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charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, Mar 24, 2026 at 1:52=E2=80=AFAM David Sterba wrot= e: > This is called during mount indirectly from open_ctree() and this is > single threaded (partially), so the lock may not be needed. It would be > needed if there's eg. caching thread possibly accessing the same > structures, I haven't looked closely. > > > + for (node =3D rb_first_cached(&fs_info->mapping_tree); node; > > + node =3D rb_next(node)) { > > struct btrfs_chunk_map *map; > > struct btrfs_block_group *bg; > > > > - /* > > - * btrfs_find_chunk_map() will return the first chunk map > > - * intersecting the range, so setting @length to 1 is eno= ugh to > > - * get the first chunk. > > - */ > > - map =3D btrfs_find_chunk_map(fs_info, start, 1); > > - if (!map) > > - break; > > - > > + map =3D rb_entry(node, struct btrfs_chunk_map, rb_node); > > bg =3D btrfs_lookup_block_group(fs_info, map->start); > > What concerns me is this lookup. Previously the references avoided > taking the big lock. The time the lock is held may add up significanly > for all block groups but as said before it might not be necessary due to > the mount context. Thanks for the suggestion, I=E2=80=99ll take a closer look at the locking h= ere. If the lock turns out to be unnecessary in this context, I=E2=80=99ll drop = it and include the change in v3. Thanks, ZhengYuan Huang