Commit 51684082 authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: run the backing dev more often in the submit_bio helper



The submit_bio helper thread can decide to loop back around to
service more bios.  This commit forces it to unplug first, which helps
reduce the latency seen by submitters.
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 4849f01d
......@@ -325,16 +325,6 @@ loop_lock:
num_sync_run = 0;
blk_run_backing_dev(bdi, NULL);
}
cond_resched();
if (again)
goto loop;
spin_lock(&device->io_lock);
if (device->pending_bios.head || device->pending_sync_bios.head)
goto loop_lock;
spin_unlock(&device->io_lock);
/*
* IO has already been through a long path to get here. Checksumming,
* async helper threads, perhaps compression. We've done a pretty
......@@ -346,6 +336,16 @@ loop_lock:
* cared about found its way down here.
*/
blk_run_backing_dev(bdi, NULL);
cond_resched();
if (again)
goto loop;
spin_lock(&device->io_lock);
if (device->pending_bios.head || device->pending_sync_bios.head)
goto loop_lock;
spin_unlock(&device->io_lock);
done:
return 0;
}
......
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