From 9c09a7cf6220a11dac0f4845b7e8925706cdc458 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 2 Aug 2023 17:41:26 +0200 Subject: fs: stop using get_super in fs_mark_dead fs_mark_dead currently uses get_super to find the superblock for the block device that is going away. This means it is limited to the main device stored in sb->s_dev, leading to a lot of code duplication for file systems that can use multiple block devices. Now that the holder for all block devices used by file systems is set to the super_block, we can instead look at that holder and then check if the file system is born and active, so do that instead. Signed-off-by: Christoph Hellwig Reviewed-by: Jan Kara Reviewed-by: Christian Brauner Message-Id: <20230802154131.2221419-8-hch@lst.de> Signed-off-by: Christian Brauner --- fs/super.c | 30 ++++++++++++++++++++++++++---- 1 file changed, 26 insertions(+), 4 deletions(-) (limited to 'fs/super.c') diff --git a/fs/super.c b/fs/super.c index 3c7e4633efeb..9cf7fc67727b 100644 --- a/fs/super.c +++ b/fs/super.c @@ -1209,17 +1209,39 @@ int get_tree_keyed(struct fs_context *fc, EXPORT_SYMBOL(get_tree_keyed); #ifdef CONFIG_BLOCK +/* + * Lock a super block that the callers holds a reference to. + * + * The caller needs to ensure that the super_block isn't being freed while + * calling this function, e.g. by holding a lock over the call to this function + * and the place that clears the pointer to the superblock used by this function + * before freeing the superblock. + */ +static bool lock_active_super(struct super_block *sb) +{ + down_read(&sb->s_umount); + if (!sb->s_root || + (sb->s_flags & (SB_ACTIVE | SB_BORN)) != (SB_ACTIVE | SB_BORN)) { + up_read(&sb->s_umount); + return false; + } + return true; +} + static void fs_mark_dead(struct block_device *bdev) { - struct super_block *sb; + struct super_block *sb = bdev->bd_holder; - sb = get_super(bdev); - if (!sb) + /* bd_holder_lock ensures that the sb isn't freed */ + lockdep_assert_held(&bdev->bd_holder_lock); + + if (!lock_active_super(sb)) return; if (sb->s_op->shutdown) sb->s_op->shutdown(sb); - drop_super(sb); + + up_read(&sb->s_umount); } static const struct blk_holder_ops fs_holder_ops = { -- cgit