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Date: Fri, 29 Jul 2011 23:09:53 +0800
From: Liu Yuan <namei.unix@...il.com>
To: "Michael S. Tsirkin" <mst@...hat.com>
CC: Rusty Russell <rusty@...tcorp.com.au>, Avi Kivity <avi@...hat.com>,
kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] vhost-blk: An in-kernel accelerator for virtio-blk
On 07/28/2011 11:22 PM, Michael S. Tsirkin wrote:
> On Thu, Jul 28, 2011 at 10:29:05PM +0800, Liu Yuan wrote:
>> From: Liu Yuan<tailai.ly@...bao.com>
>>
>> Vhost-blk driver is an in-kernel accelerator, intercepting the
>> IO requests from KVM virtio-capable guests. It is based on the
>> vhost infrastructure.
>>
>> This is supposed to be a module over latest kernel tree, but it
>> needs some symbols from fs/aio.c and fs/eventfd.c to compile with.
>> So currently, after applying the patch, you need to *recomplie*
>> the kernel.
>>
>> Usage:
>> $kernel-src: make M=drivers/vhost
>> $kernel-src: sudo insmod drivers/vhost/vhost_blk.ko
>>
>> After insmod, you'll see /dev/vhost-blk created. done!
>>
>> Signed-off-by: Liu Yuan<tailai.ly@...bao.com>
> Thanks, this is an interesting patch.
>
> There are some coding style issues in this patch, could you please
> change the code to match the kernel coding style?
>
> In particular pls prefix functions macros etc with vhost_blk to avoid
> confusion.
>
> scripts/checkpatch.pl can find some, but not all, issues.
>
>> ---
>> drivers/vhost/Makefile | 3 +
>> drivers/vhost/blk.c | 568 ++++++++++++++++++++++++++++++++++++++++++++++++
>> drivers/vhost/vhost.h | 11 +
>> fs/aio.c | 44 ++---
>> fs/eventfd.c | 1 +
>> include/linux/aio.h | 31 +++
> As others said, core changes need to be split out
> and get acks from relevant people.
>
> Use scripts/get_maintainer.pl to get a list.
>
>
>> 6 files changed, 631 insertions(+), 27 deletions(-)
>> create mode 100644 drivers/vhost/blk.c
>>
>> diff --git a/drivers/vhost/Makefile b/drivers/vhost/Makefile
>> index 72dd020..31f8b2e 100644
>> --- a/drivers/vhost/Makefile
>> +++ b/drivers/vhost/Makefile
>> @@ -1,2 +1,5 @@
>> obj-$(CONFIG_VHOST_NET) += vhost_net.o
>> +obj-m += vhost_blk.o
>> +
>> vhost_net-y := vhost.o net.o
>> +vhost_blk-y := vhost.o blk.o
>> diff --git a/drivers/vhost/blk.c b/drivers/vhost/blk.c
>> new file mode 100644
>> index 0000000..f3462be
>> --- /dev/null
>> +++ b/drivers/vhost/blk.c
>> @@ -0,0 +1,568 @@
>> +/* Copyright (C) 2011 Taobao, Inc.
>> + * Author: Liu Yuan<tailai.ly@...bao.com>
>> + *
>> + * This work is licensed under the terms of the GNU GPL, version 2.
>> + *
>> + * Vhost-blk driver is an in-kernel accelerator, intercepting the
>> + * IO requests from KVM virtio-capable guests. It is based on the
>> + * vhost infrastructure.
>> + */
>> +
>> +#include<linux/miscdevice.h>
>> +#include<linux/module.h>
>> +#include<linux/virtio_net.h>
>> +#include<linux/vhost.h>
>> +#include<linux/eventfd.h>
>> +#include<linux/mutex.h>
>> +#include<linux/workqueue.h>
>> +#include<linux/virtio_blk.h>
>> +#include<linux/file.h>
>> +#include<linux/mmu_context.h>
>> +#include<linux/kthread.h>
>> +#include<linux/anon_inodes.h>
>> +#include<linux/syscalls.h>
>> +#include<linux/blkdev.h>
>> +
>> +#include "vhost.h"
>> +
>> +#define DEBUG 0
>> +
>> +#if DEBUG> 0
>> +#define dprintk printk
>> +#else
>> +#define dprintk(x...) do { ; } while (0)
>> +#endif
> There are standard macros for these.
>
>> +
>> +enum {
>> + virtqueue_max = 1,
>> +};
>> +
>> +#define MAX_EVENTS 128
>> +
>> +struct vhost_blk {
>> + struct vhost_virtqueue vq;
>> + struct vhost_dev dev;
>> + int should_stop;
>> + struct kioctx *ioctx;
>> + struct eventfd_ctx *ectx;
>> + struct file *efile;
>> + struct task_struct *worker;
>> +};
>> +
>> +struct used_info {
>> + void *status;
>> + int head;
>> + int len;
>> +};
>> +
>> +static struct io_event events[MAX_EVENTS];
>> +
>> +static void blk_flush(struct vhost_blk *blk)
>> +{
>> + vhost_poll_flush(&blk->vq.poll);
>> +}
>> +
>> +static long blk_set_features(struct vhost_blk *blk, u64 features)
>> +{
>> + blk->dev.acked_features = features;
>> + return 0;
>> +}
>> +
>> +static void blk_stop(struct vhost_blk *blk)
>> +{
>> + struct vhost_virtqueue *vq =&blk->vq;
>> + struct file *f;
>> +
>> + mutex_lock(&vq->mutex);
>> + f = rcu_dereference_protected(vq->private_data,
>> + lockdep_is_held(&vq->mutex));
>> + rcu_assign_pointer(vq->private_data, NULL);
>> + mutex_unlock(&vq->mutex);
>> +
>> + if (f)
>> + fput(f);
>> +}
>> +
>> +static long blk_set_backend(struct vhost_blk *blk, struct vhost_vring_file *backend)
>> +{
>> + int idx = backend->index;
>> + struct vhost_virtqueue *vq =&blk->vq;
>> + struct file *file, *oldfile;
>> + int ret;
>> +
>> + mutex_lock(&blk->dev.mutex);
>> + ret = vhost_dev_check_owner(&blk->dev);
>> + if (ret)
>> + goto err_dev;
>> + if (idx>= virtqueue_max) {
>> + ret = -ENOBUFS;
>> + goto err_dev;
>> + }
>> +
>> + mutex_lock(&vq->mutex);
>> +
>> + if (!vhost_vq_access_ok(vq)) {
>> + ret = -EFAULT;
>> + goto err_vq;
>> + }
> NET used -1 backend to remove a backend.
> I think it's a good idea, to make an operation reversible.
>
>> +
>> + file = fget(backend->fd);
> We need to verify that the file type passed makes sense.
> For example, it's possible to create reference loops
> by passng the vhost-blk fd.
>
>
>> + if (IS_ERR(file)) {
>> + ret = PTR_ERR(file);
>> + goto err_vq;
>> + }
>> +
>> + oldfile = rcu_dereference_protected(vq->private_data,
>> + lockdep_is_held(&vq->mutex));
>> + if (file != oldfile)
>> + rcu_assign_pointer(vq->private_data, file);
>> +
>> + mutex_unlock(&vq->mutex);
>> +
>> + if (oldfile) {
>> + blk_flush(blk);
>> + fput(oldfile);
>> + }
>> +
>> + mutex_unlock(&blk->dev.mutex);
>> + return 0;
>> +err_vq:
>> + mutex_unlock(&vq->mutex);
>> +err_dev:
>> + mutex_unlock(&blk->dev.mutex);
>> + return ret;
>> +}
>> +
>> +static long blk_reset_owner(struct vhost_blk *b)
>> +{
>> + int ret;
>> +
>> + mutex_lock(&b->dev.mutex);
>> + ret = vhost_dev_check_owner(&b->dev);
>> + if (ret)
>> + goto err;
>> + blk_stop(b);
>> + blk_flush(b);
>> + ret = vhost_dev_reset_owner(&b->dev);
>> + if (b->worker) {
>> + b->should_stop = 1;
>> + smp_mb();
>> + eventfd_signal(b->ectx, 1);
>> + }
>> +err:
>> + mutex_unlock(&b->dev.mutex);
>> + return ret;
>> +}
>> +
>> +static int kernel_io_setup(unsigned nr_events, struct kioctx **ioctx)
>> +{
>> + int ret = 0;
>> + *ioctx = ioctx_alloc(nr_events);
>> + if (IS_ERR(ioctx))
>> + ret = PTR_ERR(ioctx);
>> + return ret;
>> +}
>> +
>> +static inline int kernel_read_events(struct kioctx *ctx, long min_nr, long nr, struct io_event *event,
>> + struct timespec *ts)
>> +{
>> + mm_segment_t old_fs;
>> + int ret;
>> +
>> + old_fs = get_fs();
>> + set_fs(get_ds());
>> + ret = read_events(ctx, min_nr, nr, event, ts);
>> + set_fs(old_fs);
>> +
>> + return ret;
>> +}
>> +
>> +static inline ssize_t io_event_ret(struct io_event *ev)
>> +{
>> + return (ssize_t)(((uint64_t)ev->res2<< 32) | ev->res);
>> +}
>> +
>> +static inline void aio_prep_req(struct kiocb *iocb, struct eventfd_ctx *ectx, struct file *file,
>> + struct iovec *iov, int nvecs, u64 offset, int opcode, struct used_info *ui)
>> +{
>> + iocb->ki_filp = file;
>> + iocb->ki_eventfd = ectx;
>> + iocb->ki_pos = offset;
>> + iocb->ki_buf = (void *)iov;
>> + iocb->ki_left = iocb->ki_nbytes = nvecs;
>> + iocb->ki_opcode = opcode;
>> + iocb->ki_obj.user = ui;
>> +}
>> +
>> +static inline int kernel_io_submit(struct vhost_blk *blk, struct iovec *iov, u64 nvecs, loff_t pos, int opcode, int head, int len)
>> +{
>> + int ret = -EAGAIN;
>> + struct kiocb *req;
>> + struct kioctx *ioctx = blk->ioctx;
>> + struct used_info *ui = kzalloc(sizeof *ui, GFP_KERNEL);
>> + struct file *f = blk->vq.private_data;
>> +
>> + try_get_ioctx(ioctx);
>> + atomic_long_inc_not_zero(&f->f_count);
>> + eventfd_ctx_get(blk->ectx);
>> +
>> +
>> + req = aio_get_req(ioctx); /* return 2 refs of req*/
>> + if (unlikely(!req))
>> + goto out;
>> +
>> + ui->head = head;
>> + ui->status = blk->vq.iov[nvecs + 1].iov_base;
>> + ui->len = len;
>> + aio_prep_req(req, blk->ectx, f, iov, nvecs, pos, opcode, ui);
>> +
>> + ret = aio_setup_iocb(req, 0);
>> + if (unlikely(ret))
>> + goto out_put_req;
>> +
>> + spin_lock_irq(&ioctx->ctx_lock);
>> + if (unlikely(ioctx->dead)) {
>> + spin_unlock_irq(&ioctx->ctx_lock);
>> + ret = -EINVAL;
>> + goto out_put_req;
>> + }
>> +
>> + aio_run_iocb(req);
>> + if (!list_empty(&ioctx->run_list)) {
>> + while (__aio_run_iocbs(ioctx))
>> + ;
>> + }
>> + spin_unlock_irq(&ioctx->ctx_lock);
>> +
>> + aio_put_req(req);
>> + put_ioctx(blk->ioctx);
>> +
>> + return ret;
>> +
>> +out_put_req:
>> + aio_put_req(req);
>> + aio_put_req(req);
>> +out:
>> + put_ioctx(blk->ioctx);
>> + return ret;
>> +}
>> +
>> +static int blk_completion_worker(void *priv)
>> +{
>> + struct vhost_blk *blk = priv;
>> + u64 count;
>> + int ret;
>> +
>> + use_mm(blk->dev.mm);
>> + for (;;) {
> It would be nicer to reuse the worker infrastructure
> from vhost.c. In particular this one ignores cgroups that
> the owner belongs to if any.
> Does this one do anything that vhost.c doesn't?
>
>> + struct timespec ts = { 0 };
>> + int i, nr;
>> +
>> + do {
>> + ret = eventfd_ctx_read(blk->ectx, 0,&count);
>> + } while (unlikely(ret == -ERESTARTSYS));
>> +
>> + if (unlikely(blk->should_stop))
>> + break;
>> +
>> + do {
>> + nr = kernel_read_events(blk->ioctx, count, MAX_EVENTS, events,&ts);
>> + } while (unlikely(nr == -EINTR));
>> + dprintk("%s, count %llu, nr %d\n", __func__, count, nr);
>> +
>> + if (unlikely(nr< 0))
>> + continue;
>> +
>> + for (i = 0; i< nr; i++) {
>> + struct used_info *u = (struct used_info *)events[i].obj;
>> + int len, status;
>> +
>> + dprintk("%s, head %d complete in %d\n", __func__, u->head, i);
>> + len = io_event_ret(&events[i]);
>> + //status = u->len == len ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR;
>> + status = len> 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR;
>> + if (copy_to_user(u->status,&status, sizeof status)) {
>> + vq_err(&blk->vq, "%s failed to write status\n", __func__);
>> + BUG(); /* FIXME: maybe a bit radical? */
> On an invalid userspace address?
> You may very well say so.
>
>> + }
>> + vhost_add_used(&blk->vq, u->head, u->len);
>> + kfree(u);
>> + }
>> +
>> + vhost_signal(&blk->dev,&blk->vq);
>> + }
>> + unuse_mm(blk->dev.mm);
>> + return 0;
>> +}
>> +
>> +static int completion_thread_setup(struct vhost_blk *blk)
>> +{
>> + int ret = 0;
>> + struct task_struct *worker;
>> + worker = kthread_create(blk_completion_worker, blk, "vhost-blk-%d", current->pid);
>> + if (IS_ERR(worker)) {
>> + ret = PTR_ERR(worker);
>> + goto err;
>> + }
>> + blk->worker = worker;
>> + blk->should_stop = 0;
>> + smp_mb();
>> + wake_up_process(worker);
>> +err:
>> + return ret;
>> +}
>> +
>> +static void completion_thread_destory(struct vhost_blk *blk)
>> +{
>> + if (blk->worker) {
>> + blk->should_stop = 1;
>> + smp_mb();
>> + eventfd_signal(blk->ectx, 1);
>> + }
>> +}
>> +
>> +
>> +static long blk_set_owner(struct vhost_blk *blk)
>> +{
>> + return completion_thread_setup(blk);
>> +}
>> +
>> +static long vhost_blk_ioctl(struct file *f, unsigned int ioctl,
>> + unsigned long arg)
>> +{
>> + struct vhost_blk *blk = f->private_data;
>> + struct vhost_vring_file backend;
>> + u64 features = VHOST_BLK_FEATURES;
>> + int ret = -EFAULT;
>> +
>> + switch (ioctl) {
>> + case VHOST_NET_SET_BACKEND:
>> + if(copy_from_user(&backend, (void __user *)arg, sizeof backend))
>> + break;
>> + ret = blk_set_backend(blk,&backend);
>> + break;
> Please create your own ioctl for this one.
>
>> + case VHOST_GET_FEATURES:
>> + features = VHOST_BLK_FEATURES;
>> + if (copy_to_user((void __user *)arg ,&features, sizeof features))
>> + break;
>> + ret = 0;
>> + break;
>> + case VHOST_SET_FEATURES:
>> + if (copy_from_user(&features, (void __user *)arg, sizeof features))
>> + break;
>> + if (features& ~VHOST_BLK_FEATURES) {
>> + ret = -EOPNOTSUPP;
>> + break;
>> + }
>> + ret = blk_set_features(blk, features);
>> + break;
>> + case VHOST_RESET_OWNER:
>> + ret = blk_reset_owner(blk);
>> + break;
>> + default:
>> + mutex_lock(&blk->dev.mutex);
>> + ret = vhost_dev_ioctl(&blk->dev, ioctl, arg);
>> + if (!ret&& ioctl == VHOST_SET_OWNER)
>> + ret = blk_set_owner(blk);
>> + blk_flush(blk);
>> + mutex_unlock(&blk->dev.mutex);
>> + break;
>> + }
>> + return ret;
>> +}
>> +
>> +#define BLK_HDR 0
>> +#define BLK_HDR_LEN 16
>> +
>> +static inline int do_request(struct vhost_virtqueue *vq, struct virtio_blk_outhdr *hdr,
>> + u64 nr_vecs, int head)
>> +{
>> + struct file *f = vq->private_data;
>> + struct vhost_blk *blk = container_of(vq->dev, struct vhost_blk, dev);
>> + struct iovec *iov =&vq->iov[BLK_HDR + 1];
>> + loff_t pos = hdr->sector<< 9;
>> + int ret = 0, len = 0, status;
>> +// int i;
>> +
>> + dprintk("sector %llu, num %lu, type %d\n", hdr->sector, iov->iov_len / 512, hdr->type);
>> + //Guest virtio-blk driver dosen't use len currently.
>> + //for (i = 0; i< nr_vecs; i++) {
>> + // len += iov[i].iov_len;
>> + //}
>> + switch (hdr->type) {
>> + case VIRTIO_BLK_T_OUT:
>> + kernel_io_submit(blk, iov, nr_vecs, pos, IOCB_CMD_PWRITEV, head, len);
>> + break;
>> + case VIRTIO_BLK_T_IN:
>> + kernel_io_submit(blk, iov, nr_vecs, pos, IOCB_CMD_PREADV, head, len);
>> + break;
>> + case VIRTIO_BLK_T_FLUSH:
>> + ret = vfs_fsync(f, 1);
>> + /* fall through */
>> + case VIRTIO_BLK_T_GET_ID:
>> + status = ret< 0 ? VIRTIO_BLK_S_IOERR :VIRTIO_BLK_S_OK;
>> + if ((vq->iov[nr_vecs + 1].iov_len != 1))
>> + BUG();
> Why is this one a bug?
>
>
>> +
>> + if (copy_to_user(vq->iov[nr_vecs + 1].iov_base,&status, sizeof status)) {
>> + vq_err(vq, "%s failed to write status!\n", __func__);
>> + vhost_discard_vq_desc(vq, 1);
>> + ret = -EFAULT;
>> + break;
>> + }
>> +
>> + vhost_add_used_and_signal(&blk->dev, vq, head, ret);
>> + break;
>> + default:
>> + pr_info("%s, unsupported request type %d\n", __func__, hdr->type);
>> + vhost_discard_vq_desc(vq, 1);
>> + ret = -EFAULT;
>> + break;
>> + }
>> + return ret;
>> +}
>> +
>> +static inline void handle_kick(struct vhost_blk *blk)
>> +{
>> + struct vhost_virtqueue *vq =&blk->vq;
>> + struct virtio_blk_outhdr hdr;
>> + u64 nr_vecs;
>> + int in, out, head;
>> + struct blk_plug plug;
>> +
>> + mutex_lock(&vq->mutex);
>> + vhost_disable_notify(&blk->dev, vq);
>> +
>> + blk_start_plug(&plug);
>> + for (;;) {
>> + head = vhost_get_vq_desc(&blk->dev, vq, vq->iov,
>> + ARRAY_SIZE(vq->iov),
>> + &out,&in, NULL, NULL);
>> + /* No awailable descriptors from Guest? */
>> + if (head == vq->num) {
>> + if (unlikely(vhost_enable_notify(&blk->dev, vq))) {
>> + vhost_disable_notify(&blk->dev, vq);
>> + continue;
>> + }
>> + break;
>> + }
>> + if (unlikely(head< 0))
>> + break;
>> +
>> + dprintk("head %d, in %d, out %d\n", head, in, out);
>> + if(unlikely(vq->iov[BLK_HDR].iov_len != BLK_HDR_LEN)) {
>> + vq_err(vq, "%s bad block header lengh!\n", __func__);
>> + vhost_discard_vq_desc(vq, 1);
>> + break;
>> + }
>> +
>> + if (copy_from_user(&hdr, vq->iov[BLK_HDR].iov_base, sizeof hdr)) {
>> + vq_err(vq, "%s failed to get block header!\n", __func__);
>> + vhost_discard_vq_desc(vq, 1);
>> + break;
>> + }
>> +
>> + if (hdr.type == VIRTIO_BLK_T_IN || hdr.type == VIRTIO_BLK_T_GET_ID)
>> + nr_vecs = in - 1;
>> + else
>> + nr_vecs = out - 1;
>> +
>> + if (do_request(vq,&hdr, nr_vecs, head)< 0)
>> + break;
>> + }
>> + blk_finish_plug(&plug);
>> + mutex_unlock(&vq->mutex);
>> +}
>> +
>> +static void handle_guest_kick(struct vhost_work *work)
>> +{
>> + struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue, poll.work);
>> + struct vhost_blk *blk = container_of(vq->dev, struct vhost_blk, dev);
>> + handle_kick(blk);
>> +}
>> +
>> +static void eventfd_setup(struct vhost_blk *blk)
>> +{
>> + blk->efile = eventfd_file_create(0, 0);
>> + blk->ectx = eventfd_ctx_fileget(blk->efile);
>> +}
>> +
>> +static int vhost_blk_open(struct inode *inode, struct file *f)
>> +{
>> + int ret = -ENOMEM;
>> + struct vhost_blk *blk = kmalloc(sizeof *blk, GFP_KERNEL);
>> + if (!blk)
>> + goto err;
>> +
>> + blk->vq.handle_kick = handle_guest_kick;
>> + ret = vhost_dev_init(&blk->dev,&blk->vq, virtqueue_max);
>> + if (ret< 0)
>> + goto err_init;
>> +
>> + ret = kernel_io_setup(MAX_EVENTS,&blk->ioctx);
>> + if (ret< 0)
>> + goto err_io_setup;
>> +
>> + eventfd_setup(blk);
>> + f->private_data = blk;
>> + return ret;
>> +err_init:
>> +err_io_setup:
>> + kfree(blk);
>> +err:
>> + return ret;
>> +}
>> +
>> +static void eventfd_destroy(struct vhost_blk *blk)
>> +{
>> + eventfd_ctx_put(blk->ectx);
>> + fput(blk->efile);
>> +}
>> +
>> +static int vhost_blk_release(struct inode *inode, struct file *f)
>> +{
>> + struct vhost_blk *blk = f->private_data;
>> +
>> + blk_stop(blk);
>> + blk_flush(blk);
>> + vhost_dev_cleanup(&blk->dev);
>> + /* Yet another flush? See comments in vhost_net_release() */
>> + blk_flush(blk);
>> + completion_thread_destory(blk);
>> + eventfd_destroy(blk);
>> + kfree(blk);
>> +
>> + return 0;
>> +}
>> +
>> +const static struct file_operations vhost_blk_fops = {
>> + .owner = THIS_MODULE,
>> + .release = vhost_blk_release,
>> + .open = vhost_blk_open,
>> + .unlocked_ioctl = vhost_blk_ioctl,
>> + .llseek = noop_llseek,
>> +};
>> +
>> +
>> +static struct miscdevice vhost_blk_misc = {
>> + 234,
> Don't get a major unless you really must.
>
>> + "vhost-blk",
>> + &vhost_blk_fops,
> And use C99 initializers.
>
>> +};
>> +
>> +int vhost_blk_init(void)
>> +{
>> + return misc_register(&vhost_blk_misc);
>> +}
>> +void vhost_blk_exit(void)
>> +{
>> + misc_deregister(&vhost_blk_misc);
>> +}
>> +
>> +module_init(vhost_blk_init);
>> +module_exit(vhost_blk_exit);
>> +
>> +MODULE_VERSION("0.0.1");
>> +MODULE_LICENSE("GPL v2");
>> +MODULE_AUTHOR("Liu Yuan");
>> +MODULE_DESCRIPTION("Host kernel accelerator for virtio_blk");
>> diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
>> index 8e03379..9e17152 100644
>> --- a/drivers/vhost/vhost.h
>> +++ b/drivers/vhost/vhost.h
>> @@ -12,6 +12,7 @@
>> #include<linux/virtio_config.h>
>> #include<linux/virtio_ring.h>
>> #include<asm/atomic.h>
>> +#include<linux/virtio_blk.h>
>>
>> struct vhost_device;
>>
>> @@ -174,6 +175,16 @@ enum {
>> (1ULL<< VHOST_F_LOG_ALL) |
>> (1ULL<< VHOST_NET_F_VIRTIO_NET_HDR) |
>> (1ULL<< VIRTIO_NET_F_MRG_RXBUF),
>> +
>> + VHOST_BLK_FEATURES = (1ULL<< VIRTIO_F_NOTIFY_ON_EMPTY) |
>> + (1ULL<< VIRTIO_RING_F_INDIRECT_DESC) |
>> + (1ULL<< VIRTIO_RING_F_EVENT_IDX) |
>> + (1ULL<< VIRTIO_BLK_F_SEG_MAX) |
>> + (1ULL<< VIRTIO_BLK_F_GEOMETRY) |
>> + (1ULL<< VIRTIO_BLK_F_TOPOLOGY) |
>> + (1ULL<< VIRTIO_BLK_F_SCSI) |
>> + (1ULL<< VIRTIO_BLK_F_BLK_SIZE),
>> +
>> };
>>
>> static inline int vhost_has_feature(struct vhost_dev *dev, int bit)
>> diff --git a/fs/aio.c b/fs/aio.c
>> index e29ec48..534d396 100644
>> --- a/fs/aio.c
>> +++ b/fs/aio.c
>> @@ -215,7 +215,7 @@ static void ctx_rcu_free(struct rcu_head *head)
>> * Called when the last user of an aio context has gone away,
>> * and the struct needs to be freed.
>> */
>> -static void __put_ioctx(struct kioctx *ctx)
>> +void __put_ioctx(struct kioctx *ctx)
>> {
>> BUG_ON(ctx->reqs_active);
>>
>> @@ -227,29 +227,12 @@ static void __put_ioctx(struct kioctx *ctx)
>> pr_debug("__put_ioctx: freeing %p\n", ctx);
>> call_rcu(&ctx->rcu_head, ctx_rcu_free);
>> }
>> -
>> -static inline void get_ioctx(struct kioctx *kioctx)
>> -{
>> - BUG_ON(atomic_read(&kioctx->users)<= 0);
>> - atomic_inc(&kioctx->users);
>> -}
>> -
>> -static inline int try_get_ioctx(struct kioctx *kioctx)
>> -{
>> - return atomic_inc_not_zero(&kioctx->users);
>> -}
>> -
>> -static inline void put_ioctx(struct kioctx *kioctx)
>> -{
>> - BUG_ON(atomic_read(&kioctx->users)<= 0);
>> - if (unlikely(atomic_dec_and_test(&kioctx->users)))
>> - __put_ioctx(kioctx);
>> -}
>> +EXPORT_SYMBOL(__put_ioctx);
>>
>> /* ioctx_alloc
>> * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
>> */
>> -static struct kioctx *ioctx_alloc(unsigned nr_events)
>> +struct kioctx *ioctx_alloc(unsigned nr_events)
>> {
>> struct mm_struct *mm;
>> struct kioctx *ctx;
>> @@ -327,6 +310,7 @@ out_freectx:
>> dprintk("aio: error allocating ioctx %p\n", ctx);
>> return ctx;
>> }
>> +EXPORT_SYMBOL(ioctx_alloc);
>>
>> /* aio_cancel_all
>> * Cancels all outstanding aio requests on an aio context. Used
>> @@ -437,7 +421,7 @@ void exit_aio(struct mm_struct *mm)
>> * This prevents races between the aio code path referencing the
>> * req (after submitting it) and aio_complete() freeing the req.
>> */
>> -static struct kiocb *__aio_get_req(struct kioctx *ctx)
>> +struct kiocb *__aio_get_req(struct kioctx *ctx)
>> {
>> struct kiocb *req = NULL;
>> struct aio_ring *ring;
>> @@ -480,7 +464,7 @@ static struct kiocb *__aio_get_req(struct kioctx *ctx)
>> return req;
>> }
>>
>> -static inline struct kiocb *aio_get_req(struct kioctx *ctx)
>> +struct kiocb *aio_get_req(struct kioctx *ctx)
>> {
>> struct kiocb *req;
>> /* Handle a potential starvation case -- should be exceedingly rare as
>> @@ -494,6 +478,7 @@ static inline struct kiocb *aio_get_req(struct kioctx *ctx)
>> }
>> return req;
>> }
>> +EXPORT_SYMBOL(aio_get_req);
>>
>> static inline void really_put_req(struct kioctx *ctx, struct kiocb *req)
>> {
>> @@ -659,7 +644,7 @@ static inline int __queue_kicked_iocb(struct kiocb *iocb)
>> * simplifies the coding of individual aio operations as
>> * it avoids various potential races.
>> */
>> -static ssize_t aio_run_iocb(struct kiocb *iocb)
>> +ssize_t aio_run_iocb(struct kiocb *iocb)
>> {
>> struct kioctx *ctx = iocb->ki_ctx;
>> ssize_t (*retry)(struct kiocb *);
>> @@ -753,6 +738,7 @@ out:
>> }
>> return ret;
>> }
>> +EXPORT_SYMBOL(aio_run_iocb);
>>
>> /*
>> * __aio_run_iocbs:
>> @@ -761,7 +747,7 @@ out:
>> * Assumes it is operating within the aio issuer's mm
>> * context.
>> */
>> -static int __aio_run_iocbs(struct kioctx *ctx)
>> +int __aio_run_iocbs(struct kioctx *ctx)
>> {
>> struct kiocb *iocb;
>> struct list_head run_list;
>> @@ -784,6 +770,7 @@ static int __aio_run_iocbs(struct kioctx *ctx)
>> return 1;
>> return 0;
>> }
>> +EXPORT_SYMBOL(__aio_run_iocbs);
>>
>> static void aio_queue_work(struct kioctx * ctx)
>> {
>> @@ -1074,7 +1061,7 @@ static inline void clear_timeout(struct aio_timeout *to)
>> del_singleshot_timer_sync(&to->timer);
>> }
>>
>> -static int read_events(struct kioctx *ctx,
>> +int read_events(struct kioctx *ctx,
>> long min_nr, long nr,
>> struct io_event __user *event,
>> struct timespec __user *timeout)
>> @@ -1190,11 +1177,12 @@ out:
>> destroy_timer_on_stack(&to.timer);
>> return i ? i : ret;
>> }
>> +EXPORT_SYMBOL(read_events);
>>
>> /* Take an ioctx and remove it from the list of ioctx's. Protects
>> * against races with itself via ->dead.
>> */
>> -static void io_destroy(struct kioctx *ioctx)
>> +void io_destroy(struct kioctx *ioctx)
>> {
>> struct mm_struct *mm = current->mm;
>> int was_dead;
>> @@ -1221,6 +1209,7 @@ static void io_destroy(struct kioctx *ioctx)
>> wake_up_all(&ioctx->wait);
>> put_ioctx(ioctx); /* once for the lookup */
>> }
>> +EXPORT_SYMBOL(io_destroy);
>>
>> /* sys_io_setup:
>> * Create an aio_context capable of receiving at least nr_events.
>> @@ -1423,7 +1412,7 @@ static ssize_t aio_setup_single_vector(struct kiocb *kiocb)
>> * Performs the initial checks and aio retry method
>> * setup for the kiocb at the time of io submission.
>> */
>> -static ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat)
>> +ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat)
>> {
>> struct file *file = kiocb->ki_filp;
>> ssize_t ret = 0;
>> @@ -1513,6 +1502,7 @@ static ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat)
>>
>> return 0;
>> }
>> +EXPORT_SYMBOL(aio_setup_iocb);
>>
>> static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
>> struct iocb *iocb, bool compat)
>> diff --git a/fs/eventfd.c b/fs/eventfd.c
>> index d9a5917..6343bc9 100644
>> --- a/fs/eventfd.c
>> +++ b/fs/eventfd.c
>> @@ -406,6 +406,7 @@ struct file *eventfd_file_create(unsigned int count, int flags)
>>
>> return file;
>> }
>> +EXPORT_SYMBOL_GPL(eventfd_file_create);
> You can avoid the need for this export if you pass
> the eventfd in from userspace.
>
>>
>> SYSCALL_DEFINE2(eventfd2, unsigned int, count, int, flags)
>> {
>> diff --git a/include/linux/aio.h b/include/linux/aio.h
>> index 7a8db41..d63bc04 100644
>> --- a/include/linux/aio.h
>> +++ b/include/linux/aio.h
>> @@ -214,6 +214,37 @@ struct mm_struct;
>> extern void exit_aio(struct mm_struct *mm);
>> extern long do_io_submit(aio_context_t ctx_id, long nr,
>> struct iocb __user *__user *iocbpp, bool compat);
>> +extern void __put_ioctx(struct kioctx *ctx);
>> +extern struct kioctx *ioctx_alloc(unsigned nr_events);
>> +extern struct kiocb *aio_get_req(struct kioctx *ctx);
>> +extern ssize_t aio_run_iocb(struct kiocb *iocb);
>> +extern int __aio_run_iocbs(struct kioctx *ctx);
>> +extern int read_events(struct kioctx *ctx,
>> + long min_nr, long nr,
>> + struct io_event __user *event,
>> + struct timespec __user *timeout);
>> +extern void io_destroy(struct kioctx *ioctx);
>> +extern ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat);
>> +extern void __put_ioctx(struct kioctx *ctx);
>> +
>> +static inline void get_ioctx(struct kioctx *kioctx)
>> +{
>> + BUG_ON(atomic_read(&kioctx->users)<= 0);
>> + atomic_inc(&kioctx->users);
>> +}
>> +
>> +static inline int try_get_ioctx(struct kioctx *kioctx)
>> +{
>> + return atomic_inc_not_zero(&kioctx->users);
>> +}
>> +
>> +static inline void put_ioctx(struct kioctx *kioctx)
>> +{
>> + BUG_ON(atomic_read(&kioctx->users)<= 0);
>> + if (unlikely(atomic_dec_and_test(&kioctx->users)))
>> + __put_ioctx(kioctx);
>> +}
>> +
>> #else
>> static inline ssize_t wait_on_sync_kiocb(struct kiocb *iocb) { return 0; }
>> static inline int aio_put_req(struct kiocb *iocb) { return 0; }
>> --
>> 1.7.5.1
Thanks, I'll split the patch, prepare v2 to address your comments.
Yuan
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