From 37f758a036da56c7cff81b68d1d872752079eb6c Mon Sep 17 00:00:00 2001 From: Shmulik Ladkani Date: Wed, 4 Jul 2012 11:06:01 +0300 Subject: UBI: limit amount of reserved eraseblocks for bad PEB handling The existing mechanism of reserving PEBs for bad PEB handling has two flaws: - It is calculated as a percentage of good PEBs instead of total PEBs. - There's no limit on the amount of PEBs UBI reserves for future bad eraseblock handling. This patch changes the mechanism to overcome these flaws. The desired level of PEBs reserved for bad PEB handling (beb_rsvd_level) is set to the maximum expected bad eraseblocks (bad_peb_limit) minus the existing number of bad eraseblocks (bad_peb_count). The actual amount of PEBs reserved for bad PEB handling is usually set to the desired level (but in some circumstances may be lower than the desired level, e.g. when attaching to a device that has too few available PEBs to satisfy the desired level). In the case where the device has too many bad PEBs (above the expected limit), then the desired level, and the actual amount of PEBs reserved are set to zero. No PEBs will be set aside for future bad eraseblock handling - even if some PEBs are made available (e.g. by shrinking a volume). If another PEB goes bad, and there are available PEBs, then the eraseblock will be marked bad (consuming one available PEB). But if there are no available PEBs, ubi will go into readonly mode. Signed-off-by: Shmulik Ladkani --- drivers/mtd/ubi/misc.c | 16 ++++++++++++---- drivers/mtd/ubi/wl.c | 46 +++++++++++++++++++++++++++++----------------- 2 files changed, 41 insertions(+), 21 deletions(-) (limited to 'drivers/mtd/ubi') diff --git a/drivers/mtd/ubi/misc.c b/drivers/mtd/ubi/misc.c index 8bbfb444b895..d089df055484 100644 --- a/drivers/mtd/ubi/misc.c +++ b/drivers/mtd/ubi/misc.c @@ -121,10 +121,18 @@ void ubi_update_reserved(struct ubi_device *ubi) */ void ubi_calculate_reserved(struct ubi_device *ubi) { - ubi->beb_rsvd_level = ubi->good_peb_count/100; - ubi->beb_rsvd_level *= CONFIG_MTD_UBI_BEB_RESERVE; - if (ubi->beb_rsvd_level < MIN_RESEVED_PEBS) - ubi->beb_rsvd_level = MIN_RESEVED_PEBS; + /* + * Calculate the actual number of PEBs currently needed to be reserved + * for future bad eraseblock handling. + */ + ubi->beb_rsvd_level = ubi->bad_peb_limit - ubi->bad_peb_count; + if (ubi->beb_rsvd_level < 0) { + ubi->beb_rsvd_level = 0; + ubi_warn("number of bad PEBs (%d) is above the expected limit " + "(%d), not reserving any PEBs for bad PEB handling, " + "will use available PEBs (if any)", + ubi->bad_peb_count, ubi->bad_peb_limit); + } } /** diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c index b6be644e7b85..bd05276252fb 100644 --- a/drivers/mtd/ubi/wl.c +++ b/drivers/mtd/ubi/wl.c @@ -978,9 +978,10 @@ static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk, int cancel) { struct ubi_wl_entry *e = wl_wrk->e; - int pnum = e->pnum, err, need; + int pnum = e->pnum; int vol_id = wl_wrk->vol_id; int lnum = wl_wrk->lnum; + int err, available_consumed = 0; if (cancel) { dbg_wl("cancel erasure of PEB %d EC %d", pnum, e->ec); @@ -1045,20 +1046,14 @@ static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk, } spin_lock(&ubi->volumes_lock); - need = ubi->beb_rsvd_level - ubi->beb_rsvd_pebs + 1; - if (need > 0) { - need = ubi->avail_pebs >= need ? need : ubi->avail_pebs; - ubi->avail_pebs -= need; - ubi->rsvd_pebs += need; - ubi->beb_rsvd_pebs += need; - if (need > 0) - ubi_msg("reserve more %d PEBs", need); - } - if (ubi->beb_rsvd_pebs == 0) { - spin_unlock(&ubi->volumes_lock); - ubi_err("no reserved physical eraseblocks"); - goto out_ro; + if (ubi->avail_pebs == 0) { + spin_unlock(&ubi->volumes_lock); + ubi_err("no reserved/available physical eraseblocks"); + goto out_ro; + } + ubi->avail_pebs -= 1; + available_consumed = 1; } spin_unlock(&ubi->volumes_lock); @@ -1068,19 +1063,36 @@ static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk, goto out_ro; spin_lock(&ubi->volumes_lock); - ubi->beb_rsvd_pebs -= 1; + if (ubi->beb_rsvd_pebs > 0) { + if (available_consumed) { + /* + * The amount of reserved PEBs increased since we last + * checked. + */ + ubi->avail_pebs += 1; + available_consumed = 0; + } + ubi->beb_rsvd_pebs -= 1; + } ubi->bad_peb_count += 1; ubi->good_peb_count -= 1; ubi_calculate_reserved(ubi); - if (ubi->beb_rsvd_pebs) + if (available_consumed) + ubi_warn("no PEBs in the reserved pool, used an available PEB"); + else if (ubi->beb_rsvd_pebs) ubi_msg("%d PEBs left in the reserve", ubi->beb_rsvd_pebs); else - ubi_warn("last PEB from the reserved pool was used"); + ubi_warn("last PEB from the reserve was used"); spin_unlock(&ubi->volumes_lock); return err; out_ro: + if (available_consumed) { + spin_lock(&ubi->volumes_lock); + ubi->avail_pebs += 1; + spin_unlock(&ubi->volumes_lock); + } ubi_ro_mode(ubi); return err; } -- cgit v1.2.3