Using UBI_IOCRPEB and UBI_IOCSPEB userspace can force reading and scrubbing of PEBs.
In case of bitflips UBI will automatically take action and move data to a different PEB. This interface allows a daemon to foster your NAND. Signed-off-by: Richard Weinberger <[email protected]> --- drivers/mtd/ubi/cdev.c | 30 ++++++++ drivers/mtd/ubi/ubi.h | 1 + drivers/mtd/ubi/wl.c | 144 ++++++++++++++++++++++++++++++++++++ include/uapi/mtd/ubi-user.h | 5 ++ 4 files changed, 180 insertions(+) diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c index 22547d7a84ea..947a8adbc799 100644 --- a/drivers/mtd/ubi/cdev.c +++ b/drivers/mtd/ubi/cdev.c @@ -974,6 +974,36 @@ static long ubi_cdev_ioctl(struct file *file, unsigned int cmd, break; } + /* Check a specific PEB for bitflips and scrub it if needed */ + case UBI_IOCRPEB: + { + int pnum; + + err = get_user(pnum, (__user int32_t *)argp); + if (err) { + err = -EFAULT; + break; + } + + err = ubi_bitflip_check(ubi, pnum, 0); + break; + } + + /* Force scrubbing for a specific PEB */ + case UBI_IOCSPEB: + { + int pnum; + + err = get_user(pnum, (__user int32_t *)argp); + if (err) { + err = -EFAULT; + break; + } + + err = ubi_bitflip_check(ubi, pnum, 1); + break; + } + default: err = -ENOTTY; break; diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h index d47b9e436e67..a1b9e764d489 100644 --- a/drivers/mtd/ubi/ubi.h +++ b/drivers/mtd/ubi/ubi.h @@ -929,6 +929,7 @@ int ubi_wl_put_fm_peb(struct ubi_device *ubi, struct ubi_wl_entry *used_e, int ubi_is_erase_work(struct ubi_work *wrk); void ubi_refill_pools(struct ubi_device *ubi); int ubi_ensure_anchor_pebs(struct ubi_device *ubi); +int ubi_bitflip_check(struct ubi_device *ubi, int pnum, int force_scrub); /* io.c */ int ubi_io_read(const struct ubi_device *ubi, void *buf, int pnum, int offset, diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c index ca1b31385eb5..5540599a60c6 100644 --- a/drivers/mtd/ubi/wl.c +++ b/drivers/mtd/ubi/wl.c @@ -1440,6 +1440,150 @@ int ubi_wl_flush(struct ubi_device *ubi, int vol_id, int lnum) return err; } +static bool scrub_possible(struct ubi_device *ubi, struct ubi_wl_entry *e) +{ + if (in_wl_tree(e, &ubi->scrub)) + return false; + else if (in_wl_tree(e, &ubi->erroneous)) + return false; + else if (ubi->move_from == e) + return false; + else if (ubi->move_to == e) + return false; + + return true; +} + +/** + * ubi_bitflip_check - Check an eraseblock for bitflips and scrub it if needed. + * @ubi: UBI device description object + * @pnum: the physical eraseblock to schedule + * @force_scrub: force scrubbing if non-zero, schedule erase otherwise + * + * This function reads the given eraseblock and checks if bitflips occured. + * In case of bitflips, the eraseblock is scheduled for scrubbing. + * If scrubbing is forced with @force_scrub, the eraseblock is not read, + * but scheduled for scrubbing right away. + * + * Returns: + * %EINVAL, PEB is out of range + * %ENOENT, PEB is no longer used by UBI + * %EBUSY, PEB cannot be checked now or a check is currently running on it + * %EAGAIN, bit flips happened but scrubbing is currently not possible + * %EUCLEAN, bit flips happened and PEB is scheduled for scrubbing + * %0, no bit flips detected + */ +int ubi_bitflip_check(struct ubi_device *ubi, int pnum, int force_scrub) +{ + int err; + struct ubi_wl_entry *e; + + if (pnum < 0 || pnum >= ubi->peb_count) { + err = -EINVAL; + goto out; + } + + /* + * Pause all parallel work, otherwise it can happen that the + * erase worker frees a wl entry under us. + */ + down_write(&ubi->work_sem); + + /* + * Make sure that the wl entry does not change state while + * inspecting it. + */ + spin_lock(&ubi->wl_lock); + e = ubi->lookuptbl[pnum]; + if (!e) { + spin_unlock(&ubi->wl_lock); + err = -ENOENT; + goto out_resume; + } + + /* + * Does it make sense to check this PEB? + */ + if (!scrub_possible(ubi, e)) { + spin_unlock(&ubi->wl_lock); + err = -EBUSY; + goto out_resume; + } + spin_unlock(&ubi->wl_lock); + + if (!force_scrub) { + mutex_lock(&ubi->buf_mutex); + err = ubi_io_read(ubi, ubi->peb_buf, pnum, 0, ubi->peb_size); + mutex_unlock(&ubi->buf_mutex); + } + + if (err == UBI_IO_BITFLIPS || force_scrub) { + /* + * Okay, bit flip happened, let's figure out what we can do. + */ + spin_lock(&ubi->wl_lock); + + /* + * Recheck. We released wl_lock, UBI might have killed the + * wl entry under us. + */ + e = ubi->lookuptbl[pnum]; + if (!e) { + spin_unlock(&ubi->wl_lock); + err = -ENOENT; + goto out_resume; + } + + /* + * Need to re-check state + */ + if (!scrub_possible(ubi, e)) { + spin_unlock(&ubi->wl_lock); + err = -EBUSY; + goto out_resume; + } + + if (in_pq(ubi, e)) { + prot_queue_del(ubi, e->pnum); + wl_tree_add(e, &ubi->scrub); + spin_unlock(&ubi->wl_lock); + + err = ensure_wear_leveling(ubi, 1); + } else if (in_wl_tree(e, &ubi->used)) { + rb_erase(&e->u.rb, &ubi->used); + wl_tree_add(e, &ubi->scrub); + spin_unlock(&ubi->wl_lock); + + err = ensure_wear_leveling(ubi, 1); + } else if (in_wl_tree(e, &ubi->free)) { + rb_erase(&e->u.rb, &ubi->free); + ubi->free_count--; + spin_unlock(&ubi->wl_lock); + + /* + * This PEB is empty we can schedule it for + * erasure right away. No wear leveling needed. + */ + err = schedule_erase(ubi, e, UBI_UNKNOWN, UBI_UNKNOWN, + force_scrub ? 0 : 1, true); + } else { + spin_unlock(&ubi->wl_lock); + err = -EAGAIN; + } + + if (!err && !force_scrub) + err = -EUCLEAN; + } else { + err = 0; + } + +out_resume: + up_write(&ubi->work_sem); +out: + + return err; +} + /** * tree_destroy - destroy an RB-tree. * @ubi: UBI device description object diff --git a/include/uapi/mtd/ubi-user.h b/include/uapi/mtd/ubi-user.h index aad3b6201fc0..b69e9ba6742b 100644 --- a/include/uapi/mtd/ubi-user.h +++ b/include/uapi/mtd/ubi-user.h @@ -171,6 +171,11 @@ /* Re-name volumes */ #define UBI_IOCRNVOL _IOW(UBI_IOC_MAGIC, 3, struct ubi_rnvol_req) +/* Read the specified PEB and scrub it if there are bitflips */ +#define UBI_IOCRPEB _IOW(UBI_IOC_MAGIC, 4, __s32) +/* Force scrubbing on the specified PEB */ +#define UBI_IOCSPEB _IOW(UBI_IOC_MAGIC, 5, __s32) + /* ioctl commands of the UBI control character device */ #define UBI_CTRL_IOC_MAGIC 'o' -- 2.19.1
