linux-kernel - [PATCH 08/12] badblocks: fix merge issue when new badblocks align with pre+1

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Message-Id: <20250221081109.734170-9-zhengqixing@huaweicloud.com>
Date: Fri, 21 Feb 2025 16:11:05 +0800
From: Zheng Qixing <zhengqixing@...weicloud.com>
To: axboe@...nel.dk,
	song@...nel.org,
	colyli@...nel.org,
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Cc: linux-block@...r.kernel.org,
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Subject: [PATCH 08/12] badblocks: fix merge issue when new badblocks align with pre+1

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

There is a merge issue when adding badblocks as follow:
  echo 0 10 > bad_blocks
  echo 30 10 > bad_blocks
  echo 20 10 > bad_blocks
  cat bad_blocks
  0 10
  20 10    //should be merged with (30 10)
  30 10

In this case, if new badblocks does not intersect with prev, it is added
by insert_at(). If there is an intersection with prev+1, the merge will
be processed in the next re_insert loop.

However, when the end of the new badblocks is exactly equal to the offset
of prev+1, no further re_insert loop occurs, and the two badblocks are not
merge.

Fix it by inc prev, badblocks can be merged during the subsequent code.

Fixes: aa511ff8218b ("badblocks: switch to the improved badblock handling code")
Signed-off-by: Li Nan <linan122@...wei.com>
---
 block/badblocks.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/badblocks.c b/block/badblocks.c
index bb46bab7e99f..381f9db423d6 100644
--- a/block/badblocks.c
+++ b/block/badblocks.c
@@ -892,7 +892,7 @@ static int _badblocks_set(struct badblocks *bb, sector_t s, int sectors,
 		len = insert_at(bb, 0, &bad);
 		bb->count++;
 		added++;
-		hint = 0;
+		hint = ++prev;
 		goto update_sectors;
 	}
 
@@ -947,7 +947,7 @@ static int _badblocks_set(struct badblocks *bb, sector_t s, int sectors,
 	len = insert_at(bb, prev + 1, &bad);
 	bb->count++;
 	added++;
-	hint = prev + 1;
+	hint = ++prev;
 
 update_sectors:
 	s += len;
-- 
2.39.2