Messages in this thread | | | Date | Tue, 18 Jul 2006 08:01:56 -0500 | Subject | [RFC PATCH 33/33] Add Xen virtual block device driver. | From | (Dave Boutcher) |
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On Tue, 18 Jul 2006 00:00:33 -0700, Chris Wright <chrisw@sous-sol.org> said: > > The block device frontend driver allows the kernel to access block > devices exported exported by a virtual machine containing a physical > block device driver.
First, I think this belongs in drivers/block (and the network driver belongs in drivers/net). If we're going to bring xen to the party, lets not leave it hiding out in a corner.
> +static void connect(struct blkfront_info *); > +static void blkfront_closing(struct xenbus_device *); > +static int blkfront_remove(struct xenbus_device *); > +static int talk_to_backend(struct xenbus_device *, struct blkfront_info *); > +static int setup_blkring(struct xenbus_device *, struct blkfront_info *); > + > +static void kick_pending_request_queues(struct blkfront_info *); > + > +static irqreturn_t blkif_int(int irq, void *dev_id, struct pt_regs *ptregs); > +static void blkif_restart_queue(void *arg); > +static void blkif_recover(struct blkfront_info *); > +static void blkif_completion(struct blk_shadow *); > +static void blkif_free(struct blkfront_info *, int);
I'm pretty sure you can rearrange the code to get rid of the forward references.
> +/** > + * We are reconnecting to the backend, due to a suspend/resume, or a backend > + * driver restart. We tear down our blkif structure and recreate it, but > + * leave the device-layer structures intact so that this is transparent to the > + * rest of the kernel. > + */ > +static int blkfront_resume(struct xenbus_device *dev) > +{ > + struct blkfront_info *info = dev->dev.driver_data; > + int err; > + > + DPRINTK("blkfront_resume: %s\n", dev->nodename); > + > + blkif_free(info, 1); > + > + err = talk_to_backend(dev, info); > + if (!err) > + blkif_recover(info); > + > + return err; > +} Should blkfront_resume grab blkif_io_lock?
> + switch (backend_state) { > + case XenbusStateUnknown: > + case XenbusStateInitialising: > + case XenbusStateInitWait: > + case XenbusStateInitialised: > + case XenbusStateClosed:
This actually should get fixed elsewhere, but SillyCaps???
> +static inline int GET_ID_FROM_FREELIST( > + struct blkfront_info *info) > +{ > + unsigned long free = info->shadow_free; > + BUG_ON(free > BLK_RING_SIZE); > + info->shadow_free = info->shadow[free].req.id; > + info->shadow[free].req.id = 0x0fffffee; /* debug */ > + return free; > +} > + > +static inline void ADD_ID_TO_FREELIST( > + struct blkfront_info *info, unsigned long id) > +{ > + info->shadow[id].req.id = info->shadow_free; > + info->shadow[id].request = 0; > + info->shadow_free = id; > +}
A real nit..but why are these routines SHOUTING?
> +int blkif_release(struct inode *inode, struct file *filep) > +{ > + struct blkfront_info *info = inode->i_bdev->bd_disk->private_data; > + info->users--; > + if (info->users == 0) {
Hrm...this strikes me as racey. Don't you need at least a memory barrier here to handle SMP?
> +static struct xlbd_major_info xvd_major_info = { > + .major = 201, > + .type = &xvd_type_info > +};
I've forgotten what the current policy is around new major numbers.
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