It adds spin_lock() in add_block_entry() but out path does not unlock
it.
Detected by CoversityScan, CID# 1463343:(Missing unlock)
Fixes: fd708b81d972a (Btrfs: add a extent ref verify tool)
Signed-off-by: Bo YU <[email protected]>
---
fs/btrfs/ref-verify.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/ref-verify.c b/fs/btrfs/ref-verify.c
index 7887317033c9..8f644511006d 100644
--- a/fs/btrfs/ref-verify.c
+++ b/fs/btrfs/ref-verify.c
@@ -894,8 +894,10 @@ int btrfs_ref_tree_mod(struct btrfs_fs_info *fs_info,
out_unlock:
spin_unlock(&fs_info->ref_verify_lock);
out:
- if (ret)
+ if (ret) {
+ spin_unlock(&fs_info->ref_verify_lock);
btrfs_clear_opt(fs_info->mount_opt, REF_VERIFY);
+ }
return ret;
}
--
2.11.0
On 15/05/2020 04:17, Bo YU wrote:
> It adds spin_lock() in add_block_entry() but out path does not unlock
> it.
Which call path doesn't unlock it? There is an out_unlock label with a
spin_unlock() right above your insert. So either coverity messed something
up or the call path that needs the unlock has to jump to out_unlock instead
of out.
Hi,
On Fri, May 15, 2020 at 5:03 PM Johannes Thumshirn
<[email protected]> wrote:
>
> On 15/05/2020 04:17, Bo YU wrote:
> > It adds spin_lock() in add_block_entry() but out path does not unlock
> > it.
>
> Which call path doesn't unlock it? There is an out_unlock label with a
> spin_unlock() right above your insert. So either coverity messed something
> up or the call path that needs the unlock has to jump to out_unlock instead
> of out.
This is out label without unlocking it. It will be offered spin_lock
in add_block_entry()
for be. But here I was worried about that unlock it in if() whether it
is right or not.
On 15/05/2020 11:24, Bo YU wrote:
> Hi,
> On Fri, May 15, 2020 at 5:03 PM Johannes Thumshirn
> <[email protected]> wrote:
>>
>> On 15/05/2020 04:17, Bo YU wrote:
>>> It adds spin_lock() in add_block_entry() but out path does not unlock
>>> it.
>>
>> Which call path doesn't unlock it? There is an out_unlock label with a
>> spin_unlock() right above your insert. So either coverity messed something
>> up or the call path that needs the unlock has to jump to out_unlock instead
>> of out.
> This is out label without unlocking it. It will be offered spin_lock
> in add_block_entry()
> for be. But here I was worried about that unlock it in if() whether it
> is right or not.
>
No add_block_entry() returns with the ref_verify_lock held on success only:
static struct block_entry *add_block_entry(struct btrfs_fs_info *fs_info,
u64 bytenr, u64 len,
u64 root_objectid)
{
struct block_entry *be = NULL, *exist;
struct root_entry *re = NULL;
re = kzalloc(sizeof(struct root_entry), GFP_KERNEL);
be = kzalloc(sizeof(struct block_entry), GFP_KERNEL);
if (!be || !re) {
kfree(re);
kfree(be);
return ERR_PTR(-ENOMEM);
}
be->bytenr = bytenr;
be->len = len;
re->root_objectid = root_objectid;
re->num_refs = 0;
spin_lock(&fs_info->ref_verify_lock);
[...]
While the code caller checks for an error:
if (action == BTRFS_ADD_DELAYED_EXTENT) {
/*
* For subvol_create we'll just pass in whatever the parent root
* is and the new root objectid, so let's not treat the passed
* in root as if it really has a ref for this bytenr.
*/
be = add_block_entry(fs_info, bytenr, num_bytes, ref_root);
if (IS_ERR(be)) {
kfree(ref);
kfree(ra);
ret = PTR_ERR(be);
goto out;
}
So if add_block_entry returns -ENOMEM it didn't take the lock and thus no unlock
is needed.
Or did I miss something?
On Fri, May 15, 2020 at 5:36 PM Johannes Thumshirn
<[email protected]> wrote:
>
> On 15/05/2020 11:24, Bo YU wrote:
> > Hi,
> > On Fri, May 15, 2020 at 5:03 PM Johannes Thumshirn
> > <[email protected]> wrote:
> >>
> >> On 15/05/2020 04:17, Bo YU wrote:
> >>> It adds spin_lock() in add_block_entry() but out path does not unlock
> >>> it.
> >>
> >> Which call path doesn't unlock it? There is an out_unlock label with a
> >> spin_unlock() right above your insert. So either coverity messed something
> >> up or the call path that needs the unlock has to jump to out_unlock instead
> >> of out.
> > This is out label without unlocking it. It will be offered spin_lock
> > in add_block_entry()
> > for be. But here I was worried about that unlock it in if() whether it
> > is right or not.
> >
>
> No add_block_entry() returns with the ref_verify_lock held on success only:
> static struct block_entry *add_block_entry(struct btrfs_fs_info *fs_info,
> u64 bytenr, u64 len,
> u64 root_objectid)
> {
> struct block_entry *be = NULL, *exist;
> struct root_entry *re = NULL;
>
> re = kzalloc(sizeof(struct root_entry), GFP_KERNEL);
> be = kzalloc(sizeof(struct block_entry), GFP_KERNEL);
> if (!be || !re) {
> kfree(re);
> kfree(be);
> return ERR_PTR(-ENOMEM);
> }
> be->bytenr = bytenr;
> be->len = len;
>
> re->root_objectid = root_objectid;
> re->num_refs = 0;
>
> spin_lock(&fs_info->ref_verify_lock);
> [...]
>
>
> While the code caller checks for an error:
>
> if (action == BTRFS_ADD_DELAYED_EXTENT) {
> /*
> * For subvol_create we'll just pass in whatever the parent root
> * is and the new root objectid, so let's not treat the passed
> * in root as if it really has a ref for this bytenr.
> */
> be = add_block_entry(fs_info, bytenr, num_bytes, ref_root);
> if (IS_ERR(be)) {
> kfree(ref);
> kfree(ra);
> ret = PTR_ERR(be);
> goto out;
> }
>
> So if add_block_entry returns -ENOMEM it didn't take the lock and thus no unlock
> is needed.
Ok, I got it. Please drop it.
Thank you!
>
> Or did I miss something?