The commit is pushed to "branch-rh7-3.10.0-327.10.1.vz7.12.x-ovz" and will
appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-327.10.1.vz7.12.7
------>
commit 11ebbfd6d14abc7bbd38cf0af5a1ebd3f504517e
Author: Maxim Patlasov <[email protected]>
Date: Tue Apr 12 14:24:14 2016 +0400
cbt: factor out alloc_page
Patchset description:
cbt: fix page allocation and add blk_cbt_map_copy_once() helper
The first part of the patch set fixes a bug: it's not valid to call
alloc_page with disabled irqs (hidden inside on_each_cpu internals).
The remaining part (last patch) implements blk_cbt_map_copy_once() --
a helper for ploop making a private "snapshot" copy of CBT mask.
https://jira.sw.ru/browse/PSBM-45000
Maxim Patlasov (5):
cbt: factor out alloc_page
cbt: introduce CBT_PAGE_MISSED
cbt: make __blk_cbt_set() smarter
cbt: fix page allocation
cbt: add blk_cbt_map_copy_once() helper
=======================
This patch description:
The patch moves the logic of allocating new page for cbt->map[idx] to
a separate function. It will be used in further patches.
Signed-off-by: Maxim Patlasov <[email protected]>
Acked-by: Dmitry Monakhov <[email protected]>
---
block/blk-cbt.c | 98 ++++++++++++++++++++++++++++++++++++---------------------
1 file changed, 62 insertions(+), 36 deletions(-)
diff --git a/block/blk-cbt.c b/block/blk-cbt.c
index b66f513..08cefd8 100644
--- a/block/blk-cbt.c
+++ b/block/blk-cbt.c
@@ -76,6 +76,61 @@ static void set_bits(void *bm, int cur, int len, bool is_set)
}
}
+/*
+ * Return values:
+ * 0 if OK,
+ * -EAGAIN if cbt was updated,
+ * -EBADF if cbt is dead,
+ * -ENOMEM if alloc_page failed.
+ */
+static int cbt_page_alloc(struct cbt_info **cbt_pp, unsigned long idx,
+ int in_rcu)
+{
+ struct cbt_info *cbt = *cbt_pp;
+ struct page *page;
+
+ /* Page not allocated yet. Synchronization required */
+ spin_lock_irq(&cbt->lock);
+ if (likely(!test_bit(CBT_DEAD, &cbt->flags))) {
+ cbt->count++;
+ } else {
+ struct cbt_info *new = rcu_dereference(cbt->queue->cbt);
+
+ spin_unlock_irq(&cbt->lock);
+ /* was cbt updated ? */
+ if (new != cbt) {
+ *cbt_pp = new;
+ return -EAGAIN;
+ } else {
+ return -EBADF;
+ }
+ }
+ spin_unlock_irq(&cbt->lock);
+ if (in_rcu)
+ rcu_read_unlock();
+ page = alloc_page(GFP_NOIO|__GFP_ZERO);
+ if (in_rcu)
+ rcu_read_lock();
+ spin_lock_irq(&cbt->lock);
+ if (unlikely(!cbt->count-- && test_bit(CBT_DEAD, &cbt->flags))) {
+ spin_unlock_irq(&cbt->lock);
+ call_rcu(&cbt->rcu, &cbt_release_callback);
+ if (page)
+ __free_page(page);
+ return -EBADF;
+ }
+ if (unlikely(!page)) {
+ set_bit(CBT_ERROR, &cbt->flags);
+ spin_unlock_irq(&cbt->lock);
+ return -ENOMEM;
+ }
+ cbt->map[idx] = page;
+ page = NULL;
+ spin_unlock_irq(&cbt->lock);
+
+ return 0;
+}
+
static int __blk_cbt_set(struct cbt_info *cbt, blkcnt_t block,
blkcnt_t count, bool in_rcu, bool set)
{
@@ -95,6 +150,7 @@ static int __blk_cbt_set(struct cbt_info *cbt, blkcnt_t
block,
unsigned long off = block & (BITS_PER_PAGE -1);
unsigned long len = min_t(unsigned long, BITS_PER_PAGE - off,
count);
+ int ret;
page = cbt->map[idx];
if (page) {
@@ -112,44 +168,14 @@ static int __blk_cbt_set(struct cbt_info *cbt, blkcnt_t
block,
continue;
}
}
- /* Page not allocated yet. Synchronization required */
- spin_lock_irq(&cbt->lock);
- if (likely(!test_bit(CBT_DEAD, &cbt->flags))) {
- cbt->count++;
- } else {
- struct cbt_info *new = rcu_dereference(cbt->queue->cbt);
- spin_unlock_irq(&cbt->lock);
- /* was cbt updated ? */
- if (new != cbt) {
- cbt = new;
- continue;
- } else {
- break;
- }
- }
- spin_unlock_irq(&cbt->lock);
- if (in_rcu)
- rcu_read_unlock();
- page = alloc_page(GFP_NOIO|__GFP_ZERO);
- if (in_rcu)
- rcu_read_lock();
- spin_lock_irq(&cbt->lock);
- if (unlikely(!cbt->count-- && test_bit(CBT_DEAD, &cbt->flags)))
{
- spin_unlock_irq(&cbt->lock);
- call_rcu(&cbt->rcu, &cbt_release_callback);
- if (page)
- __free_page(page);
+ ret = cbt_page_alloc(&cbt, idx, in_rcu);
+ if (ret == -EAGAIN) /* new cbt */
+ continue;
+ else if (ret == -EBADF) /* dead cbt */
break;
- }
- if (unlikely(!page)) {
- set_bit(CBT_ERROR, &cbt->flags);
- spin_unlock_irq(&cbt->lock);
- return -ENOMEM;
- }
- cbt->map[idx] = page;
- page = NULL;
- spin_unlock_irq(&cbt->lock);
+ else if (ret)
+ return ret;
}
return 0;
}
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