Btrfs: fix small race with delalloc flushing waitqueue's
Everytime we start a new flushing thread, we init the waitqueue if there isn't a
flushing thread running. The problem with this is we check
space_info->flushing, which we clear right before doing a wake_up on the
flushing waitqueue, which causes problems if we init the waitqueue in the middle
of clearing the flushing flagh and calling wake_up. This is hard to hit, but
the code is wrong anyway, so init the flushing/allocating waitqueue when
creating the space info and let it be. I haven't seen the panic since I've been
using this patch. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 5f6bc28..101041d 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2676,6 +2676,8 @@
INIT_LIST_HEAD(&found->block_groups);
init_rwsem(&found->groups_sem);
+ init_waitqueue_head(&found->flush_wait);
+ init_waitqueue_head(&found->allocate_wait);
spin_lock_init(&found->lock);
found->flags = flags;
found->total_bytes = total_bytes;
@@ -2944,12 +2946,10 @@
spin_lock(&info->lock);
- if (!info->flushing) {
+ if (!info->flushing)
info->flushing = 1;
- init_waitqueue_head(&info->flush_wait);
- } else {
+ else
wait = true;
- }
spin_unlock(&info->lock);
@@ -3011,7 +3011,6 @@
if (!info->allocating_chunk) {
info->force_alloc = 1;
info->allocating_chunk = 1;
- init_waitqueue_head(&info->allocate_wait);
} else {
wait = true;
}