[PATCH v3 1/6] exfat: fix incorrect directory checksum after rename to shorter name

Chi Zhiling
2026-04-03T08:06:46Z

When renaming a file in-place to a shorter name, exfat_remove_entries
marks excess entries as DELETED, but es->num_entries is not updated
accordingly. As a result, exfat_update_dir_chksum iterates over the
deleted entries and computes an incorrect checksum.

This does not lead to persistent corruption because mark_inode_dirty()
is called afterward, and __exfat_write_inode later recomputes the
checksum using the correct num_entries value.

Fix by setting es->num_entries = num_entries in exfat_init_ext_entry.

Signed-off-by: Chi Zhiling <chizhiling@kylinos.cn>
---
fs/exfat/dir.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c
index a2c2b998808c..7619410d668e 100644
--- a/fs/exfat/dir.c
+++ b/fs/exfat/dir.c
@@ -490,6 +490,7 @@ void exfat_init_ext_entry(struct exfat_entry_set_cache *es, int num_entries,
unsigned short *uniname = p_uniname->name;
struct exfat_dentry *ep;

+ es->num_entries = num_entries;
ep = exfat_get_dentry_cached(es, ES_IDX_FILE);
ep->dentry.file.num_ext = (unsigned char)(num_entries - 1);

--
2.43.0