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

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

[Hyeongseok Kim]

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@gmail.com>
Acked-by: Sungjong Seo <sj1557.seo@samsung.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

RE: [PATCH v2] exfat: fix erroneous discard when clear cluster bit

[Namjae Jeon]

> 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")
Cc: stable@vger.kernel.org # v5.7+
> Signed-off-by: Hyeongseok Kim <hyeongseok@gmail.com>
> Acked-by: Sungjong Seo <sj1557.seo@samsung.com>
Applied. Thanks for your patch!

> ---
>  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