linux-kernel - [PATCH v2] exfat: fix erroneous discard when clear cluster bit

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Date:   Tue,  2 Mar 2021 14:20:20 +0900
From:   Hyeongseok Kim <hyeongseok@...il.com>
To:     namjae.jeon@...sung.com, sj1557.seo@...sung.com
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Hyeongseok Kim <hyeongseok@...il.com>
Subject: [PATCH v2] exfat: fix erroneous discard when clear cluster bit

If mounted with discard option, exFAT issues discard command when clear
cluster bit to remove file. But the input parameter of cluster-to-sector
calculation is abnormally added by reserved cluster size which is 2,
leading to discard unrelated sectors included in target+2 cluster.
With fixing this, remove the wrong comments in set/clear/find bitmap
functions.

Fixes: 1e49a94cf707 ("exfat: add bitmap operations")
Signed-off-by: Hyeongseok Kim <hyeongseok@...il.com>
Acked-by: Sungjong Seo <sj1557.seo@...sung.com>
---
 fs/exfat/balloc.c | 15 +--------------
 1 file changed, 1 insertion(+), 14 deletions(-)

diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c
index 761c79c3a4ba..54f1bcbddb26 100644
--- a/fs/exfat/balloc.c
+++ b/fs/exfat/balloc.c
@@ -141,10 +141,6 @@ void exfat_free_bitmap(struct exfat_sb_info *sbi)
 	kfree(sbi->vol_amap);
 }
 
-/*
- * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
- * the cluster heap.
- */
 int exfat_set_bitmap(struct inode *inode, unsigned int clu)
 {
 	int i, b;
@@ -162,10 +158,6 @@ int exfat_set_bitmap(struct inode *inode, unsigned int clu)
 	return 0;
 }
 
-/*
- * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
- * the cluster heap.
- */
 void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
 {
 	int i, b;
@@ -186,8 +178,7 @@ void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
 		int ret_discard;
 
 		ret_discard = sb_issue_discard(sb,
-			exfat_cluster_to_sector(sbi, clu +
-						EXFAT_RESERVED_CLUSTERS),
+			exfat_cluster_to_sector(sbi, clu),
 			(1 << sbi->sect_per_clus_bits), GFP_NOFS, 0);
 
 		if (ret_discard == -EOPNOTSUPP) {
@@ -197,10 +188,6 @@ void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
 	}
 }
 
-/*
- * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
- * the cluster heap.
- */
 unsigned int exfat_find_free_bitmap(struct super_block *sb, unsigned int clu)
 {
 	unsigned int i, map_i, map_b, ent_idx;
-- 
2.27.0.83.g0313f36