--- /dev/null
+/******************************************************************************
+ * blkback/vbd.c
+ *
+ * Routines for managing virtual block devices (VBDs).
+ *
+ * NOTE: vbd_lock protects updates to the rb_tree against concurrent lookups
+ * in vbd_translate. All other lookups are implicitly protected because the
+ * only caller (the control message dispatch routine) serializes the calls.
+ *
+ * Copyright (c) 2003-2005, Keir Fraser & Steve Hand
+ */
+
+#include "common.h"
+
+struct vbd {
+ blkif_vdev_t vdevice; /* what the domain refers to this vbd as */
+ unsigned char readonly; /* Non-zero -> read-only */
+ unsigned char type; /* VDISK_TYPE_xxx */
+ blkif_pdev_t pdevice; /* phys device that this vbd maps to */
+ struct block_device *bdev;
+ rb_node_t rb; /* for linking into R-B tree lookup struct */
+};
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+static inline dev_t vbd_map_devnum(blkif_pdev_t cookie)
+{ return MKDEV(cookie>>8, cookie&0xff); }
+#define vbd_sz(_v) ((_v)->bdev->bd_part ? \
+ (_v)->bdev->bd_part->nr_sects : (_v)->bdev->bd_disk->capacity)
+#define bdev_put(_b) blkdev_put(_b)
+#else
+#define vbd_sz(_v) (blk_size[MAJOR((_v)->pdevice)][MINOR((_v)->pdevice)]*2)
+#define bdev_put(_b) ((void)0)
+#endif
+
+void vbd_create(blkif_be_vbd_create_t *create)
+{
+ struct vbd *vbd;
+ rb_node_t **rb_p, *rb_parent = NULL;
+ blkif_t *blkif;
+ blkif_vdev_t vdevice = create->vdevice;
+
+ blkif = blkif_find_by_handle(create->domid, create->blkif_handle);
+ if ( unlikely(blkif == NULL) )
+ {
+ DPRINTK("vbd_create attempted for non-existent blkif (%u,%u)\n",
+ create->domid, create->blkif_handle);
+ create->status = BLKIF_BE_STATUS_INTERFACE_NOT_FOUND;
+ return;
+ }
+
+ rb_p = &blkif->vbd_rb.rb_node;
+ while ( *rb_p != NULL )
+ {
+ rb_parent = *rb_p;
+ vbd = rb_entry(rb_parent, struct vbd, rb);
+ if ( vdevice < vbd->vdevice )
+ {
+ rb_p = &rb_parent->rb_left;
+ }
+ else if ( vdevice > vbd->vdevice )
+ {
+ rb_p = &rb_parent->rb_right;
+ }
+ else
+ {
+ DPRINTK("vbd_create attempted for already existing vbd\n");
+ create->status = BLKIF_BE_STATUS_VBD_EXISTS;
+ return;
+ }
+ }
+
+ if ( unlikely((vbd = kmalloc(sizeof(struct vbd), GFP_KERNEL)) == NULL) )
+ {
+ DPRINTK("vbd_create: out of memory\n");
+ create->status = BLKIF_BE_STATUS_OUT_OF_MEMORY;
+ return;
+ }
+
+ vbd->vdevice = vdevice;
+ vbd->readonly = create->readonly;
+ vbd->type = VDISK_TYPE_DISK | VDISK_FLAG_VIRT;
+
+ /* Mask to 16-bit for compatibility with old tools */
+ vbd->pdevice = create->pdevice & 0xffff;
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+ vbd->bdev = open_by_devnum(
+ vbd_map_devnum(vbd->pdevice),
+ vbd->readonly ? FMODE_READ : FMODE_WRITE);
+ if ( IS_ERR(vbd->bdev) )
+ {
+ DPRINTK("vbd_creat: device %08x doesn't exist.\n", vbd->pdevice);
+ create->status = BLKIF_BE_STATUS_PHYSDEV_NOT_FOUND;
+ return;
+ }
+
+ if ( (vbd->bdev->bd_disk == NULL) )
+ {
+ DPRINTK("vbd_creat: device %08x doesn't exist.\n", vbd->pdevice);
+ create->status = BLKIF_BE_STATUS_PHYSDEV_NOT_FOUND;
+ bdev_put(vbd->bdev);
+ return;
+ }
+#else
+ if ( (blk_size[MAJOR(vbd->pdevice)] == NULL) || (vbd_sz(vbd) == 0) )
+ {
+ DPRINTK("vbd_creat: device %08x doesn't exist.\n", vbd->pdevice);
+ create->status = BLKIF_BE_STATUS_PHYSDEV_NOT_FOUND;
+ return;
+ }
+#endif
+
+ spin_lock(&blkif->vbd_lock);
+ rb_link_node(&vbd->rb, rb_parent, rb_p);
+ rb_insert_color(&vbd->rb, &blkif->vbd_rb);
+ spin_unlock(&blkif->vbd_lock);
+
+ DPRINTK("Successful creation of vdev=%04x (dom=%u)\n",
+ vdevice, create->domid);
+ create->status = BLKIF_BE_STATUS_OKAY;
+}
+
+
+void vbd_destroy(blkif_be_vbd_destroy_t *destroy)
+{
+ blkif_t *blkif;
+ struct vbd *vbd;
+ rb_node_t *rb;
+ blkif_vdev_t vdevice = destroy->vdevice;
+
+ blkif = blkif_find_by_handle(destroy->domid, destroy->blkif_handle);
+ if ( unlikely(blkif == NULL) )
+ {
+ DPRINTK("vbd_destroy attempted for non-existent blkif (%u,%u)\n",
+ destroy->domid, destroy->blkif_handle);
+ destroy->status = BLKIF_BE_STATUS_INTERFACE_NOT_FOUND;
+ return;
+ }
+
+ rb = blkif->vbd_rb.rb_node;
+ while ( rb != NULL )
+ {
+ vbd = rb_entry(rb, struct vbd, rb);
+ if ( vdevice < vbd->vdevice )
+ rb = rb->rb_left;
+ else if ( vdevice > vbd->vdevice )
+ rb = rb->rb_right;
+ else
+ goto found;
+ }
+
+ destroy->status = BLKIF_BE_STATUS_VBD_NOT_FOUND;
+ return;
+
+ found:
+ spin_lock(&blkif->vbd_lock);
+ rb_erase(rb, &blkif->vbd_rb);
+ spin_unlock(&blkif->vbd_lock);
+ bdev_put(vbd->bdev);
+ kfree(vbd);
+}
+
+
+void destroy_all_vbds(blkif_t *blkif)
+{
+ struct vbd *vbd;
+ rb_node_t *rb;
+
+ spin_lock(&blkif->vbd_lock);
+
+ while ( (rb = blkif->vbd_rb.rb_node) != NULL )
+ {
+ vbd = rb_entry(rb, struct vbd, rb);
+ rb_erase(rb, &blkif->vbd_rb);
+ spin_unlock(&blkif->vbd_lock);
+ bdev_put(vbd->bdev);
+ kfree(vbd);
+ spin_lock(&blkif->vbd_lock);
+ }
+
+ spin_unlock(&blkif->vbd_lock);
+}
+
+
+static void vbd_probe_single(
+ blkif_t *blkif, vdisk_t *vbd_info, struct vbd *vbd)
+{
+ vbd_info->device = vbd->vdevice;
+ vbd_info->info = vbd->type | (vbd->readonly ? VDISK_FLAG_RO : 0);
+ vbd_info->capacity = vbd_sz(vbd);
+}
+
+
+int vbd_probe(blkif_t *blkif, vdisk_t *vbd_info, int max_vbds)
+{
+ int rc = 0, nr_vbds = 0;
+ rb_node_t *rb;
+
+ spin_lock(&blkif->vbd_lock);
+
+ if ( (rb = blkif->vbd_rb.rb_node) == NULL )
+ goto out;
+
+ new_subtree:
+ /* STEP 1. Find least node (it'll be left-most). */
+ while ( rb->rb_left != NULL )
+ rb = rb->rb_left;
+
+ for ( ; ; )
+ {
+ /* STEP 2. Dealt with left subtree. Now process current node. */
+ vbd_probe_single(blkif, &vbd_info[nr_vbds],
+ rb_entry(rb, struct vbd, rb));
+ if ( ++nr_vbds == max_vbds )
+ goto out;
+
+ /* STEP 3. Process right subtree, if any. */
+ if ( rb->rb_right != NULL )
+ {
+ rb = rb->rb_right;
+ goto new_subtree;
+ }
+
+ /* STEP 4. Done both subtrees. Head back through ancesstors. */
+ for ( ; ; )
+ {
+ /* We're done when we get back to the root node. */
+ if ( rb->rb_parent == NULL )
+ goto out;
+ /* If we are left of parent, then parent is next to process. */
+ if ( rb->rb_parent->rb_left == rb )
+ break;
+ /* If we are right of parent, then we climb to grandparent. */
+ rb = rb->rb_parent;
+ }
+
+ rb = rb->rb_parent;
+ }
+
+ out:
+ spin_unlock(&blkif->vbd_lock);
+ return (rc == 0) ? nr_vbds : rc;
+}
+
+
+int vbd_translate(struct phys_req *req, blkif_t *blkif, int operation)
+{
+ struct vbd *vbd;
+ rb_node_t *rb;
+ int rc = -EACCES;
+
+ /* Take the vbd_lock because another thread could be updating the tree. */
+ spin_lock(&blkif->vbd_lock);
+
+ rb = blkif->vbd_rb.rb_node;
+ while ( rb != NULL )
+ {
+ vbd = rb_entry(rb, struct vbd, rb);
+ if ( req->dev < vbd->vdevice )
+ rb = rb->rb_left;
+ else if ( req->dev > vbd->vdevice )
+ rb = rb->rb_right;
+ else
+ goto found;
+ }
+
+ DPRINTK("vbd_translate; domain %u attempted to access "
+ "non-existent VBD.\n", blkif->domid);
+ rc = -ENODEV;
+ goto out;
+
+ found:
+
+ if ( (operation == WRITE) && vbd->readonly )
+ goto out;
+
+ if ( unlikely((req->sector_number + req->nr_sects) > vbd_sz(vbd)) )
+ goto out;
+
+ req->dev = vbd->pdevice;
+ req->bdev = vbd->bdev;
+ rc = 0;
+
+ out:
+ spin_unlock(&blkif->vbd_lock);
+ return rc;
+}
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