Commit 93314e3b authored Aug 06, 2015 by Zhaolei Committed by Chris Mason Aug 09, 2015

btrfs: abort transaction on btrfs_reloc_cow_block()



When btrfs_reloc_cow_block() failed in __btrfs_cow_block(), current
code just return a err-value to caller, but leave new_created extent
buffer exist and locked.

Then subsequent code (in relocate) try to lock above eb again,
and caused deadlock without any dmesg.
(eb lock use wait_event(), so no lockdep message)

It is hard to do recover work in __btrfs_cow_block() at this error
point, but we can abort transaction to avoid deadlock and operate on
unstable state.a

It also helps developer to find wrong place quickly.
(better than a frozen fs without any dmesg before patch)

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

parent 147d256e

fs/btrfs/ctree.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -1159,9 +1159,11 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,

		if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
		ret = btrfs_reloc_cow_block(trans, root, buf, cow);
		if (ret)
		if (ret) {
		btrfs_abort_transaction(trans, root, ret);
		return ret;
		}
		}

		if (buf == root->node) {
		WARN_ON(parent && parent != buf);

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