linux-kernel - [PATCH v3 3/4] block/badblocks: fix badblocks loss when badblocks combine

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Date:   Thu, 22 Jun 2023 01:20:51 +0800
From:   linan666@...weicloud.com
To:     axboe@...nel.dk, linan122@...wei.com, dan.j.williams@...el.com,
        vishal.l.verma@...el.com
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        yukuai3@...wei.com, yi.zhang@...wei.com, houtao1@...wei.com,
        yangerkun@...wei.com
Subject: [PATCH v3 3/4] block/badblocks: fix badblocks loss when badblocks combine

From: Li Nan <linan122@...wei.com>

badblocks will loss if we set it as below:

  # echo 1 1 > bad_blocks
  # echo 3 1 > bad_blocks
  # echo 1 5 > bad_blocks
  # cat bad_blocks
    1 3

In badblocks_set(), if there is an intersection between p[lo] and p[hi],
we will combine them. The end of new badblocks is p[hi]'s end now. but
p[lo] may cross p[hi] and new end should be the larger of p[lo] and p[hi].

Fixes: 9e0e252a048b ("badblocks: Add core badblock management code")
Signed-off-by: Li Nan <linan122@...wei.com>
---
 block/badblocks.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/block/badblocks.c b/block/badblocks.c
index 7e6ebe2ac12c..2c2ef8284a3f 100644
--- a/block/badblocks.c
+++ b/block/badblocks.c
@@ -267,16 +267,14 @@ int badblocks_set(struct badblocks *bb, sector_t s, int sectors,
 	if (sectors == 0 && hi < bb->count) {
 		/* we might be able to combine lo and hi */
 		/* Note: 's' is at the end of 'lo' */
-		sector_t a = BB_OFFSET(p[hi]);
-		int lolen = BB_LEN(p[lo]);
-		int hilen = BB_LEN(p[hi]);
-		int newlen = lolen + hilen - (s - a);
+		sector_t a = BB_OFFSET(p[lo]);
+		int newlen = max(s, BB_OFFSET(p[hi]) + BB_LEN(p[hi])) - a;
 
-		if (s >= a && newlen < BB_MAX_LEN) {
+		if (s >= BB_OFFSET(p[hi]) && newlen < BB_MAX_LEN) {
 			/* yes, we can combine them */
 			int ack = BB_ACK(p[lo]) && BB_ACK(p[hi]);
 
-			p[lo] = BB_MAKE(BB_OFFSET(p[lo]), newlen, ack);
+			p[lo] = BB_MAKE(a, newlen, ack);
 			memmove(p + hi, p + hi + 1,
 				(bb->count - hi - 1) * 8);
 			bb->count--;
-- 
2.39.2