From a9e9acaeb0a981a6dfa54b32dd756103aeefa6a7 Mon Sep 17 00:00:00 2001 From: Xue jiufei Date: Wed, 4 Jun 2014 16:06:13 -0700 Subject: [PATCH] ocfs2: fix umount hang while shutting down truncate log Revert commit 75f82eaa502c ("ocfs2: fix NULL pointer dereference when dismount and ocfs2rec simultaneously") because it may cause a umount hang while shutting down the truncate log. fix NULL pointer dereference when dismount and ocfs2rec simultaneously The situation is as followes: ocfs2_dismout_volume -> ocfs2_recovery_exit -> free osb->recovery_map -> ocfs2_truncate_shutdown -> lock global bitmap inode -> ocfs2_wait_for_recovery -> check whether osb->recovery_map->rm_used is zero Because osb->recovery_map is already freed, rm_used can be any other values, so it may yield umount hang. To prevent NULL pointer dereference while getting sys_root_inode, we use a osb_tl_disable flag to disable schedule osb_truncate_log_wq after truncate log shutdown. Signed-off-by: joyce.xue Cc: Mark Fasheh Cc: Joel Becker Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ocfs2/alloc.c | 6 +++++- fs/ocfs2/ocfs2.h | 1 + 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c index b4deb5f750d9..9d8fcf2f3b94 100644 --- a/fs/ocfs2/alloc.c +++ b/fs/ocfs2/alloc.c @@ -6046,7 +6046,8 @@ static void ocfs2_truncate_log_worker(struct work_struct *work) void ocfs2_schedule_truncate_log_flush(struct ocfs2_super *osb, int cancel) { - if (osb->osb_tl_inode) { + if (osb->osb_tl_inode && + atomic_read(&osb->osb_tl_disable) == 0) { /* We want to push off log flushes while truncates are * still running. */ if (cancel) @@ -6223,6 +6224,8 @@ void ocfs2_truncate_log_shutdown(struct ocfs2_super *osb) int status; struct inode *tl_inode = osb->osb_tl_inode; + atomic_set(&osb->osb_tl_disable, 1); + if (tl_inode) { cancel_delayed_work(&osb->osb_truncate_log_wq); flush_workqueue(ocfs2_wq); @@ -6254,6 +6257,7 @@ int ocfs2_truncate_log_init(struct ocfs2_super *osb) * until we're sure all is well. */ INIT_DELAYED_WORK(&osb->osb_truncate_log_wq, ocfs2_truncate_log_worker); + atomic_set(&osb->osb_tl_disable, 0); osb->osb_tl_bh = tl_bh; osb->osb_tl_inode = tl_inode; diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h index 8d64a97a9d5e..bbec539230fd 100644 --- a/fs/ocfs2/ocfs2.h +++ b/fs/ocfs2/ocfs2.h @@ -422,6 +422,7 @@ struct ocfs2_super struct inode *osb_tl_inode; struct buffer_head *osb_tl_bh; struct delayed_work osb_truncate_log_wq; + atomic_t osb_tl_disable; /* * How many clusters in our truncate log. * It must be protected by osb_tl_inode->i_mutex.