Re: [PATCH v2 10/13] exfat: support multi-cluster for exfat_map_cluster

[Chi Zhiling]

On 1/13/26 14:37, Yuezhang.Mo@xxxxxxxx wrote:
> > @@ -281,7 +285,7 @@ static int exfat_get_block(struct inode *inode, sector_t iblock,
> >         sec_offset = iblock & (sbi->sect_per_clus - 1);
> >
> >         phys = exfat_cluster_to_sector(sbi, cluster) + sec_offset;
> > -       mapped_blocks = sbi->sect_per_clus - sec_offset;
> > +       mapped_blocks = (count << sbi->sect_per_clus_bits) - sec_offset;
>
> This left shift will cause an overflow if the file is larger than 2TB
> and the clusters are contiguous.

Thank you for pointing this out, I will change the type to blkcnt_t in 
v3 to fix this bug.

diff --git a/fs/exfat/inode.c b/fs/exfat/inode.c
index e8b74185b0ad..9c1e00f5b011 100644
--- a/fs/exfat/inode.c
+++ b/fs/exfat/inode.c
@@ -250,9 +250,9 @@ static int exfat_get_block(struct inode *inode, 
sector_t iblock,
        struct exfat_inode_info *ei = EXFAT_I(inode);
        struct super_block *sb = inode->i_sb;
        struct exfat_sb_info *sbi = EXFAT_SB(sb);
-       unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
+       blkcnt_t max_blocks = EXFAT_B_TO_BLK(bh_result->b_size, sb);
+       blkcnt_t mapped_blocks = 0;
        int err = 0;
-       unsigned long mapped_blocks = 0;
        unsigned int cluster, sec_offset, count;
        sector_t last_block;
        sector_t phys = 0;

> The others look good.
> Reviewed-by: Yuezhang Mo <Yuezhang.Mo@xxxxxxxx>


Thanks,