diff options
Diffstat (limited to 'drivers/mtd/ubi/scan.c')
| -rw-r--r-- | drivers/mtd/ubi/scan.c | 95 |
1 files changed, 61 insertions, 34 deletions
diff --git a/drivers/mtd/ubi/scan.c b/drivers/mtd/ubi/scan.c index 79ca304fc4db..11eb8ef12485 100644 --- a/drivers/mtd/ubi/scan.c +++ b/drivers/mtd/ubi/scan.c @@ -39,32 +39,46 @@ * eraseblocks are put to the @free list and the physical eraseblock to be * erased are put to the @erase list. * + * About corruptions + * ~~~~~~~~~~~~~~~~~ + * + * UBI protects EC and VID headers with CRC-32 checksums, so it can detect + * whether the headers are corrupted or not. Sometimes UBI also protects the + * data with CRC-32, e.g., when it executes the atomic LEB change operation, or + * when it moves the contents of a PEB for wear-leveling purposes. + * * UBI tries to distinguish between 2 types of corruptions. - * 1. Corruptions caused by power cuts. These are harmless and expected - * corruptions and UBI tries to handle them gracefully, without printing too - * many warnings and error messages. The idea is that we do not lose - * important data in these case - we may lose only the data which was being - * written to the media just before the power cut happened, and the upper - * layers (e.g., UBIFS) are supposed to handle these situations. UBI puts - * these PEBs to the head of the @erase list and they are scheduled for - * erasure. + * + * 1. Corruptions caused by power cuts. These are expected corruptions and UBI + * tries to handle them gracefully, without printing too many warnings and + * error messages. The idea is that we do not lose important data in these case + * - we may lose only the data which was being written to the media just before + * the power cut happened, and the upper layers (e.g., UBIFS) are supposed to + * handle such data losses (e.g., by using the FS journal). + * + * When UBI detects a corruption (CRC-32 mismatch) in a PEB, and it looks like + * the reason is a power cut, UBI puts this PEB to the @erase list, and all + * PEBs in the @erase list are scheduled for erasure later. * * 2. Unexpected corruptions which are not caused by power cuts. During - * scanning, such PEBs are put to the @corr list and UBI preserves them. - * Obviously, this lessens the amount of available PEBs, and if at some - * point UBI runs out of free PEBs, it switches to R/O mode. UBI also loudly - * informs about such PEBs every time the MTD device is attached. + * scanning, such PEBs are put to the @corr list and UBI preserves them. + * Obviously, this lessens the amount of available PEBs, and if at some point + * UBI runs out of free PEBs, it switches to R/O mode. UBI also loudly informs + * about such PEBs every time the MTD device is attached. * * However, it is difficult to reliably distinguish between these types of - * corruptions and UBI's strategy is as follows. UBI assumes (2.) if the VID - * header is corrupted and the data area does not contain all 0xFFs, and there - * were not bit-flips or integrity errors while reading the data area. Otherwise - * UBI assumes (1.). The assumptions are: - * o if the data area contains only 0xFFs, there is no data, and it is safe - * to just erase this PEB. - * o if the data area has bit-flips and data integrity errors (ECC errors on + * corruptions and UBI's strategy is as follows. UBI assumes corruption type 2 + * if the VID header is corrupted and the data area does not contain all 0xFFs, + * and there were no bit-flips or integrity errors while reading the data area. + * Otherwise UBI assumes corruption type 1. So the decision criteria are as + * follows. + * o If the data area contains only 0xFFs, there is no data, and it is safe + * to just erase this PEB - this is corruption type 1. + * o If the data area has bit-flips or data integrity errors (ECC errors on * NAND), it is probably a PEB which was being erased when power cut - * happened. + * happened, so this is corruption type 1. However, this is just a guess, + * which might be wrong. + * o Otherwise this it corruption type 2. */ #include <linux/err.h> @@ -74,7 +88,7 @@ #include <linux/random.h> #include "ubi.h" -#ifdef CONFIG_MTD_UBI_DEBUG_PARANOID +#ifdef CONFIG_MTD_UBI_DEBUG static int paranoid_check_si(struct ubi_device *ubi, struct ubi_scan_info *si); #else #define paranoid_check_si(ubi, si) 0 @@ -115,7 +129,7 @@ static int add_to_list(struct ubi_scan_info *si, int pnum, int ec, int to_head, } else BUG(); - seb = kmalloc(sizeof(struct ubi_scan_leb), GFP_KERNEL); + seb = kmem_cache_alloc(si->scan_leb_slab, GFP_KERNEL); if (!seb) return -ENOMEM; @@ -144,7 +158,7 @@ static int add_corrupted(struct ubi_scan_info *si, int pnum, int ec) dbg_bld("add to corrupted: PEB %d, EC %d", pnum, ec); - seb = kmalloc(sizeof(struct ubi_scan_leb), GFP_KERNEL); + seb = kmem_cache_alloc(si->scan_leb_slab, GFP_KERNEL); if (!seb) return -ENOMEM; @@ -553,7 +567,7 @@ int ubi_scan_add_used(struct ubi_device *ubi, struct ubi_scan_info *si, if (err) return err; - seb = kmalloc(sizeof(struct ubi_scan_leb), GFP_KERNEL); + seb = kmem_cache_alloc(si->scan_leb_slab, GFP_KERNEL); if (!seb) return -ENOMEM; @@ -1152,9 +1166,15 @@ struct ubi_scan_info *ubi_scan(struct ubi_device *ubi) si->volumes = RB_ROOT; err = -ENOMEM; + si->scan_leb_slab = kmem_cache_create("ubi_scan_leb_slab", + sizeof(struct ubi_scan_leb), + 0, 0, NULL); + if (!si->scan_leb_slab) + goto out_si; + ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL); if (!ech) - goto out_si; + goto out_slab; vidh = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL); if (!vidh) @@ -1215,6 +1235,8 @@ out_vidh: ubi_free_vid_hdr(ubi, vidh); out_ech: kfree(ech); +out_slab: + kmem_cache_destroy(si->scan_leb_slab); out_si: ubi_scan_destroy_si(si); return ERR_PTR(err); @@ -1223,11 +1245,12 @@ out_si: /** * destroy_sv - free the scanning volume information * @sv: scanning volume information + * @si: scanning information * * This function destroys the volume RB-tree (@sv->root) and the scanning * volume information. */ -static void destroy_sv(struct ubi_scan_volume *sv) +static void destroy_sv(struct ubi_scan_info *si, struct ubi_scan_volume *sv) { struct ubi_scan_leb *seb; struct rb_node *this = sv->root.rb_node; @@ -1247,7 +1270,7 @@ static void destroy_sv(struct ubi_scan_volume *sv) this->rb_right = NULL; } - kfree(seb); + kmem_cache_free(si->scan_leb_slab, seb); } } kfree(sv); @@ -1265,19 +1288,19 @@ void ubi_scan_destroy_si(struct ubi_scan_info *si) list_for_each_entry_safe(seb, seb_tmp, &si->alien, u.list) { list_del(&seb->u.list); - kfree(seb); + kmem_cache_free(si->scan_leb_slab, seb); } list_for_each_entry_safe(seb, seb_tmp, &si->erase, u.list) { list_del(&seb->u.list); - kfree(seb); + kmem_cache_free(si->scan_leb_slab, seb); } list_for_each_entry_safe(seb, seb_tmp, &si->corr, u.list) { list_del(&seb->u.list); - kfree(seb); + kmem_cache_free(si->scan_leb_slab, seb); } list_for_each_entry_safe(seb, seb_tmp, &si->free, u.list) { list_del(&seb->u.list); - kfree(seb); + kmem_cache_free(si->scan_leb_slab, seb); } /* Destroy the volume RB-tree */ @@ -1298,14 +1321,15 @@ void ubi_scan_destroy_si(struct ubi_scan_info *si) rb->rb_right = NULL; } - destroy_sv(sv); + destroy_sv(si, sv); } } + kmem_cache_destroy(si->scan_leb_slab); kfree(si); } -#ifdef CONFIG_MTD_UBI_DEBUG_PARANOID +#ifdef CONFIG_MTD_UBI_DEBUG /** * paranoid_check_si - check the scanning information. @@ -1323,6 +1347,9 @@ static int paranoid_check_si(struct ubi_device *ubi, struct ubi_scan_info *si) struct ubi_scan_leb *seb, *last_seb; uint8_t *buf; + if (!(ubi_chk_flags & UBI_CHK_GEN)) + return 0; + /* * At first, check that scanning information is OK. */ @@ -1575,4 +1602,4 @@ out: return -EINVAL; } -#endif /* CONFIG_MTD_UBI_DEBUG_PARANOID */ +#endif /* CONFIG_MTD_UBI_DEBUG */ |
