From 6f5fc7de98857c75dad05e9f3fe2e6f358d4583e Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 2 Aug 2023 17:41:28 +0200 Subject: [PATCH] ext4: drop s_umount over opening the log device Just like get_tree_bdev needs to drop s_umount when opening the main device, we need to do the same for the ext4 log device to avoid a potential lock order reversal with s_unmount for the mark_dead path. It might be preferable to just drop s_umount over ->fill_super entirely, but that will require a fairly massive audit first, so we'll do the easy version here first. Signed-off-by: Christoph Hellwig Acked-by: Theodore Ts'o Reviewed-by: Jan Kara Reviewed-by: Christian Brauner Message-Id: <20230802154131.2221419-10-hch@lst.de> Signed-off-by: Christian Brauner --- fs/ext4/super.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index fa8888f..47e3272 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -5842,7 +5842,10 @@ static journal_t *ext4_get_dev_journal(struct super_block *sb, if (WARN_ON_ONCE(!ext4_has_feature_journal(sb))) return NULL; + /* see get_tree_bdev why this is needed and safe */ + up_write(&sb->s_umount); bdev = ext4_blkdev_get(j_dev, sb); + down_write(&sb->s_umount); if (bdev == NULL) return NULL; -- 2.7.4