Kernel with MTD_UBI_FASTMAP=y, fm_autoconvert=0 fails to attach and resize UBI image

[Philipp Zabel]

Hi,

on v3.7-rc7 with CONFIG_MTD_UBI_FASTMAP=y, I see the following error
when trying to attach an UBI image without fastmap information that has
to be resized because it is smaller than the mtd partition size:

    $ cat /sys/module/ubi/parameters/fm_autoconvert
    N

    $ ubiattach -p /dev/mtd3
    ubiattach: error!: cannot attach "/dev/mtd3"
               error 28 (No space left on device)

If I either disable MTD_UBI_FASTMAP in the kernel config or enable the
fm_autoconvert module parameter, attaching works just fine.

Without fm_autoconvert, ubi_resize_volume fails with -ENOSPC, caused by
ubi_wl_get_peb due to pool->size == 0.
It gets to this point on an otherwise empty flash because ubi_scan_all
puts all PEBs into the erase list. erase_work doesn't seem to be
scheduled before ubi_wl_init returns with ubi->free.rb_node == NULL and
ubi->free_count == 0. Because of this, refill_wl_user_pool breaks out of
its loop immediately and never increases the pool->size counter.

If I force synchronous erase in ubi_wl_init, the ubiattach succeeds the
next time I try it as now all PEBs go in the free list:

@@ -1899,7 +1907,7 @@ int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
                e->ec = aeb->ec;
                ubi_assert(!ubi_is_fm_block(ubi, e->pnum));
                ubi->lookuptbl[e->pnum] = e;
-               if (schedule_erase(ubi, e, aeb->vol_id, aeb->lnum, 0)) {
+               if (do_sync_erase(ubi, e, aeb->vol_id, aeb->lnum, 0)) {
                        kmem_cache_free(ubi_wl_entry_slab, e);
                        goto out_free;
                }

regards
Philipp