badblocks: fix missing bad blocks on retry in _badblocks_check()

The bad blocks check would miss bad blocks when retrying under contention,
as checking parameters are not reset. These stale values from the previous
attempt could lead to incorrect scanning in the subsequent retry.

Move seqlock to outer function and reinitialize checking state for each
retry. This ensures a clean state for each check attempt, preventing any
missed bad blocks.

Fixes: 3ea3354cb9f0 ("badblocks: improve badblocks_check() for multiple ranges handling")
Signed-off-by: Zheng Qixing <zhengqixing@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Coly Li <colyli@kernel.org>
Link: https://lore.kernel.org/r/20250227075507.151331-10-zhengqixing@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/badblocks.c b/block/badblocks.c
index 92bd43f7fff1fcec05aba2cb13550bce7e0dadbe..b66d5f12a7669f6dcffe1caad269355d6d03e683 100644 (file)
--- a/block/badblocks.c
+++ b/block/badblocks.c
@@ -1191,31 +1191,12 @@ update_sectors:
 static int _badblocks_check(struct badblocks *bb, sector_t s, int sectors,
                            sector_t *first_bad, int *bad_sectors)
 {
-       int unacked_badblocks, acked_badblocks;
        int prev = -1, hint = -1, set = 0;
        struct badblocks_context bad;
-       unsigned int seq;
+       int unacked_badblocks = 0;
+       int acked_badblocks = 0;
+       u64 *p = bb->page;
        int len, rv;
-       u64 *p;
-
-       WARN_ON(bb->shift < 0 || sectors == 0);
-
-       if (bb->shift > 0) {
-               sector_t target;
-
-               /* round the start down, and the end up */
-               target = s + sectors;
-               rounddown(s, 1 << bb->shift);
-               roundup(target, 1 << bb->shift);
-               sectors = target - s;
-       }
-
-retry:
-       seq = read_seqbegin(&bb->lock);
-
-       p = bb->page;
-       unacked_badblocks = 0;
-       acked_badblocks = 0;
 
 re_check:
        bad.start = s;
@@ -1281,9 +1262,6 @@ update_sectors:
        else
                rv = 0;
 
-       if (read_seqretry(&bb->lock, seq))
-               goto retry;
-
        return rv;
 }
 
@@ -1324,7 +1302,27 @@ update_sectors:
 int badblocks_check(struct badblocks *bb, sector_t s, int sectors,
                        sector_t *first_bad, int *bad_sectors)
 {
-       return _badblocks_check(bb, s, sectors, first_bad, bad_sectors);
+       unsigned int seq;
+       int rv;
+
+       WARN_ON(bb->shift < 0 || sectors == 0);
+
+       if (bb->shift > 0) {
+               /* round the start down, and the end up */
+               sector_t target = s + sectors;
+
+               rounddown(s, 1 << bb->shift);
+               roundup(target, 1 << bb->shift);
+               sectors = target - s;
+       }
+
+retry:
+       seq = read_seqbegin(&bb->lock);
+       rv = _badblocks_check(bb, s, sectors, first_bad, bad_sectors);
+       if (read_seqretry(&bb->lock, seq))
+               goto retry;
+
+       return rv;
 }
 EXPORT_SYMBOL_GPL(badblocks_check);