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authorJens Axboe <axboe@fb.com>2015-04-17 16:23:59 -0600
committerJens Axboe <axboe@fb.com>2015-05-05 13:32:49 -0600
commitdac56212e8127dbc0bff7be35c508bc280213309 (patch)
treea1a066d7f6deb7d66403137b8edafb394ce0ca6a /fs/btrfs/volumes.c
parentc4cf5261f8bffd9de132b50660a69148e7575bd6 (diff)
bio: skip atomic inc/dec of ->bi_cnt for most use cases
Struct bio has a reference count that controls when it can be freed. Most uses cases is allocating the bio, which then returns with a single reference to it, doing IO, and then dropping that single reference. We can remove this atomic_dec_and_test() in the completion path, if nobody else is holding a reference to the bio. If someone does call bio_get() on the bio, then we flag the bio as now having valid count and that we must properly honor the reference count when it's being put. Tested-by: Robert Elliott <elliott@hp.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'fs/btrfs/volumes.c')
-rw-r--r--fs/btrfs/volumes.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 96aebf3bcd5b..8e8d1d1e28a5 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -345,7 +345,7 @@ loop_lock:
waitqueue_active(&fs_info->async_submit_wait))
wake_up(&fs_info->async_submit_wait);
- BUG_ON(atomic_read(&cur->bi_cnt) == 0);
+ BUG_ON(atomic_read(&cur->__bi_cnt) == 0);
/*
* if we're doing the sync list, record that our