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-rw-r--r--drivers/md/bitmap.c45
1 files changed, 38 insertions, 7 deletions
diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 7e65bad522cb..ac89a5deaca2 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -238,15 +238,47 @@ static struct page *read_sb_page(mddev_t *mddev, long offset, unsigned long inde
}
+static mdk_rdev_t *next_active_rdev(mdk_rdev_t *rdev, mddev_t *mddev)
+{
+ /* Iterate the disks of an mddev, using rcu to protect access to the
+ * linked list, and raising the refcount of devices we return to ensure
+ * they don't disappear while in use.
+ * As devices are only added or removed when raid_disk is < 0 and
+ * nr_pending is 0 and In_sync is clear, the entries we return will
+ * still be in the same position on the list when we re-enter
+ * list_for_each_continue_rcu.
+ */
+ struct list_head *pos;
+ rcu_read_lock();
+ if (rdev == NULL)
+ /* start at the beginning */
+ pos = &mddev->disks;
+ else {
+ /* release the previous rdev and start from there. */
+ rdev_dec_pending(rdev, mddev);
+ pos = &rdev->same_set;
+ }
+ list_for_each_continue_rcu(pos, &mddev->disks) {
+ rdev = list_entry(pos, mdk_rdev_t, same_set);
+ if (rdev->raid_disk >= 0 &&
+ test_bit(In_sync, &rdev->flags) &&
+ !test_bit(Faulty, &rdev->flags)) {
+ /* this is a usable devices */
+ atomic_inc(&rdev->nr_pending);
+ rcu_read_unlock();
+ return rdev;
+ }
+ }
+ rcu_read_unlock();
+ return NULL;
+}
+
static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
{
- mdk_rdev_t *rdev;
+ mdk_rdev_t *rdev = NULL;
mddev_t *mddev = bitmap->mddev;
- rcu_read_lock();
- rdev_for_each_rcu(rdev, mddev)
- if (test_bit(In_sync, &rdev->flags)
- && !test_bit(Faulty, &rdev->flags)) {
+ while ((rdev = next_active_rdev(rdev, mddev)) != NULL) {
int size = PAGE_SIZE;
if (page->index == bitmap->file_pages-1)
size = roundup(bitmap->last_page_size,
@@ -281,8 +313,7 @@ static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
+ page->index * (PAGE_SIZE/512),
size,
page);
- }
- rcu_read_unlock();
+ }
if (wait)
md_super_wait(mddev);
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