Re: [PATCH 1/3] btrfs: get rid of path allocation in btrfs_del_inode_extref()

[Filipe Manana]

On Wed, Apr 16, 2025 at 2:24 PM 李扬韬 <frank.li@xxxxxxxx> wrote:
>
>
>
> > Also a good point, the path should be in a pristine state, as if it were just allocated. Releasing paths in other functions may want to keep the bits but in this case we're crossing a function boundary and the same assumptions may not be the same.
>
> > Release resets the ->nodes, so what's left is from ->slots until the the end of the structure. And a helper for that would be desirable rather than opencoding that.
>
> IIUC, use btrfs_reset_path instead of btrfs_release_path?
>
> noinline void btrfs_reset_path(struct btrfs_path *p)
> {
>         int i;
>
>         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
>                 if (!p->nodes[i])
>                         continue;
>                 if (p->locks[i])
>                         btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
>                 free_extent_buffer(p->nodes[i]);
>         }
>         memset(p, 0, sizeof(struct btrfs_path));
> }
>
> BTW, I have seen released paths being passed across functions in some other paths.
>
> Should these also be changed to reset paths, or should these flags be cleared in the release path?

Please don't complicate things unnecessarily.
The patch is fine, all that needs to be done is to call
btrfs_release_path() before passing the path to
btrfs_del_inode_extref(), which resets nodes, slots and locks.

>
> Thx,
> Yangtao