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Diffstat (limited to 'drivers/block/xen-blkback')
-rw-r--r--drivers/block/xen-blkback/blkback.c391
-rw-r--r--drivers/block/xen-blkback/common.h86
-rw-r--r--drivers/block/xen-blkback/xenbus.c416
3 files changed, 529 insertions, 364 deletions
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index 41fb1a917..4809c1501 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -84,6 +84,16 @@ MODULE_PARM_DESC(max_persistent_grants,
"Maximum number of grants to map persistently");
/*
+ * Maximum number of rings/queues blkback supports, allow as many queues as there
+ * are CPUs if user has not specified a value.
+ */
+unsigned int xenblk_max_queues;
+module_param_named(max_queues, xenblk_max_queues, uint, 0644);
+MODULE_PARM_DESC(max_queues,
+ "Maximum number of hardware queues per virtual disk." \
+ "By default it is the number of online CPUs.");
+
+/*
* Maximum order of pages to be used for the shared ring between front and
* backend, 4KB page granularity is used.
*/
@@ -113,71 +123,71 @@ module_param(log_stats, int, 0644);
/* Number of free pages to remove on each call to gnttab_free_pages */
#define NUM_BATCH_FREE_PAGES 10
-static inline int get_free_page(struct xen_blkif *blkif, struct page **page)
+static inline int get_free_page(struct xen_blkif_ring *ring, struct page **page)
{
unsigned long flags;
- spin_lock_irqsave(&blkif->free_pages_lock, flags);
- if (list_empty(&blkif->free_pages)) {
- BUG_ON(blkif->free_pages_num != 0);
- spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
+ spin_lock_irqsave(&ring->free_pages_lock, flags);
+ if (list_empty(&ring->free_pages)) {
+ BUG_ON(ring->free_pages_num != 0);
+ spin_unlock_irqrestore(&ring->free_pages_lock, flags);
return gnttab_alloc_pages(1, page);
}
- BUG_ON(blkif->free_pages_num == 0);
- page[0] = list_first_entry(&blkif->free_pages, struct page, lru);
+ BUG_ON(ring->free_pages_num == 0);
+ page[0] = list_first_entry(&ring->free_pages, struct page, lru);
list_del(&page[0]->lru);
- blkif->free_pages_num--;
- spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
+ ring->free_pages_num--;
+ spin_unlock_irqrestore(&ring->free_pages_lock, flags);
return 0;
}
-static inline void put_free_pages(struct xen_blkif *blkif, struct page **page,
+static inline void put_free_pages(struct xen_blkif_ring *ring, struct page **page,
int num)
{
unsigned long flags;
int i;
- spin_lock_irqsave(&blkif->free_pages_lock, flags);
+ spin_lock_irqsave(&ring->free_pages_lock, flags);
for (i = 0; i < num; i++)
- list_add(&page[i]->lru, &blkif->free_pages);
- blkif->free_pages_num += num;
- spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
+ list_add(&page[i]->lru, &ring->free_pages);
+ ring->free_pages_num += num;
+ spin_unlock_irqrestore(&ring->free_pages_lock, flags);
}
-static inline void shrink_free_pagepool(struct xen_blkif *blkif, int num)
+static inline void shrink_free_pagepool(struct xen_blkif_ring *ring, int num)
{
/* Remove requested pages in batches of NUM_BATCH_FREE_PAGES */
struct page *page[NUM_BATCH_FREE_PAGES];
unsigned int num_pages = 0;
unsigned long flags;
- spin_lock_irqsave(&blkif->free_pages_lock, flags);
- while (blkif->free_pages_num > num) {
- BUG_ON(list_empty(&blkif->free_pages));
- page[num_pages] = list_first_entry(&blkif->free_pages,
+ spin_lock_irqsave(&ring->free_pages_lock, flags);
+ while (ring->free_pages_num > num) {
+ BUG_ON(list_empty(&ring->free_pages));
+ page[num_pages] = list_first_entry(&ring->free_pages,
struct page, lru);
list_del(&page[num_pages]->lru);
- blkif->free_pages_num--;
+ ring->free_pages_num--;
if (++num_pages == NUM_BATCH_FREE_PAGES) {
- spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
+ spin_unlock_irqrestore(&ring->free_pages_lock, flags);
gnttab_free_pages(num_pages, page);
- spin_lock_irqsave(&blkif->free_pages_lock, flags);
+ spin_lock_irqsave(&ring->free_pages_lock, flags);
num_pages = 0;
}
}
- spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
+ spin_unlock_irqrestore(&ring->free_pages_lock, flags);
if (num_pages != 0)
gnttab_free_pages(num_pages, page);
}
#define vaddr(page) ((unsigned long)pfn_to_kaddr(page_to_pfn(page)))
-static int do_block_io_op(struct xen_blkif *blkif);
-static int dispatch_rw_block_io(struct xen_blkif *blkif,
+static int do_block_io_op(struct xen_blkif_ring *ring);
+static int dispatch_rw_block_io(struct xen_blkif_ring *ring,
struct blkif_request *req,
struct pending_req *pending_req);
-static void make_response(struct xen_blkif *blkif, u64 id,
+static void make_response(struct xen_blkif_ring *ring, u64 id,
unsigned short op, int st);
#define foreach_grant_safe(pos, n, rbtree, node) \
@@ -190,7 +200,7 @@ static void make_response(struct xen_blkif *blkif, u64 id,
/*
* We don't need locking around the persistent grant helpers
- * because blkback uses a single-thread for each backed, so we
+ * because blkback uses a single-thread for each backend, so we
* can be sure that this functions will never be called recursively.
*
* The only exception to that is put_persistent_grant, that can be called
@@ -198,19 +208,20 @@ static void make_response(struct xen_blkif *blkif, u64 id,
* bit operations to modify the flags of a persistent grant and to count
* the number of used grants.
*/
-static int add_persistent_gnt(struct xen_blkif *blkif,
+static int add_persistent_gnt(struct xen_blkif_ring *ring,
struct persistent_gnt *persistent_gnt)
{
struct rb_node **new = NULL, *parent = NULL;
struct persistent_gnt *this;
+ struct xen_blkif *blkif = ring->blkif;
- if (blkif->persistent_gnt_c >= xen_blkif_max_pgrants) {
+ if (ring->persistent_gnt_c >= xen_blkif_max_pgrants) {
if (!blkif->vbd.overflow_max_grants)
blkif->vbd.overflow_max_grants = 1;
return -EBUSY;
}
/* Figure out where to put new node */
- new = &blkif->persistent_gnts.rb_node;
+ new = &ring->persistent_gnts.rb_node;
while (*new) {
this = container_of(*new, struct persistent_gnt, node);
@@ -229,19 +240,19 @@ static int add_persistent_gnt(struct xen_blkif *blkif,
set_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags);
/* Add new node and rebalance tree. */
rb_link_node(&(persistent_gnt->node), parent, new);
- rb_insert_color(&(persistent_gnt->node), &blkif->persistent_gnts);
- blkif->persistent_gnt_c++;
- atomic_inc(&blkif->persistent_gnt_in_use);
+ rb_insert_color(&(persistent_gnt->node), &ring->persistent_gnts);
+ ring->persistent_gnt_c++;
+ atomic_inc(&ring->persistent_gnt_in_use);
return 0;
}
-static struct persistent_gnt *get_persistent_gnt(struct xen_blkif *blkif,
+static struct persistent_gnt *get_persistent_gnt(struct xen_blkif_ring *ring,
grant_ref_t gref)
{
struct persistent_gnt *data;
struct rb_node *node = NULL;
- node = blkif->persistent_gnts.rb_node;
+ node = ring->persistent_gnts.rb_node;
while (node) {
data = container_of(node, struct persistent_gnt, node);
@@ -255,24 +266,24 @@ static struct persistent_gnt *get_persistent_gnt(struct xen_blkif *blkif,
return NULL;
}
set_bit(PERSISTENT_GNT_ACTIVE, data->flags);
- atomic_inc(&blkif->persistent_gnt_in_use);
+ atomic_inc(&ring->persistent_gnt_in_use);
return data;
}
}
return NULL;
}
-static void put_persistent_gnt(struct xen_blkif *blkif,
+static void put_persistent_gnt(struct xen_blkif_ring *ring,
struct persistent_gnt *persistent_gnt)
{
if(!test_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags))
pr_alert_ratelimited("freeing a grant already unused\n");
set_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags);
clear_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags);
- atomic_dec(&blkif->persistent_gnt_in_use);
+ atomic_dec(&ring->persistent_gnt_in_use);
}
-static void free_persistent_gnts(struct xen_blkif *blkif, struct rb_root *root,
+static void free_persistent_gnts(struct xen_blkif_ring *ring, struct rb_root *root,
unsigned int num)
{
struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
@@ -303,7 +314,7 @@ static void free_persistent_gnts(struct xen_blkif *blkif, struct rb_root *root,
unmap_data.count = segs_to_unmap;
BUG_ON(gnttab_unmap_refs_sync(&unmap_data));
- put_free_pages(blkif, pages, segs_to_unmap);
+ put_free_pages(ring, pages, segs_to_unmap);
segs_to_unmap = 0;
}
@@ -320,15 +331,15 @@ void xen_blkbk_unmap_purged_grants(struct work_struct *work)
struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
struct persistent_gnt *persistent_gnt;
int segs_to_unmap = 0;
- struct xen_blkif *blkif = container_of(work, typeof(*blkif), persistent_purge_work);
+ struct xen_blkif_ring *ring = container_of(work, typeof(*ring), persistent_purge_work);
struct gntab_unmap_queue_data unmap_data;
unmap_data.pages = pages;
unmap_data.unmap_ops = unmap;
unmap_data.kunmap_ops = NULL;
- while(!list_empty(&blkif->persistent_purge_list)) {
- persistent_gnt = list_first_entry(&blkif->persistent_purge_list,
+ while(!list_empty(&ring->persistent_purge_list)) {
+ persistent_gnt = list_first_entry(&ring->persistent_purge_list,
struct persistent_gnt,
remove_node);
list_del(&persistent_gnt->remove_node);
@@ -343,7 +354,7 @@ void xen_blkbk_unmap_purged_grants(struct work_struct *work)
if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST) {
unmap_data.count = segs_to_unmap;
BUG_ON(gnttab_unmap_refs_sync(&unmap_data));
- put_free_pages(blkif, pages, segs_to_unmap);
+ put_free_pages(ring, pages, segs_to_unmap);
segs_to_unmap = 0;
}
kfree(persistent_gnt);
@@ -351,11 +362,11 @@ void xen_blkbk_unmap_purged_grants(struct work_struct *work)
if (segs_to_unmap > 0) {
unmap_data.count = segs_to_unmap;
BUG_ON(gnttab_unmap_refs_sync(&unmap_data));
- put_free_pages(blkif, pages, segs_to_unmap);
+ put_free_pages(ring, pages, segs_to_unmap);
}
}
-static void purge_persistent_gnt(struct xen_blkif *blkif)
+static void purge_persistent_gnt(struct xen_blkif_ring *ring)
{
struct persistent_gnt *persistent_gnt;
struct rb_node *n;
@@ -363,23 +374,23 @@ static void purge_persistent_gnt(struct xen_blkif *blkif)
bool scan_used = false, clean_used = false;
struct rb_root *root;
- if (blkif->persistent_gnt_c < xen_blkif_max_pgrants ||
- (blkif->persistent_gnt_c == xen_blkif_max_pgrants &&
- !blkif->vbd.overflow_max_grants)) {
- return;
+ if (ring->persistent_gnt_c < xen_blkif_max_pgrants ||
+ (ring->persistent_gnt_c == xen_blkif_max_pgrants &&
+ !ring->blkif->vbd.overflow_max_grants)) {
+ goto out;
}
- if (work_busy(&blkif->persistent_purge_work)) {
+ if (work_busy(&ring->persistent_purge_work)) {
pr_alert_ratelimited("Scheduled work from previous purge is still busy, cannot purge list\n");
- return;
+ goto out;
}
num_clean = (xen_blkif_max_pgrants / 100) * LRU_PERCENT_CLEAN;
- num_clean = blkif->persistent_gnt_c - xen_blkif_max_pgrants + num_clean;
- num_clean = min(blkif->persistent_gnt_c, num_clean);
+ num_clean = ring->persistent_gnt_c - xen_blkif_max_pgrants + num_clean;
+ num_clean = min(ring->persistent_gnt_c, num_clean);
if ((num_clean == 0) ||
- (num_clean > (blkif->persistent_gnt_c - atomic_read(&blkif->persistent_gnt_in_use))))
- return;
+ (num_clean > (ring->persistent_gnt_c - atomic_read(&ring->persistent_gnt_in_use))))
+ goto out;
/*
* At this point, we can assure that there will be no calls
@@ -394,8 +405,8 @@ static void purge_persistent_gnt(struct xen_blkif *blkif)
pr_debug("Going to purge %u persistent grants\n", num_clean);
- BUG_ON(!list_empty(&blkif->persistent_purge_list));
- root = &blkif->persistent_gnts;
+ BUG_ON(!list_empty(&ring->persistent_purge_list));
+ root = &ring->persistent_gnts;
purge_list:
foreach_grant_safe(persistent_gnt, n, root, node) {
BUG_ON(persistent_gnt->handle ==
@@ -414,7 +425,7 @@ purge_list:
rb_erase(&persistent_gnt->node, root);
list_add(&persistent_gnt->remove_node,
- &blkif->persistent_purge_list);
+ &ring->persistent_purge_list);
if (--num_clean == 0)
goto finished;
}
@@ -435,30 +446,32 @@ finished:
goto purge_list;
}
- blkif->persistent_gnt_c -= (total - num_clean);
- blkif->vbd.overflow_max_grants = 0;
+ ring->persistent_gnt_c -= (total - num_clean);
+ ring->blkif->vbd.overflow_max_grants = 0;
/* We can defer this work */
- schedule_work(&blkif->persistent_purge_work);
+ schedule_work(&ring->persistent_purge_work);
pr_debug("Purged %u/%u\n", (total - num_clean), total);
+
+out:
return;
}
/*
* Retrieve from the 'pending_reqs' a free pending_req structure to be used.
*/
-static struct pending_req *alloc_req(struct xen_blkif *blkif)
+static struct pending_req *alloc_req(struct xen_blkif_ring *ring)
{
struct pending_req *req = NULL;
unsigned long flags;
- spin_lock_irqsave(&blkif->pending_free_lock, flags);
- if (!list_empty(&blkif->pending_free)) {
- req = list_entry(blkif->pending_free.next, struct pending_req,
+ spin_lock_irqsave(&ring->pending_free_lock, flags);
+ if (!list_empty(&ring->pending_free)) {
+ req = list_entry(ring->pending_free.next, struct pending_req,
free_list);
list_del(&req->free_list);
}
- spin_unlock_irqrestore(&blkif->pending_free_lock, flags);
+ spin_unlock_irqrestore(&ring->pending_free_lock, flags);
return req;
}
@@ -466,17 +479,17 @@ static struct pending_req *alloc_req(struct xen_blkif *blkif)
* Return the 'pending_req' structure back to the freepool. We also
* wake up the thread if it was waiting for a free page.
*/
-static void free_req(struct xen_blkif *blkif, struct pending_req *req)
+static void free_req(struct xen_blkif_ring *ring, struct pending_req *req)
{
unsigned long flags;
int was_empty;
- spin_lock_irqsave(&blkif->pending_free_lock, flags);
- was_empty = list_empty(&blkif->pending_free);
- list_add(&req->free_list, &blkif->pending_free);
- spin_unlock_irqrestore(&blkif->pending_free_lock, flags);
+ spin_lock_irqsave(&ring->pending_free_lock, flags);
+ was_empty = list_empty(&ring->pending_free);
+ list_add(&req->free_list, &ring->pending_free);
+ spin_unlock_irqrestore(&ring->pending_free_lock, flags);
if (was_empty)
- wake_up(&blkif->pending_free_wq);
+ wake_up(&ring->pending_free_wq);
}
/*
@@ -556,10 +569,10 @@ abort:
/*
* Notification from the guest OS.
*/
-static void blkif_notify_work(struct xen_blkif *blkif)
+static void blkif_notify_work(struct xen_blkif_ring *ring)
{
- blkif->waiting_reqs = 1;
- wake_up(&blkif->wq);
+ ring->waiting_reqs = 1;
+ wake_up(&ring->wq);
}
irqreturn_t xen_blkif_be_int(int irq, void *dev_id)
@@ -572,31 +585,33 @@ irqreturn_t xen_blkif_be_int(int irq, void *dev_id)
* SCHEDULER FUNCTIONS
*/
-static void print_stats(struct xen_blkif *blkif)
+static void print_stats(struct xen_blkif_ring *ring)
{
pr_info("(%s): oo %3llu | rd %4llu | wr %4llu | f %4llu"
" | ds %4llu | pg: %4u/%4d\n",
- current->comm, blkif->st_oo_req,
- blkif->st_rd_req, blkif->st_wr_req,
- blkif->st_f_req, blkif->st_ds_req,
- blkif->persistent_gnt_c,
+ current->comm, ring->st_oo_req,
+ ring->st_rd_req, ring->st_wr_req,
+ ring->st_f_req, ring->st_ds_req,
+ ring->persistent_gnt_c,
xen_blkif_max_pgrants);
- blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000);
- blkif->st_rd_req = 0;
- blkif->st_wr_req = 0;
- blkif->st_oo_req = 0;
- blkif->st_ds_req = 0;
+ ring->st_print = jiffies + msecs_to_jiffies(10 * 1000);
+ ring->st_rd_req = 0;
+ ring->st_wr_req = 0;
+ ring->st_oo_req = 0;
+ ring->st_ds_req = 0;
}
int xen_blkif_schedule(void *arg)
{
- struct xen_blkif *blkif = arg;
+ struct xen_blkif_ring *ring = arg;
+ struct xen_blkif *blkif = ring->blkif;
struct xen_vbd *vbd = &blkif->vbd;
unsigned long timeout;
int ret;
xen_blkif_get(blkif);
+ set_freezable();
while (!kthread_should_stop()) {
if (try_to_freeze())
continue;
@@ -606,50 +621,50 @@ int xen_blkif_schedule(void *arg)
timeout = msecs_to_jiffies(LRU_INTERVAL);
timeout = wait_event_interruptible_timeout(
- blkif->wq,
- blkif->waiting_reqs || kthread_should_stop(),
+ ring->wq,
+ ring->waiting_reqs || kthread_should_stop(),
timeout);
if (timeout == 0)
goto purge_gnt_list;
timeout = wait_event_interruptible_timeout(
- blkif->pending_free_wq,
- !list_empty(&blkif->pending_free) ||
+ ring->pending_free_wq,
+ !list_empty(&ring->pending_free) ||
kthread_should_stop(),
timeout);
if (timeout == 0)
goto purge_gnt_list;
- blkif->waiting_reqs = 0;
+ ring->waiting_reqs = 0;
smp_mb(); /* clear flag *before* checking for work */
- ret = do_block_io_op(blkif);
+ ret = do_block_io_op(ring);
if (ret > 0)
- blkif->waiting_reqs = 1;
+ ring->waiting_reqs = 1;
if (ret == -EACCES)
- wait_event_interruptible(blkif->shutdown_wq,
+ wait_event_interruptible(ring->shutdown_wq,
kthread_should_stop());
purge_gnt_list:
if (blkif->vbd.feature_gnt_persistent &&
- time_after(jiffies, blkif->next_lru)) {
- purge_persistent_gnt(blkif);
- blkif->next_lru = jiffies + msecs_to_jiffies(LRU_INTERVAL);
+ time_after(jiffies, ring->next_lru)) {
+ purge_persistent_gnt(ring);
+ ring->next_lru = jiffies + msecs_to_jiffies(LRU_INTERVAL);
}
/* Shrink if we have more than xen_blkif_max_buffer_pages */
- shrink_free_pagepool(blkif, xen_blkif_max_buffer_pages);
+ shrink_free_pagepool(ring, xen_blkif_max_buffer_pages);
- if (log_stats && time_after(jiffies, blkif->st_print))
- print_stats(blkif);
+ if (log_stats && time_after(jiffies, ring->st_print))
+ print_stats(ring);
}
/* Drain pending purge work */
- flush_work(&blkif->persistent_purge_work);
+ flush_work(&ring->persistent_purge_work);
if (log_stats)
- print_stats(blkif);
+ print_stats(ring);
- blkif->xenblkd = NULL;
+ ring->xenblkd = NULL;
xen_blkif_put(blkif);
return 0;
@@ -658,22 +673,22 @@ purge_gnt_list:
/*
* Remove persistent grants and empty the pool of free pages
*/
-void xen_blkbk_free_caches(struct xen_blkif *blkif)
+void xen_blkbk_free_caches(struct xen_blkif_ring *ring)
{
/* Free all persistent grant pages */
- if (!RB_EMPTY_ROOT(&blkif->persistent_gnts))
- free_persistent_gnts(blkif, &blkif->persistent_gnts,
- blkif->persistent_gnt_c);
+ if (!RB_EMPTY_ROOT(&ring->persistent_gnts))
+ free_persistent_gnts(ring, &ring->persistent_gnts,
+ ring->persistent_gnt_c);
- BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts));
- blkif->persistent_gnt_c = 0;
+ BUG_ON(!RB_EMPTY_ROOT(&ring->persistent_gnts));
+ ring->persistent_gnt_c = 0;
/* Since we are shutting down remove all pages from the buffer */
- shrink_free_pagepool(blkif, 0 /* All */);
+ shrink_free_pagepool(ring, 0 /* All */);
}
static unsigned int xen_blkbk_unmap_prepare(
- struct xen_blkif *blkif,
+ struct xen_blkif_ring *ring,
struct grant_page **pages,
unsigned int num,
struct gnttab_unmap_grant_ref *unmap_ops,
@@ -683,7 +698,7 @@ static unsigned int xen_blkbk_unmap_prepare(
for (i = 0; i < num; i++) {
if (pages[i]->persistent_gnt != NULL) {
- put_persistent_gnt(blkif, pages[i]->persistent_gnt);
+ put_persistent_gnt(ring, pages[i]->persistent_gnt);
continue;
}
if (pages[i]->handle == BLKBACK_INVALID_HANDLE)
@@ -700,17 +715,18 @@ static unsigned int xen_blkbk_unmap_prepare(
static void xen_blkbk_unmap_and_respond_callback(int result, struct gntab_unmap_queue_data *data)
{
- struct pending_req* pending_req = (struct pending_req*) (data->data);
- struct xen_blkif *blkif = pending_req->blkif;
+ struct pending_req *pending_req = (struct pending_req *)(data->data);
+ struct xen_blkif_ring *ring = pending_req->ring;
+ struct xen_blkif *blkif = ring->blkif;
/* BUG_ON used to reproduce existing behaviour,
but is this the best way to deal with this? */
BUG_ON(result);
- put_free_pages(blkif, data->pages, data->count);
- make_response(blkif, pending_req->id,
+ put_free_pages(ring, data->pages, data->count);
+ make_response(ring, pending_req->id,
pending_req->operation, pending_req->status);
- free_req(blkif, pending_req);
+ free_req(ring, pending_req);
/*
* Make sure the request is freed before releasing blkif,
* or there could be a race between free_req and the
@@ -723,7 +739,7 @@ static void xen_blkbk_unmap_and_respond_callback(int result, struct gntab_unmap_
* pending_free_wq if there's a drain going on, but it has
* to be taken into account if the current model is changed.
*/
- if (atomic_dec_and_test(&blkif->inflight) && atomic_read(&blkif->drain)) {
+ if (atomic_dec_and_test(&ring->inflight) && atomic_read(&blkif->drain)) {
complete(&blkif->drain_complete);
}
xen_blkif_put(blkif);
@@ -732,11 +748,11 @@ static void xen_blkbk_unmap_and_respond_callback(int result, struct gntab_unmap_
static void xen_blkbk_unmap_and_respond(struct pending_req *req)
{
struct gntab_unmap_queue_data* work = &req->gnttab_unmap_data;
- struct xen_blkif *blkif = req->blkif;
+ struct xen_blkif_ring *ring = req->ring;
struct grant_page **pages = req->segments;
unsigned int invcount;
- invcount = xen_blkbk_unmap_prepare(blkif, pages, req->nr_segs,
+ invcount = xen_blkbk_unmap_prepare(ring, pages, req->nr_segs,
req->unmap, req->unmap_pages);
work->data = req;
@@ -757,7 +773,7 @@ static void xen_blkbk_unmap_and_respond(struct pending_req *req)
* of hypercalls, but since this is only used in error paths there's
* no real need.
*/
-static void xen_blkbk_unmap(struct xen_blkif *blkif,
+static void xen_blkbk_unmap(struct xen_blkif_ring *ring,
struct grant_page *pages[],
int num)
{
@@ -768,20 +784,20 @@ static void xen_blkbk_unmap(struct xen_blkif *blkif,
while (num) {
unsigned int batch = min(num, BLKIF_MAX_SEGMENTS_PER_REQUEST);
-
- invcount = xen_blkbk_unmap_prepare(blkif, pages, batch,
+
+ invcount = xen_blkbk_unmap_prepare(ring, pages, batch,
unmap, unmap_pages);
if (invcount) {
ret = gnttab_unmap_refs(unmap, NULL, unmap_pages, invcount);
BUG_ON(ret);
- put_free_pages(blkif, unmap_pages, invcount);
+ put_free_pages(ring, unmap_pages, invcount);
}
pages += batch;
num -= batch;
}
}
-static int xen_blkbk_map(struct xen_blkif *blkif,
+static int xen_blkbk_map(struct xen_blkif_ring *ring,
struct grant_page *pages[],
int num, bool ro)
{
@@ -794,6 +810,7 @@ static int xen_blkbk_map(struct xen_blkif *blkif,
int ret = 0;
int last_map = 0, map_until = 0;
int use_persistent_gnts;
+ struct xen_blkif *blkif = ring->blkif;
use_persistent_gnts = (blkif->vbd.feature_gnt_persistent);
@@ -806,10 +823,11 @@ again:
for (i = map_until; i < num; i++) {
uint32_t flags;
- if (use_persistent_gnts)
+ if (use_persistent_gnts) {
persistent_gnt = get_persistent_gnt(
- blkif,
+ ring,
pages[i]->gref);
+ }
if (persistent_gnt) {
/*
@@ -819,7 +837,7 @@ again:
pages[i]->page = persistent_gnt->page;
pages[i]->persistent_gnt = persistent_gnt;
} else {
- if (get_free_page(blkif, &pages[i]->page))
+ if (get_free_page(ring, &pages[i]->page))
goto out_of_memory;
addr = vaddr(pages[i]->page);
pages_to_gnt[segs_to_map] = pages[i]->page;
@@ -852,7 +870,7 @@ again:
BUG_ON(new_map_idx >= segs_to_map);
if (unlikely(map[new_map_idx].status != 0)) {
pr_debug("invalid buffer -- could not remap it\n");
- put_free_pages(blkif, &pages[seg_idx]->page, 1);
+ put_free_pages(ring, &pages[seg_idx]->page, 1);
pages[seg_idx]->handle = BLKBACK_INVALID_HANDLE;
ret |= 1;
goto next;
@@ -862,7 +880,7 @@ again:
continue;
}
if (use_persistent_gnts &&
- blkif->persistent_gnt_c < xen_blkif_max_pgrants) {
+ ring->persistent_gnt_c < xen_blkif_max_pgrants) {
/*
* We are using persistent grants, the grant is
* not mapped but we might have room for it.
@@ -880,7 +898,7 @@ again:
persistent_gnt->gnt = map[new_map_idx].ref;
persistent_gnt->handle = map[new_map_idx].handle;
persistent_gnt->page = pages[seg_idx]->page;
- if (add_persistent_gnt(blkif,
+ if (add_persistent_gnt(ring,
persistent_gnt)) {
kfree(persistent_gnt);
persistent_gnt = NULL;
@@ -888,7 +906,7 @@ again:
}
pages[seg_idx]->persistent_gnt = persistent_gnt;
pr_debug("grant %u added to the tree of persistent grants, using %u/%u\n",
- persistent_gnt->gnt, blkif->persistent_gnt_c,
+ persistent_gnt->gnt, ring->persistent_gnt_c,
xen_blkif_max_pgrants);
goto next;
}
@@ -913,7 +931,7 @@ next:
out_of_memory:
pr_alert("%s: out of memory\n", __func__);
- put_free_pages(blkif, pages_to_gnt, segs_to_map);
+ put_free_pages(ring, pages_to_gnt, segs_to_map);
return -ENOMEM;
}
@@ -921,7 +939,7 @@ static int xen_blkbk_map_seg(struct pending_req *pending_req)
{
int rc;
- rc = xen_blkbk_map(pending_req->blkif, pending_req->segments,
+ rc = xen_blkbk_map(pending_req->ring, pending_req->segments,
pending_req->nr_segs,
(pending_req->operation != BLKIF_OP_READ));
@@ -934,7 +952,7 @@ static int xen_blkbk_parse_indirect(struct blkif_request *req,
struct phys_req *preq)
{
struct grant_page **pages = pending_req->indirect_pages;
- struct xen_blkif *blkif = pending_req->blkif;
+ struct xen_blkif_ring *ring = pending_req->ring;
int indirect_grefs, rc, n, nseg, i;
struct blkif_request_segment *segments = NULL;
@@ -945,7 +963,7 @@ static int xen_blkbk_parse_indirect(struct blkif_request *req,
for (i = 0; i < indirect_grefs; i++)
pages[i]->gref = req->u.indirect.indirect_grefs[i];
- rc = xen_blkbk_map(blkif, pages, indirect_grefs, true);
+ rc = xen_blkbk_map(ring, pages, indirect_grefs, true);
if (rc)
goto unmap;
@@ -977,15 +995,16 @@ static int xen_blkbk_parse_indirect(struct blkif_request *req,
unmap:
if (segments)
kunmap_atomic(segments);
- xen_blkbk_unmap(blkif, pages, indirect_grefs);
+ xen_blkbk_unmap(ring, pages, indirect_grefs);
return rc;
}
-static int dispatch_discard_io(struct xen_blkif *blkif,
+static int dispatch_discard_io(struct xen_blkif_ring *ring,
struct blkif_request *req)
{
int err = 0;
int status = BLKIF_RSP_OKAY;
+ struct xen_blkif *blkif = ring->blkif;
struct block_device *bdev = blkif->vbd.bdev;
unsigned long secure;
struct phys_req preq;
@@ -1002,7 +1021,7 @@ static int dispatch_discard_io(struct xen_blkif *blkif,
preq.sector_number + preq.nr_sects, blkif->vbd.pdevice);
goto fail_response;
}
- blkif->st_ds_req++;
+ ring->st_ds_req++;
secure = (blkif->vbd.discard_secure &&
(req->u.discard.flag & BLKIF_DISCARD_SECURE)) ?
@@ -1018,26 +1037,28 @@ fail_response:
} else if (err)
status = BLKIF_RSP_ERROR;
- make_response(blkif, req->u.discard.id, req->operation, status);
+ make_response(ring, req->u.discard.id, req->operation, status);
xen_blkif_put(blkif);
return err;
}
-static int dispatch_other_io(struct xen_blkif *blkif,
+static int dispatch_other_io(struct xen_blkif_ring *ring,
struct blkif_request *req,
struct pending_req *pending_req)
{
- free_req(blkif, pending_req);
- make_response(blkif, req->u.other.id, req->operation,
+ free_req(ring, pending_req);
+ make_response(ring, req->u.other.id, req->operation,
BLKIF_RSP_EOPNOTSUPP);
return -EIO;
}
-static void xen_blk_drain_io(struct xen_blkif *blkif)
+static void xen_blk_drain_io(struct xen_blkif_ring *ring)
{
+ struct xen_blkif *blkif = ring->blkif;
+
atomic_set(&blkif->drain, 1);
do {
- if (atomic_read(&blkif->inflight) == 0)
+ if (atomic_read(&ring->inflight) == 0)
break;
wait_for_completion_interruptible_timeout(
&blkif->drain_complete, HZ);
@@ -1058,12 +1079,12 @@ static void __end_block_io_op(struct pending_req *pending_req, int error)
if ((pending_req->operation == BLKIF_OP_FLUSH_DISKCACHE) &&
(error == -EOPNOTSUPP)) {
pr_debug("flush diskcache op failed, not supported\n");
- xen_blkbk_flush_diskcache(XBT_NIL, pending_req->blkif->be, 0);
+ xen_blkbk_flush_diskcache(XBT_NIL, pending_req->ring->blkif->be, 0);
pending_req->status = BLKIF_RSP_EOPNOTSUPP;
} else if ((pending_req->operation == BLKIF_OP_WRITE_BARRIER) &&
(error == -EOPNOTSUPP)) {
pr_debug("write barrier op failed, not supported\n");
- xen_blkbk_barrier(XBT_NIL, pending_req->blkif->be, 0);
+ xen_blkbk_barrier(XBT_NIL, pending_req->ring->blkif->be, 0);
pending_req->status = BLKIF_RSP_EOPNOTSUPP;
} else if (error) {
pr_debug("Buffer not up-to-date at end of operation,"
@@ -1097,9 +1118,9 @@ static void end_block_io_op(struct bio *bio)
* and transmute it to the block API to hand it over to the proper block disk.
*/
static int
-__do_block_io_op(struct xen_blkif *blkif)
+__do_block_io_op(struct xen_blkif_ring *ring)
{
- union blkif_back_rings *blk_rings = &blkif->blk_rings;
+ union blkif_back_rings *blk_rings = &ring->blk_rings;
struct blkif_request req;
struct pending_req *pending_req;
RING_IDX rc, rp;
@@ -1112,7 +1133,7 @@ __do_block_io_op(struct xen_blkif *blkif)
if (RING_REQUEST_PROD_OVERFLOW(&blk_rings->common, rp)) {
rc = blk_rings->common.rsp_prod_pvt;
pr_warn("Frontend provided bogus ring requests (%d - %d = %d). Halting ring processing on dev=%04x\n",
- rp, rc, rp - rc, blkif->vbd.pdevice);
+ rp, rc, rp - rc, ring->blkif->vbd.pdevice);
return -EACCES;
}
while (rc != rp) {
@@ -1125,14 +1146,14 @@ __do_block_io_op(struct xen_blkif *blkif)
break;
}
- pending_req = alloc_req(blkif);
+ pending_req = alloc_req(ring);
if (NULL == pending_req) {
- blkif->st_oo_req++;
+ ring->st_oo_req++;
more_to_do = 1;
break;
}
- switch (blkif->blk_protocol) {
+ switch (ring->blkif->blk_protocol) {
case BLKIF_PROTOCOL_NATIVE:
memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req));
break;
@@ -1156,16 +1177,16 @@ __do_block_io_op(struct xen_blkif *blkif)
case BLKIF_OP_WRITE_BARRIER:
case BLKIF_OP_FLUSH_DISKCACHE:
case BLKIF_OP_INDIRECT:
- if (dispatch_rw_block_io(blkif, &req, pending_req))
+ if (dispatch_rw_block_io(ring, &req, pending_req))
goto done;
break;
case BLKIF_OP_DISCARD:
- free_req(blkif, pending_req);
- if (dispatch_discard_io(blkif, &req))
+ free_req(ring, pending_req);
+ if (dispatch_discard_io(ring, &req))
goto done;
break;
default:
- if (dispatch_other_io(blkif, &req, pending_req))
+ if (dispatch_other_io(ring, &req, pending_req))
goto done;
break;
}
@@ -1178,13 +1199,13 @@ done:
}
static int
-do_block_io_op(struct xen_blkif *blkif)
+do_block_io_op(struct xen_blkif_ring *ring)
{
- union blkif_back_rings *blk_rings = &blkif->blk_rings;
+ union blkif_back_rings *blk_rings = &ring->blk_rings;
int more_to_do;
do {
- more_to_do = __do_block_io_op(blkif);
+ more_to_do = __do_block_io_op(ring);
if (more_to_do)
break;
@@ -1197,7 +1218,7 @@ do_block_io_op(struct xen_blkif *blkif)
* Transmutation of the 'struct blkif_request' to a proper 'struct bio'
* and call the 'submit_bio' to pass it to the underlying storage.
*/
-static int dispatch_rw_block_io(struct xen_blkif *blkif,
+static int dispatch_rw_block_io(struct xen_blkif_ring *ring,
struct blkif_request *req,
struct pending_req *pending_req)
{
@@ -1225,17 +1246,17 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
switch (req_operation) {
case BLKIF_OP_READ:
- blkif->st_rd_req++;
+ ring->st_rd_req++;
operation = READ;
break;
case BLKIF_OP_WRITE:
- blkif->st_wr_req++;
+ ring->st_wr_req++;
operation = WRITE_ODIRECT;
break;
case BLKIF_OP_WRITE_BARRIER:
drain = true;
case BLKIF_OP_FLUSH_DISKCACHE:
- blkif->st_f_req++;
+ ring->st_f_req++;
operation = WRITE_FLUSH;
break;
default:
@@ -1260,7 +1281,7 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
preq.nr_sects = 0;
- pending_req->blkif = blkif;
+ pending_req->ring = ring;
pending_req->id = req->u.rw.id;
pending_req->operation = req_operation;
pending_req->status = BLKIF_RSP_OKAY;
@@ -1287,12 +1308,12 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
goto fail_response;
}
- if (xen_vbd_translate(&preq, blkif, operation) != 0) {
+ if (xen_vbd_translate(&preq, ring->blkif, operation) != 0) {
pr_debug("access denied: %s of [%llu,%llu] on dev=%04x\n",
operation == READ ? "read" : "write",
preq.sector_number,
preq.sector_number + preq.nr_sects,
- blkif->vbd.pdevice);
+ ring->blkif->vbd.pdevice);
goto fail_response;
}
@@ -1304,7 +1325,7 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
if (((int)preq.sector_number|(int)seg[i].nsec) &
((bdev_logical_block_size(preq.bdev) >> 9) - 1)) {
pr_debug("Misaligned I/O request from domain %d\n",
- blkif->domid);
+ ring->blkif->domid);
goto fail_response;
}
}
@@ -1313,7 +1334,7 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
* issue the WRITE_FLUSH.
*/
if (drain)
- xen_blk_drain_io(pending_req->blkif);
+ xen_blk_drain_io(pending_req->ring);
/*
* If we have failed at this point, we need to undo the M2P override,
@@ -1328,8 +1349,8 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
* This corresponding xen_blkif_put is done in __end_block_io_op, or
* below (in "!bio") if we are handling a BLKIF_OP_DISCARD.
*/
- xen_blkif_get(blkif);
- atomic_inc(&blkif->inflight);
+ xen_blkif_get(ring->blkif);
+ atomic_inc(&ring->inflight);
for (i = 0; i < nseg; i++) {
while ((bio == NULL) ||
@@ -1377,19 +1398,19 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
blk_finish_plug(&plug);
if (operation == READ)
- blkif->st_rd_sect += preq.nr_sects;
+ ring->st_rd_sect += preq.nr_sects;
else if (operation & WRITE)
- blkif->st_wr_sect += preq.nr_sects;
+ ring->st_wr_sect += preq.nr_sects;
return 0;
fail_flush:
- xen_blkbk_unmap(blkif, pending_req->segments,
+ xen_blkbk_unmap(ring, pending_req->segments,
pending_req->nr_segs);
fail_response:
/* Haven't submitted any bio's yet. */
- make_response(blkif, req->u.rw.id, req_operation, BLKIF_RSP_ERROR);
- free_req(blkif, pending_req);
+ make_response(ring, req->u.rw.id, req_operation, BLKIF_RSP_ERROR);
+ free_req(ring, pending_req);
msleep(1); /* back off a bit */
return -EIO;
@@ -1407,21 +1428,22 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
/*
* Put a response on the ring on how the operation fared.
*/
-static void make_response(struct xen_blkif *blkif, u64 id,
+static void make_response(struct xen_blkif_ring *ring, u64 id,
unsigned short op, int st)
{
struct blkif_response resp;
unsigned long flags;
- union blkif_back_rings *blk_rings = &blkif->blk_rings;
+ union blkif_back_rings *blk_rings;
int notify;
resp.id = id;
resp.operation = op;
resp.status = st;
- spin_lock_irqsave(&blkif->blk_ring_lock, flags);
+ spin_lock_irqsave(&ring->blk_ring_lock, flags);
+ blk_rings = &ring->blk_rings;
/* Place on the response ring for the relevant domain. */
- switch (blkif->blk_protocol) {
+ switch (ring->blkif->blk_protocol) {
case BLKIF_PROTOCOL_NATIVE:
memcpy(RING_GET_RESPONSE(&blk_rings->native, blk_rings->native.rsp_prod_pvt),
&resp, sizeof(resp));
@@ -1439,9 +1461,9 @@ static void make_response(struct xen_blkif *blkif, u64 id,
}
blk_rings->common.rsp_prod_pvt++;
RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify);
- spin_unlock_irqrestore(&blkif->blk_ring_lock, flags);
+ spin_unlock_irqrestore(&ring->blk_ring_lock, flags);
if (notify)
- notify_remote_via_irq(blkif->irq);
+ notify_remote_via_irq(ring->irq);
}
static int __init xen_blkif_init(void)
@@ -1457,6 +1479,9 @@ static int __init xen_blkif_init(void)
xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
}
+ if (xenblk_max_queues == 0)
+ xenblk_max_queues = num_online_cpus();
+
rc = xen_blkif_interface_init();
if (rc)
goto failed_init;
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
index c929ae227..dea61f6ab 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -46,6 +46,7 @@
#include <xen/interface/io/protocols.h>
extern unsigned int xen_blkif_max_ring_order;
+extern unsigned int xenblk_max_queues;
/*
* This is the maximum number of segments that would be allowed in indirect
* requests. This value will also be passed to the frontend.
@@ -269,68 +270,79 @@ struct persistent_gnt {
struct list_head remove_node;
};
-struct xen_blkif {
- /* Unique identifier for this interface. */
- domid_t domid;
- unsigned int handle;
+/* Per-ring information. */
+struct xen_blkif_ring {
/* Physical parameters of the comms window. */
unsigned int irq;
- /* Comms information. */
- enum blkif_protocol blk_protocol;
union blkif_back_rings blk_rings;
void *blk_ring;
- /* The VBD attached to this interface. */
- struct xen_vbd vbd;
- /* Back pointer to the backend_info. */
- struct backend_info *be;
/* Private fields. */
spinlock_t blk_ring_lock;
- atomic_t refcnt;
wait_queue_head_t wq;
- /* for barrier (drain) requests */
- struct completion drain_complete;
- atomic_t drain;
atomic_t inflight;
- /* One thread per one blkif. */
+ /* One thread per blkif ring. */
struct task_struct *xenblkd;
unsigned int waiting_reqs;
- /* tree to store persistent grants */
+ /* List of all 'pending_req' available */
+ struct list_head pending_free;
+ /* And its spinlock. */
+ spinlock_t pending_free_lock;
+ wait_queue_head_t pending_free_wq;
+
+ /* Tree to store persistent grants. */
+ spinlock_t pers_gnts_lock;
struct rb_root persistent_gnts;
unsigned int persistent_gnt_c;
atomic_t persistent_gnt_in_use;
unsigned long next_lru;
- /* used by the kworker that offload work from the persistent purge */
+ /* Statistics. */
+ unsigned long st_print;
+ unsigned long long st_rd_req;
+ unsigned long long st_wr_req;
+ unsigned long long st_oo_req;
+ unsigned long long st_f_req;
+ unsigned long long st_ds_req;
+ unsigned long long st_rd_sect;
+ unsigned long long st_wr_sect;
+
+ /* Used by the kworker that offload work from the persistent purge. */
struct list_head persistent_purge_list;
struct work_struct persistent_purge_work;
- /* buffer of free pages to map grant refs */
+ /* Buffer of free pages to map grant refs. */
spinlock_t free_pages_lock;
int free_pages_num;
struct list_head free_pages;
- /* List of all 'pending_req' available */
- struct list_head pending_free;
- /* And its spinlock. */
- spinlock_t pending_free_lock;
- wait_queue_head_t pending_free_wq;
-
- /* statistics */
- unsigned long st_print;
- unsigned long long st_rd_req;
- unsigned long long st_wr_req;
- unsigned long long st_oo_req;
- unsigned long long st_f_req;
- unsigned long long st_ds_req;
- unsigned long long st_rd_sect;
- unsigned long long st_wr_sect;
-
struct work_struct free_work;
/* Thread shutdown wait queue. */
wait_queue_head_t shutdown_wq;
- unsigned int nr_ring_pages;
+ struct xen_blkif *blkif;
+};
+
+struct xen_blkif {
+ /* Unique identifier for this interface. */
+ domid_t domid;
+ unsigned int handle;
+ /* Comms information. */
+ enum blkif_protocol blk_protocol;
+ /* The VBD attached to this interface. */
+ struct xen_vbd vbd;
+ /* Back pointer to the backend_info. */
+ struct backend_info *be;
+ atomic_t refcnt;
+ /* for barrier (drain) requests */
+ struct completion drain_complete;
+ atomic_t drain;
+
+ struct work_struct free_work;
+ unsigned int nr_ring_pages;
+ /* All rings for this device. */
+ struct xen_blkif_ring *rings;
+ unsigned int nr_rings;
};
struct seg_buf {
@@ -352,7 +364,7 @@ struct grant_page {
* response queued for it, with the saved 'id' passed back.
*/
struct pending_req {
- struct xen_blkif *blkif;
+ struct xen_blkif_ring *ring;
u64 id;
int nr_segs;
atomic_t pendcnt;
@@ -394,7 +406,7 @@ int xen_blkif_xenbus_init(void);
irqreturn_t xen_blkif_be_int(int irq, void *dev_id);
int xen_blkif_schedule(void *arg);
int xen_blkif_purge_persistent(void *arg);
-void xen_blkbk_free_caches(struct xen_blkif *blkif);
+void xen_blkbk_free_caches(struct xen_blkif_ring *ring);
int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
struct backend_info *be, int state);
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index f53cff42f..876763f7f 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -86,9 +86,11 @@ static void xen_update_blkif_status(struct xen_blkif *blkif)
{
int err;
char name[BLKBACK_NAME_LEN];
+ struct xen_blkif_ring *ring;
+ int i;
/* Not ready to connect? */
- if (!blkif->irq || !blkif->vbd.bdev)
+ if (!blkif->rings || !blkif->rings[0].irq || !blkif->vbd.bdev)
return;
/* Already connected? */
@@ -113,13 +115,55 @@ static void xen_update_blkif_status(struct xen_blkif *blkif)
}
invalidate_inode_pages2(blkif->vbd.bdev->bd_inode->i_mapping);
- blkif->xenblkd = kthread_run(xen_blkif_schedule, blkif, "%s", name);
- if (IS_ERR(blkif->xenblkd)) {
- err = PTR_ERR(blkif->xenblkd);
- blkif->xenblkd = NULL;
- xenbus_dev_error(blkif->be->dev, err, "start xenblkd");
- return;
+ for (i = 0; i < blkif->nr_rings; i++) {
+ ring = &blkif->rings[i];
+ ring->xenblkd = kthread_run(xen_blkif_schedule, ring, "%s-%d", name, i);
+ if (IS_ERR(ring->xenblkd)) {
+ err = PTR_ERR(ring->xenblkd);
+ ring->xenblkd = NULL;
+ xenbus_dev_fatal(blkif->be->dev, err,
+ "start %s-%d xenblkd", name, i);
+ goto out;
+ }
+ }
+ return;
+
+out:
+ while (--i >= 0) {
+ ring = &blkif->rings[i];
+ kthread_stop(ring->xenblkd);
+ }
+ return;
+}
+
+static int xen_blkif_alloc_rings(struct xen_blkif *blkif)
+{
+ unsigned int r;
+
+ blkif->rings = kzalloc(blkif->nr_rings * sizeof(struct xen_blkif_ring), GFP_KERNEL);
+ if (!blkif->rings)
+ return -ENOMEM;
+
+ for (r = 0; r < blkif->nr_rings; r++) {
+ struct xen_blkif_ring *ring = &blkif->rings[r];
+
+ spin_lock_init(&ring->blk_ring_lock);
+ init_waitqueue_head(&ring->wq);
+ INIT_LIST_HEAD(&ring->pending_free);
+ INIT_LIST_HEAD(&ring->persistent_purge_list);
+ INIT_WORK(&ring->persistent_purge_work, xen_blkbk_unmap_purged_grants);
+ spin_lock_init(&ring->free_pages_lock);
+ INIT_LIST_HEAD(&ring->free_pages);
+
+ spin_lock_init(&ring->pending_free_lock);
+ init_waitqueue_head(&ring->pending_free_wq);
+ init_waitqueue_head(&ring->shutdown_wq);
+ ring->blkif = blkif;
+ ring->st_print = jiffies;
+ xen_blkif_get(blkif);
}
+
+ return 0;
}
static struct xen_blkif *xen_blkif_alloc(domid_t domid)
@@ -133,41 +177,25 @@ static struct xen_blkif *xen_blkif_alloc(domid_t domid)
return ERR_PTR(-ENOMEM);
blkif->domid = domid;
- spin_lock_init(&blkif->blk_ring_lock);
atomic_set(&blkif->refcnt, 1);
- init_waitqueue_head(&blkif->wq);
init_completion(&blkif->drain_complete);
- atomic_set(&blkif->drain, 0);
- blkif->st_print = jiffies;
- blkif->persistent_gnts.rb_node = NULL;
- spin_lock_init(&blkif->free_pages_lock);
- INIT_LIST_HEAD(&blkif->free_pages);
- INIT_LIST_HEAD(&blkif->persistent_purge_list);
- blkif->free_pages_num = 0;
- atomic_set(&blkif->persistent_gnt_in_use, 0);
- atomic_set(&blkif->inflight, 0);
- INIT_WORK(&blkif->persistent_purge_work, xen_blkbk_unmap_purged_grants);
-
- INIT_LIST_HEAD(&blkif->pending_free);
INIT_WORK(&blkif->free_work, xen_blkif_deferred_free);
- spin_lock_init(&blkif->pending_free_lock);
- init_waitqueue_head(&blkif->pending_free_wq);
- init_waitqueue_head(&blkif->shutdown_wq);
return blkif;
}
-static int xen_blkif_map(struct xen_blkif *blkif, grant_ref_t *gref,
+static int xen_blkif_map(struct xen_blkif_ring *ring, grant_ref_t *gref,
unsigned int nr_grefs, unsigned int evtchn)
{
int err;
+ struct xen_blkif *blkif = ring->blkif;
/* Already connected through? */
- if (blkif->irq)
+ if (ring->irq)
return 0;
err = xenbus_map_ring_valloc(blkif->be->dev, gref, nr_grefs,
- &blkif->blk_ring);
+ &ring->blk_ring);
if (err < 0)
return err;
@@ -175,24 +203,24 @@ static int xen_blkif_map(struct xen_blkif *blkif, grant_ref_t *gref,
case BLKIF_PROTOCOL_NATIVE:
{
struct blkif_sring *sring;
- sring = (struct blkif_sring *)blkif->blk_ring;
- BACK_RING_INIT(&blkif->blk_rings.native, sring,
+ sring = (struct blkif_sring *)ring->blk_ring;
+ BACK_RING_INIT(&ring->blk_rings.native, sring,
XEN_PAGE_SIZE * nr_grefs);
break;
}
case BLKIF_PROTOCOL_X86_32:
{
struct blkif_x86_32_sring *sring_x86_32;
- sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring;
- BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32,
+ sring_x86_32 = (struct blkif_x86_32_sring *)ring->blk_ring;
+ BACK_RING_INIT(&ring->blk_rings.x86_32, sring_x86_32,
XEN_PAGE_SIZE * nr_grefs);
break;
}
case BLKIF_PROTOCOL_X86_64:
{
struct blkif_x86_64_sring *sring_x86_64;
- sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring;
- BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64,
+ sring_x86_64 = (struct blkif_x86_64_sring *)ring->blk_ring;
+ BACK_RING_INIT(&ring->blk_rings.x86_64, sring_x86_64,
XEN_PAGE_SIZE * nr_grefs);
break;
}
@@ -202,13 +230,13 @@ static int xen_blkif_map(struct xen_blkif *blkif, grant_ref_t *gref,
err = bind_interdomain_evtchn_to_irqhandler(blkif->domid, evtchn,
xen_blkif_be_int, 0,
- "blkif-backend", blkif);
+ "blkif-backend", ring);
if (err < 0) {
- xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring);
- blkif->blk_rings.common.sring = NULL;
+ xenbus_unmap_ring_vfree(blkif->be->dev, ring->blk_ring);
+ ring->blk_rings.common.sring = NULL;
return err;
}
- blkif->irq = err;
+ ring->irq = err;
return 0;
}
@@ -216,50 +244,69 @@ static int xen_blkif_map(struct xen_blkif *blkif, grant_ref_t *gref,
static int xen_blkif_disconnect(struct xen_blkif *blkif)
{
struct pending_req *req, *n;
- int i = 0, j;
+ unsigned int j, r;
- if (blkif->xenblkd) {
- kthread_stop(blkif->xenblkd);
- wake_up(&blkif->shutdown_wq);
- blkif->xenblkd = NULL;
- }
+ for (r = 0; r < blkif->nr_rings; r++) {
+ struct xen_blkif_ring *ring = &blkif->rings[r];
+ unsigned int i = 0;
- /* The above kthread_stop() guarantees that at this point we
- * don't have any discard_io or other_io requests. So, checking
- * for inflight IO is enough.
- */
- if (atomic_read(&blkif->inflight) > 0)
- return -EBUSY;
+ if (ring->xenblkd) {
+ kthread_stop(ring->xenblkd);
+ wake_up(&ring->shutdown_wq);
+ ring->xenblkd = NULL;
+ }
- if (blkif->irq) {
- unbind_from_irqhandler(blkif->irq, blkif);
- blkif->irq = 0;
- }
+ /* The above kthread_stop() guarantees that at this point we
+ * don't have any discard_io or other_io requests. So, checking
+ * for inflight IO is enough.
+ */
+ if (atomic_read(&ring->inflight) > 0)
+ return -EBUSY;
- if (blkif->blk_rings.common.sring) {
- xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring);
- blkif->blk_rings.common.sring = NULL;
- }
+ if (ring->irq) {
+ unbind_from_irqhandler(ring->irq, ring);
+ ring->irq = 0;
+ }
- /* Remove all persistent grants and the cache of ballooned pages. */
- xen_blkbk_free_caches(blkif);
+ if (ring->blk_rings.common.sring) {
+ xenbus_unmap_ring_vfree(blkif->be->dev, ring->blk_ring);
+ ring->blk_rings.common.sring = NULL;
+ }
- /* Check that there is no request in use */
- list_for_each_entry_safe(req, n, &blkif->pending_free, free_list) {
- list_del(&req->free_list);
+ /* Remove all persistent grants and the cache of ballooned pages. */
+ xen_blkbk_free_caches(ring);
- for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++)
- kfree(req->segments[j]);
+ /* Check that there is no request in use */
+ list_for_each_entry_safe(req, n, &ring->pending_free, free_list) {
+ list_del(&req->free_list);
- for (j = 0; j < MAX_INDIRECT_PAGES; j++)
- kfree(req->indirect_pages[j]);
+ for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++)
+ kfree(req->segments[j]);
- kfree(req);
- i++;
- }
+ for (j = 0; j < MAX_INDIRECT_PAGES; j++)
+ kfree(req->indirect_pages[j]);
+
+ kfree(req);
+ i++;
+ }
- WARN_ON(i != (XEN_BLKIF_REQS_PER_PAGE * blkif->nr_ring_pages));
+ BUG_ON(atomic_read(&ring->persistent_gnt_in_use) != 0);
+ BUG_ON(!list_empty(&ring->persistent_purge_list));
+ BUG_ON(!RB_EMPTY_ROOT(&ring->persistent_gnts));
+ BUG_ON(!list_empty(&ring->free_pages));
+ BUG_ON(ring->free_pages_num != 0);
+ BUG_ON(ring->persistent_gnt_c != 0);
+ WARN_ON(i != (XEN_BLKIF_REQS_PER_PAGE * blkif->nr_ring_pages));
+ xen_blkif_put(blkif);
+ }
blkif->nr_ring_pages = 0;
+ /*
+ * blkif->rings was allocated in connect_ring, so we should free it in
+ * here.
+ */
+ kfree(blkif->rings);
+ blkif->rings = NULL;
+ blkif->nr_rings = 0;
return 0;
}
@@ -271,13 +318,6 @@ static void xen_blkif_free(struct xen_blkif *blkif)
xen_vbd_free(&blkif->vbd);
/* Make sure everything is drained before shutting down */
- BUG_ON(blkif->persistent_gnt_c != 0);
- BUG_ON(atomic_read(&blkif->persistent_gnt_in_use) != 0);
- BUG_ON(blkif->free_pages_num != 0);
- BUG_ON(!list_empty(&blkif->persistent_purge_list));
- BUG_ON(!list_empty(&blkif->free_pages));
- BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts));
-
kmem_cache_free(xen_blkif_cachep, blkif);
}
@@ -296,25 +336,38 @@ int __init xen_blkif_interface_init(void)
* sysfs interface for VBD I/O requests
*/
-#define VBD_SHOW(name, format, args...) \
+#define VBD_SHOW_ALLRING(name, format) \
static ssize_t show_##name(struct device *_dev, \
struct device_attribute *attr, \
char *buf) \
{ \
struct xenbus_device *dev = to_xenbus_device(_dev); \
struct backend_info *be = dev_get_drvdata(&dev->dev); \
+ struct xen_blkif *blkif = be->blkif; \
+ unsigned int i; \
+ unsigned long long result = 0; \
\
- return sprintf(buf, format, ##args); \
+ if (!blkif->rings) \
+ goto out; \
+ \
+ for (i = 0; i < blkif->nr_rings; i++) { \
+ struct xen_blkif_ring *ring = &blkif->rings[i]; \
+ \
+ result += ring->st_##name; \
+ } \
+ \
+out: \
+ return sprintf(buf, format, result); \
} \
static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
-VBD_SHOW(oo_req, "%llu\n", be->blkif->st_oo_req);
-VBD_SHOW(rd_req, "%llu\n", be->blkif->st_rd_req);
-VBD_SHOW(wr_req, "%llu\n", be->blkif->st_wr_req);
-VBD_SHOW(f_req, "%llu\n", be->blkif->st_f_req);
-VBD_SHOW(ds_req, "%llu\n", be->blkif->st_ds_req);
-VBD_SHOW(rd_sect, "%llu\n", be->blkif->st_rd_sect);
-VBD_SHOW(wr_sect, "%llu\n", be->blkif->st_wr_sect);
+VBD_SHOW_ALLRING(oo_req, "%llu\n");
+VBD_SHOW_ALLRING(rd_req, "%llu\n");
+VBD_SHOW_ALLRING(wr_req, "%llu\n");
+VBD_SHOW_ALLRING(f_req, "%llu\n");
+VBD_SHOW_ALLRING(ds_req, "%llu\n");
+VBD_SHOW_ALLRING(rd_sect, "%llu\n");
+VBD_SHOW_ALLRING(wr_sect, "%llu\n");
static struct attribute *xen_vbdstat_attrs[] = {
&dev_attr_oo_req.attr,
@@ -332,6 +385,18 @@ static struct attribute_group xen_vbdstat_group = {
.attrs = xen_vbdstat_attrs,
};
+#define VBD_SHOW(name, format, args...) \
+ static ssize_t show_##name(struct device *_dev, \
+ struct device_attribute *attr, \
+ char *buf) \
+ { \
+ struct xenbus_device *dev = to_xenbus_device(_dev); \
+ struct backend_info *be = dev_get_drvdata(&dev->dev); \
+ \
+ return sprintf(buf, format, ##args); \
+ } \
+ static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
+
VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor);
VBD_SHOW(mode, "%s\n", be->mode);
@@ -440,11 +505,11 @@ static int xen_blkbk_remove(struct xenbus_device *dev)
dev_set_drvdata(&dev->dev, NULL);
- if (be->blkif) {
+ if (be->blkif)
xen_blkif_disconnect(be->blkif);
- xen_blkif_put(be->blkif);
- }
+ /* Put the reference we set in xen_blkif_alloc(). */
+ xen_blkif_put(be->blkif);
kfree(be->mode);
kfree(be);
return 0;
@@ -553,6 +618,12 @@ static int xen_blkbk_probe(struct xenbus_device *dev,
goto fail;
}
+ /* Multi-queue: advertise how many queues are supported by us.*/
+ err = xenbus_printf(XBT_NIL, dev->nodename,
+ "multi-queue-max-queues", "%u", xenblk_max_queues);
+ if (err)
+ pr_warn("Error writing multi-queue-max-queues\n");
+
/* setup back pointer */
be->blkif->be = be;
@@ -708,8 +779,14 @@ static void frontend_changed(struct xenbus_device *dev,
}
err = connect_ring(be);
- if (err)
+ if (err) {
+ /*
+ * Clean up so that memory resources can be used by
+ * other devices. connect_ring reported already error.
+ */
+ xen_blkif_disconnect(be->blkif);
break;
+ }
xen_update_blkif_status(be->blkif);
break;
@@ -825,50 +902,43 @@ again:
xenbus_transaction_end(xbt, 1);
}
-
-static int connect_ring(struct backend_info *be)
+/*
+ * Each ring may have multi pages, depends on "ring-page-order".
+ */
+static int read_per_ring_refs(struct xen_blkif_ring *ring, const char *dir)
{
- struct xenbus_device *dev = be->dev;
unsigned int ring_ref[XENBUS_MAX_RING_GRANTS];
- unsigned int evtchn, nr_grefs, ring_page_order;
- unsigned int pers_grants;
- char protocol[64] = "";
struct pending_req *req, *n;
int err, i, j;
+ struct xen_blkif *blkif = ring->blkif;
+ struct xenbus_device *dev = blkif->be->dev;
+ unsigned int ring_page_order, nr_grefs, evtchn;
- pr_debug("%s %s\n", __func__, dev->otherend);
-
- err = xenbus_scanf(XBT_NIL, dev->otherend, "event-channel", "%u",
+ err = xenbus_scanf(XBT_NIL, dir, "event-channel", "%u",
&evtchn);
if (err != 1) {
err = -EINVAL;
- xenbus_dev_fatal(dev, err, "reading %s/event-channel",
- dev->otherend);
+ xenbus_dev_fatal(dev, err, "reading %s/event-channel", dir);
return err;
}
- pr_info("event-channel %u\n", evtchn);
err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-page-order", "%u",
&ring_page_order);
if (err != 1) {
- err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-ref",
- "%u", &ring_ref[0]);
+ err = xenbus_scanf(XBT_NIL, dir, "ring-ref", "%u", &ring_ref[0]);
if (err != 1) {
err = -EINVAL;
- xenbus_dev_fatal(dev, err, "reading %s/ring-ref",
- dev->otherend);
+ xenbus_dev_fatal(dev, err, "reading %s/ring-ref", dir);
return err;
}
nr_grefs = 1;
- pr_info("%s:using single page: ring-ref %d\n", dev->otherend,
- ring_ref[0]);
} else {
unsigned int i;
if (ring_page_order > xen_blkif_max_ring_order) {
err = -EINVAL;
xenbus_dev_fatal(dev, err, "%s/request %d ring page order exceed max:%d",
- dev->otherend, ring_page_order,
+ dir, ring_page_order,
xen_blkif_max_ring_order);
return err;
}
@@ -878,52 +948,23 @@ static int connect_ring(struct backend_info *be)
char ring_ref_name[RINGREF_NAME_LEN];
snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
- err = xenbus_scanf(XBT_NIL, dev->otherend, ring_ref_name,
+ err = xenbus_scanf(XBT_NIL, dir, ring_ref_name,
"%u", &ring_ref[i]);
if (err != 1) {
err = -EINVAL;
xenbus_dev_fatal(dev, err, "reading %s/%s",
- dev->otherend, ring_ref_name);
+ dir, ring_ref_name);
return err;
}
- pr_info("ring-ref%u: %u\n", i, ring_ref[i]);
}
}
-
- be->blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT;
- err = xenbus_gather(XBT_NIL, dev->otherend, "protocol",
- "%63s", protocol, NULL);
- if (err)
- strcpy(protocol, "unspecified, assuming default");
- else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
- be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
- else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
- be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
- else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64))
- be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
- else {
- xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
- return -1;
- }
- err = xenbus_gather(XBT_NIL, dev->otherend,
- "feature-persistent", "%u",
- &pers_grants, NULL);
- if (err)
- pers_grants = 0;
-
- be->blkif->vbd.feature_gnt_persistent = pers_grants;
- be->blkif->vbd.overflow_max_grants = 0;
- be->blkif->nr_ring_pages = nr_grefs;
-
- pr_info("ring-pages:%d, event-channel %d, protocol %d (%s) %s\n",
- nr_grefs, evtchn, be->blkif->blk_protocol, protocol,
- pers_grants ? "persistent grants" : "");
+ blkif->nr_ring_pages = nr_grefs;
for (i = 0; i < nr_grefs * XEN_BLKIF_REQS_PER_PAGE; i++) {
req = kzalloc(sizeof(*req), GFP_KERNEL);
if (!req)
goto fail;
- list_add_tail(&req->free_list, &be->blkif->pending_free);
+ list_add_tail(&req->free_list, &ring->pending_free);
for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) {
req->segments[j] = kzalloc(sizeof(*req->segments[0]), GFP_KERNEL);
if (!req->segments[j])
@@ -938,7 +979,7 @@ static int connect_ring(struct backend_info *be)
}
/* Map the shared frame, irq etc. */
- err = xen_blkif_map(be->blkif, ring_ref, nr_grefs, evtchn);
+ err = xen_blkif_map(ring, ring_ref, nr_grefs, evtchn);
if (err) {
xenbus_dev_fatal(dev, err, "mapping ring-ref port %u", evtchn);
return err;
@@ -947,7 +988,7 @@ static int connect_ring(struct backend_info *be)
return 0;
fail:
- list_for_each_entry_safe(req, n, &be->blkif->pending_free, free_list) {
+ list_for_each_entry_safe(req, n, &ring->pending_free, free_list) {
list_del(&req->free_list);
for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) {
if (!req->segments[j])
@@ -962,6 +1003,93 @@ fail:
kfree(req);
}
return -ENOMEM;
+
+}
+
+static int connect_ring(struct backend_info *be)
+{
+ struct xenbus_device *dev = be->dev;
+ unsigned int pers_grants;
+ char protocol[64] = "";
+ int err, i;
+ char *xspath;
+ size_t xspathsize;
+ const size_t xenstore_path_ext_size = 11; /* sufficient for "/queue-NNN" */
+ unsigned int requested_num_queues = 0;
+
+ pr_debug("%s %s\n", __func__, dev->otherend);
+
+ be->blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT;
+ err = xenbus_gather(XBT_NIL, dev->otherend, "protocol",
+ "%63s", protocol, NULL);
+ if (err)
+ strcpy(protocol, "unspecified, assuming default");
+ else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
+ be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
+ else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
+ be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
+ else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64))
+ be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
+ else {
+ xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
+ return -ENOSYS;
+ }
+ err = xenbus_gather(XBT_NIL, dev->otherend,
+ "feature-persistent", "%u",
+ &pers_grants, NULL);
+ if (err)
+ pers_grants = 0;
+
+ be->blkif->vbd.feature_gnt_persistent = pers_grants;
+ be->blkif->vbd.overflow_max_grants = 0;
+
+ /*
+ * Read the number of hardware queues from frontend.
+ */
+ err = xenbus_scanf(XBT_NIL, dev->otherend, "multi-queue-num-queues",
+ "%u", &requested_num_queues);
+ if (err < 0) {
+ requested_num_queues = 1;
+ } else {
+ if (requested_num_queues > xenblk_max_queues
+ || requested_num_queues == 0) {
+ /* Buggy or malicious guest. */
+ xenbus_dev_fatal(dev, err,
+ "guest requested %u queues, exceeding the maximum of %u.",
+ requested_num_queues, xenblk_max_queues);
+ return -ENOSYS;
+ }
+ }
+ be->blkif->nr_rings = requested_num_queues;
+ if (xen_blkif_alloc_rings(be->blkif))
+ return -ENOMEM;
+
+ pr_info("%s: using %d queues, protocol %d (%s) %s\n", dev->nodename,
+ be->blkif->nr_rings, be->blkif->blk_protocol, protocol,
+ pers_grants ? "persistent grants" : "");
+
+ if (be->blkif->nr_rings == 1)
+ return read_per_ring_refs(&be->blkif->rings[0], dev->otherend);
+ else {
+ xspathsize = strlen(dev->otherend) + xenstore_path_ext_size;
+ xspath = kmalloc(xspathsize, GFP_KERNEL);
+ if (!xspath) {
+ xenbus_dev_fatal(dev, -ENOMEM, "reading ring references");
+ return -ENOMEM;
+ }
+
+ for (i = 0; i < be->blkif->nr_rings; i++) {
+ memset(xspath, 0, xspathsize);
+ snprintf(xspath, xspathsize, "%s/queue-%u", dev->otherend, i);
+ err = read_per_ring_refs(&be->blkif->rings[i], xspath);
+ if (err) {
+ kfree(xspath);
+ return err;
+ }
+ }
+ kfree(xspath);
+ }
+ return 0;
}
static const struct xenbus_device_id xen_blkbk_ids[] = {