[PATCH v3 2/6] exfat: introduce exfat_cluster_walk helper

Chi Zhiling
2026-04-03T08:06:44Z

Introduce exfat_cluster_walk() to walk the FAT chain by a given step,
handling both ALLOC_NO_FAT_CHAIN and ALLOC_FAT_CHAIN modes. Also
redefine exfat_get_next_cluster as a thin wrapper around it for
backward compatibility.

Signed-off-by: Chi Zhiling <chizhiling@kylinos.cn>
---
fs/exfat/exfat_fs.h | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index 9fed9fb33cae..7f9d0cfa252b 100644
--- a/fs/exfat/exfat_fs.h
+++ b/fs/exfat/exfat_fs.h
@@ -437,7 +437,8 @@ int exfat_set_volume_dirty(struct super_block *sb);
int exfat_clear_volume_dirty(struct super_block *sb);

/* fatent.c */
-#define exfat_get_next_cluster(sb, pclu) exfat_ent_get(sb, *(pclu), pclu, NULL)
+#define exfat_get_next_cluster(sb, pclu) \
+ exfat_cluster_walk(sb, (pclu), 1, ALLOC_FAT_CHAIN)

int exfat_alloc_cluster(struct inode *inode, unsigned int num_alloc,
struct exfat_chain *p_chain, bool sync_bmap);
@@ -456,6 +457,26 @@ int exfat_count_num_clusters(struct super_block *sb,
int exfat_blk_readahead(struct super_block *sb, sector_t sec,
sector_t *ra, blkcnt_t *ra_cnt, sector_t end);

+static inline int
+exfat_cluster_walk(struct super_block *sb, unsigned int *clu,
+ unsigned int step, int flags)
+{
+ struct buffer_head *bh = NULL;
+
+ if (flags == ALLOC_NO_FAT_CHAIN) {
+ (*clu) += step;
+ return 0;
+ }
+
+ while (step--) {
+ if (exfat_ent_get(sb, *clu, clu, &bh))
+ return -EIO;
+ }
+ brelse(bh);
+
+ return 0;
+}
+
/* balloc.c */
int exfat_load_bitmap(struct super_block *sb);
void exfat_free_bitmap(struct exfat_sb_info *sbi);
--
2.43.0