Re: [PATCH 00/06] fid refcounting improvements and fixes

Tyler Hicks
2022-06-13T20:57:23Z

On 2022-06-12 17:53:23, Dominique Martinet wrote:
> So:
> - I could reproduce Tyler's generic 531 leak, fixed it by the first
> commit in v9fs_vfs_atomic_open_dotl
> - Found another less likely leak while reworking code
> - Christian's comment that it's not obvious that clunk is just a
> refcount decrease was very true: I think it's worth the churn,
> so I've rename this all through a new helper...
> - ... with the not-so-hidden intent to improve debugging by adding
> a tracepoint for them, which I have also done.
>
> I've also taken my comment in the other thread further and went ahead
> and made it in its own commit. Tyler, if you're ok with this I'll just
> squash it up. You can see rebased patches here:
> https://github.com/martinetd/linux/
>
> Note that I also took the permission to add back '/* clone */' as a
> comment to your changing p9_client_walk's arguments: while I can agree
> variables are hard to track, figuring out what the heck that boolean
> argument means is much harder to me and I honestly preferred the
> variable.
> Having both through a comment is good enough for me if you'll accept
> this:
> ----
> @@ -222,7 +221,8 @@ static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
> * We need to hold rename lock when doing a multipath
> * walk to ensure none of the patch component change
> */
> - fid = p9_client_walk(old_fid, l, &wnames[i], clone);
> + fid = p9_client_walk(old_fid, l, &wnames[i],
> + old_fid == root_fid /* clone */);

This is no problem at all. The rebased patches look good to me. Squash
your fix to my fix and it should be ready to go.

Thanks again!

Tyler

> /* non-cloning walk will return the same fid */
> if (fid != old_fid) {
> p9_client_clunk(old_fid);
> ----
>
>
> The last commit is just cleanups and should be no real change.
>
> Dominique Martinet (6):
> 9p: fix fid refcount leak in v9fs_vfs_atomic_open_dotl
> 9p: fix fid refcount leak in v9fs_vfs_get_link
> 9p: v9fs_fid_lookup_with_uid fix's fix suggestion
> 9p fid refcount: add p9_fid_get/put wrappers
> 9p fid refcount: add a 9p_fid_ref tracepoint
> 9p fid refcount: cleanup p9_fid_put calls
>
>
> (diff stats include Tyler's commits)
>
> fs/9p/fid.c | 71 +++++++++++++++-------------
> fs/9p/fid.h | 6 +--
> fs/9p/vfs_addr.c | 4 +-
> fs/9p/vfs_dentry.c | 4 +-
> fs/9p/vfs_dir.c | 2 +-
> fs/9p/vfs_file.c | 9 ++--
> fs/9p/vfs_inode.c | 97 +++++++++++++++++----------------------
> fs/9p/vfs_inode_dotl.c | 79 ++++++++++++-------------------
> fs/9p/vfs_super.c | 8 ++--
> fs/9p/xattr.c | 8 ++--
> include/net/9p/client.h | 3 ++
> include/trace/events/9p.h | 48 +++++++++++++++++++
> net/9p/client.c | 42 +++++++++++------
> 13 files changed, 211 insertions(+), 170 deletions(-)
>
> --
> 2.35.1
>