[Ocfs2-devel] [PATCH 0/6 v3] ocfs2: Avoid pending orphaned inodes

[Ocfs2-devel] [PATCH 0/6 v3] ocfs2: Avoid pending orphaned inodes

[Jan Kara]

  Hello,

  here is the third version of my patchset to solve deadlocks when we do not
defer dropping of inode reference from downconvert worker. I have tested the
patches (also with lockdep enabled) and they seem to work fine. Comments are
welcome!

Changes since v2:
- Added Reviewed-by tags
- Modified special handling of downconvert thread in
  ocfs2_mark_lockres_freeing() to use generic unblocking function instead of
  opencoding it.


								Honza

[Ocfs2-devel] [PATCH 1/6] ocfs2: Remove OCFS2_INODE_SKIP_DELETE flag

[Jan Kara]

The flag was never set, delete it.

Reviewed-by: Srinivas Eeda <srinivas.eeda@oracle.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ocfs2/inode.c   | 6 ------
 fs/ocfs2/inode.h   | 8 +++-----
 fs/ocfs2/journal.c | 6 ------
 3 files changed, 3 insertions(+), 17 deletions(-)

diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index f29a90fde619..b4baaefe4dd4 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -822,12 +822,6 @@ static int ocfs2_inode_is_valid_to_delete(struct inode *inode)
 		goto bail_unlock;
 	}
 
-	/* If we have allowd wipe of this inode for another node, it
-	 * will be marked here so we can safely skip it. Recovery will
-	 * cleanup any inodes we might inadvertently skip here. */
-	if (oi->ip_flags & OCFS2_INODE_SKIP_DELETE)
-		goto bail_unlock;
-
 	ret = 1;
 bail_unlock:
 	spin_unlock(&oi->ip_lock);
diff --git a/fs/ocfs2/inode.h b/fs/ocfs2/inode.h
index 621fc73bf23d..f60bc314ee0a 100644
--- a/fs/ocfs2/inode.h
+++ b/fs/ocfs2/inode.h
@@ -84,8 +84,6 @@ struct ocfs2_inode_info
 #define OCFS2_INODE_BITMAP		0x00000004
 /* This inode has been wiped from disk */
 #define OCFS2_INODE_DELETED		0x00000008
-/* Another node is deleting, so our delete is a nop */
-#define OCFS2_INODE_SKIP_DELETE		0x00000010
 /* Has the inode been orphaned on another node?
  *
  * This hints to ocfs2_drop_inode that it should clear i_nlink before
@@ -100,11 +98,11 @@ struct ocfs2_inode_info
  * rely on ocfs2_delete_inode to sort things out under the proper
  * cluster locks.
  */
-#define OCFS2_INODE_MAYBE_ORPHANED	0x00000020
+#define OCFS2_INODE_MAYBE_ORPHANED	0x00000010
 /* Does someone have the file open O_DIRECT */
-#define OCFS2_INODE_OPEN_DIRECT		0x00000040
+#define OCFS2_INODE_OPEN_DIRECT		0x00000020
 /* Tell the inode wipe code it's not in orphan dir */
-#define OCFS2_INODE_SKIP_ORPHAN_DIR     0x00000080
+#define OCFS2_INODE_SKIP_ORPHAN_DIR     0x00000040
 
 static inline struct ocfs2_inode_info *OCFS2_I(struct inode *inode)
 {
diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index 44fc3e530c3d..03ea9314fecd 100644
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -2132,12 +2132,6 @@ static int ocfs2_recover_orphans(struct ocfs2_super *osb,
 		iter = oi->ip_next_orphan;
 
 		spin_lock(&oi->ip_lock);
-		/* The remote delete code may have set these on the
-		 * assumption that the other node would wipe them
-		 * successfully.  If they are still in the node's
-		 * orphan dir, we need to reset that state. */
-		oi->ip_flags &= ~(OCFS2_INODE_DELETED|OCFS2_INODE_SKIP_DELETE);
-
 		/* Set the proper information to get us going into
 		 * ocfs2_delete_inode. */
 		oi->ip_flags |= OCFS2_INODE_MAYBE_ORPHANED;
-- 
1.8.1.4

[Ocfs2-devel] [PATCH 1/6] ocfs2: Remove OCFS2_INODE_SKIP_DELETE flag

[Mark Fasheh]

On Fri, Feb 21, 2014 at 10:44:59AM +0100, Jan Kara wrote:
> The flag was never set, delete it.
> 
> Reviewed-by: Srinivas Eeda <srinivas.eeda@oracle.com>
> Signed-off-by: Jan Kara <jack@suse.cz>

< ok, that was easy :) >

Reviewed-by: Mark Fasheh <mfasheh@suse.de>
	--Mark

--
Mark Fasheh

[Ocfs2-devel] [PATCH 2/6] ocfs2: Move dquot_initialize() in ocfs2_delete_inode() somewhat later

[Jan Kara]

Move dquot_initalize() call in ocfs2_delete_inode() after the moment we
verify inode is actually a sane one to delete. We certainly don't want
to initialize quota for system inodes etc. This also avoids calling into
quota code from downconvert thread.

Add more details into the comment why bailing out from
ocfs2_delete_inode() when we are in downconvert thread is OK.

Reviewed-by: Srinivas Eeda <srinivas.eeda@oracle.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ocfs2/inode.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index b4baaefe4dd4..3b0d722de35e 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -804,11 +804,13 @@ static int ocfs2_inode_is_valid_to_delete(struct inode *inode)
 		goto bail;
 	}
 
-	/* If we're coming from downconvert_thread we can't go into our own
-	 * voting [hello, deadlock city!], so unforuntately we just
-	 * have to skip deleting this guy. That's OK though because
-	 * the node who's doing the actual deleting should handle it
-	 * anyway. */
+	/*
+	 * If we're coming from downconvert_thread we can't go into our own
+	 * voting [hello, deadlock city!] so we cannot delete the inode. But
+	 * since we dropped last inode ref when downconverting dentry lock,
+	 * we cannot have the file open and thus the node doing unlink will
+	 * take care of deleting the inode.
+	 */
 	if (current == osb->dc_task)
 		goto bail;
 
@@ -954,8 +956,6 @@ static void ocfs2_delete_inode(struct inode *inode)
 	if (is_bad_inode(inode) || !OCFS2_I(inode)->ip_blkno)
 		goto bail;
 
-	dquot_initialize(inode);
-
 	if (!ocfs2_inode_is_valid_to_delete(inode)) {
 		/* It's probably not necessary to truncate_inode_pages
 		 * here but we do it for safety anyway (it will most
@@ -964,6 +964,8 @@ static void ocfs2_delete_inode(struct inode *inode)
 		goto bail;
 	}
 
+	dquot_initialize(inode);
+
 	/* We want to block signals in delete_inode as the lock and
 	 * messaging paths may return us -ERESTARTSYS. Which would
 	 * cause us to exit early, resulting in inodes being orphaned
-- 
1.8.1.4

[Ocfs2-devel] [PATCH 2/6] ocfs2: Move dquot_initialize() in ocfs2_delete_inode() somewhat later

[Mark Fasheh]

On Fri, Feb 21, 2014 at 10:45:00AM +0100, Jan Kara wrote:
> Move dquot_initalize() call in ocfs2_delete_inode() after the moment we
> verify inode is actually a sane one to delete. We certainly don't want
> to initialize quota for system inodes etc. This also avoids calling into
> quota code from downconvert thread.
> 
> Add more details into the comment why bailing out from
> ocfs2_delete_inode() when we are in downconvert thread is OK.
> 
> Reviewed-by: Srinivas Eeda <srinivas.eeda@oracle.com>
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
>  fs/ocfs2/inode.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)

Reviewed-by: Mark Fasheh <mfasheh@suse.de>

--
Mark Fasheh

[Ocfs2-devel] [PATCH 3/6] quota: Provide function to grab quota structure reference

[Jan Kara]

Provide dqgrab() function to get quota structure reference when we are
sure it already has at least one active reference. Make use of this
function inside quota code.

Reviewed-by: Srinivas Eeda <srinivas.eeda@oracle.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/quota/dquot.c         | 4 ++--
 include/linux/quotaops.h | 8 ++++++++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 831d49a4111f..e3f09e34d0b2 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -528,7 +528,7 @@ restart:
 		if (atomic_read(&dquot->dq_count)) {
 			DEFINE_WAIT(wait);
 
-			atomic_inc(&dquot->dq_count);
+			dqgrab(dquot);
 			prepare_to_wait(&dquot->dq_wait_unused, &wait,
 					TASK_UNINTERRUPTIBLE);
 			spin_unlock(&dq_list_lock);
@@ -624,7 +624,7 @@ int dquot_writeback_dquots(struct super_block *sb, int type)
 			/* Now we have active dquot from which someone is
  			 * holding reference so we can safely just increase
 			 * use count */
-			atomic_inc(&dquot->dq_count);
+			dqgrab(dquot);
 			spin_unlock(&dq_list_lock);
 			dqstats_inc(DQST_LOOKUPS);
 			err = sb->dq_op->write_dquot(dquot);
diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h
index 6965fe394c3b..1d3eee594cd6 100644
--- a/include/linux/quotaops.h
+++ b/include/linux/quotaops.h
@@ -46,6 +46,14 @@ void inode_reclaim_rsv_space(struct inode *inode, qsize_t number);
 void dquot_initialize(struct inode *inode);
 void dquot_drop(struct inode *inode);
 struct dquot *dqget(struct super_block *sb, struct kqid qid);
+static inline struct dquot *dqgrab(struct dquot *dquot)
+{
+	/* Make sure someone else has active reference to dquot */
+	WARN_ON_ONCE(!atomic_read(&dquot->dq_count));
+	WARN_ON_ONCE(!test_bit(DQ_ACTIVE_B, &dquot->dq_flags));
+	atomic_inc(&dquot->dq_count);
+	return dquot;
+}
 void dqput(struct dquot *dquot);
 int dquot_scan_active(struct super_block *sb,
 		      int (*fn)(struct dquot *dquot, unsigned long priv),
-- 
1.8.1.4

[Ocfs2-devel] [PATCH 3/6] quota: Provide function to grab quota structure reference

[Mark Fasheh]

On Fri, Feb 21, 2014 at 10:45:01AM +0100, Jan Kara wrote:
> Provide dqgrab() function to get quota structure reference when we are
> sure it already has at least one active reference. Make use of this
> function inside quota code.
> 
> Reviewed-by: Srinivas Eeda <srinivas.eeda@oracle.com>
> Signed-off-by: Jan Kara <jack@suse.cz>

Reviewed-by: Mark Fasheh <mfasheh@suse.de>
	--Mark

--
Mark Fasheh

[Ocfs2-devel] [PATCH 4/6] ocfs2: Implement delayed dropping of last dquot reference

[Jan Kara]

We cannot drop last dquot reference from downconvert thread as that
creates the following deadlock:

NODE 1                                  NODE2
holds dentry lock for 'foo'
holds inode lock for GLOBAL_BITMAP_SYSTEM_INODE
                                        dquot_initialize(bar)
                                          ocfs2_dquot_acquire()
                                            ocfs2_inode_lock(USER_QUOTA_SYSTEM_INODE)
                                            ...
downconvert thread (triggered from another
node or a different process from NODE2)
  ocfs2_dentry_post_unlock()
    ...
    iput(foo)
      ocfs2_evict_inode(foo)
        ocfs2_clear_inode(foo)
          dquot_drop(inode)
            ...
	    ocfs2_dquot_release()
              ocfs2_inode_lock(USER_QUOTA_SYSTEM_INODE)
               - blocks
                                            finds we need more space in
                                            quota file
                                            ...
                                            ocfs2_extend_no_holes()
                                              ocfs2_inode_lock(GLOBAL_BITMAP_SYSTEM_INODE)
                                                - deadlocks waiting for
                                                  downconvert thread

We solve the problem by postponing dropping of the last dquot reference
to a workqueue if it happens from the downconvert thread.

Reviewed-by: Srinivas Eeda <srinivas.eeda@oracle.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ocfs2/ocfs2.h        |  5 +++++
 fs/ocfs2/quota.h        |  2 ++
 fs/ocfs2/quota_global.c | 35 +++++++++++++++++++++++++++++++++++
 fs/ocfs2/super.c        |  8 ++++++++
 4 files changed, 50 insertions(+)

diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index 553f53cc73ae..64c02239ba46 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -30,6 +30,7 @@
 #include <linux/sched.h>
 #include <linux/wait.h>
 #include <linux/list.h>
+#include <linux/llist.h>
 #include <linux/rbtree.h>
 #include <linux/workqueue.h>
 #include <linux/kref.h>
@@ -419,6 +420,10 @@ struct ocfs2_super
 	struct ocfs2_dentry_lock *dentry_lock_list;
 	struct work_struct dentry_lock_work;
 
+	/* List of dquot structures to drop last reference to */
+	struct llist_head dquot_drop_list;
+	struct work_struct dquot_drop_work;
+
 	wait_queue_head_t		osb_mount_event;
 
 	/* Truncate log info */
diff --git a/fs/ocfs2/quota.h b/fs/ocfs2/quota.h
index d5ab56cbe5c5..f266d67df3c6 100644
--- a/fs/ocfs2/quota.h
+++ b/fs/ocfs2/quota.h
@@ -28,6 +28,7 @@ struct ocfs2_dquot {
 	unsigned int dq_use_count;	/* Number of nodes having reference to this entry in global quota file */
 	s64 dq_origspace;	/* Last globally synced space usage */
 	s64 dq_originodes;	/* Last globally synced inode usage */
+	struct llist_node list;	/* Member of list of dquots to drop */
 };
 
 /* Description of one chunk to recover in memory */
@@ -110,6 +111,7 @@ int ocfs2_read_quota_phys_block(struct inode *inode, u64 p_block,
 int ocfs2_create_local_dquot(struct dquot *dquot);
 int ocfs2_local_release_dquot(handle_t *handle, struct dquot *dquot);
 int ocfs2_local_write_dquot(struct dquot *dquot);
+void ocfs2_drop_dquot_refs(struct work_struct *work);
 
 extern const struct dquot_operations ocfs2_quota_operations;
 extern struct quota_format_type ocfs2_quota_format;
diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c
index aaa50611ec66..7921e209c64b 100644
--- a/fs/ocfs2/quota_global.c
+++ b/fs/ocfs2/quota_global.c
@@ -10,6 +10,7 @@
 #include <linux/jiffies.h>
 #include <linux/writeback.h>
 #include <linux/workqueue.h>
+#include <linux/llist.h>
 
 #include <cluster/masklog.h>
 
@@ -679,6 +680,27 @@ static int ocfs2_calc_qdel_credits(struct super_block *sb, int type)
 	       OCFS2_INODE_UPDATE_CREDITS;
 }
 
+void ocfs2_drop_dquot_refs(struct work_struct *work)
+{
+	struct ocfs2_super *osb = container_of(work, struct ocfs2_super,
+					       dquot_drop_work);
+	struct llist_node *list;
+	struct ocfs2_dquot *odquot, *next_odquot;
+
+	list = llist_del_all(&osb->dquot_drop_list);
+	llist_for_each_entry_safe(odquot, next_odquot, list, list) {
+		/* Drop the reference we acquired in ocfs2_dquot_release() */
+		dqput(&odquot->dq_dquot);
+	}
+}
+
+/*
+ * Called when the last reference to dquot is dropped. If we are called from
+ * downconvert thread, we cannot do all the handling here because grabbing
+ * quota lock could deadlock (the node holding the quota lock could need some
+ * other cluster lock to proceed but with blocked downconvert thread we cannot
+ * release any lock).
+ */
 static int ocfs2_release_dquot(struct dquot *dquot)
 {
 	handle_t *handle;
@@ -694,6 +716,19 @@ static int ocfs2_release_dquot(struct dquot *dquot)
 	/* Check whether we are not racing with some other dqget() */
 	if (atomic_read(&dquot->dq_count) > 1)
 		goto out;
+	/* Running from downconvert thread? Postpone quota processing to wq */
+	if (current == osb->dc_task) {
+		/*
+		 * Grab our own reference to dquot and queue it for delayed
+		 * dropping.  Quota code rechecks after calling
+		 * ->release_dquot() and won't free dquot structure.
+		 */
+		dqgrab(dquot);
+		/* First entry on list -> queue work */
+		if (llist_add(&OCFS2_DQUOT(dquot)->list, &osb->dquot_drop_list))
+			queue_work(ocfs2_wq, &osb->dquot_drop_work);
+		goto out;
+	}
 	status = ocfs2_lock_global_qf(oinfo, 1);
 	if (status < 0)
 		goto out;
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index 49d84f80f36c..0a8972deae2b 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -1943,6 +1943,11 @@ static void ocfs2_dismount_volume(struct super_block *sb, int mnt_err)
 
 	ocfs2_disable_quotas(osb);
 
+	/* All dquots should be freed by now */
+	WARN_ON(!llist_empty(&osb->dquot_drop_list));
+	/* Wait for worker to be done with the work structure in osb */
+	cancel_work_sync(&osb->dquot_drop_work);
+
 	ocfs2_shutdown_local_alloc(osb);
 
 	/* This will disable recovery and flush any recovery work. */
@@ -2279,6 +2284,9 @@ static int ocfs2_initialize_super(struct super_block *sb,
 	INIT_WORK(&osb->dentry_lock_work, ocfs2_drop_dl_inodes);
 	osb->dentry_lock_list = NULL;
 
+	INIT_WORK(&osb->dquot_drop_work, ocfs2_drop_dquot_refs);
+	init_llist_head(&osb->dquot_drop_list);
+
 	/* get some pseudo constants for clustersize bits */
 	osb->s_clustersize_bits =
 		le32_to_cpu(di->id2.i_super.s_clustersize_bits);
-- 
1.8.1.4

[Ocfs2-devel] [PATCH 4/6] ocfs2: Implement delayed dropping of last dquot reference

[Mark Fasheh]

On Fri, Feb 21, 2014 at 10:45:02AM +0100, Jan Kara wrote:
> We cannot drop last dquot reference from downconvert thread as that
> creates the following deadlock:
> 
> NODE 1                                  NODE2
> holds dentry lock for 'foo'
> holds inode lock for GLOBAL_BITMAP_SYSTEM_INODE
>                                         dquot_initialize(bar)
>                                           ocfs2_dquot_acquire()
>                                             ocfs2_inode_lock(USER_QUOTA_SYSTEM_INODE)
>                                             ...
> downconvert thread (triggered from another
> node or a different process from NODE2)
>   ocfs2_dentry_post_unlock()
>     ...
>     iput(foo)
>       ocfs2_evict_inode(foo)
>         ocfs2_clear_inode(foo)
>           dquot_drop(inode)
>             ...
> 	    ocfs2_dquot_release()
>               ocfs2_inode_lock(USER_QUOTA_SYSTEM_INODE)
>                - blocks
>                                             finds we need more space in
>                                             quota file
>                                             ...
>                                             ocfs2_extend_no_holes()
>                                               ocfs2_inode_lock(GLOBAL_BITMAP_SYSTEM_INODE)
>                                                 - deadlocks waiting for
>                                                   downconvert thread
> 
> We solve the problem by postponing dropping of the last dquot reference
> to a workqueue if it happens from the downconvert thread.
> 
> Reviewed-by: Srinivas Eeda <srinivas.eeda@oracle.com>
> Signed-off-by: Jan Kara <jack@suse.cz>

Looks good, I especially like the usuage of llist.

Reviewed-by: Mark Fasheh <mfasheh@suse.de>
	--Mark

--
Mark Fasheh

[Ocfs2-devel] [PATCH 5/6] ocfs2: Avoid blocking in ocfs2_mark_lockres_freeing() in downconvert thread

[Jan Kara]

If we are dropping last inode reference from downconvert thread, we will
end up calling ocfs2_mark_lockres_freeing() which can block if the lock
we are freeing is queued thus creating an A-A deadlock. Luckily, since
we are the downconvert thread, we can immediately dequeue the lock and
thus avoid waiting in this case.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ocfs2/dlmglue.c | 42 +++++++++++++++++++++++++++++++++++++++---
 fs/ocfs2/dlmglue.h |  3 ++-
 fs/ocfs2/inode.c   |  7 ++++---
 3 files changed, 45 insertions(+), 7 deletions(-)

diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 19986959d149..43d5e65b1e09 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -3150,16 +3150,51 @@ out:
  * it safe to drop.
  *
  * You can *not* attempt to call cluster_lock on this lockres anymore. */
-void ocfs2_mark_lockres_freeing(struct ocfs2_lock_res *lockres)
+void ocfs2_mark_lockres_freeing(struct ocfs2_super *osb,
+				struct ocfs2_lock_res *lockres)
 {
 	int status;
 	struct ocfs2_mask_waiter mw;
-	unsigned long flags;
+	unsigned long flags, flags2;
 
 	ocfs2_init_mask_waiter(&mw);
 
 	spin_lock_irqsave(&lockres->l_lock, flags);
 	lockres->l_flags |= OCFS2_LOCK_FREEING;
+	if (lockres->l_flags & OCFS2_LOCK_QUEUED && current == osb->dc_task) {
+		/*
+		 * We know the downconvert is queued but not in progress
+		 * because we are the downconvert thread and processing
+		 * different lock. So we can just remove the lock from the
+		 * queue. This is not only an optimization but also a way
+		 * to avoid the following deadlock:
+		 *   ocfs2_dentry_post_unlock()
+		 *     ocfs2_dentry_lock_put()
+		 *       ocfs2_drop_dentry_lock()
+		 *         iput()
+		 *           ocfs2_evict_inode()
+		 *             ocfs2_clear_inode()
+		 *               ocfs2_mark_lockres_freeing()
+		 *                 ... blocks waiting for OCFS2_LOCK_QUEUED
+		 *                 since we are the downconvert thread which
+		 *                 should clear the flag.
+		 */
+		spin_unlock_irqrestore(&lockres->l_lock, flags);
+		spin_lock_irqsave(&osb->dc_task_lock, flags2);
+		list_del_init(&lockres->l_blocked_list);
+		osb->blocked_lock_count--;
+		spin_unlock_irqrestore(&osb->dc_task_lock, flags2);
+		/*
+		 * Warn if we recurse into another post_unlock call.  Strictly
+		 * speaking it isn't a problem but we need to be careful if
+		 * that happens (stack overflow, deadlocks, ...) so warn if
+		 * ocfs2 grows a path for which this can happen.
+		 */
+		WARN_ON_ONCE(lockres->l_ops->post_unlock);
+		/* Since the lock is freeing we don't do much in the fn below */
+		ocfs2_process_blocked_lock(osb, lockres);
+		return;
+	}
 	while (lockres->l_flags & OCFS2_LOCK_QUEUED) {
 		lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_QUEUED, 0);
 		spin_unlock_irqrestore(&lockres->l_lock, flags);
@@ -3172,6 +3207,7 @@ void ocfs2_mark_lockres_freeing(struct ocfs2_lock_res *lockres)
 
 		spin_lock_irqsave(&lockres->l_lock, flags);
 	}
+out_unlock:
 	spin_unlock_irqrestore(&lockres->l_lock, flags);
 }
 
@@ -3180,7 +3216,7 @@ void ocfs2_simple_drop_lockres(struct ocfs2_super *osb,
 {
 	int ret;
 
-	ocfs2_mark_lockres_freeing(lockres);
+	ocfs2_mark_lockres_freeing(osb, lockres);
 	ret = ocfs2_drop_lock(osb, lockres);
 	if (ret)
 		mlog_errno(ret);
diff --git a/fs/ocfs2/dlmglue.h b/fs/ocfs2/dlmglue.h
index 1d596d8c4a4a..d293a22c32c5 100644
--- a/fs/ocfs2/dlmglue.h
+++ b/fs/ocfs2/dlmglue.h
@@ -157,7 +157,8 @@ int ocfs2_refcount_lock(struct ocfs2_refcount_tree *ref_tree, int ex);
 void ocfs2_refcount_unlock(struct ocfs2_refcount_tree *ref_tree, int ex);
 
 
-void ocfs2_mark_lockres_freeing(struct ocfs2_lock_res *lockres);
+void ocfs2_mark_lockres_freeing(struct ocfs2_super *osb,
+				struct ocfs2_lock_res *lockres);
 void ocfs2_simple_drop_lockres(struct ocfs2_super *osb,
 			       struct ocfs2_lock_res *lockres);
 
diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index 3b0d722de35e..9661f8db21dc 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -1053,6 +1053,7 @@ static void ocfs2_clear_inode(struct inode *inode)
 {
 	int status;
 	struct ocfs2_inode_info *oi = OCFS2_I(inode);
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
 	clear_inode(inode);
 	trace_ocfs2_clear_inode((unsigned long long)oi->ip_blkno,
@@ -1069,9 +1070,9 @@ static void ocfs2_clear_inode(struct inode *inode)
 
 	/* Do these before all the other work so that we don't bounce
 	 * the downconvert thread while waiting to destroy the locks. */
-	ocfs2_mark_lockres_freeing(&oi->ip_rw_lockres);
-	ocfs2_mark_lockres_freeing(&oi->ip_inode_lockres);
-	ocfs2_mark_lockres_freeing(&oi->ip_open_lockres);
+	ocfs2_mark_lockres_freeing(osb, &oi->ip_rw_lockres);
+	ocfs2_mark_lockres_freeing(osb, &oi->ip_inode_lockres);
+	ocfs2_mark_lockres_freeing(osb, &oi->ip_open_lockres);
 
 	ocfs2_resv_discard(&OCFS2_SB(inode->i_sb)->osb_la_resmap,
 			   &oi->ip_la_data_resv);
-- 
1.8.1.4

[Ocfs2-devel] [PATCH 5/6] ocfs2: Avoid blocking in ocfs2_mark_lockres_freeing() in downconvert thread

[Mark Fasheh]

On Fri, Feb 21, 2014 at 10:45:03AM +0100, Jan Kara wrote:
> If we are dropping last inode reference from downconvert thread, we will
> end up calling ocfs2_mark_lockres_freeing() which can block if the lock
> we are freeing is queued thus creating an A-A deadlock. Luckily, since
> we are the downconvert thread, we can immediately dequeue the lock and
> thus avoid waiting in this case.
> 
> Signed-off-by: Jan Kara <jack@suse.cz>

Latest version of this looks good, thanks Jan!

Reviewed-by: Mark Fasheh <mfasheh@suse.de>
	--Mark

--
Mark Fasheh

[Ocfs2-devel] [PATCH 5/6] ocfs2: Avoid blocking in ocfs2_mark_lockres_freeing() in downconvert thread

[Srinivas Eeda]

On 02/25/2014 11:12 AM, Mark Fasheh wrote:
> On Fri, Feb 21, 2014 at 10:45:03AM +0100, Jan Kara wrote:
>> If we are dropping last inode reference from downconvert thread, we will
>> end up calling ocfs2_mark_lockres_freeing() which can block if the lock
>> we are freeing is queued thus creating an A-A deadlock. Luckily, since
>> we are the downconvert thread, we can immediately dequeue the lock and
>> thus avoid waiting in this case.
>>
>> Signed-off-by: Jan Kara <jack@suse.cz>
> Latest version of this looks good, thanks Jan!
>
> Reviewed-by: Mark Fasheh <mfasheh@suse.de>
> 	--Mark
I didn't sent my reviewed by as akpm already queued this patch. But yes 
the new version looks good to me.

Reviewed-by: Srinivas Eeda<srinivas.eeda@oracle.com>

> --
> Mark Fasheh

[Ocfs2-devel] [PATCH 6/6] ocfs2: Revert iput deferring code in ocfs2_drop_dentry_lock

[Jan Kara]

From: Goldwyn Rodrigues <rgoldwyn@suse.de>

The following patches are reverted in this patch because these
patches caused performance regression in the remote unlink() calls.

ea455f8ab68338ba69f5d3362b342c115bea8e13 - ocfs2: Push out dropping
of dentry lock to ocfs2_wq
f7b1aa69be138ad9d7d3f31fa56f4c9407f56b6a - ocfs2: Fix deadlock on umount
5fd131893793567c361ae64cbeb28a2a753bbe35 - ocfs2: Don't oops in
ocfs2_kill_sb on a failed mount

Previous patches in this series removed the possible deadlocks from
downconvert thread so the above patches shouldn't be needed anymore.

The regression is caused because these patches delay the iput() in case
of dentry unlocks. This also delays the unlocking of the open lockres.
The open lockresource is required to test if the inode can be wiped from
disk or not. When the deleting node does not get the open lock, it marks
it as orphan (even though it is not in use by another node/process)
and causes a journal checkpoint. This delays operations following the
inode eviction. This also moves the inode to the orphaned inode
which further causes more I/O and a lot of unneccessary orphans.

The following script can be used to generate the load causing issues:
declare -a create
declare -a remove
declare -a iterations=(1 2 4 8 16 32 64 128 256 512 1024 2048 4096 8192 16384)
unique="`mktemp -u XXXXX`"
script="/tmp/idontknow-${unique}.sh"
cat <<EOF > "${script}"
for n in {1..8}; do mkdir -p test/dir\${n}
  eval touch test/dir\${n}/foo{1.."\$1"}
done
EOF
chmod 700 "${script}"

function fcreate ()
{
  exec 2>&1 /usr/bin/time --format=%E "${script}" "$1"
}

function fremove ()
{
  exec 2>&1 /usr/bin/time --format=%E ssh node2 "cd `pwd`; rm -Rf test*"
}

function fcp ()
{
  exec 2>&1 /usr/bin/time --format=%E ssh node3 "cd `pwd`; cp -R test test.new"
}

echo -------------------------------------------------
echo "| # files | create #s | copy #s | remove #s |"
echo -------------------------------------------------
for ((x=0; x < ${#iterations[*]} ; x++)) do
  create[$x]="`fcreate ${iterations[$x]}`"
  copy[$x]="`fcp ${iterations[$x]}`"
  remove[$x]="`fremove`"
  printf "| %8d | %9s | %9s | %9s |\n" ${iterations[$x]} ${create[$x]} ${copy[$x]} ${remove[$x]}
done
rm "${script}"
echo "------------------------"

Signed-off-by: Srinivas Eeda <srinivas.eeda@oracle.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ocfs2/dcache.c | 61 +++----------------------------------------------------
 fs/ocfs2/dcache.h | 12 +----------
 fs/ocfs2/ocfs2.h  | 28 ++++---------------------
 fs/ocfs2/super.c  | 30 +--------------------------
 4 files changed, 9 insertions(+), 122 deletions(-)

diff --git a/fs/ocfs2/dcache.c b/fs/ocfs2/dcache.c
index 0d3a97d2d5f6..e2e05a106beb 100644
--- a/fs/ocfs2/dcache.c
+++ b/fs/ocfs2/dcache.c
@@ -37,7 +37,6 @@
 #include "dlmglue.h"
 #include "file.h"
 #include "inode.h"
-#include "super.h"
 #include "ocfs2_trace.h"
 
 void ocfs2_dentry_attach_gen(struct dentry *dentry)
@@ -346,52 +345,6 @@ out_attach:
 	return ret;
 }
 
-DEFINE_SPINLOCK(dentry_list_lock);
-
-/* We limit the number of dentry locks to drop in one go. We have
- * this limit so that we don't starve other users of ocfs2_wq. */
-#define DL_INODE_DROP_COUNT 64
-
-/* Drop inode references from dentry locks */
-static void __ocfs2_drop_dl_inodes(struct ocfs2_super *osb, int drop_count)
-{
-	struct ocfs2_dentry_lock *dl;
-
-	spin_lock(&dentry_list_lock);
-	while (osb->dentry_lock_list && (drop_count < 0 || drop_count--)) {
-		dl = osb->dentry_lock_list;
-		osb->dentry_lock_list = dl->dl_next;
-		spin_unlock(&dentry_list_lock);
-		iput(dl->dl_inode);
-		kfree(dl);
-		spin_lock(&dentry_list_lock);
-	}
-	spin_unlock(&dentry_list_lock);
-}
-
-void ocfs2_drop_dl_inodes(struct work_struct *work)
-{
-	struct ocfs2_super *osb = container_of(work, struct ocfs2_super,
-					       dentry_lock_work);
-
-	__ocfs2_drop_dl_inodes(osb, DL_INODE_DROP_COUNT);
-	/*
-	 * Don't queue dropping if umount is in progress. We flush the
-	 * list in ocfs2_dismount_volume
-	 */
-	spin_lock(&dentry_list_lock);
-	if (osb->dentry_lock_list &&
-	    !ocfs2_test_osb_flag(osb, OCFS2_OSB_DROP_DENTRY_LOCK_IMMED))
-		queue_work(ocfs2_wq, &osb->dentry_lock_work);
-	spin_unlock(&dentry_list_lock);
-}
-
-/* Flush the whole work queue */
-void ocfs2_drop_all_dl_inodes(struct ocfs2_super *osb)
-{
-	__ocfs2_drop_dl_inodes(osb, -1);
-}
-
 /*
  * ocfs2_dentry_iput() and friends.
  *
@@ -416,24 +369,16 @@ void ocfs2_drop_all_dl_inodes(struct ocfs2_super *osb)
 static void ocfs2_drop_dentry_lock(struct ocfs2_super *osb,
 				   struct ocfs2_dentry_lock *dl)
 {
+	iput(dl->dl_inode);
 	ocfs2_simple_drop_lockres(osb, &dl->dl_lockres);
 	ocfs2_lock_res_free(&dl->dl_lockres);
-
-	/* We leave dropping of inode reference to ocfs2_wq as that can
-	 * possibly lead to inode deletion which gets tricky */
-	spin_lock(&dentry_list_lock);
-	if (!osb->dentry_lock_list &&
-	    !ocfs2_test_osb_flag(osb, OCFS2_OSB_DROP_DENTRY_LOCK_IMMED))
-		queue_work(ocfs2_wq, &osb->dentry_lock_work);
-	dl->dl_next = osb->dentry_lock_list;
-	osb->dentry_lock_list = dl;
-	spin_unlock(&dentry_list_lock);
+	kfree(dl);
 }
 
 void ocfs2_dentry_lock_put(struct ocfs2_super *osb,
 			   struct ocfs2_dentry_lock *dl)
 {
-	int unlock;
+	int unlock = 0;
 
 	BUG_ON(dl->dl_count == 0);
 
diff --git a/fs/ocfs2/dcache.h b/fs/ocfs2/dcache.h
index b79eff709958..55f58892b153 100644
--- a/fs/ocfs2/dcache.h
+++ b/fs/ocfs2/dcache.h
@@ -29,13 +29,8 @@
 extern const struct dentry_operations ocfs2_dentry_ops;
 
 struct ocfs2_dentry_lock {
-	/* Use count of dentry lock */
 	unsigned int		dl_count;
-	union {
-		/* Linked list of dentry locks to release */
-		struct ocfs2_dentry_lock *dl_next;
-		u64			dl_parent_blkno;
-	};
+	u64			dl_parent_blkno;
 
 	/*
 	 * The ocfs2_dentry_lock keeps an inode reference until
@@ -49,14 +44,9 @@ struct ocfs2_dentry_lock {
 int ocfs2_dentry_attach_lock(struct dentry *dentry, struct inode *inode,
 			     u64 parent_blkno);
 
-extern spinlock_t dentry_list_lock;
-
 void ocfs2_dentry_lock_put(struct ocfs2_super *osb,
 			   struct ocfs2_dentry_lock *dl);
 
-void ocfs2_drop_dl_inodes(struct work_struct *work);
-void ocfs2_drop_all_dl_inodes(struct ocfs2_super *osb);
-
 struct dentry *ocfs2_find_local_alias(struct inode *inode, u64 parent_blkno,
 				      int skip_unhashed);
 
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index 64c02239ba46..a780e20d4fba 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -275,19 +275,16 @@ enum ocfs2_mount_options
 	OCFS2_MOUNT_HB_GLOBAL = 1 << 14, /* Global heartbeat */
 };
 
-#define OCFS2_OSB_SOFT_RO			0x0001
-#define OCFS2_OSB_HARD_RO			0x0002
-#define OCFS2_OSB_ERROR_FS			0x0004
-#define OCFS2_OSB_DROP_DENTRY_LOCK_IMMED	0x0008
-
-#define OCFS2_DEFAULT_ATIME_QUANTUM		60
+#define OCFS2_OSB_SOFT_RO	0x0001
+#define OCFS2_OSB_HARD_RO	0x0002
+#define OCFS2_OSB_ERROR_FS	0x0004
+#define OCFS2_DEFAULT_ATIME_QUANTUM	60
 
 struct ocfs2_journal;
 struct ocfs2_slot_info;
 struct ocfs2_recovery_map;
 struct ocfs2_replay_map;
 struct ocfs2_quota_recovery;
-struct ocfs2_dentry_lock;
 struct ocfs2_super
 {
 	struct task_struct *commit_task;
@@ -415,11 +412,6 @@ struct ocfs2_super
 	struct list_head blocked_lock_list;
 	unsigned long blocked_lock_count;
 
-	/* List of dentry locks to release. Anyone can add locks to
-	 * the list, ocfs2_wq processes the list  */
-	struct ocfs2_dentry_lock *dentry_lock_list;
-	struct work_struct dentry_lock_work;
-
 	/* List of dquot structures to drop last reference to */
 	struct llist_head dquot_drop_list;
 	struct work_struct dquot_drop_work;
@@ -584,18 +576,6 @@ static inline void ocfs2_set_osb_flag(struct ocfs2_super *osb,
 	spin_unlock(&osb->osb_lock);
 }
 
-
-static inline unsigned long  ocfs2_test_osb_flag(struct ocfs2_super *osb,
-						 unsigned long flag)
-{
-	unsigned long ret;
-
-	spin_lock(&osb->osb_lock);
-	ret = osb->osb_flags & flag;
-	spin_unlock(&osb->osb_lock);
-	return ret;
-}
-
 static inline void ocfs2_set_ro_flag(struct ocfs2_super *osb,
 				     int hard)
 {
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index 0a8972deae2b..5597e42eae54 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -1238,30 +1238,11 @@ static struct dentry *ocfs2_mount(struct file_system_type *fs_type,
 	return mount_bdev(fs_type, flags, dev_name, data, ocfs2_fill_super);
 }
 
-static void ocfs2_kill_sb(struct super_block *sb)
-{
-	struct ocfs2_super *osb = OCFS2_SB(sb);
-
-	/* Failed mount? */
-	if (!osb || atomic_read(&osb->vol_state) == VOLUME_DISABLED)
-		goto out;
-
-	/* Prevent further queueing of inode drop events */
-	spin_lock(&dentry_list_lock);
-	ocfs2_set_osb_flag(osb, OCFS2_OSB_DROP_DENTRY_LOCK_IMMED);
-	spin_unlock(&dentry_list_lock);
-	/* Wait for work to finish and/or remove it */
-	cancel_work_sync(&osb->dentry_lock_work);
-out:
-	kill_block_super(sb);
-}
-
 static struct file_system_type ocfs2_fs_type = {
 	.owner          = THIS_MODULE,
 	.name           = "ocfs2",
 	.mount          = ocfs2_mount,
-	.kill_sb        = ocfs2_kill_sb,
-
+	.kill_sb        = kill_block_super,
 	.fs_flags       = FS_REQUIRES_DEV|FS_RENAME_DOES_D_MOVE,
 	.next           = NULL
 };
@@ -1932,12 +1913,6 @@ static void ocfs2_dismount_volume(struct super_block *sb, int mnt_err)
 
 	debugfs_remove(osb->osb_ctxt);
 
-	/*
-	 * Flush inode dropping work queue so that deletes are
-	 * performed while the filesystem is still working
-	 */
-	ocfs2_drop_all_dl_inodes(osb);
-
 	/* Orphan scan should be stopped as early as possible */
 	ocfs2_orphan_scan_stop(osb);
 
@@ -2281,9 +2256,6 @@ static int ocfs2_initialize_super(struct super_block *sb,
 	INIT_WORK(&journal->j_recovery_work, ocfs2_complete_recovery);
 	journal->j_state = OCFS2_JOURNAL_FREE;
 
-	INIT_WORK(&osb->dentry_lock_work, ocfs2_drop_dl_inodes);
-	osb->dentry_lock_list = NULL;
-
 	INIT_WORK(&osb->dquot_drop_work, ocfs2_drop_dquot_refs);
 	init_llist_head(&osb->dquot_drop_list);
 
-- 
1.8.1.4

[Ocfs2-devel] [PATCH 6/6] ocfs2: Revert iput deferring code in ocfs2_drop_dentry_lock

[Mark Fasheh]

I think I would have preferred this be broken up to make review easier. That
said, I didn't find anything wrong with the code changes (which took me
longer to review, etc)

Reviewed-by: Mark Fasheh <mfasheh@suse.de>



On Fri, Feb 21, 2014 at 10:45:04AM +0100, Jan Kara wrote:
> From: Goldwyn Rodrigues <rgoldwyn@suse.de>
> 
> The following patches are reverted in this patch because these
> patches caused performance regression in the remote unlink() calls.
> 
> ea455f8ab68338ba69f5d3362b342c115bea8e13 - ocfs2: Push out dropping
> of dentry lock to ocfs2_wq
> f7b1aa69be138ad9d7d3f31fa56f4c9407f56b6a - ocfs2: Fix deadlock on umount
> 5fd131893793567c361ae64cbeb28a2a753bbe35 - ocfs2: Don't oops in
> ocfs2_kill_sb on a failed mount
> 
> Previous patches in this series removed the possible deadlocks from
> downconvert thread so the above patches shouldn't be needed anymore.
> 
> The regression is caused because these patches delay the iput() in case
> of dentry unlocks. This also delays the unlocking of the open lockres.
> The open lockresource is required to test if the inode can be wiped from
> disk or not. When the deleting node does not get the open lock, it marks
> it as orphan (even though it is not in use by another node/process)
> and causes a journal checkpoint. This delays operations following the
> inode eviction. This also moves the inode to the orphaned inode
> which further causes more I/O and a lot of unneccessary orphans.
> 

--
Mark Fasheh

[Ocfs2-devel] [PATCH 6/6] ocfs2: Revert iput deferring code in ocfs2_drop_dentry_lock

[Jan Kara]

On Tue 25-02-14 12:02:36, Mark Fasheh wrote:
> I think I would have preferred this be broken up to make review easier. That
> said, I didn't find anything wrong with the code changes (which took me
> longer to review, etc)
> 
> Reviewed-by: Mark Fasheh <mfasheh@suse.de>
  Thanks for review Mark!

								Honza

> On Fri, Feb 21, 2014 at 10:45:04AM +0100, Jan Kara wrote:
> > From: Goldwyn Rodrigues <rgoldwyn@suse.de>
> > 
> > The following patches are reverted in this patch because these
> > patches caused performance regression in the remote unlink() calls.
> > 
> > ea455f8ab68338ba69f5d3362b342c115bea8e13 - ocfs2: Push out dropping
> > of dentry lock to ocfs2_wq
> > f7b1aa69be138ad9d7d3f31fa56f4c9407f56b6a - ocfs2: Fix deadlock on umount
> > 5fd131893793567c361ae64cbeb28a2a753bbe35 - ocfs2: Don't oops in
> > ocfs2_kill_sb on a failed mount
> > 
> > Previous patches in this series removed the possible deadlocks from
> > downconvert thread so the above patches shouldn't be needed anymore.
> > 
> > The regression is caused because these patches delay the iput() in case
> > of dentry unlocks. This also delays the unlocking of the open lockres.
> > The open lockresource is required to test if the inode can be wiped from
> > disk or not. When the deleting node does not get the open lock, it marks
> > it as orphan (even though it is not in use by another node/process)
> > and causes a journal checkpoint. This delays operations following the
> > inode eviction. This also moves the inode to the orphaned inode
> > which further causes more I/O and a lot of unneccessary orphans.
> > 
> 
> --
> Mark Fasheh
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR