Commit 2b8195bb authored Feb 07, 2013 by Miao Xie Committed by Josef Bacik Feb 20, 2013

Btrfs: fix the race between bio and btrfs_stop_workers



open_ctree() need read the metadata to initialize the global information
of btrfs. But it may fail after it submit some bio, and then it will jump
to the error path. Unfortunately, it doesn't check if there are some bios
in flight, and just stop all the worker threads. As a result, when the
submitted bios end, they can not find any worker thread which can deal with
subsequent work, then oops happen.

kernel BUG at fs/btrfs/async-thread.c:605!

Fix this problem by invoking invalidate_inode_pages2() before we stop the
worker threads. This function will wait until the bio end because it need
lock the pages which are going to be invalidated, and if a page is under
disk read IO, it must be locked. invalidate_inode_pages2() need wait until
end bio handler to unlocked it.

Reported-and-Tested-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

parent cb95e7bf

fs/btrfs/disk-io.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -2711,13 +2711,13 @@ fail_cleaner:
		* kthreads
		*/
		filemap_write_and_wait(fs_info->btree_inode->i_mapping);
		invalidate_inode_pages2(fs_info->btree_inode->i_mapping);

		fail_block_groups:
		btrfs_free_block_groups(fs_info);

		fail_tree_roots:
		free_root_pointers(fs_info, 1);
		invalidate_inode_pages2(fs_info->btree_inode->i_mapping);

		fail_sb_buffer:
		btrfs_stop_workers(&fs_info->generic_worker);
		@@ -2738,7 +2738,6 @@ fail_alloc:
		fail_iput:
		btrfs_mapping_tree_free(&fs_info->mapping_tree);

		invalidate_inode_pages2(fs_info->btree_inode->i_mapping);
		iput(fs_info->btree_inode);
		fail_delalloc_bytes:
		percpu_counter_destroy(&fs_info->delalloc_bytes);

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