[PATCH AUTOSEL 5.6 051/129] btrfs: handle NULL roots in btrfs_put/btrfs_grab_fs_root

Sasha Levin
2020-04-15T13:09:51Z

From: Josef Bacik <josef@toxicpanda.com>

[ Upstream commit 4cdfd93002cb84471ed85b4999cd38077a317873 ]

We want to use this for dropping all roots, and in some error cases we
may not have a root, so handle this to make the cleanup code easier.
Make btrfs_grab_fs_root the same so we can use it in cases where the
root may not exist (like the quota root).

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/btrfs/disk-io.h | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index 8c2d6cf1ce596..424c9c97b1ce8 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -97,6 +97,8 @@ struct btrfs_root *btrfs_alloc_dummy_root(struct btrfs_fs_info *fs_info);
*/
static inline struct btrfs_root *btrfs_grab_fs_root(struct btrfs_root *root)
{
+ if (!root)
+ return NULL;
if (refcount_inc_not_zero(&root->refs))
return root;
return NULL;
@@ -104,6 +106,8 @@ static inline struct btrfs_root *btrfs_grab_fs_root(struct btrfs_root *root)

static inline void btrfs_put_fs_root(struct btrfs_root *root)
{
+ if (!root)
+ return;
if (refcount_dec_and_test(&root->refs))
kfree(root);
}
--
2.20.1