[PATCH 6.18.y] hfsplus: avoid double unload_nls() on mount failure

[PATCH 6.18.y] hfsplus: avoid double unload_nls() on mount failure

[Artem Martynenko]

From: Shardul Bankar <shardulsb08@gmail.com>

commit ebebb04baefdace1e0dc17f7779e5549063ca592 upstream.

The recent commit "hfsplus: ensure sb->s_fs_info is always cleaned up"
[1] introduced a custom ->kill_sb() handler (hfsplus_kill_super) that
cleans up the s_fs_info structure (including the NLS table) on
superblock destruction.

However, the error handling path in hfsplus_fill_super() still calls
unload_nls() before returning an error. Since the VFS layer calls
->kill_sb() when fill_super fails, this results in unload_nls() being
called twice for the same sbi->nls pointer: once in hfsplus_fill_super()
and again in hfsplus_kill_super() (via delayed_free).

Remove the explicit unload_nls() call from the error path in
hfsplus_fill_super() to rely solely on the cleanup in ->kill_sb().

[1] https://lore.kernel.org/r/20251201222843.82310-3-mehdi.benhadjkhelifa@gmail.com/

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/r/20260203043806.GF3183987@ZenIV/
Signed-off-by: Shardul Bankar <shardul.b@mpiricsoftware.com>
Link: https://lore.kernel.org/r/20260204170440.1337261-1-shardul.b@mpiricsoftware.com
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Artem Martynenko <amartynenko140@gmail.com>
---
Tested on 6.18.54 in QEMU: "modprobe nls_utf8; mount -t hfsplus" on a
blank image fails as expected. Without the patch nls_utf8 refcnt goes
to -1 afterwards, with the patch it stays at 0.
Discussion: https://lore.kernel.org/linux-fsdevel/9AD67E49-86E9-4508-BBC0-26919C72FB6A@gmail.com

 fs/hfsplus/super.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/hfsplus/super.c b/fs/hfsplus/super.c
index d031c77fb..0d619945d 100644
--- a/fs/hfsplus/super.c
+++ b/fs/hfsplus/super.c
@@ -652,7 +652,6 @@ static int hfsplus_fill_super(struct super_block *sb, struct fs_context *fc)
 	kfree(sbi->s_vhdr_buf);
 	kfree(sbi->s_backup_vhdr_buf);
 out_unload_nls:
-	unload_nls(sbi->nls);
 	unload_nls(nls);
 	return err;
 }
-- 
2.55.0