Btrfs: fix small race with delalloc flushing waitqueue's (b5cb1600) · Commits · 戴 / test

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>

fs/btrfs/extent-tree.c

+4 −5

Original line number	Diff line number	Diff line
		@@ -2676,6 +2676,8 @@ static int update_space_info(struct btrfs_fs_info *info, u64 flags,

		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 @@ static void flush_delalloc(struct btrfs_root *root,

		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 @@ static int maybe_allocate_chunk(struct btrfs_root *root,
		if (!info->allocating_chunk) {
		info->force_alloc = 1;
		info->allocating_chunk = 1;
		init_waitqueue_head(&info->allocate_wait);
		} else {
		wait = true;
		}

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