This is a note to let you know that I've just added the patch titled

ubi: fastmap: Erase outdated anchor PEBs during attach

to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: ubi-fastmap-erase-outdated-anchor-pebs-during-attach.patch and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From f78e5623f45bab2b726eec29dc5cefbbab2d0b1c Mon Sep 17 00:00:00 2001

From: Sascha Hauer s.hauer@pengutronix.de Date: Tue, 5 Dec 2017 16:01:20 +0100 Subject: ubi: fastmap: Erase outdated anchor PEBs during attach

From: Sascha Hauer s.hauer@pengutronix.de

commit f78e5623f45bab2b726eec29dc5cefbbab2d0b1c upstream.

The fastmap update code might erase the current fastmap anchor PEB in case it doesn't find any new free PEB. When a power cut happens in this situation we must not have any outdated fastmap anchor PEB on the device, because that would be used to attach during next boot. The easiest way to make that sure is to erase all outdated fastmap anchor PEBs synchronously during attach.

Signed-off-by: Sascha Hauer s.hauer@pengutronix.de Reviewed-by: Richard Weinberger richard@nod.at Fixes: dbb7d2a88d2a ("UBI: Add fastmap core") Signed-off-by: Richard Weinberger richard@nod.at Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- drivers/mtd/ubi/wl.c | 77 +++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 57 insertions(+), 20 deletions(-)

--- a/drivers/mtd/ubi/wl.c +++ b/drivers/mtd/ubi/wl.c @@ -1529,6 +1529,46 @@ static void shutdown_work(struct ubi_dev }

/** + * erase_aeb - erase a PEB given in UBI attach info PEB + * @ubi: UBI device description object + * @aeb: UBI attach info PEB + * @sync: If true, erase synchronously. Otherwise schedule for erasure + */ +static int erase_aeb(struct ubi_device *ubi, struct ubi_ainf_peb *aeb, bool sync) +{ + struct ubi_wl_entry *e; + int err; + + e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL); + if (!e) + return -ENOMEM; + + e->pnum = aeb->pnum; + e->ec = aeb->ec; + ubi->lookuptbl[e->pnum] = e; + + if (sync) { + err = sync_erase(ubi, e, false); + if (err) + goto out_free; + + wl_tree_add(e, &ubi->free); + ubi->free_count++; + } else { + err = schedule_erase(ubi, e, aeb->vol_id, aeb->lnum, 0, false); + if (err) + goto out_free; + } + + return 0; + +out_free: + wl_entry_destroy(ubi, e); + + return err; +} + +/** * ubi_wl_init - initialize the WL sub-system using attaching information. * @ubi: UBI device description object * @ai: attaching information @@ -1566,17 +1606,9 @@ int ubi_wl_init(struct ubi_device *ubi, list_for_each_entry_safe(aeb, tmp, &ai->erase, u.list) { cond_resched();

- e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL); - if (!e) - goto out_free; - - e->pnum = aeb->pnum; - e->ec = aeb->ec; - ubi->lookuptbl[e->pnum] = e; - if (schedule_erase(ubi, e, aeb->vol_id, aeb->lnum, 0, false)) { - wl_entry_destroy(ubi, e); + err = erase_aeb(ubi, aeb, false); + if (err) goto out_free; - }

found_pebs++; } @@ -1635,6 +1667,8 @@ int ubi_wl_init(struct ubi_device *ubi, ubi_assert(!ubi->lookuptbl[e->pnum]); ubi->lookuptbl[e->pnum] = e; } else { + bool sync = false; + /* * Usually old Fastmap PEBs are scheduled for erasure * and we don't have to care about them but if we face @@ -1644,18 +1678,21 @@ int ubi_wl_init(struct ubi_device *ubi, if (ubi->lookuptbl[aeb->pnum]) continue;

- e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL); - if (!e) - goto out_free; + /* + * The fastmap update code might not find a free PEB for + * writing the fastmap anchor to and then reuses the + * current fastmap anchor PEB. When this PEB gets erased + * and a power cut happens before it is written again we + * must make sure that the fastmap attach code doesn't + * find any outdated fastmap anchors, hence we erase the + * outdated fastmap anchor PEBs synchronously here. + */ + if (aeb->vol_id == UBI_FM_SB_VOLUME_ID) + sync = true;

- e->pnum = aeb->pnum; - e->ec = aeb->ec; - ubi_assert(!ubi->lookuptbl[e->pnum]); - ubi->lookuptbl[e->pnum] = e; - if (schedule_erase(ubi, e, aeb->vol_id, aeb->lnum, 0, false)) { - wl_entry_destroy(ubi, e); + err = erase_aeb(ubi, aeb, sync); + if (err) goto out_free; - } }

found_pebs++;

Patches currently in stable-queue which might be from s.hauer@pengutronix.de are

queue-4.9/ubi-fastmap-erase-outdated-anchor-pebs-during-attach.patch