Btrfs: Wait for async bio submissions to make some progress at queue time
Before, the btrfs bdi congestion function was used to test for too many
async bios. This keeps that check to throttle pdflush, but also
adds a check while queuing bios.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 23a5b0a..2652660 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -138,12 +138,18 @@
{
struct bio *pending;
struct backing_dev_info *bdi;
+ struct btrfs_fs_info *fs_info;
struct bio *tail;
struct bio *cur;
int again = 0;
unsigned long num_run = 0;
+ unsigned long limit;
bdi = device->bdev->bd_inode->i_mapping->backing_dev_info;
+ fs_info = device->dev_root->fs_info;
+ limit = btrfs_async_submit_limit(fs_info);
+ limit = limit * 2 / 3;
+
loop:
spin_lock(&device->io_lock);
@@ -179,7 +185,11 @@
cur = pending;
pending = pending->bi_next;
cur->bi_next = NULL;
- atomic_dec(&device->dev_root->fs_info->nr_async_bios);
+ atomic_dec(&fs_info->nr_async_bios);
+
+ if (atomic_read(&fs_info->nr_async_bios) < limit &&
+ waitqueue_active(&fs_info->async_submit_wait))
+ wake_up(&fs_info->async_submit_wait);
BUG_ON(atomic_read(&cur->bi_cnt) == 0);
bio_get(cur);
@@ -2135,6 +2145,7 @@
int rw, struct bio *bio)
{
int should_queue = 1;
+ unsigned long limit;
/* don't bother with additional async steps for reads, right now */
if (!(rw & (1 << BIO_RW))) {
@@ -2171,6 +2182,11 @@
if (should_queue)
btrfs_queue_worker(&root->fs_info->submit_workers,
&device->work);
+
+ limit = btrfs_async_submit_limit(root->fs_info);
+ wait_event_timeout(root->fs_info->async_submit_wait,
+ (atomic_read(&root->fs_info->nr_async_bios) < limit),
+ HZ/10);
return 0;
}