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ocfs2: fix umount hang while shutting down truncate log

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Revert commit 75f82eaa50 ("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 <xuejiufei@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Xue jiufei 2014-06-04 16:06:13 -07:00 committed by Linus Torvalds
parent c253ed1f6f
commit a9e9acaeb0
2 changed files with 6 additions and 1 deletions
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6
fs/ocfs2/alloc.c
View File

@ -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;

1
fs/ocfs2/ocfs2.h
View File

@ -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.