linux-kernel - [PATCH 3.16 089/306] ubi: Deal with interrupted erasures in WL

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Message-ID: <lsq.1487198500.385517085@decadent.org.uk>
Date:   Wed, 15 Feb 2017 22:41:40 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Richard Weinberger" <richard@....at>
Subject: [PATCH 3.16 089/306] ubi: Deal with interrupted erasures in WL

3.16.40-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Richard Weinberger <richard@....at>

commit 2365418879e9abf12ea9def7f9f3caf0dfa7ffb0 upstream.

When Fastmap is used we can face here an -EBADMSG
since Fastmap cannot know about unmaps.
If the erasure was interrupted the PEB may show ECC
errors and UBI would go to ro-mode as it assumes
that the PEB was check during attach time, which is
not the case with Fastmap.

Fixes: dbb7d2a88d ("UBI: Add fastmap core")
Signed-off-by: Richard Weinberger <richard@....at>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/mtd/ubi/wl.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -1000,7 +1000,7 @@ static int wear_leveling_worker(struct u
 				int cancel)
 {
 	int err, scrubbing = 0, torture = 0, protect = 0, erroneous = 0;
-	int vol_id = -1, lnum = -1;
+	int erase = 0, keep = 0, vol_id = -1, lnum = -1;
 #ifdef CONFIG_MTD_UBI_FASTMAP
 	int anchor = wrk->anchor;
 #endif
@@ -1134,6 +1134,16 @@ static int wear_leveling_worker(struct u
 			       e1->pnum);
 			scrubbing = 1;
 			goto out_not_moved;
+		} else if (ubi->fast_attach && err == UBI_IO_BAD_HDR_EBADMSG) {
+			/*
+			 * While a full scan would detect interrupted erasures
+			 * at attach time we can face them here when attached from
+			 * Fastmap.
+			 */
+			dbg_wl("PEB %d has ECC errors, maybe from an interrupted erasure",
+			       e1->pnum);
+			erase = 1;
+			goto out_not_moved;
 		}
 
 		ubi_err("error %d while reading VID header from PEB %d",
@@ -1167,6 +1177,7 @@ static int wear_leveling_worker(struct u
 			 * Target PEB had bit-flips or write error - torture it.
 			 */
 			torture = 1;
+			keep = 1;
 			goto out_not_moved;
 		}
 
@@ -1252,7 +1263,7 @@ out_not_moved:
 		ubi->erroneous_peb_count += 1;
 	} else if (scrubbing)
 		wl_tree_add(e1, &ubi->scrub);
-	else
+	else if (keep)
 		wl_tree_add(e1, &ubi->used);
 	ubi_assert(!ubi->move_to_put);
 	ubi->move_from = ubi->move_to = NULL;
@@ -1264,6 +1275,12 @@ out_not_moved:
 	if (err)
 		goto out_ro;
 
+	if (erase) {
+		err = do_sync_erase(ubi, e1, vol_id, lnum, 1);
+		if (err)
+			goto out_ro;
+	}
+
 	mutex_unlock(&ubi->move_mutex);
 	return 0;