK_PERM_ALL;
        } else {
            locked_perm = 0;
            locked_shared_perm = 0;
        }
    }

    PERM_FOREACH(i) {
        int off = RAW_LOCK_PERM_BASE + i;
        uint64_t bit = (1ULL << i);
        if ((perm_lock_bits & bit) && !(locked_perm & bit)) {
            ret = qemu_lock_fd(fd, off, 1, false);
            if (ret) {
                error_setg(errp, "Failed to lock byte %d", off);
                return ret;
            } else if (s) {
                s->locked_perm |= bit;
            }
        } else if (unlock && (locked_perm & bit) && !(perm_lock_bits & bit)) {
            ret = qemu_unlock_fd(fd, off, 1);
            if (ret) {
                error_setg(errp, "Failed to unlock byte %d", off);
                return ret;
            } else if (s) {
                s->locked_perm &= ~bit;
            }
        }
    }
    PERM_FOREACH(i) {
        int off = RAW_LOCK_SHARED_BASE + i;
        uint64_t bit = (1ULL << i);
        if ((shared_perm_lock_bits & bit) && !(locked_shared_perm & bit)) {
            ret = qemu_lock_fd(fd, off, 1, false);
            if (ret) {
                error_setg(errp, "Failed to lock byte %d", off);
                return ret;
            } else if (s) {
                s->locked_shared_perm |= bit;
            }
        } else if (unlock && (locked_shared_perm & bit) &&
                   !(shared_perm_lock_bits & bit)) {
            ret = qemu_unlock_fd(fd, off, 1);
            if (ret) {
                error_setg(errp, "Failed to unlock byte %d", off);
                return ret;
            } else if (s) {
                s->locked_shared_perm &= ~bit;
            }
        }
    }
    return 0;
}

/* Check "unshared" bytes implied by @perm and ~@shared_perm in the file. */
static int raw_check_lock_bytes(int fd, uint64_t perm, uint64_t shared_perm,
                                Error **errp)
{
    int ret;
    int i;

    PERM_FOREACH(i) {
        int off = RAW_LOCK_SHARED_BASE + i;
        uint64_t p = 1ULL << i;
        if (perm & p) {
            ret = qemu_lock_fd_test(fd, off, 1, true);
            if (ret) {
                char *perm_name = bdrv_perm_names(p);
                error_setg(errp,
                           "Failed to get \"%s\" lock",
                           perm_name);
                g_free(perm_name);
                return ret;
            }
        }
    }
    PERM_FOREACH(i) {
        int off = RAW_LOCK_PERM_BASE + i;
        uint64_t p = 1ULL << i;
        if (!(shared_perm & p)) {
            ret = qemu_lock_fd_test(fd, off, 1, true);
            if (ret) {
                char *perm_name = bdrv_perm_names(p);
                error_setg(errp,
                           "Failed to get shared \"%s\" lock",
                           perm_name);
                g_free(perm_name);
                return ret;
            }
        }
    }
    return 0;
}

static int raw_handle_perm_lock(BlockDriverState *bs,
                                RawPermLockOp op,
                                uint64_t new_perm, uint64_t new_shared,
                                Error **errp)
{
    BDRVRawState *s = bs->opaque;
    int ret = 0;
    Error *local_err = NULL;

    if (!s->use_lock) {
        return 0;
    }

    if (bdrv_get_flags(bs) & BDRV_O_INACTIVE) {
        return 0;
    }

    switch (op) {
    case RAW_PL_PREPARE:
        if ((s->perm | new_perm) == s->perm &&
            (s->shared_perm & new_shared) == s->shared_perm)
        {
            /*
             * We are going to unlock bytes, it should not fail. If it fail due
             * to some fs-dependent permission-unrelated reasons (which occurs
             * sometimes on NFS and leads to abort in bdrv_replace_child) we
             * can't prevent such errors by any check here. And we ignore them
             * anyway in ABORT and COMMIT.
             */
            return 0;
        }
        ret = raw_apply_lock_bytes(s, s->fd, s->perm | new_perm,
                                   ~s->shared_perm | ~new_shared,
                                   false, errp);
        if (!ret) {
            ret = raw_check_lock_bytes(s->fd, new_perm, new_shared, errp);
            if (!ret) {
                return 0;
            }
            error_append_hint(errp,
                              "Is another process using the image [%s]?\n",
                              bs->filename);
        }
        op = RAW_PL_ABORT;
        /* fall through to unlock bytes. */
    case RAW_PL_ABORT:
        raw_apply_lock_bytes(s, s->fd, s->perm, ~s->shared_perm,
                             true, &local_err);
        if (local_err) {
            /* Theoretically the above call only unlocks bytes and it cannot
             * fail. Something weird happened, report it.
             */
            warn_report_err(local_err);
        }
        break;
    case RAW_PL_COMMIT:
        raw_apply_lock_bytes(s, s->fd, new_perm, ~new_shared,
                             true, &local_err);
        if (local_err) {
            /* Theoretically the above call only unlocks bytes and it cannot
             * fail. Something weird happened, report it.
             */
            warn_report_err(local_err);
        }
        break;
    }
    return ret;
}

static int raw_reconfigure_getfd(BlockDriverState *bs, int flags,
                                 int *open_flags, uint64_t perm, bool force_dup,
                                 Error **errp)
{
    BDRVRawState *s = bs->opaque;
    int fd = -1;
    int ret;
    bool has_writers = perm &
        (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED | BLK_PERM_RESIZE);
    int fcntl_flags = O_APPEND | O_NONBLOCK;
#ifdef O_NOATIME
    fcntl_flags |= O_NOATIME;
#endif

    *open_flags = 0;
    if (s->type == FTYPE_CD) {
        *open_flags |= O_NONBLOCK;
    }

    raw_parse_flags(flags, open_flags, has_writers);

#ifdef O_ASYNC
    /* Not all operating systems have O_ASYNC, and those that don't
     * will not let us track the state into rs->open_flags (typically
     * you achieve the same effect with an ioctl, for example I_SETSIG
     * on Solaris). But we do not use O_ASYNC, so that's fine.
     */
    assert((s->open_flags & O_ASYNC) == 0);
#endif

    if (!force_dup && *open_flags == s->open_flags) {
        /* We're lucky, the existing fd is fine */
        return s->fd;
    }

    if ((*open_flags & ~fcntl_flags) == (s->open_flags & ~fcntl_flags)) {
        /* dup the original fd */
        fd = qemu_dup(s->fd);
        if (fd >= 0) {
            ret = fcntl_setfl(fd, *open_flags);
            if (ret) {
                qemu_close(fd);
                fd = -1;
            }
        }
    }

    /* If we cannot use fcntl, or fcntl failed, fall back to qemu_open() */
    if (fd == -1) {
        const char *normalized_filename = bs->filename;
        ret = raw_normalize_devicepath(&normalized_filename, errp);
        if (ret >= 0) {
            assert(!(*open_flags & O_CREAT));
            fd = qemu_open(normalized_filename, *open_flags);
            if (fd == -1) {
                error_setg_errno(errp, errno, "Could not reopen file");
                return -1;
            }
        }
    }

    return fd;
}

static int raw_reopen_prepare(BDRVReopenState *state,
                              BlockReopenQueue *queue, Error **errp)
{
    BDRVRawState *s;
    BDRVRawReopenState *rs;
    QemuOpts *opts;
    int ret;
    Error *local_err = NULL;

    assert(state != NULL);
    assert(state->bs != NULL);

    s = state->bs->opaque;

    state->opaque = g_new0(BDRVRawReopenState, 1);
    rs = state->opaque;

    /* Handle options changes */
    opts = qemu_opts_create(&raw_runtime_opts, NULL, 0, &error_abort);
    qemu_opts_absorb_qdict(opts, state->options, &local_err);
    if (local_err) {
        error_propagate(errp, local_err);
        ret = -EINVAL;
        goto out;
    }

    rs->drop_cache = qemu_opt_get_bool_del(opts, "drop-cache", true);
    rs->check_cache_dropped =
        qemu_opt_get_bool_del(opts, "x-check-cache-dropped", false);

    /* This driver's reopen function doesn't currently allow changing
     * other options, so let's put them back in the original QDict and
     * bdrv_reopen_prepare() will detect changes and complain. */
    qemu_opts_to_qdict(opts, state->options);

    rs->fd = raw_reconfigure_getfd(state->bs, state->flags, &rs->open_flags,
                                   state->perm, true, &local_err);
    if (local_err) {
        error_propagate(errp, local_err);
        ret = -1;
        goto out;
    }

    /* Fail already reopen_prepare() if we can't get a working O_DIRECT
     * alignment with the new fd. */
    if (rs->fd != -1) {
        raw_probe_alignment(state->bs, rs->fd, &local_err);
        if (local_err) {
            error_propagate(errp, local_err);
            ret = -EINVAL;
            goto out_fd;
        }
    }

    s->reopen_state = state;
    ret = 0;
out_fd:
    if (ret < 0) {
        qemu_close(rs->fd);
        rs->fd = -1;
    }
out:
    qemu_opts_del(opts);
    return ret;
}

static void raw_reopen_commit(BDRVReopenState *state)
{
    BDRVRawReopenState *rs = state->opaque;
    BDRVRawState *s = state->bs->opaque;

    s->drop_cache = rs->drop_cache;
    s->check_cache_dropped = rs->check_cache_dropped;
    s->open_flags = rs->open_flags;

    qemu_close(s->fd);
    s->fd = rs->fd;

    g_free(state->opaque);
    state->opaque = NULL;

    assert(s->reopen_state == state);
    s->reopen_state = NULL;
}


static void raw_reopen_abort(BDRVReopenState *state)
{
    BDRVRawReopenState *rs = state->opaque;
    BDRVRawState *s = state->bs->opaque;

     /* nothing to do if NULL, we didn't get far enough */
    if (rs == NULL) {
        return;
    }

    if (rs->fd >= 0) {
        qemu_close(rs->fd);
        rs->fd = -1;
    }
    g_free(state->opaque);
    state->opaque = NULL;

    assert(s->reopen_state == state);
    s->reopen_state = NULL;
}

static int sg_get_max_transfer_length(int fd)
{
#ifdef BLKSECTGET
    int max_bytes = 0;

    if (ioctl(fd, BLKSECTGET, &max_bytes) == 0) {
        return max_bytes;
    } else {
        return -errno;
    }
#else
    return -ENOSYS;
#endif
}

static int sg_get_max_segments(int fd)
{
#ifdef CONFIG_LINUX
    char buf[32];
    const char *end;
    char *sysfspath = NULL;
    int ret;
    int sysfd = -1;
    long max_segments;
    struct stat st;

    if (fstat(fd, &st)) {
        ret = -errno;
        goto out;
    }

    sysfspath = g_strdup_printf("/sys/dev/block/%u:%u/queue/max_segments",
                                major(st.st_rdev), minor(st.st_rdev));
    sysfd = open(sysfspath, O_RDONLY);
    if (sysfd == -1) {
        ret = -errno;
        goto out;
    }
    do {
        ret = read(sysfd, buf, sizeof(buf) - 1);
    } while (ret == -1 && errno == EINTR);
    if (ret < 0) {
        ret = -errno;
        goto out;
    } else if (ret == 0) {
        ret = -EIO;
        goto out;
    }
    buf[ret] = 0;
    /* The file is ended with '\n', pass 'end' to accept that. */
    ret = qemu_strtol(buf, &end, 10, &max_segments);
    if (ret == 0 && end && *end == '\n') {
        ret = max_segments;
    }

out:
    if (sysfd != -1) {
        close(sysfd);
    }
    g_free(sysfspath);
    return ret;
#else
    return -ENOTSUP;
#endif
}

static void raw_refresh_limits(BlockDriverState *bs, Error **errp)
{
    BDRVRawState *s = bs->opaque;

    if (bs->sg) {
        int ret = sg_get_max_transfer_length(s->fd);

        if (ret > 0 && ret <= BDRV_REQUEST_MAX_BYTES) {
            bs->bl.max_transfer = pow2floor(ret);
        }

        ret = sg_get_max_segments(s->fd);
        if (ret > 0) {
            bs->bl.max_transfer = MIN(bs->bl.max_transfer,
                                      ret * qemu_real_host_page_size);
        }
    }

    raw_probe_alignment(bs, s->fd, errp);
    bs->bl.min_mem_alignment = s->buf_align;
    bs->bl.opt_mem_alignment = MAX(s->buf_align, qemu_real_host_page_size);
}

static int check_for_dasd(int fd)
{
#ifdef BIODASDINFO2
    struct dasd_information2_t info = {0};

    return ioctl(fd, BIODASDINFO2, &info);
#else
    return -1;
#endif
}

/**
 * Try to get @bs's logical and physical block size.
 * On success, store them in @bsz and return zero.
 * On failure, return negative errno.
 */
static int hdev_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz)
{
    BDRVRawState *s = bs->opaque;
    int ret;

    /* If DASD, get blocksizes */
    if (check_for_dasd(s->fd) < 0) {
        return -ENOTSUP;
    }
    ret = probe_logical_blocksize(s->fd, &bsz->log);
    if (ret < 0) {
        return ret;
    }
    return probe_physical_blocksize(s->fd, &bsz->phys);
}

/**
 * Try to get @bs's geometry: cyls, heads, sectors.
 * On success, store them in @geo and return 0.
 * On failure return -errno.
 * (Allows block driver to assign default geometry values that guest sees)
 */
#ifdef __linux__
static int hdev_probe_geometry(BlockDriverState *bs, HDGeometry *geo)
{
    BDRVRawState *s = bs->opaque;
    struct hd_geometry ioctl_geo = {0};

    /* If DASD, get its geometry */
    if (check_for_dasd(s->fd) < 0) {
        return -ENOTSUP;
    }
    if (ioctl(s->fd, HDIO_GETGEO, &ioctl_geo) < 0) {
        return -errno;
    }
    /* HDIO_GETGEO may return success even though geo contains zeros
       (e.g. certain multipath setups) */
    if (!ioctl_geo.heads || !ioctl_geo.sectors || !ioctl_geo.cylinders) {
        return -ENOTSUP;
    }
    /* Do not return a geometry for partition */
    if (ioctl_geo.start != 0) {
        return -ENOTSUP;
    }
    geo->heads = ioctl_geo.heads;
    geo->sectors = ioctl_geo.sectors;
    geo->cylinders = ioctl_geo.cylinders;

    return 0;
}
#else /* __linux__ */
static int hdev_probe_geometry(BlockDriverState *bs, HDGeometry *geo)
{
    return -ENOTSUP;
}
#endif

#if defined(__linux__)
static int handle_aiocb_ioctl(void *opaque)
{
    RawPosixAIOData *aiocb = opaque;
    int ret;

    ret = ioctl(aiocb->aio_fildes, aiocb->ioctl.cmd, aiocb->ioctl.buf);
    if (ret == -1) {
        return -errno;
    }

    return 0;
}
#endif /* linux */

static int handle_aiocb_flush(void *opaque)
{
    RawPosixAIOData *aiocb = opaque;
    BDRVRawState *s = aiocb->bs->opaque;
    int ret;

    if (s->page_cache_inconsistent) {
        return -EIO;
    }

    ret = qemu_fdatasync(aiocb->aio_fildes);
    if (ret == -1) {
        /* There is no clear definition of the semantics of a failing fsync(),
         * so we may have to assume the worst. The sad truth is that this
         * assumption is correct for Linux. Some pages are now probably marked
         * clean in the page cache even though they are inconsistent with the
         * on-disk contents. The next fdatasync() call would succeed, but no
         * further writeback attempt will be made. We can't get back to a state
         * in which we know what is on disk (we would have to rewrite
         * everything that was touched since the last fdatasync() at least), so
         * make bdrv_flush() fail permanently. Given that the behaviour isn't
         * really defined, I have little hope that other OSes are doing better.
         *
         * Obviously, this doesn't affect O_DIRECT, which bypasses the page
         * cache. */
        if ((s->open_flags & O_DIRECT) == 0) {
            s->page_cache_inconsistent = true;
        }
        return -errno;
    }
    return 0;
}

#ifdef CONFIG_PREADV

static bool preadv_present = true;

static ssize_t
qemu_preadv(int fd, const struct iovec *iov, int nr_iov, off_t offset)
{
    return preadv(fd, iov, nr_iov, offset);
}

static ssize_t
qemu_pwritev(int fd, const struct iovec *iov, int nr_iov, off_t offset)
{
    return pwritev(fd, iov, nr_iov, offset);
}

#else

static bool preadv_present = false;

static ssize_t
qemu_preadv(int fd, const struct iovec *iov, int nr_iov, off_t offset)
{
    return -ENOSYS;
}

static ssize_t
qemu_pwritev(int fd, const struct iovec *iov, int nr_iov, off_t offset)
{
    return -ENOSYS;
}

#endif

static ssize_t handle_aiocb_rw_vector(RawPosixAIOData *aiocb)
{
    ssize_t len;

    do {
        if (aiocb->aio_type & QEMU_AIO_WRITE)
            len = qemu_pwritev(aiocb->aio_fildes,
                               aiocb->io.iov,
                               aiocb->io.niov,
                               aiocb->aio_offset);
         else
            len = qemu_preadv(aiocb->aio_fildes,
                              aiocb->io.iov,
                              aiocb->io.niov,
                              aiocb->aio_offset);
    } while (len == -1 && errno == EINTR);

    if (len == -1) {
        return -errno;
    }
    return len;
}

/*
 * Read/writes the data to/from a given linear buffer.
 *
 * Returns the number of bytes handles or -errno in case of an error. Short
 * reads are only returned if the end of the file is reached.
 */
static ssize_t handle_aiocb_rw_linear(RawPosixAIOData *aiocb, char *buf)
{
    ssize_t offset = 0;
    ssize_t len;

    while (offset < aiocb->aio_nbytes) {
        if (aiocb->aio_type & QEMU_AIO_WRITE) {
            len = pwrite(aiocb->aio_fildes,
                         (const char *)buf + offset,
                         aiocb->aio_nbytes - offset,
                         aiocb->aio_offset + offset);
        } else {
            len = pread(aiocb->aio_fildes,
                        buf + offset,
                        aiocb->aio_nbytes - offset,
                        aiocb->aio_offset + offset);
        }
        if (len == -1 && errno == EINTR) {
            continue;
        } else if (len == -1 && errno == EINVAL &&
                   (aiocb->bs->open_flags & BDRV_O_NOCACHE) &&
                   !(aiocb->aio_type & QEMU_AIO_WRITE) &&
                   offset > 0) {
            /* O_DIRECT pread() may fail with EINVAL when offset is unaligned
             * after a short read.  Assume that O_DIRECT short reads only occur
             * at EOF.  Therefore this is a short read, not an I/O error.
             */
            break;
        } else if (len == -1) {
            offset = -errno;
            break;
        } else if (len == 0) {
            break;
        }
        offset += len;
    }

    return offset;
}

static int handle_aiocb_rw(void *opaque)
{
    RawPosixAIOData *aiocb = opaque;
    ssize_t nbytes;
    char *buf;

    if (!(aiocb->aio_type & QEMU_AIO_MISALIGNED)) {
        /*
         * If there is just a single buffer, and it is properly aligned
         * we can just use plain pread/pwrite without any problems.
         */
        if (aiocb->io.niov == 1) {
            nbytes = handle_aiocb_rw_linear(aiocb, aiocb->io.iov->iov_base);
            goto out;
        }
        /*
         * We have more than one iovec, and all are properly aligned.
         *
         * Try preadv/pwritev first and fall back to linearizing the
         * buffer if it's not supported.
         */
        if (preadv_present) {
            nbytes = handle_aiocb_rw_vector(aiocb);
            if (nbytes == aiocb->aio_nbytes ||
                (nbytes < 0 && nbytes != -ENOSYS)) {
                goto out;
            }
            preadv_present = false;
        }

        /*
         * XXX(hch): short read/write.  no easy way to handle the reminder
         * using these interfaces.  For now retry using plain
         * pread/pwrite?
         */
    }

    /*
     * Ok, we have to do it the hard way, copy all segments into
     * a single aligned buffer.
     */
    buf = qemu_try_blockalign(aiocb->bs, aiocb->aio_nbytes);
    if (buf == NULL) {
        nbytes = -ENOMEM;
        goto out;
    }

    if (aiocb->aio_type & QEMU_AIO_WRITE) {
        char *p = buf;
        int i;

        for (i = 0; i < aiocb->io.niov; ++i) {
            memcpy(p, aiocb->io.iov[i].iov_base, aiocb->io.iov[i].iov_len);
            p += aiocb->io.iov[i].iov_len;
        }
        assert(p - buf == aiocb->aio_nbytes);
    }

    nbytes = handle_aiocb_rw_linear(aiocb, buf);
    if (!(aiocb->aio_type & QEMU_AIO_WRITE)) {
        char *p = buf;
        size_t count = aiocb->aio_nbytes, copy;
        int i;

        for (i = 0; i < aiocb->io.niov && count; ++i) {
            copy = count;
            if (copy > aiocb->io.iov[i].iov_len) {
                copy = aiocb->io.iov[i].iov_len;
            }
            memcpy(aiocb->io.iov[i].iov_base, p, copy);
            assert(count >= copy);
            p     += copy;
            count -= copy;
        }
        assert(count == 0);
    }
    qemu_vfree(buf);

out:
    if (nbytes == aiocb->aio_nbytes) {
        return 0;
    } else if (nbytes >= 0 && nbytes < aiocb->aio_nbytes) {
        if (aiocb->aio_type & QEMU_AIO_WRITE) {
            return -EINVAL;
        } else {
            iov_memset(aiocb->io.iov, aiocb->io.niov, nbytes,
                      0, aiocb->aio_nbytes - nbytes);
            return 0;
        }
    } else {
        assert(nbytes < 0);
        return nbytes;
    }
}

static int translate_err(int err)
{
    if (err == -ENODEV || err == -ENOSYS || err == -EOPNOTSUPP ||
        err == -ENOTTY) {
        err = -ENOTSUP;
    }
    return err;
}

#ifdef CONFIG_FALLOCATE
static int do_fallocate(int fd, int mode, off_t offset, off_t len)
{
    do {
        if (fallocate(fd, mode, offset, len) == 0) {
            return 0;
        }
    } while (errno == EINTR);
    return translate_err(-errno);
}
#endif

static ssize_t handle_aiocb_write_zeroes_block(RawPosixAIOData *aiocb)
{
    int ret = -ENOTSUP;
    BDRVRawState *s = aiocb->bs->opaque;

    if (!s->has_write_zeroes) {
        return -ENOTSUP;
    }

#ifdef BLKZEROOUT
    /* The BLKZEROOUT implementation in the kernel doesn't set
     * BLKDEV_ZERO_NOFALLBACK, so we can't call this if we have to avoid slow
     * fallbacks. */
    if (!(aiocb->aio_type & QEMU_AIO_NO_FALLBACK)) {
        do {
            uint64_t range[2] = { aiocb->aio_offset, aiocb->aio_nbytes };
            if (ioctl(aiocb->aio_fildes, BLKZEROOUT, range) == 0) {
                return 0;
            }
        } while (errno == EINTR);

        ret = translate_err(-errno);
        if (ret == -ENOTSUP) {
            s->has_write_zeroes = false;
        }
    }
#endif

    return ret;
}

static int handle_aiocb_write_zeroes(void *opaque)
{
    RawPosixAIOData *aiocb = opaque;
#ifdef CONFIG_FALLOCATE
    BDRVRawState *s = aiocb->bs->opaque;
    int64_t len;
#endif

    if (aiocb->aio_type & QEMU_AIO_BLKDEV) {
        return handle_aiocb_write_zeroes_block(aiocb);
    }

#ifdef CONFIG_FALLOCATE_ZERO_RANGE
    if (s->has_write_zeroes) {
        int ret = do_fallocate(s->fd, FALLOC_FL_ZERO_RANGE,
                               aiocb->aio_offset, aiocb->aio_nbytes);
        if (ret == -EINVAL) {
            /*
             * Allow falling back to pwrite for file systems that
             * do not support fallocate() for an unaligned byte range.
             */
            return -ENOTSUP;
        }
        if (ret == 0 || ret != -ENOTSUP) {
            return ret;
        }
        s->has_write_zeroes = false;
    }
#endif

#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
    if (s->has_discard && s->has_fallocate) {
        int ret = do_fallocate(s->fd,
                               FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
                               aiocb->aio_offset, aiocb->aio_nbytes);
        if (ret == 0) {
            ret = do_fallocate(s->fd, 0, aiocb->aio_offset, aiocb->aio_nbytes);
            if (ret == 0 || ret != -ENOTSUP) {
                return ret;
            }
            s->has_fallocate = false;
        } else if (ret != -ENOTSUP) {
            return ret;
        } else {
            s->has_discard = false;
        }
    }
#endif

#ifdef CONFIG_FALLOCATE
    /* Last resort: we are trying to extend the file with zeroed data. This
     * can be done via fallocate(fd, 0) */
    len = bdrv_getlength(aiocb->bs);
    if (s->has_fallocate && len >= 0 && aiocb->aio_offset >= len) {
        int ret = do_fallocate(s->fd, 0, aiocb->aio_offset, aiocb->aio_nbytes);
        if (ret == 0 || ret != -ENOTSUP) {
            return ret;
        }
        s->has_fallocate = false;
    }
#endif

    return -ENOTSUP;
}

static int handle_aiocb_write_zeroes_unmap(void *opaque)
{
    RawPosixAIOData *aiocb = opaque;
    BDRVRawState *s G_GNUC_UNUSED = aiocb->bs->opaque;
    int ret;

    /* First try to write zeros and unmap at the same time */

#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
    ret = do_fallocate(s->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
                       aiocb->aio_offset, aiocb->aio_nbytes);
    if (ret != -ENOTSUP) {
        return ret;
    }
#endif

    /* If we couldn't manage to unmap while guaranteed that the area reads as
     * all-zero afterwards, just write zeroes without unmapping */
    ret = handle_aiocb_write_zeroes(aiocb);
    return ret;
}

#ifndef HAVE_COPY_FILE_RANGE
static off_t copy_file_range(int in_fd, off_t *in_off, int out_fd,
                             off_t *out_off, size_t len, unsigned int flags)
{
#ifdef __NR_copy_file_range
    return syscall(__NR_copy_file_range, in_fd, in_off, out_fd,
                   out_off, len, flags);
#else
    errno = ENOSYS;
    return -1;
#endif
}
#endif

static int handle_aiocb_copy_range(void *opaque)
{
    RawPosixAIOData *aiocb = opaque;
    uint64_t bytes = aiocb->aio_nbytes;
    off_t in_off = aiocb->aio_offset;
    off_t out_off = aiocb->copy_range.aio_offset2;

    while (bytes) {
        ssize_t ret = copy_file_range(aiocb->aio_fildes, &in_off,
                                      aiocb->copy_range.aio_fd2, &out_off,
                                      bytes, 0);
        trace_file_copy_file_range(aiocb->bs, aiocb->aio_fildes, in_off,
                                   aiocb->copy_range.aio_fd2, out_off, bytes,
                                   0, ret);
        if (ret == 0) {
            /* No progress (e.g. when beyond EOF), let the caller fall back to
             * buffer I/O. */
            return -ENOSPC;
        }
        if (ret < 0) {
            switch (errno) {
            case ENOSYS:
                return -ENOTSUP;
            case EINTR:
                continue;
            default:
                return -errno;
            }
        }
        bytes -= ret;
    }
    return 0;
}

static int handle_aiocb_discard(void *opaque)
{
    RawPosixAIOData *aiocb = opaque;
    int ret = -EOPNOTSUPP;
    BDRVRawState *s = aiocb->bs->opaque;

    if (!s->has_discard) {
        return -ENOTSUP;
    }

    if (aiocb->aio_type & QEMU_AIO_BLKDEV) {
#ifdef BLKDISCARD
        do {
            uint64_t range[2] = { aiocb->aio_offset, aiocb->aio_nbytes };
            if (ioctl(aiocb->aio_fildes, BLKDISCARD, range) == 0) {
                return 0;
            }
        } while (errno == EINTR);

        ret = -errno;
#endif
    } else {
#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
        ret = do_fallocate(s->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
                           aiocb->aio_offset, aiocb->aio_nbytes);
#endif
    }

    ret = translate_err(ret);
    if (ret == -ENOTSUP) {
        s->has_discard = false;
    }
    return ret;
}

/*
 * Help alignment probing by allocating the first block.
 *
 * When reading with direct I/O from unallocated area on Gluster backed by XFS,
 * reading succeeds regardless of request length. In this case we fallback to
 * safe alignment which is not optimal. Allocating the first block avoids this
 * fallback.
 *
 * fd may be opened with O_DIRECT, but we don't know the buffer alignment or
 * request alignment, so we use safe values.
 *
 * Returns: 0 on success, -errno on failure. Since this is an optimization,
 * caller may ignore failures.
 */
static int allocate_first_block(int fd, size_t max_size)
{
    size_t write_size = (max_size < MAX_BLOCKSIZE)
        ? BDRV_SECTOR_SIZE
        : MAX_BLOCKSIZE;
    size_t max_align = MAX(MAX_BLOCKSIZE, qemu_real_host_page_size);
    void *buf;
    ssize_t n;
    int ret;

    buf = qemu_memalign(max_align, write_size);
    memset(buf, 0, write_size);

    do {
        n = pwrite(fd, buf, write_size, 0);
    } while (n == -1 && errno == EINTR);

    ret = (n == -1) ? -errno : 0;

    qemu_vfree(buf);
    return ret;
}

static int handle_aiocb_truncate(void *opaque)
{
    RawPosixAIOData *aiocb = opaque;
    int result = 0;
    int64_t current_length = 0;
    char *buf = NULL;
    struct stat st;
    int fd = aiocb->aio_fildes;
    int64_t offset = aiocb->aio_offset;
    PreallocMode prealloc = aiocb->truncate.prealloc;
    Error **errp = aiocb->truncate.errp;

    if (fstat(fd, &st) < 0) {
        result = -errno;
        error_setg_errno(errp, -result, "Could not stat file");
        return result;
    }

    current_length = st.st_size;
    if (current_length > offset && prealloc != PREALLOC_MODE_OFF) {
        error_setg(errp, "Cannot use preallocation for shrinking files");
        return -ENOTSUP;
    }

    switch (prealloc) {
#ifdef CONFIG_POSIX_FALLOCATE
    case PREALLOC_MODE_FALLOC:
        /*
         * Truncating before posix_fallocate() makes it about twice slower on
         * file systems that do not support fallocate(), trying to check if a
         * block is allocated before allocating it, so don't do that here.
         */
        if (offset != current_length) {
            result = -posix_fallocate(fd, current_length,
                                      offset - current_length);
            if (result != 0) {
                /* posix_fallocate() doesn't set errno. */
                error_setg_errno(errp, -result,
                                 "Could not preallocate new data");
            } else if (current_length == 0) {
                /*
                 * posix_fallocate() uses fallocate() if the filesystem
                 * supports it, or fallback to manually writing zeroes. If
                 * fallocate() was used, unaligned reads from the fallocated
                 * area in raw_probe_alignment() will succeed, hence we need to
                 * allocate the first block.
                 *
                 * Optimize future alignment probing; ignore failures.
                 */
                allocate_first_block(fd, offset);
            }
        } else {
            result = 0;
        }
        goto out;
#endif
    case PREALLOC_MODE_FULL:
    {
        int64_t num = 0, left = offset - current_length;
        off_t seek_result;

        /*
         * Knowing the final size from the beginning could allow the file
         * system driver to do less allocations and possibly avoid
         * fragmentation of the file.
         */
        if (ftruncate(fd, offset) != 0) {
            result = -errno;
            error_setg_errno(errp, -result, "Could not resize file");
            goto out;
        }

        buf = g_malloc0(65536);

        seek_result = lseek(fd, current_length, SEEK_SET);
        if (seek_result < 0) {
            result = -errno;
            error_setg_errno(errp, -result,
                             "Failed to seek to the old end of file");
            goto out;
        }

        while (left > 0) {
            num = MIN(left, 65536);
            result = write(fd, buf, num);
            if (result < 0) {
                if (errno == EINTR) {
                    continue;
                }
                result = -errno;
                error_setg_errno(errp, -result,
                                 "Could not write zeros for preallocation");
                goto out;
            }
            left -= result;
        }
        if (result >= 0) {
            result = fsync(fd);
            if (result < 0) {
                result = -errno;
                error_setg_errno(errp, -result,
                                 "Could not flush file to disk");
                goto out;
            }
        }
        goto out;
    }
    case PREALLOC_MODE_OFF:
        if (ftruncate(fd, offset) != 0) {
            result = -errno;
            error_setg_errno(errp, -result, "Could not resize file");
        } else if (current_length == 0 && offset > current_length) {
            /* Optimize future alignment probing; ignore failures. */
            allocate_first_block(fd, offset);
        }
        return result;
    default:
        result = -ENOTSUP;
        error_setg(errp, "Unsupported preallocation mode: %s",
                   PreallocMode_str(prealloc));
        return result;
    }

out:
    if (result < 0) {
        if (ftruncate(fd, current_length) < 0) {
            error_report("Failed to restore old file length: %s",
                         strerror(errno));
        }
    }

    g_free(buf);
    return result;
}

static int coroutine_fn raw_thread_pool_submit(BlockDriverState *bs,
                                               ThreadPoolFunc func, void *arg)
{
    /* @bs can be NULL, bdrv_get_aio_context() returns the main context then */
    ThreadPool *pool = aio_get_thread_pool(bdrv_get_aio_context(bs));
    return thread_pool_submit_co(pool, func, arg);
}

static int coroutine_fn raw_co_prw(BlockDriverState *bs, uint64_t offset,
                                   uint64_t bytes, QEMUIOVector *qiov, int type)
{
    BDRVRawState *s = bs->opaque;
    RawPosixAIOData acb;

    if (fd_open(bs) < 0)
        return -EIO;

    /*
     * Check if the underlying device requires requests to be aligned,
     * and if the request we are trying to submit is aligned or not.
     * If this is the case tell the low-level driver that it needs
     * to copy the buffer.
     */
    if (s->needs_alignment) {
        if (!bdrv_qiov_is_aligned(bs, qiov)) {
            type |= QEMU_AIO_MISALIGNED;
#ifdef CONFIG_LINUX_AIO
        } else if (s->use_linux_aio) {
            LinuxAioState *aio = aio_get_linux_aio(bdrv_get_aio_context(bs));
            assert(qiov->size == bytes);
            return laio_co_submit(bs, aio, s->fd, offset, qiov, type);
#endif
        }
    }

    acb = (RawPosixAIOData) {
        .bs             = bs,
        .aio_fildes     = s->fd,
        .aio_type       = type,
        .aio_offset     = offset,
        .aio_nbytes     = bytes,
        .io             = {
            .iov            = qiov->iov,
            .niov           = qiov->niov,
        },
    };

    assert(qiov->size == bytes);
    return raw_thread_pool_submit(bs, handle_aiocb_rw, &acb);
}

static int coroutine_fn raw_co_preadv(BlockDriverState *bs, uint64_t offset,
                                      uint64_t bytes, QEMUIOVector *qiov,
                                      int flags)
{
    return raw_co_prw(bs, offset, bytes, qiov, QEMU_AIO_READ);
}

static int coroutine_fn raw_co_pwritev(BlockDriverState *bs, uint64_t offset,
                                       uint64_t bytes, QEMUIOVector *qiov,
                                       int flags)
{
    assert(flags == 0);
    return raw_co_prw(bs, offset, bytes, qiov, QEMU_AIO_WRITE);
}

static void raw_aio_plug(BlockDriverState *bs)
{
#ifdef CONFIG_LINUX_AIO
    BDRVRawState *s = bs->opaque;
    if (s->use_linux_aio) {
        LinuxAioState *aio = aio_get_linux_aio(bdrv_get_aio_context(bs));
        laio_io_plug(bs, aio);
    }
#endif
}

static void raw_aio_unplug(BlockDriverState *bs)
{
#ifdef CONFIG_LINUX_AIO
    BDRVRawState *s = bs->opaque;
    if (s->use_linux_aio) {
        LinuxAioState *aio = aio_get_linux_aio(bdrv_get_aio_context(bs));
        laio_io_unplug(bs, aio);
    }
#endif
}

static int raw_co_flush_to_disk(BlockDriverState *bs)
{
    BDRVRawState *s = bs->opaque;
    RawPosixAIOData acb;
    int ret;

    ret = fd_open(bs);
    if (ret < 0) {
        return ret;
    }

    acb = (RawPosixAIOData) {
        .bs             = bs,
        .aio_fildes     = s->fd,
        .aio_type       = QEMU_AIO_FLUSH,
    };

    return raw_thread_pool_submit(bs, handle_aiocb_flush, &acb);
}

static void raw_aio_attach_aio_context(BlockDriverState *bs,
                                       AioContext *new_context)
{
#ifdef CONFIG_LINUX_AIO
    BDRVRawState *s = bs->opaque;
    if (s->use_linux_aio) {
        Error *local_err = NULL;
        if (!aio_setup_linux_aio(new_context, &local_err)) {
            error_reportf_err(local_err, "Unable to use native AIO, "
                                         "falling back to thread pool: ");
            s->use_linux_aio = false;
        }
    }
#endif
}

static void raw_close(BlockDriverState *bs)
{
    BDRVRawState *s = bs->opaque;

    if (s->fd >= 0) {
        qemu_close(s->fd);
        s->fd = -1;
    }
}

/**
 * Truncates the given regular file @fd to @offset and, when growing, fills the
 * new space according to @prealloc.
 *
 * Returns: 0 on success, -errno on failure.
 */
static int coroutine_fn
raw_regular_truncate(BlockDriverState *bs, int fd, int64_t offset,
                     PreallocMode prealloc, Error **errp)
{
    RawPosixAIOData acb;

    acb = (RawPosixAIOData) {
        .bs             = bs,
        .aio_fildes     = fd,
        .aio_type       = QEMU_AIO_TRUNCATE,
        .aio_offset     = offset,
        .truncate       = {
            .prealloc       = prealloc,
            .errp           = errp,
        },
    };

    return raw_thread_pool_submit(bs, handle_aiocb_truncate, &acb);
}

static int coroutine_fn raw_co_truncate(BlockDriverState *bs, int64_t offset,
                                        bool exact, PreallocMode prealloc,
                                        Error **errp)
{
    BDRVRawState *s = bs->opaque;
    struct stat st;
    int ret;

    if (fstat(s->fd, &st)) {
        ret = -errno;
        error_setg_errno(errp, -ret, "Failed to fstat() the file");
        return ret;
    }

    if (S_ISREG(st.st_mode)) {
        /* Always resizes to the exact @offset */
        return raw_regular_truncate(bs, s->fd, offset, prealloc, errp);
    }

    if (prealloc != PREALLOC_MODE_OFF) {
        error_setg(errp, "Preallocation mode '%s' unsupported for this "
                   "non-regular file", PreallocMode_str(prealloc));
        return -ENOTSUP;
    }

    if (S_ISCHR(st.st_mode) || S_ISBLK(st.st_mode)) {
        int64_t cur_length = raw_getlength(bs);

        if (offset != cur_length && exact) {
            error_setg(errp, "Cannot resize device files");
            return -ENOTSUP;
        } else if (offset > cur_length) {
            error_setg(errp, "Cannot grow device files");
            return -EINVAL;
        }
    } else {
        error_setg(errp, "Resizing this file is not supported");
        return -ENOTSUP;
    }

    return 0;
}

#ifdef __OpenBSD__
static int64_t raw_getlength(BlockDriverState *bs)
{
    BDRVRawState *s = bs->opaque;
    int fd = s->fd;
    struct stat st;

    if (fstat(fd, &st))
        return -errno;
    if (S_ISCHR(st.st_mode) || S_ISBLK(st.st_mode)) {
        struct disklabel dl;

        if (ioctl(fd, DIOCGDINFO, &dl))
            return -errno;
        return (uint64_t)dl.d_secsize *
            dl.d_partitions[DISKPART(st.st_rdev)].p_size;
    } else
        return st.st_size;
}
#elif defined(__NetBSD__)
static int64_t raw_getlength(BlockDriverState *bs)
{
    BDRVRawState *s = bs->opaque;
    int fd = s->fd;
    struct stat st;

    if (fstat(fd, &st))
        return -errno;
    if (S_ISCHR(st.st_mode) || S_ISBLK(st.st_mode)) {
        struct dkwedge_info dkw;

        if (ioctl(fd, DIOCGWEDGEINFO, &dkw) != -1) {
            return dkw.dkw_size * 512;
        } else {
            struct disklabel dl;

            if (ioctl(fd, DIOCGDINFO, &dl))
                return -errno;
            return (uint64_t)dl.d_secsize *
                dl.d_partitions[DISKPART(st.st_rdev)].p_size;
        }
    } else
        return st.st_size;
}
#elif defined(__sun__)
static int64_t raw_getlength(BlockDriverState *bs)
{
    BDRVRawState *s = bs->opaque;
    struct dk_minfo minfo;
    int ret;
    int64_t size;

    ret = fd_open(bs);
    if (ret < 0) {
        return ret;
    }

    /*
     * Use the DKIOCGMEDIAINFO ioctl to read the size.
     */
    ret = ioctl(s->fd, DKIOCGMEDIAINFO, &minfo);
    if (ret != -1) {
        return minfo.dki_lbsize * minfo.dki_capacity;
    }

    /*
     * There are reports that lseek on some devices fails, but
     * irc discussion said that contingency on contingency was overkill.
     */
    size = lseek(s->fd, 0, SEEK_END);
    if (size < 0) {
        return -errno;
    }
    return size;
}
#elif defined(CONFIG_BSD)
static int64_t raw_getlength(BlockDriverState *bs)
{
    BDRVRawState *s = bs->opaque;
    int fd = s->fd;
    int64_t size;
    struct stat sb;
#if defined (__FreeBSD__) || defined(__FreeBSD_kernel__)
    int reopened = 0;
#endif
    int ret;

    ret = fd_open(bs);
    if (ret < 0)
        return ret;

#if defined (__FreeBSD__) || defined(__FreeBSD_kernel__)
again:
#endif
    if (!fstat(fd, &sb) && (S_IFCHR & sb.st_mode)) {
#ifdef DIOCGMEDIASIZE
        if (ioctl(fd, DIOCGMEDIASIZE, (off_t *)&size))
#elif defined(DIOCGPART)
        {
                struct partinfo pi;
                if (ioctl(fd, DIOCGPART, &pi) == 0)
                        size = pi.media_size;
                else
                        size = 0;
        }
        if (size == 0)
#endif
#if defined(__APPLE__) && defined(__MACH__)
        {
            uint64_t sectors = 0;
            uint32_t sector_size = 0;

            if (ioctl(fd, DKIOCGETBLOCKCOUNT, &sectors) == 0
               && ioctl(fd, DKIOCGETBLOCKSIZE, &sector_size) == 0) {
                size = sectors * sector_size;
            } else {
                size = lseek(fd, 0LL, SEEK_END);
                if (size < 0) {
                    return -errno;
                }
            }
        }
#else
        size = lseek(fd, 0LL, SEEK_END);
        if (size < 0) {
            return -errno;
        }
#endif
#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
        switch(s->type) {
        case FTYPE_CD:
            /* XXX FreeBSD acd returns UINT_MAX sectors for an empty drive */
            if (size == 2048LL * (unsigned)-1)
                size = 0;
            /* XXX no disc?  maybe we need to reopen... */
            if (size <= 0 && !reopened && cdrom_reopen(bs) >= 0) {
                reopened = 1;
                goto again;
            }
        }
#endif
    } else {
        size = lseek(fd, 0, SEEK_END);
        if (size < 0) {
            return -errno;
        }
    }
    return size;
}
#else
static int64_t raw_getlength(BlockDriverState *bs)
{
    BDRVRawState *s = bs->opaque;
    int ret;
    int64_t size;

    ret = fd_open(bs);
    if (ret < 0) {
        return ret;
    }

    size = lseek(s->fd, 0, SEEK_END);
    if (size < 0) {
        return -errno;
    }
    return size;
}
#endif

static int64_t raw_get_allocated_file_size(BlockDriverState *bs)
{
    struct stat st;
    BDRVRawState *s = bs->opaque;

    if (fstat(s->fd, &st) < 0) {
        return -errno;
    }
    return (int64_t)st.st_blocks * 512;
}

static int coroutine_fn
raw_co_create(BlockdevCreateOptions *options, Error **errp)
{
    BlockdevCreateOptionsFile *file_opts;
    Error *local_err = NULL;
    int fd;
    uint64_t perm, shared;
    int result = 0;

    /* Validate options and set default values */
    assert(options->driver == BLOCKDEV_DRIVER_FILE);
    file_opts = &options->u.file;

    if (!file_opts->has_nocow) {
        file_opts->nocow = false;
    }
    if (!file_opts->has_preallocation) {
        file_opts->preallocation = PREALLOC_MODE_OFF;
    }

    /* Create file */
    fd = qemu_open(file_opts->filename, O_RDWR | O_CREAT | O_BINARY, 0644);
    if (fd < 0) {
        result = -errno;
        error_setg_errno(errp, -result, "Could not create file");
        goto out;
    }

    /* Take permissions: We want to discard everything, so we need
     * BLK_PERM_WRITE; and truncation to the desired size requires
     * BLK_PERM_RESIZE.
     * On the other hand, we cannot share the RESIZE permission
     * because we promise that after this function, the file has the
     * size given in the options.  If someone else were to resize it
     * concurrently, we could not guarantee that.
     * Note that after this function, we can no longer guarantee that
     * the file is not touched by a third party, so it may be resized
     * then. */
    perm = BLK_PERM_WRITE | BLK_PERM_RESIZE;
    shared = BLK_PERM_ALL & ~BLK_PERM_RESIZE;

    /* Step one: Take locks */
    result = raw_apply_lock_bytes(NULL, fd, perm, ~shared, false, errp);
    if (result < 0) {
        goto out_close;
    }

    /* Step two: Check that nobody else has taken conflicting locks */
    result = raw_check_lock_bytes(fd, perm, shared, errp);
    if (result < 0) {
        error_append_hint(errp,
                          "Is another process using the image [%s]?\n",
                          file_opts->filename);
        goto out_unlock;
    }

    /* Clear the file by truncating it to 0 */
    result = raw_regular_truncate(NULL, fd, 0, PREALLOC_MODE_OFF, errp);
    if (result < 0) {
        goto out_unlock;
    }

    if (file_opts->nocow) {
#ifdef __linux__
        /* Set NOCOW flag to solve performance issue on fs like btrfs.
         * This is an optimisation. The FS_IOC_SETFLAGS ioctl return value
         * will be ignored since any failure of this operation should not
         * block the left work.
         */
        int attr;
        if (ioctl(fd, FS_IOC_GETFLAGS, &attr) == 0) {
            attr |= FS_NOCOW_FL;
            ioctl(fd, FS_IOC_SETFLAGS, &attr);
        }
#endif
    }

    /* Resize and potentially preallocate the file to the desired
     * final size */
    result = raw_regular_truncate(NULL, fd, file_opts->size,
                                  file_opts->preallocation, errp);
    if (result < 0) {
        goto out_unlock;
    }

out_unlock:
    raw_apply_lock_bytes(NULL, fd, 0, 0, true, &local_err);
    if (local_err) {
        /* The above call should not fail, and if it does, that does
         * not mean the whole creation operation has failed.  So
         * report it the user for their convenience, but do not report
         * it to the caller. */
        warn_report_err(local_err);
    }

out_close:
    if (qemu_close(fd) != 0 && result == 0) {
        result = -errno;
        error_setg_errno(errp, -result, "Could not close the new file");
    }
out:
    return result;
}

static int coroutine_fn raw_co_create_opts(const char *filename, QemuOpts *opts,
                                           Error **errp)
{
    BlockdevCreateOptions options;
    int64_t total_size = 0;
    bool nocow = false;
    PreallocMode prealloc;
    char *buf = NULL;
    Error *local_err = NULL;

    /* Skip file: protocol prefix */
    strstart(filename, "file:", &filename);

    /* Read out options */
    total_size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
                          BDRV_SECTOR_SIZE);
    nocow = qemu_opt_get_bool(opts, BLOCK_OPT_NOCOW, false);
    buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC);
    prealloc = qapi_enum_parse(&PreallocMode_lookup, buf,
                               PREALLOC_MODE_OFF, &local_err);
    g_free(buf);
    if (local_err) {
        error_propagate(errp, local_err);
        return -EINVAL;
    }

    options = (BlockdevCreateOptions) {
        .driver     = BLOCKDEV_DRIVER_FILE,
        .u.file     = {
            .filename           = (char *) filename,
            .size               = total_size,
            .has_preallocation  = true,
            .preallocation      = prealloc,
            .has_nocow          = true,
            .nocow              = nocow,
        },
    };
    return raw_co_create(&options, errp);
}

/*
 * Find allocation range in @bs around offset @start.
 * May change underlying file descriptor's file offset.
 * If @start is not in a hole, store @start in @data, and the
 * beginning of the next hole in @hole, and return 0.
 * If @start is in a non-trailing hole, store @start in @hole and the
 * beginning of the next non-hole in @data, and return 0.
 * If @start is in a trailing hole or beyond EOF, return -ENXIO.
 * If we can't find out, return a negative errno other than -ENXIO.
 */
static int find_allocation(BlockDriverState *bs, off_t start,
                           off_t *data, off_t *hole)
{
#if defined SEEK_HOLE && defined SEEK_DATA
    BDRVRawState *s = bs->opaque;
    off_t offs;

    /*
     * SEEK_DATA cases:
     * D1. offs == start: start is in data
     * D2. offs > start: start is in a hole, next data at offs
     * D3. offs < 0, errno = ENXIO: either start is in a trailing hole
     *                              or start is beyond EOF
     *     If the latter happens, the file has been truncated behind
     *     our back since we opened it.  All bets are off then.
     *     Treating like a trailing hole is simplest.
     * D4. offs < 0, errno != ENXIO: we learned nothing
     */
    offs = lseek(s->fd, start, SEEK_DATA);
    if (offs < 0) {
        return -errno;          /* D3 or D4 */
    }

    if (offs < start) {
        /* This is not a valid return by lseek().  We are safe to just return
         * -EIO in this case, and we'll treat it like D4. */
        return -EIO;
    }

    if (offs > start) {
        /* D2: in hole, next data at offs */
        *hole = start;
        *data = offs;
        return 0;
    }

    /* D1: in data, end not yet known */

    /*
     * SEEK_HOLE cases:
     * H1. offs == start: start is in a hole
     *     If this happens here, a hole has been dug behind our back
     *     since the previous lseek().
     * H2. offs > start: either start is in data, next hole at offs,
     *                   or start is in trailing hole, EOF at offs
     *     Linux treats trailing holes like any other hole: offs ==
     *     start.  Solaris seeks to EOF instead: offs > start (blech).
     *     If that happens here, a hole has been dug behind our back
     *     since the previous lseek().
     * H3. offs < 0, errno = ENXIO: start is beyond EOF
     *     If this happens, the file has been truncated behind our
     *     back since we opened it.  Treat it like a trailing hole.
     * H4. offs < 0, errno != ENXIO: we learned nothing
     *     Pretend we know nothing at all, i.e. "forget" about D1.
     */
    offs = lseek(s->fd, start, SEEK_HOLE);
    if (offs < 0) {
        return -errno;          /* D1 and (H3 or H4) */
    }

    if (offs < start) {
        /* This is not a valid return by lseek().  We are safe to just return
         * -EIO in this case, and we'll treat it like H4. */
        return -EIO;
    }

    if (offs > start) {
        /*
         * D1 and H2: either in data, next hole at offs, or it was in
         * data but is now in a trailing hole.  In the latter case,
         * all bets are off.  Treating it as if it there was data all
         * the way to EOF is safe, so simply do that.
         */
        *data = start;
        *hole = offs;
        return 0;
    }

    /* D1 and H1 */
    return -EBUSY;
#else
    return -ENOTSUP;
#endif
}

/*
 * Returns the allocation status of the specified offset.
 *
 * The block layer guarantees 'offset' and 'bytes' are within bounds.
 *
 * 'pnum' is set to the number of bytes (including and immediately following
 * the specified offset) that are known to be in the same
 * allocated/unallocated state.
 *
 * 'bytes' is the max value 'pnum' should be set to.
 */
static int coroutine_fn raw_co_block_status(BlockDriverState *bs,
                                            bool want_zero,
                                            int64_t offset,
                                            int64_t bytes, int64_t *pnum,
                                            int64_t *map,
                                            BlockDriverState **file)
{
    off_t data = 0, hole = 0;
    int ret;

    assert(QEMU_IS_ALIGNED(offset | bytes, bs->bl.request_alignment));

    ret = fd_open(bs);
    if (ret < 0) {
        return ret;
    }

    if (!want_zero) {
        *pnum = bytes;
        *map = offset;
        *file = bs;
        return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID;
    }

    ret = find_allocation(bs, offset, &data, &hole);
    if (ret == -ENXIO) {
        /* Trailing hole */
        *pnum = bytes;
        ret = BDRV_BLOCK_ZERO;
    } else if (ret < 0) {
        /* No info available, so pretend there are no holes */
        *pnum = bytes;
        ret = BDRV_BLOCK_DATA;
    } else if (data == offset) {
        /* On a data extent, compute bytes to the end of the extent,
         * possibly including a partial sector at EOF. */
        *pnum = MIN(bytes, hole - offset);

        /*
         * We are not allowed to return partial sectors, though, so
         * round up if necessary.
         */
        if (!QEMU_IS_ALIGNED(*pnum, bs->bl.request_alignment)) {
            int64_t file_length = raw_getlength(bs);
            if (file_length > 0) {
                /* Ignore errors, this is just a safeguard */
                assert(hole == file_length);
            }
            *pnum = ROUND_UP(*pnum, bs->bl.request_alignment);
        }

        ret = BDRV_BLOCK_DATA;
    } else {
        /* On a hole, compute bytes to the beginning of the next extent.  */
        assert(hole == offset);
        *pnum = MIN(bytes, data - offset);
        ret = BDRV_BLOCK_ZERO;
    }
    *map = offset;
    *file = bs;
    return ret | BDRV_BLOCK_OFFSET_VALID;
}

#if defined(__linux__)
/* Verify that the file is not in the page cache */
static void check_cache_dropped(BlockDriverState *bs, Error **errp)
{
    const size_t window_size = 128 * 1024 * 1024;
    BDRVRawState *s = bs->opaque;
    void *window = NULL;
    size_t length = 0;
    unsigned char *vec;
    size_t page_size;
    off_t offset;
    off_t end;

    /* mincore(2) page status information requires 1 byte per page */
    page_size = sysconf(_SC_PAGESIZE);
    vec = g_malloc(DIV_ROUND_UP(window_size, page_size));

    end = raw_getlength(bs);

    for (offset = 0; offset < end; offset += window_size) {
        void *new_window;
        size_t new_length;
        size_t vec_end;
        size_t i;
        int ret;

        /* Unmap previous window if size has changed */
        new_length = MIN(end - offset, window_size);
        if (new_length != length) {
            munmap(window, length);
            window = NULL;
            length = 0;
        }

        new_window = mmap(window, new_length, PROT_NONE, MAP_PRIVATE,
                          s->fd, offset);
        if (new_window == MAP_FAILED) {
            error_setg_errno(errp, errno, "mmap failed");
            break;
        }

        window = new_window;
        length = new_length;

        ret = mincore(window, length, vec);
        if (ret < 0) {
            error_setg_errno(errp, errno, "mincore failed");
            break;
        }

        vec_end = DIV_ROUND_UP(length, page_size);
        for (i = 0; i < vec_end; i++) {
            if (vec[i] & 0x1) {
                error_setg(errp, "page cache still in use!");
                break;
            }
        }
    }

    if (window) {
        munmap(window, length);
    }

    g_free(vec);
}
#endif /* __linux__ */

static void coroutine_fn raw_co_invalidate_cache(BlockDriverState *bs,
                                                 Error **errp)
{
    BDRVRawState *s = bs->opaque;
    int ret;

    ret = fd_open(bs);
    if (ret < 0) {
        error_setg_errno(errp, -ret, "The file descriptor is not open");
        return;
    }

    if (!s->drop_cache) {
        return;
    }

    if (s->open_flags & O_DIRECT) {
        return; /* No host kernel page cache */
    }

#if defined(__linux__)
    /* This sets the scene for the next syscall... */
    ret = bdrv_co_flush(bs);
    if (ret < 0) {
        error_setg_errno(errp, -ret, "flush failed");
        return;
    }

    /* Linux does not invalidate pages that are dirty, locked, or mmapped by a
     * process.  These limitations are okay because we just fsynced the file,
     * we don't use mmap, and the file should not be in use by other processes.
     */
    ret = posix_fadvise(s->fd, 0, 0, POSIX_FADV_DONTNEED);
    if (ret != 0) { /* the return value is a positive errno */
        error_setg_errno(errp, ret, "fadvise failed");
        return;
    }

    if (s->check_cache_dropped) {
        check_cache_dropped(bs, errp);
    }
#else /* __linux__ */
    /* Do nothing.  Live migration to a remote host with cache.direct=off is
     * unsupported on other host operating systems.  Cache consistency issues
     * may occur but no error is reported here, partly because that's the
     * historical behavior and partly because it's hard to differentiate valid
     * configurations that should not cause errors.
     */
#endif /* !__linux__ */
}

static void raw_account_discard(BDRVRawState *s, uint64_t nbytes, int ret)
{
    if (ret) {
        s->stats.discard_nb_failed++;
    } else {
        s->stats.discard_nb_ok++;
        s->stats.discard_bytes_ok += nbytes;
    }
}

static coroutine_fn int
raw_do_pdiscard(BlockDriverState *bs, int64_t offset, int bytes, bool blkdev)
{
    BDRVRawState *s = bs->opaque;
    RawPosixAIOData acb;
    int ret;

    acb = (RawPosixAIOData) {
        .bs             = bs,
        .aio_fildes     = s->fd,
        .aio_type       = QEMU_AIO_DISCARD,
        .aio_offset     = offset,
        .aio_nbytes     = bytes,
    };

    if (blkdev) {
        acb.aio_type |= QEMU_AIO_BLKDEV;
    }

    ret = raw_thread_pool_submit(bs, handle_aiocb_discard, &acb);
    raw_account_discard(s, bytes, ret);
    return ret;
}

static coroutine_fn int
raw_co_pdiscard(BlockDriverState *bs, int64_t offset, int bytes)
{
    return raw_do_pdiscard(bs, offset, bytes, false);
}

static int coroutine_fn
raw_do_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int bytes,
                     BdrvRequestFlags flags, bool blkdev)
{
    BDRVRawState *s = bs->opaque;
    RawPosixAIOData acb;
    ThreadPoolFunc *handler;

#ifdef CONFIG_FALLOCATE
    if (offset + bytes > bs->total_sectors * BDRV_SECTOR_SIZE) {
        BdrvTrackedRequest *req;
        uint64_t end;

        /*
         * This is a workaround for a bug in the Linux XFS driver,
         * where writes submitted through the AIO interface will be
         * discarded if they happen beyond a concurrently running
         * fallocate() that increases the file length (i.e., both the
         * write and the fallocate() happen beyond the EOF).
         *
         * To work around it, we extend the tracked request for this
         * zero write until INT64_MAX (effectively infinity), and mark
         * it as serializing.
         *
         * We have to enable this workaround for all filesystems and
         * AIO modes (not just XFS with aio=native), because for
         * remote filesystems we do not know the host configuration.
         */

        req = bdrv_co_get_self_request(bs);
        assert(req);
        assert(req->type == BDRV_TRACKED_WRITE);
        assert(req->offset <= offset);
        assert(req->offset + req->bytes >= offset + bytes);

        end = INT64_MAX & -(uint64_t)bs->bl.request_alignment;
        req->bytes = end - req->offset;
        req->overlap_bytes = req->bytes;

        bdrv_mark_request_serialising(req, bs->bl.request_alignment);
        bdrv_wait_serialising_requests(req);
    }
#endif

    acb = (RawPosixAIOData) {
        .bs             = bs,
        .aio_fildes     = s->fd,
        .aio_type       = QEMU_AIO_WRITE_ZEROES,
        .aio_offset     = offset,
        .aio_nbytes     = bytes,
    };

    if (blkdev) {
        acb.aio_type |= QEMU_AIO_BLKDEV;
    }
    if (flags & BDRV_REQ_NO_FALLBACK) {
        acb.aio_type |= QEMU_AIO_NO_FALLBACK;
    }

    if (flags & BDRV_REQ_MAY_UNMAP) {
        acb.aio_type |= QEMU_AIO_DISCARD;
        handler = handle_aiocb_write_zeroes_unmap;
    } else {
        handler = handle_aiocb_write_zeroes;
    }

    return raw_thread_pool_submit(bs, handler, &acb);
}

static int coroutine_fn raw_co_pwrite_zeroes(
    BlockDriverState *bs, int64_t offset,
    int bytes, BdrvRequestFlags flags)
{
    return raw_do_pwrite_zeroes(bs, offset, bytes, flags, false);
}

static int raw_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
{
    BDRVRawState *s = bs->opaque;

    bdi->unallocated_blocks_are_zero = s->discard_zeroes;
    return 0;
}

static BlockStatsSpecificFile get_blockstats_specific_file(BlockDriverState *bs)
{
    BDRVRawState *s = bs->opaque;
    return (BlockStatsSpecificFile) {
        .discard_nb_ok = s->stats.discard_nb_ok,
        .discard_nb_failed = s->stats.discard_nb_failed,
        .discard_bytes_ok = s->stats.discard_bytes_ok,
    };
}

static BlockStatsSpecific *raw_get_specific_stats(BlockDriverState *bs)
{
    BlockStatsSpecific *stats = g_new(BlockStatsSpecific, 1);

    stats->driver = BLOCKDEV_DRIVER_FILE;
    stats->u.file = get_blockstats_specific_file(bs);

    return stats;
}

static BlockStatsSpecific *hdev_get_specific_stats(BlockDriverState *bs)
{
    BlockStatsSpecific *stats = g_new(BlockStatsSpecific, 1);

    stats->driver = BLOCKDEV_DRIVER_HOST_DEVICE;
    stats->u.host_device = get_blockstats_specific_file(bs);

    return stats;
}

static QemuOptsList raw_create_opts = {
    .name = "raw-create-opts",
    .head = QTAILQ_HEAD_INITIALIZER(raw_create_opts.head),
    .desc = {
        {
            .name = BLOCK_OPT_SIZE,
            .type = QEMU_OPT_SIZE,
            .help = "Virtual disk size"
        },
        {
            .name = BLOCK_OPT_NOCOW,
            .type = QEMU_OPT_BOOL,
            .help = "Turn off copy-on-write (valid only on btrfs)"
        },
        {
            .name = BLOCK_OPT_PREALLOC,
            .type = QEMU_OPT_STRING,
            .help = "Preallocation mode (allowed values: off"
#ifdef CONFIG_POSIX_FALLOCATE
                    ", falloc"
#endif
                    ", full)"
        },
        { /* end of list */ }
    }
};

static int raw_check_perm(BlockDriverState *bs, uint64_t perm, uint64_t shared,
                          Error **errp)
{
    BDRVRawState *s = bs->opaque;
    BDRVRawReopenState *rs = NULL;
    int open_flags;
    int ret;

    if (s->perm_change_fd) {
        /*
         * In the context of reopen, this function may be called several times
         * (directly and recursively while change permissions of the parent).
         * This is even true for children that don't inherit from the original
         * reopen node, so s->reopen_state is not set.
         *
         * Ignore all but the first call.
         */
        return 0;
    }

    if (s->reopen_state) {
        /* We already have a new file descriptor to set permissions for */
        assert(s->reopen_state->perm == perm);
        assert(s->reopen_state->shared_perm == shared);
        rs = s->reopen_state->opaque;
        s->perm_change_fd = rs->fd;
        s->perm_change_flags = rs->open_flags;
    } else {
        /* We may need a new fd if auto-read-only switches the mode */
        ret = raw_reconfigure_getfd(bs, bs->open_flags, &open_flags, perm,
                                    false, errp);
        if (ret < 0) {
            return ret;
        } else if (ret != s->fd) {
            s->perm_change_fd = ret;
            s->perm_change_flags = open_flags;
        }
    }

    /* Prepare permissions on old fd to avoid conflicts between old and new,
     * but keep everything locked that new will need. */
    ret = raw_handle_perm_lock(bs, RAW_PL_PREPARE, perm, shared, errp);
    if (ret < 0) {
        goto fail;
    }

    /* Copy locks to the new fd */
    if (s->perm_change_fd) {
        ret = raw_apply_lock_bytes(NULL, s->perm_change_fd, perm, ~shared,
                                   false, errp);
        if (ret < 0) {
            raw_handle_perm_lock(bs, RAW_PL_ABORT, 0, 0, NULL);
            goto fail;
        }
    }
    return 0;

fail:
    if (s->perm_change_fd && !s->reopen_state) {
        qemu_close(s->perm_change_fd);
    }
    s->perm_change_fd = 0;
    return ret;
}

static void raw_set_perm(BlockDriverState *bs, uint64_t perm, uint64_t shared)
{
    BDRVRawState *s = bs->opaque;

    /* For reopen, we have already switched to the new fd (.bdrv_set_perm is
     * called after .bdrv_reopen_commit) */
    if (s->perm_change_fd && s->fd != s->perm_change_fd) {
        qemu_close(s->fd);
        s->fd = s->perm_change_fd;
        s->open_flags = s->perm_change_flags;
    }
    s->perm_change_fd = 0;

    raw_handle_perm_lock(bs, RAW_PL_COMMIT, perm, shared, NULL);
    s->perm = perm;
    s->shared_perm = shared;
}

static void raw_abort_perm_update(BlockDriverState *bs)
{
    BDRVRawState *s = bs->opaque;

    /* For reopen, .bdrv_reopen_abort is called afterwards and will close
     * the file descriptor. */
    if (s->perm_change_fd && !s->reopen_state) {
        qemu_close(s->perm_change_fd);
    }
    s->perm_change_fd = 0;

    raw_handle_perm_lock(bs, RAW_PL_ABORT, 0, 0, NULL);
}

static int coroutine_fn raw_co_copy_range_from(
        BlockDriverState *bs, BdrvChild *src, uint64_t src_offset,
        BdrvChild *dst, uint64_t dst_offset, uint64_t bytes,
        BdrvRequestFlags read_flags, BdrvRequestFlags write_flags)
{
    return bdrv_co_copy_range_to(src, src_offset, dst, dst_offset, bytes,
                                 read_flags, write_flags);
}

static int coroutine_fn raw_co_copy_range_to(BlockDriverState *bs,
                                             BdrvChild *src,
                                             uint64_t src_offset,
                                             BdrvChild *dst,
                                             uint64_t dst_offset,
                                             uint64_t bytes,
                                             BdrvRequestFlags read_flags,
                                             BdrvRequestFlags write_flags)
{
    RawPosixAIOData acb;
    BDRVRawState *s = bs->opaque;
    BDRVRawState *src_s;

    assert(dst->bs == bs);
    if (src->bs->drv->bdrv_co_copy_range_to != raw_co_copy_range_to) {
        return -ENOTSUP;
    }

    src_s = src->bs->opaque;
    if (fd_open(src->bs) < 0 || fd_open(dst->bs) < 0) {
        return -EIO;
    }

    acb = (RawPosixAIOData) {
        .bs             = bs,
        .aio_type       = QEMU_AIO_COPY_RANGE,
        .aio_fildes     = src_s->fd,
        .aio_offset     = src_offset,
        .aio_nbytes     = bytes,
        .copy_range     = {
            .aio_fd2        = s->fd,
            .aio_offset2    = dst_offset,
        },
    };

    return raw_thread_pool_submit(bs, handle_aiocb_copy_range, &acb);
}

BlockDriver bdrv_file = {
    .format_name = "file",
    .protocol_name = "file",
    .instance_size = sizeof(BDRVRawState),
    .bdrv_needs_filename = true,
    .bdrv_probe = NULL, /* no probe for protocols */
    .bdrv_parse_filename = raw_parse_filename,
    .bdrv_file_open = raw_open,
    .bdrv_reopen_prepare = raw_reopen_prepare,
    .bdrv_reopen_commit = raw_reopen_commit,
    .bdrv_reopen_abort = raw_reopen_abort,
    .bdrv_close = raw_close,
    .bdrv_co_create = raw_co_create,
    .bdrv_co_create_opts = raw_co_create_opts,
    .bdrv_has_zero_init = bdrv_has_zero_init_1,
    .bdrv_has_zero_init_truncate = bdrv_has_zero_init_1,
    .bdrv_co_block_status = raw_co_block_status,
    .bdrv_co_invalidate_cache = raw_co_invalidate_cache,
    .bdrv_co_pwrite_zeroes = raw_co_pwrite_zeroes,

    .bdrv_co_preadv         = raw_co_preadv,
    .bdrv_co_pwritev        = raw_co_pwritev,
    .bdrv_co_flush_to_disk  = raw_co_flush_to_disk,
    .bdrv_co_pdiscard       = raw_co_pdiscard,
    .bdrv_co_copy_range_from = raw_co_copy_range_from,
    .bdrv_co_copy_range_to  = raw_co_copy_range_to,
    .bdrv_refresh_limits = raw_refresh_limits,
    .bdrv_io_plug = raw_aio_plug,
    .bdrv_io_unplug = raw_aio_unplug,
    .bdrv_attach_aio_context = raw_aio_attach_aio_context,

    .bdrv_co_truncate = raw_co_truncate,
    .bdrv_getlength = raw_getlength,
    .bdrv_get_info = raw_get_info,
    .bdrv_get_allocated_file_size
                        = raw_get_allocated_file_size,
    .bdrv_get_specific_stats = raw_get_specific_stats,
    .bdrv_check_perm = raw_check_perm,
    .bdrv_set_perm   = raw_set_perm,
    .bdrv_abort_perm_update = raw_abort_perm_update,
    .create_opts = &raw_create_opts,
    .mutable_opts = mutable_opts,
};

/***********************************************/
/* host device */

#if defined(__APPLE__) && defined(__MACH__)
static kern_return_t GetBSDPath(io_iterator_t mediaIterator, char *bsdPath,
                                CFIndex maxPathSize, int flags);
static char *FindEjectableOpticalMedia(io_iterator_t *mediaIterator)
{
    kern_return_t kernResult = KERN_FAILURE;
    mach_port_t     masterPort;
    CFMutableDictionaryRef  classesToMatch;
    const char *matching_array[] = {kIODVDMediaClass, kIOCDMediaClass};
    char *mediaType = NULL;

    kernResult = IOMasterPort( MACH_PORT_NULL, &masterPort );
    if ( KERN_SUCCESS != kernResult ) {
        printf( "IOMasterPort returned %d\n", kernResult );
    }

    int index;
    for (index = 0; index < ARRAY_SIZE(matching_array); index++) {
        classesToMatch = IOServiceMatching(matching_array[index]);
        if (classesToMatch == NULL) {
            error_report("IOServiceMatching returned NULL for %s",
                         matching_array[index]);
            continue;
        }
        CFDictionarySetValue(classesToMatch, CFSTR(kIOMediaEjectableKey),
                             kCFBooleanTrue);
        kernResult = IOServiceGetMatchingServices(masterPort, classesToMatch,
                                                  mediaIterator);
        if (kernResult != KERN_SUCCESS) {
            error_report("Note: IOServiceGetMatchingServices returned %d",
                         kernResult);
            continue;
        }

        /* If a match was found, leave the loop */
        if (*mediaIterator != 0) {
            trace_file_FindEjectableOpticalMedia(matching_array[index]);
            mediaType = g_strdup(matching_array[index]);
            break;
        }
    }
    return mediaType;
}

kern_return_t GetBSDPath(io_iterator_t mediaIterator, char *bsdPath,
                         CFIndex maxPathSize, int flags)
{
    io_object_t     nextMedia;
    kern_return_t   kernResult = KERN_FAILURE;
    *bsdPath = '\0';
    nextMedia = IOIteratorNext( mediaIterator );
    if ( nextMedia )
    {
        CFTypeRef   bsdPathAsCFString;
    bsdPathAsCFString = IORegistryEntryCreateCFProperty( nextMedia, CFSTR( kIOBSDNameKey ), kCFAllocatorDefault, 0 );
        if ( bsdPathAsCFString ) {
            size_t devPathLength;
            strcpy( bsdPath, _PATH_DEV );
            if (flags & BDRV_O_NOCACHE) {
                strcat(bsdPath, "r");
            }
            devPathLength = strlen( bsdPath );
            if ( CFStringGetCString( bsdPathAsCFString, bsdPath + devPathLength, maxPathSize - devPathLength, kCFStringEncodingASCII ) ) {
                kernResult = KERN_SUCCESS;
            }
            CFRelease( bsdPathAsCFString );
        }
        IOObjectRelease( nextMedia );
    }

    return kernResult;
}

/* Sets up a real cdrom for use in QEMU */
static bool setup_cdrom(char *bsd_path, Error **errp)
{
    int index, num_of_test_partitions = 2, fd;
    char test_partition[MAXPATHLEN];
    bool partition_found = false;

    /* look for a working partition */
    for (index = 0; index < num_of_test_partitions; index++) {
        snprintf(test_partition, sizeof(test_partition), "%ss%d", bsd_path,
                 index);
        fd = qemu_open(test_partition, O_RDONLY | O_BINARY | O_LARGEFILE);
        if (fd >= 0) {
            partition_found = true;
            qemu_close(fd);
            break;
        }
    }

    /* if a working partition on the device was not found */
    if (partition_found == false) {
        error_setg(errp, "Failed to find a working partition on disc");
    } else {
        trace_file_setup_cdrom(test_partition);
        pstrcpy(bsd_path, MAXPATHLEN, test_partition);
    }
    return partition_found;
}

/* Prints directions on mounting and unmounting a device */
static void print_unmounting_directions(const char *file_name)
{
    error_report("If device %s is mounted on the desktop, unmount"
                 " it first before using it in QEMU", file_name);
    error_report("Command to unmount device: diskutil unmountDisk %s",
                 file_name);
    error_report("Command to mount device: diskutil mountDisk %s", file_name);
}

#endif /* defined(__APPLE__) && defined(__MACH__) */

static int hdev_probe_device(const char *filename)
{
    struct stat st;

    /* allow a dedicated CD-ROM driver to match with a higher priority */
    if (strstart(filename, "/dev/cdrom", NULL))
        return 50;

    if (stat(filename, &st) >= 0 &&
            (S_ISCHR(st.st_mode) || S_ISBLK(st.st_mode))) {
        return 100;
    }

    return 0;
}

static int check_hdev_writable(BDRVRawState *s)
{
#if defined(BLKROGET)
    /* Linux block devices can be configured "read-only" using blockdev(8).
     * This is independent of device node permissions and therefore open(2)
     * with O_RDWR succeeds.  Actual writes fail with EPERM.
     *
     * bdrv_open() is supposed to fail if the disk is read-only.  Explicitly
     * check for read-only block devices so that Linux block devices behave
     * properly.
     */
    struct stat st;
    int readonly = 0;

    if (fstat(s->fd, &st)) {
        return -errno;
    }

    if (!S_ISBLK(st.st_mode)) {
        return 0;
    }

    if (ioctl(s->fd, BLKROGET, &readonly) < 0) {
        return -errno;
    }

    if (readonly) {
        return -EACCES;
    }
#endif /* defined(BLKROGET) */
    return 0;
}

static void hdev_parse_filename(const char *filename, QDict *options,
                                Error **errp)
{
    bdrv_parse_filename_strip_prefix(filename, "host_device:", options);
}

static bool hdev_is_sg(BlockDriverState *bs)
{

#if defined(__linux__)

    BDRVRawState *s = bs->opaque;
    struct stat st;
    struct sg_scsi_id scsiid;
    int sg_version;
    int ret;

    if (stat(bs->filename, &st) < 0 || !S_ISCHR(st.st_mode)) {
        return false;
    }

    ret = ioctl(s->fd, SG_GET_VERSION_NUM, &sg_version);
    if (ret < 0) {
        return false;
    }

    ret = ioctl(s->fd, SG_GET_SCSI_ID, &scsiid);
    if (ret >= 0) {
        trace_file_hdev_is_sg(scsiid.scsi_type, sg_version);
        return true;
    }

#endif

    return false;
}

static int hdev_open(BlockDriverState *bs, QDict *options, int flags,
                     Error **errp)
{
    BDRVRawState *s = bs->opaque;
    Error *local_err = NULL;
    int ret;

#if defined(__APPLE__) && defined(__MACH__)
    /*
     * Caution: while qdict_get_str() is fine, getting non-string types
     * would require more care.  When @options come from -blockdev or
     * blockdev_add, its members are typed according to the QAPI
     * schema, but when they come from -drive, they're all QString.
     */
    const char *filename = qdict_get_str(options, "filename");
    char bsd_path[MAXPATHLEN] = "";
    bool error_occurred = false;

    /* If using a real cdrom */
    if (strcmp(filename, "/dev/cdrom") == 0) {
        char *mediaType = NULL;
        kern_return_t ret_val;
        io_iterator_t mediaIterator = 0;

        mediaType = FindEjectableOpticalMedia(&mediaIterator);
        if (mediaType == NULL) {
            error_setg(errp, "Please make sure your CD/DVD is in the optical"
                       " drive");
            error_occurred = true;
            goto hdev_open_Mac_error;
        }

        ret_val = GetBSDPath(mediaIterator, bsd_path, sizeof(bsd_path), flags);
        if (ret_val != KERN_SUCCESS) {
            error_setg(errp, "Could not get BSD path for optical drive");
            error_occurred = true;
            goto hdev_open_Mac_error;
        }

        /* If a real optical drive was not found */
        if (bsd_path[0] == '\0') {
            error_setg(errp, "Failed to obtain bsd path for optical drive");
            error_occurred = true;
            goto hdev_open_Mac_error;
        }

        /* If using a cdrom disc and finding a partition on the disc failed */
        if (strncmp(mediaType, kIOCDMediaClass, 9) == 0 &&
            setup_cdrom(bsd_path, errp) == false) {
            print_unmounting_directions(bsd_path);
            error_occurred = true;
            goto hdev_open_Mac_error;
        }

        qdict_put_str(options, "filename", bsd_path);

hdev_open_Mac_error:
        g_free(mediaType);
        if (mediaIterator) {
            IOObjectRelease(mediaIterator);
        }
        if (error_occurred) {
            return -ENOENT;
        }
    }
#endif /* defined(__APPLE__) && defined(__MACH__) */

    s->type = FTYPE_FILE;

    ret = raw_open_common(bs, options, flags, 0, true, &local_err);
    if (ret < 0) {
        error_propagate(errp, local_err);
#if defined(__APPLE__) && defined(__MACH__)
        if (*bsd_path) {
            filename = bsd_path;
        }
        /* if a physical device experienced an error while being opened */
        if (strncmp(filename, "/dev/", 5) == 0) {
            print_unmounting_directions(filename);
        }
#endif /* defined(__APPLE__) && defined(__MACH__) */
        return ret;
    }

    /* Since this does ioctl the device must be already opened */
    bs->sg = hdev_is_sg(bs);

    if (flags & BDRV_O_RDWR) {
        ret = check_hdev_writable(s);
        if (ret < 0) {
            raw_close(bs);
            error_setg_errno(errp, -ret, "The device is not writable");
            return ret;
        }
    }

    return ret;
}

#if defined(__linux__)
static int coroutine_fn
hdev_co_ioctl(BlockDriverState *bs, unsigned long int req, void *buf)
{
    BDRVRawState *s = bs->opaque;
    RawPosixAIOData acb;
    int ret;

    ret = fd_open(bs);
    if (ret < 0) {
        return ret;
    }

    if (req == SG_IO && s->pr_mgr) {
        struct sg_io_hdr *io_hdr = buf;
        if (io_hdr->cmdp[0] == PERSISTENT_RESERVE_OUT ||
            io_hdr->cmdp[0] == PERSISTENT_RESERVE_IN) {
            return pr_manager_execute(s->pr_mgr, bdrv_get_aio_context(bs),
                                      s->fd, io_hdr);
        }
    }

    acb = (RawPosixAIOData) {
        .bs         = bs,
        .aio_type   = QEMU_AIO_IOCTL,
        .aio_fildes = s->fd,
        .aio_offset = 0,
        .ioctl      = {
            .buf        = buf,
            .cmd        = req,
        },
    };

    return raw_thread_pool_submit(bs, handle_aiocb_ioctl, &acb);
}
#endif /* linux */

static int fd_open(BlockDriverState *bs)
{
    BDRVRawState *s = bs->opaque;

    /* this is just to ensure s->fd is sane (its called by io ops) */
    if (s->fd >= 0)
        return 0;
    return -EIO;
}

static coroutine_fn int
hdev_co_pdiscard(BlockDriverState *bs, int64_t offset, int bytes)
{
    BDRVRawState *s = bs->opaque;
    int ret;

    ret = fd_open(bs);
    if (ret < 0) {
        raw_account_discard(s, bytes, ret);
        return ret;
    }
    return raw_do_pdiscard(bs, offset, bytes, true);
}

static coroutine_fn int hdev_co_pwrite_zeroes(BlockDriverState *bs,
    int64_t offset, int bytes, BdrvRequestFlags flags)
{
    int rc;

    rc = fd_open(bs);
    if (rc < 0) {
        return rc;
    }

    return raw_do_pwrite_zeroes(bs, offset, bytes, flags, true);
}

static int coroutine_fn hdev_co_create_opts(const char *filename, QemuOpts *opts,
                                            Error **errp)
{
    int fd;
    int ret = 0;
    struct stat stat_buf;
    int64_t total_size = 0;
    bool has_prefix;

    /* This function is used by both protocol block drivers and therefore either
     * of these prefixes may be given.
     * The return value has to be stored somewhere, otherwise this is an error
     * due to -Werror=unused-value. */
    has_prefix =
        strstart(filename, "host_device:", &filename) ||
        strstart(filename, "host_cdrom:" , &filename);

    (void)has_prefix;

    ret = raw_normalize_devicepath(&filename, errp);
    if (ret < 0) {
        return ret;
    }

    /* Read out options */
    total_size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
                          BDRV_SECTOR_SIZE);

    fd = qemu_open(filename, O_WRONLY | O_BINARY);
    if (fd < 0) {
        ret = -errno;
        error_setg_errno(errp, -ret, "Could not open device");
        return ret;
    }

    if (fstat(fd, &stat_buf) < 0) {
        ret = -errno;
        error_setg_errno(errp, -ret, "Could not stat device");
    } else if (!S_ISBLK(stat_buf.st_mode) && !S_ISCHR(stat_buf.st_mode)) {
        error_setg(errp,
                   "The given file is neither a block nor a character device");
        ret = -ENODEV;
    } else if (lseek(fd, 0, SEEK_END) < total_size) {
        error_setg(errp, "Device is too small");
        ret = -ENOSPC;
    }

    if (!ret && total_size) {
        uint8_t buf[BDRV_SECTOR_SIZE] = { 0 };
        int64_t zero_size = MIN(BDRV_SECTOR_SIZE, total_size);
        if (lseek(fd, 0, SEEK_SET) == -1) {
            ret = -errno;
        } else {
            ret = qemu_write_full(fd, buf, zero_size);
            ret = ret == zero_size ? 0 : -errno;
        }
    }
    qemu_close(fd);
    return ret;
}

static BlockDriver bdrv_host_device = {
    .format_name        = "host_device",
    .protocol_name        = "host_device",
    .instance_size      = sizeof(BDRVRawState),
    .bdrv_needs_filename = true,
    .bdrv_probe_device  = hdev_probe_device,
    .bdrv_parse_filename = hdev_parse_filename,
    .bdrv_file_open     = hdev_open,
    .bdrv_close         = raw_close,
    .bdrv_reopen_prepare = raw_reopen_prepare,
    .bdrv_reopen_commit  = raw_reopen_commit,
    .bdrv_reopen_abort   = raw_reopen_abort,
    .bdrv_co_create_opts = hdev_co_create_opts,
    .create_opts         = &raw_create_opts,
    .mutable_opts        = mutable_opts,
    .bdrv_co_invalidate_cache = raw_co_invalidate_cache,
    .bdrv_co_pwrite_zeroes = hdev_co_pwrite_zeroes,

    .bdrv_co_preadv         = raw_co_preadv,
    .bdrv_co_pwritev        = raw_co_pwritev,
    .bdrv_co_flush_to_disk  = raw_co_flush_to_disk,
    .bdrv_co_pdiscard       = hdev_co_pdiscard,
    .bdrv_co_copy_range_from = raw_co_copy_range_from,
    .bdrv_co_copy_range_to  = raw_co_copy_range_to,
    .bdrv_refresh_limits = raw_refresh_limits,
    .bdrv_io_plug = raw_aio_plug,
    .bdrv_io_unplug = raw_aio_unplug,
    .bdrv_attach_aio_context = raw_aio_attach_aio_context,

    .bdrv_co_truncate       = raw_co_truncate,
    .bdrv_getlength	= raw_getlength,
    .bdrv_get_info = raw_get_info,
    .bdrv_get_allocated_file_size
                        = raw_get_allocated_file_size,
    .bdrv_get_specific_stats = hdev_get_specific_stats,
    .bdrv_check_perm = raw_check_perm,
    .bdrv_set_perm   = raw_set_perm,
    .bdrv_abort_perm_update = raw_abort_perm_update,
    .bdrv_probe_blocksizes = hdev_probe_blocksizes,
    .bdrv_probe_geometry = hdev_probe_geometry,

    /* generic scsi device */
#ifdef __linux__
    .bdrv_co_ioctl          = hdev_co_ioctl,
#endif
};

#if defined(__linux__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
static void cdrom_parse_filename(const char *filename, QDict *options,
                                 Error **errp)
{
    bdrv_parse_filename_strip_prefix(filename, "host_cdrom:", options);
}
#endif

#ifdef __linux__
static int cdrom_open(BlockDriverState *bs, QDict *options, int flags,
                      Error **errp)
{
    BDRVRawState *s = bs->opaque;

    s->type = FTYPE_CD;

    /* open will not fail even if no CD is inserted, so add O_NONBLOCK */
    return raw_open_common(bs, options, flags, O_NONBLOCK, true, errp);
}

static int cdrom_probe_device(const char *filename)
{
    int fd, ret;
    int prio = 0;
    struct stat st;

    fd = qemu_open(filename, O_RDONLY | O_NONBLOCK);
    if (fd < 0) {
        goto out;
    }
    ret = fstat(fd, &st);
    if (ret == -1 || !S_ISBLK(st.st_mode)) {
        goto outc;
    }

    /* Attempt to detect via a CDROM specific ioctl */
    ret = ioctl(fd, CDROM_DRIVE_STATUS, CDSL_CURRENT);
    if (ret >= 0)
        prio = 100;

outc:
    qemu_close(fd);
out:
    return prio;
}

static bool cdrom_is_inserted(BlockDriverState *bs)
{
    BDRVRawState *s = bs->opaque;
    int ret;

    ret = ioctl(s->fd, CDROM_DRIVE_STATUS, CDSL_CURRENT);
    return ret == CDS_DISC_OK;
}

static void cdrom_eject(BlockDriverState *bs, bool eject_flag)
{
    BDRVRawState *s = bs->opaque;

    if (eject_flag) {
        if (ioctl(s->fd, CDROMEJECT, NULL) < 0)
            perror("CDROMEJECT");
    } else {
        if (ioctl(s->fd, CDROMCLOSETRAY, NULL) < 0)
            perror("CDROMEJECT");
    }
}

static void cdrom_lock_medium(BlockDriverState *bs, bool locked)
{
    BDRVRawState *s = bs->opaque;

    if (ioctl(s->fd, CDROM_LOCKDOOR, locked) < 0) {
        /*
         * Note: an error can happen if the distribution automatically
         * mounts the CD-ROM
         */
        /* perror("CDROM_LOCKDOOR"); */
    }
}

static BlockDriver bdrv_host_cdrom = {
    .format_name        = "host_cdrom",
    .protocol_name      = "host_cdrom",
    .instance_size      = sizeof(BDRVRawState),
    .bdrv_needs_filename = true,
    .bdrv_probe_device	= cdrom_probe_device,
    .bdrv_parse_filename = cdrom_parse_filename,
    .bdrv_file_open     = cdrom_open,
    .bdrv_close         = raw_close,
    .bdrv_reopen_prepare = raw_reopen_prepare,
    .bdrv_reopen_commit  = raw_reopen_commit,
    .bdrv_reopen_abort   = raw_reopen_abort,
    .bdrv_co_create_opts = hdev_co_create_opts,
    .create_opts         = &raw_create_opts,
    .mutable_opts        = mutable_opts,
    .bdrv_co_invalidate_cache = raw_co_invalidate_cache,


    .bdrv_co_preadv         = raw_co_preadv,
    .bdrv_co_pwritev        = raw_co_pwritev,
    .bdrv_co_flush_to_disk  = raw_co_flush_to_disk,
    .bdrv_refresh_limits = raw_refresh_limits,
    .bdrv_io_plug = raw_aio_plug,
    .bdrv_io_unplug = raw_aio_unplug,
    .bdrv_attach_aio_context = raw_aio_attach_aio_context,

    .bdrv_co_truncate    = raw_co_truncate,
    .bdrv_getlength      = raw_getlength,
    .has_variable_length = true,
    .bdrv_get_allocated_file_size
                        = raw_get_allocated_file_size,

    /* removable device support */
    .bdrv_is_inserted   = cdrom_is_inserted,
    .bdrv_eject         = cdrom_eject,
    .bdrv_lock_medium   = cdrom_lock_medium,

    /* generic scsi device */
    .bdrv_co_ioctl      = hdev_co_ioctl,
};
#endif /* __linux__ */

#if defined (__FreeBSD__) || defined(__FreeBSD_kernel__)
static int cdrom_open(BlockDriverState *bs, QDict *options, int flags,
                      Error **errp)
{
    BDRVRawState *s = bs->opaque;
    Error *local_err = NULL;
    int ret;

    s->type = FTYPE_CD;

    ret = raw_open_common(bs, options, flags, 0, true, &local_err);
    if (ret) {
        error_propagate(errp, local_err);
        return ret;
    }

    /* make sure the door isn't locked at this time */
    ioctl(s->fd, CDIOCALLOW);
    return 0;
}

static int cdrom_probe_device(const char *filename)
{
    if (strstart(filename, "/dev/cd", NULL) ||
            strstart(filename, "/dev/acd", NULL))
        return 100;
    return 0;
}

static int cdrom_reopen(BlockDriverState *bs)
{
    BDRVRawState *s = bs->opaque;
    int fd;

    /*
     * Force reread of possibly changed/newly loaded disc,
     * FreeBSD seems to not notice sometimes...
     */
    if (s->fd >= 0)
        qemu_close(s->fd);
    fd = qemu_open(bs->filename, s->open_flags, 0644);
    if (fd < 0) {
        s->fd = -1;
        return -EIO;
    }
    s->fd = fd;

    /* make sure the door isn't locked at this time */
    ioctl(s->fd, CDIOCALLOW);
    return 0;
}

static bool cdrom_is_inserted(BlockDriverState *bs)
{
    return raw_getlength(bs) > 0;
}

static void cdrom_eject(BlockDriverState *bs, bool eject_flag)
{
    BDRVRawState *s = bs->opaque;

    if (s->fd < 0)
        return;

    (void) ioctl(s->fd, CDIOCALLOW);

    if (eject_flag) {
        if (ioctl(s->fd, CDIOCEJECT) < 0)
            perror("CDIOCEJECT");
    } else {
        if (ioctl(s->fd, CDIOCCLOSE) < 0)
            perror("CDIOCCLOSE");
    }

    cdrom_reopen(bs);
}

static void cdrom_lock_medium(BlockDriverState *bs, bool locked)
{
    BDRVRawState *s = bs->opaque;

    if (s->fd < 0)
        return;
    if (ioctl(s->fd, (locked ? CDIOCPREVENT : CDIOCALLOW)) < 0) {
        /*
         * Note: an error can happen if the distribution automatically
         * mounts the CD-ROM
         */
        /* perror("CDROM_LOCKDOOR"); */
    }
}

static BlockDriver bdrv_host_cdrom = {
    .format_name        = "host_cdrom",
    .protocol_name      = "host_cdrom",
    .instance_size      = sizeof(BDRVRawState),
    .bdrv_needs_filename = true,
    .bdrv_probe_device	= cdrom_probe_device,
    .bdrv_parse_filename = cdrom_parse_filename,
    .bdrv_file_open     = cdrom_open,
    .bdrv_close         = raw_close,
    .bdrv_reopen_prepare = raw_reopen_prepare,
    .bdrv_reopen_commit  = raw_reopen_commit,
    .bdrv_reopen_abort   = raw_reopen_abort,
    .bdrv_co_create_opts = hdev_co_create_opts,
    .create_opts        = &raw_create_opts,
    .mutable_opts       = mutable_opts,

    .bdrv_co_preadv         = raw_co_preadv,
    .bdrv_co_pwritev        = raw_co_pwritev,
    .bdrv_co_flush_to_disk  = raw_co_flush_to_disk,
    .bdrv_refresh_limits = raw_refresh_limits,
    .bdrv_io_plug = raw_aio_plug,
    .bdrv_io_unplug = raw_aio_unplug,
    .bdrv_attach_aio_context = raw_aio_attach_aio_context,

    .bdrv_co_truncate    = raw_co_truncate,
    .bdrv_getlength      = raw_getlength,
    .has_variable_length = true,
    .bdrv_get_allocated_file_size
                        = raw_get_allocated_file_size,

    /* removable device support */
    .bdrv_is_inserted   = cdrom_is_inserted,
    .bdrv_eject         = cdrom_eject,
    .bdrv_lock_medium   = cdrom_lock_medium,
};
#endif /* __FreeBSD__ */

static void bdrv_file_init(void)
{
    /*
     * Register all the drivers.  Note that order is important, the driver
     * registered last will get probed first.
     */
    bdrv_register(&bdrv_file);
    bdrv_register(&bdrv_host_device);
#ifdef __linux__
    bdrv_register(&bdrv_host_cdrom);
#endif
#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
    bdrv_register(&bdrv_host_cdrom);
#endif
}

block_init(bdrv_file_init);