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xen/blkback: Propagate changed size of VBDs

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Support dynamic resizing of virtual block devices. This patch supports
both file backed block devices as well as physical devices that can be
dynamically resized on the host side.

Signed-off-by: K. Y. Srinivasan <ksrinivasan@novell.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
This commit is contained in:
K. Y. Srinivasan 2010-03-11 13:39:50 -08:00 committed by Konrad Rzeszutek Wilk
parent 5cf6e4f6f6
commit 2ccbfe26c1
3 changed files with 48 additions and 0 deletions
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3
drivers/xen/blkback/blkback.c
View File

@ -207,6 +207,7 @@ static void print_stats(blkif_t *blkif)
int blkif_schedule(void *arg)
{
blkif_t *blkif = arg;
struct vbd *vbd = &blkif->vbd;
blkif_get(blkif);
@ -216,6 +217,8 @@ int blkif_schedule(void *arg)
while (!kthread_should_stop()) {
if (try_to_freeze())
continue;
if (unlikely(vbd->size != vbd_size(vbd)))
vbd_resize(blkif);
wait_event_interruptible(
blkif->wq,

2
drivers/xen/blkback/common.h
View File

@ -52,6 +52,7 @@ struct vbd {
unsigned char type; /* VDISK_xxx */
u32 pdevice; /* phys device that this vbd maps to */
struct block_device *bdev;
sector_t size; /* Cached size parameter */
};
struct backend_info;
@ -98,6 +99,7 @@ blkif_t *blkif_alloc(domid_t domid);
void blkif_disconnect(blkif_t *blkif);
void blkif_free(blkif_t *blkif);
int blkif_map(blkif_t *blkif, unsigned long shared_page, unsigned int evtchn);
void vbd_resize(blkif_t *blkif);
#define blkif_get(_b) (atomic_inc(&(_b)->refcnt))
#define blkif_put(_b) \

43
drivers/xen/blkback/vbd.c
View File

@ -73,6 +73,7 @@ int vbd_create(blkif_t *blkif, blkif_vdev_t handle, unsigned major,
}
vbd->bdev = bdev;
vbd->size = vbd_size(vbd);
if (vbd->bdev->bd_disk == NULL) {
DPRINTK("vbd_creat: device %08x doesn't exist.\n",
@ -116,3 +117,45 @@ int vbd_translate(struct phys_req *req, blkif_t *blkif, int operation)
out:
return rc;
}
void vbd_resize(blkif_t *blkif)
{
struct vbd *vbd = &blkif->vbd;
struct xenbus_transaction xbt;
int err;
struct xenbus_device *dev = blkif->be->dev;
unsigned long long new_size = vbd_size(vbd);
printk(KERN_INFO "VBD Resize: new size %Lu\n", new_size);
vbd->size = new_size;
again:
err = xenbus_transaction_start(&xbt);
if (err) {
printk(KERN_WARNING "Error starting transaction");
return;
}
err = xenbus_printf(xbt, dev->nodename, "sectors", "%Lu",
vbd_size(vbd));
if (err) {
printk(KERN_WARNING "Error writing new size");
goto abort;
}
/*
* Write the current state; we will use this to synchronize
* the front-end. If the current state is "connected" the
* front-end will get the new size information online.
*/
err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state);
if (err) {
printk(KERN_WARNING "Error writing the state");
goto abort;
}
err = xenbus_transaction_end(xbt, 0);
if (err == -EAGAIN)
goto again;
if (err)
printk(KERN_WARNING "Error ending transaction");
abort:
xenbus_transaction_end(xbt, 1);
}