From: Zhaolei <zhaolei@cn.fujitsu.com>
Date: Thu, 6 Aug 2015 13:56:58 +0000 (+0800)
Subject: btrfs: abort transaction on btrfs_reloc_cow_block()
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=93314e3b64fd2e77237fdba7cfcc0d38dcd05579;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

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>
---

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 54114b4887dd..5f745eadf77d 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1159,8 +1159,10 @@ 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) {