Re: [PATCH v2] btrfs: fix tree mod log mishandling of reallocated nodes

[Josef Bacik <josef@toxicpanda.com>]

On Mon, Oct 17, 2022 at 03:51:12PM +0200, David Sterba wrote:
> On Mon, Oct 17, 2022 at 02:43:47PM +0100, Filipe Manana wrote:
> > > > Fixes: bd989ba359f2 ("Btrfs: add tree modification log functions")
> > > 
> > > Are you sure it's caused by this commit? 
> > > 
> > > The code was added in 485df7555425 ("btrfs: always pin deleted leaves
> > > when there are active tree mod log users") and slightly modified in
> > > 888dd183390d ("btrfs: use the new bit BTRFS_FS_TREE_MOD_LOG_USERS at
> > > btrfs_free_tree_block()").
> > 
> > The fixes tag is correct.
> > 
> > Not dealing correctly with extent buffers that get freed and reallocated
> > for multiple root nodes is something that exists since the tree mod log
> > was added.
> > 
> > The commits you mentioned were for a different problem, pinning only leaves,
> > while Josef's fix simply changes the logic to pin any extent buffer - it's
> > the simplest way to fix the bug regarding root replacements.
> > 
> > If those commits didn't exist, the fix this problem would be the same (just
> > pin any extent buffer if there are tree mod log users).
> 
> Ok, thanks. I'll tag it for stable 3.3 then but we'll need a backport
> for <= 5.10, ideally applicable down to 4.9.

Once you ship it to Linus let me know and I'll do the backports.  Thanks,

Josef