linux-kernel - [PATCH AUTOSEL for 4.14 064/135] btrfs: Explicitly handle btrfs_update

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Message-ID: <20171207154513.4154-64-alexander.levin@verizon.com>
Date:   Thu, 7 Dec 2017 15:45:45 +0000
From:   alexander.levin@...izon.com
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Cc:     Nikolay Borisov <nborisov@...e.com>,
        David Sterba <dsterba@...e.com>, alexander.levin@...izon.com
Subject: [PATCH AUTOSEL for 4.14 064/135] btrfs: Explicitly handle
 btrfs_update_root failure

From: Nikolay Borisov <nborisov@...e.com>

[ Upstream commit 9417ebc8a676487c6ec8825f92fb28f7dbeb5f4b ]

btrfs_udpate_root can fail and it aborts the transaction, the correct
way to handle an aborted transaction is to explicitly end with
btrfs_end_transaction.  Even now the code is correct since
btrfs_commit_transaction would handle an aborted transaction but this is
more of an implementation detail. So let's be explicit in handling
failure in btrfs_update_root.

Furthermore btrfs_commit_transaction can also fail and by ignoring it's
return value we could have left the in-memory copy of the root item in
an inconsistent state. So capture the error value which allows us to
correctly revert the RO/RW flags in case of commit failure.

Signed-off-by: Nikolay Borisov <nborisov@...e.com>
Signed-off-by: David Sterba <dsterba@...e.com>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
---
 fs/btrfs/ioctl.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 6c7a49faf4e0..1f1338d52303 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1842,8 +1842,13 @@ static noinline int btrfs_ioctl_subvol_setflags(struct file *file,

 	ret = btrfs_update_root(trans, fs_info->tree_root,
 				&root->root_key, &root->root_item);
+	if (ret < 0) {
+		btrfs_end_transaction(trans);
+		goto out_reset;
+	}
+
+	ret = btrfs_commit_transaction(trans);

-	btrfs_commit_transaction(trans);
 out_reset:
 	if (ret)
 		btrfs_set_root_flags(&root->root_item, root_flags);
-- 
2.11.0