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Commit a9e9acae authored by Xue jiufei's avatar Xue jiufei Committed by Linus Torvalds
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ocfs2: fix umount hang while shutting down truncate log 



Revert commit 75f82eaa ("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: default avatarjoyce.xue <xuejiufei@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c253ed1f

fs/ocfs2/alloc.c

+5 −1
Original line number Diff line number Diff line
@@ -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;

fs/ocfs2/ocfs2.h

+1 −0
Original line number Diff line number Diff line
@@ -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.