From f759741d9d913eb57784a94b9bca78b376fc26a9 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Thu, 23 Mar 2017 01:37:00 +0100 Subject: block: Fix oops in locked_inode_to_wb_and_lock_list() When block device is closed, we call inode_detach_wb() in __blkdev_put() which sets inode->i_wb to NULL. That is contrary to expectations that inode->i_wb stays valid once set during the whole inode's lifetime and leads to oops in wb_get() in locked_inode_to_wb_and_lock_list() because inode_to_wb() returned NULL. The reason why we called inode_detach_wb() is not valid anymore though. BDI is guaranteed to stay along until we call bdi_put() from bdev_evict_inode() so we can postpone calling inode_detach_wb() to that moment. Also add a warning to catch if someone uses inode_detach_wb() in a dangerous way. Reported-by: Thiago Jung Bauermann Acked-by: Tejun Heo Signed-off-by: Jan Kara Signed-off-by: Jens Axboe --- include/linux/writeback.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/writeback.h b/include/linux/writeback.h index a3c0cbd7c888..d5815794416c 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -237,6 +237,7 @@ static inline void inode_attach_wb(struct inode *inode, struct page *page) static inline void inode_detach_wb(struct inode *inode) { if (inode->i_wb) { + WARN_ON_ONCE(!(inode->i_state & I_CLEAR)); wb_put(inode->i_wb); inode->i_wb = NULL; } -- cgit v1.2.3-71-gd317