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[PATCH review for 4.4 01/26] locking/lockdep: Add nest_lock integrity test

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  [PATCH review for 4.4 01/26] locking/lockdep: Add nest_lock integrity  test "Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com> - 2017-09-25 03:30 +0200
    [PATCH review for 4.4 07/26] netfilter: nf_ct_expect: Change  __nf_ct_expect_check() return value. "Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com> - 2017-09-25 03:30 +0200
    [PATCH review for 4.4 05/26] mac80211: fix power saving clients  handling in iwlwifi "Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com> - 2017-09-25 03:30 +0200
    [PATCH review for 4.4 20/26] ceph: clean up unsafe d_parent accesses  in build_dentry_path "Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com> - 2017-09-25 03:30 +0200
    [PATCH review for 4.4 10/26] f2fs: do not wait for writeback in  write_begin "Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com> - 2017-09-25 03:30 +0200
    [PATCH review for 4.4 06/26] net/mlx4_en: fix overflow in  mlx4_en_init_timestamp() "Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com> - 2017-09-25 03:30 +0200
    [PATCH review for 4.4 14/26] crypto: xts - Add ECB dependency "Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com> - 2017-09-25 03:30 +0200
    [PATCH review for 4.4 15/26] ocfs2/dlmglue: prepare tracking logic to  avoid recursive cluster lock "Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com> - 2017-09-25 03:30 +0200

#1738669 — [PATCH review for 4.4 01/26] locking/lockdep: Add nest_lock integrity test

From: Peter Zijlstra <peterz@infradead.org>

[ Upstream commit 7fb4a2cea6b18dab56d609530d077f168169ed6b ]

Boqun reported that hlock->references can overflow. Add a debug test
for that to generate a clear error when this happens.

Without this, lockdep is likely to report a mysterious failure on
unlock.

Reported-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nicolai Hähnle <Nicolai.Haehnle@amd.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
---
 kernel/locking/lockdep.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 60ace56618f6..0e2c4911ba61 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3128,10 +3128,17 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 	if (depth) {
 		hlock = curr->held_locks + depth - 1;
 		if (hlock->class_idx == class_idx && nest_lock) {
-			if (hlock->references)
+			if (hlock->references) {
+				/*
+				 * Check: unsigned int references:12, overflow.
+				 */
+				if (DEBUG_LOCKS_WARN_ON(hlock->references == (1 << 12)-1))
+					return 0;
+
 				hlock->references++;
-			else
+			} else {
 				hlock->references = 2;
+			}
 
 			return 1;
 		}
-- 
2.11.0

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#1738670 — [PATCH review for 4.4 07/26] netfilter: nf_ct_expect: Change __nf_ct_expect_check() return value.

From: Jarno Rajahalme <jarno@ovn.org>

[ Upstream commit 4b86c459c7bee3acaf92f0e2b4c6ac803eaa1a58 ]

Commit 4dee62b1b9b4 ("netfilter: nf_ct_expect: nf_ct_expect_insert()
returns void") inadvertently changed the successful return value of
nf_ct_expect_related_report() from 0 to 1 due to
__nf_ct_expect_check() returning 1 on success.  Prevent this
regression in the future by changing the return value of
__nf_ct_expect_check() to 0 on success.

Signed-off-by: Jarno Rajahalme <jarno@ovn.org>
Acked-by: Joe Stringer <joe@ovn.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
---
 net/netfilter/nf_conntrack_expect.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/nf_conntrack_expect.c b/net/netfilter/nf_conntrack_expect.c
index acf5c7b3f378..7f16d19d6198 100644
--- a/net/netfilter/nf_conntrack_expect.c
+++ b/net/netfilter/nf_conntrack_expect.c
@@ -395,7 +395,7 @@ static inline int __nf_ct_expect_check(struct nf_conntrack_expect *expect)
 	struct net *net = nf_ct_exp_net(expect);
 	struct hlist_node *next;
 	unsigned int h;
-	int ret = 1;
+	int ret = 0;
 
 	if (!master_help) {
 		ret = -ESHUTDOWN;
@@ -445,7 +445,7 @@ int nf_ct_expect_related_report(struct nf_conntrack_expect *expect,
 
 	spin_lock_bh(&nf_conntrack_expect_lock);
 	ret = __nf_ct_expect_check(expect);
-	if (ret <= 0)
+	if (ret < 0)
 		goto out;
 
 	ret = nf_ct_expect_insert(expect);
-- 
2.11.0

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#1738673 — [PATCH review for 4.4 05/26] mac80211: fix power saving clients handling in iwlwifi

From: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

[ Upstream commit d98937f4ea713d21e0fcc345919f86c877dd8d6f ]

iwlwifi now supports RSS and can't let mac80211 track the
PS state based on the Rx frames since they can come out of
order. iwlwifi is now advertising AP_LINK_PS, and uses
explicit notifications to teach mac80211 about the PS state
of the stations and the PS poll / uAPSD trigger frames
coming our way from the peers.

Because of that, the TIM stopped being maintained in
mac80211. I tried to fix this in commit c68df2e7be0c
("mac80211: allow using AP_LINK_PS with mac80211-generated TIM IE")
but that was later reverted by Felix in commit 6c18a6b4e799
("Revert "mac80211: allow using AP_LINK_PS with mac80211-generated TIM IE")
since it broke drivers that do not implement set_tim.

Since none of the drivers that set AP_LINK_PS have the
set_tim() handler set besides iwlwifi, I can bail out in
__sta_info_recalc_tim if AP_LINK_PS AND .set_tim is not
implemented.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
---
 net/mac80211/sta_info.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 63ea6cbac5ad..7e7b9ef29d8d 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -661,7 +661,7 @@ static void __sta_info_recalc_tim(struct sta_info *sta, bool ignore_pending)
 	}
 
 	/* No need to do anything if the driver does all */
-	if (ieee80211_hw_check(&local->hw, AP_LINK_PS))
+	if (ieee80211_hw_check(&local->hw, AP_LINK_PS) && !local->ops->set_tim)
 		return;
 
 	if (sta->dead)
-- 
2.11.0

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#1738675 — [PATCH review for 4.4 20/26] ceph: clean up unsafe d_parent accesses in build_dentry_path

From: Jeff Layton <jlayton@redhat.com>

[ Upstream commit c6b0b656ca24ede6657abb4a2cd910fa9c1879ba ]

While we hold a reference to the dentry when build_dentry_path is
called, we could end up racing with a rename that changes d_parent.
Handle that situation correctly, by using the rcu_read_lock to
ensure that the parent dentry and inode stick around long enough
to safely check ceph_snap and ceph_ino.

Link: http://tracker.ceph.com/issues/18148
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Yan, Zheng <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
---
 fs/ceph/mds_client.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index f54f77037d22..ead89489ae71 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -1845,13 +1845,18 @@ static int build_dentry_path(struct dentry *dentry,
 			     int *pfreepath)
 {
 	char *path;
+	struct inode *dir;
 
-	if (ceph_snap(d_inode(dentry->d_parent)) == CEPH_NOSNAP) {
-		*pino = ceph_ino(d_inode(dentry->d_parent));
+	rcu_read_lock();
+	dir = d_inode_rcu(dentry->d_parent);
+	if (dir && ceph_snap(dir) == CEPH_NOSNAP) {
+		*pino = ceph_ino(dir);
+		rcu_read_unlock();
 		*ppath = dentry->d_name.name;
 		*ppathlen = dentry->d_name.len;
 		return 0;
 	}
+	rcu_read_unlock();
 	path = ceph_mdsc_build_path(dentry, ppathlen, pino, 1);
 	if (IS_ERR(path))
 		return PTR_ERR(path);
-- 
2.11.0

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#1738678 — [PATCH review for 4.4 10/26] f2fs: do not wait for writeback in write_begin

From: Jaegeuk Kim <jaegeuk@kernel.org>

[ Upstream commit 86d54795c94532075d862aa0a79f0c981dab4bdd ]

Otherwise we can get livelock like below.

[79880.428136] dbench          D    0 18405  18404 0x00000000
[79880.428139] Call Trace:
[79880.428142]  __schedule+0x219/0x6b0
[79880.428144]  schedule+0x36/0x80
[79880.428147]  schedule_timeout+0x243/0x2e0
[79880.428152]  ? update_sd_lb_stats+0x16b/0x5f0
[79880.428155]  ? ktime_get+0x3c/0xb0
[79880.428157]  io_schedule_timeout+0xa6/0x110
[79880.428161]  __lock_page+0xf7/0x130
[79880.428164]  ? unlock_page+0x30/0x30
[79880.428167]  pagecache_get_page+0x16b/0x250
[79880.428171]  grab_cache_page_write_begin+0x20/0x40
[79880.428182]  f2fs_write_begin+0xa2/0xdb0 [f2fs]
[79880.428192]  ? f2fs_mark_inode_dirty_sync+0x16/0x30 [f2fs]
[79880.428197]  ? kmem_cache_free+0x79/0x200
[79880.428203]  ? __mark_inode_dirty+0x17f/0x360
[79880.428206]  generic_perform_write+0xbb/0x190
[79880.428213]  ? file_update_time+0xa4/0xf0
[79880.428217]  __generic_file_write_iter+0x19b/0x1e0
[79880.428226]  f2fs_file_write_iter+0x9c/0x180 [f2fs]
[79880.428231]  __vfs_write+0xc5/0x140
[79880.428235]  vfs_write+0xb2/0x1b0
[79880.428238]  SyS_write+0x46/0xa0
[79880.428242]  entry_SYSCALL_64_fastpath+0x1e/0xad

Fixes: cae96a5c8ab6 ("f2fs: check io submission more precisely")
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
---
 fs/f2fs/data.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 972eab7ac071..98b2fc2678ff 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1416,7 +1416,12 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
 			goto fail;
 	}
 repeat:
-	page = grab_cache_page_write_begin(mapping, index, flags);
+	/*
+	 * Do not use grab_cache_page_write_begin() to avoid deadlock due to
+	 * wait_for_stable_page. Will wait that below with our IO control.
+	 */
+	page = pagecache_get_page(mapping, index,
+				FGP_LOCK | FGP_WRITE | FGP_CREAT, GFP_NOFS);
 	if (!page) {
 		err = -ENOMEM;
 		goto fail;
-- 
2.11.0

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#1738679 — [PATCH review for 4.4 06/26] net/mlx4_en: fix overflow in mlx4_en_init_timestamp()

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 47d3a07528ecbbccf53bc4390d70b4e3d1c04fcf ]

The cited commit makes a great job of finding optimal shift/multiplier
values assuming a 10 seconds wrap around, but forgot to change the
overflow_period computation.

It overflows in cyclecounter_cyc2ns(), and the final result is 804 ms,
which is silly.

Lets simply use 5 seconds, no need to recompute this, given how it is
supposed to work.

Later, we will use a timer instead of a work queue, since the new RX
allocation schem will no longer need mlx4_en_recover_from_oom() and the
service_task firing every 250 ms.

Fixes: 31c128b66e5b ("net/mlx4_en: Choose time-stamping shift value according to HW frequency")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Tariq Toukan <tariqt@mellanox.com>
Cc: Eugenia Emantayev <eugenia@mellanox.com>
Reviewed-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
---
 drivers/net/ethernet/mellanox/mlx4/en_clock.c | 18 ++++++++----------
 drivers/net/ethernet/mellanox/mlx4/mlx4_en.h  |  1 -
 2 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_clock.c b/drivers/net/ethernet/mellanox/mlx4/en_clock.c
index 1494997c4f7e..4dccf7287f0f 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_clock.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_clock.c
@@ -88,10 +88,17 @@ void mlx4_en_remove_timestamp(struct mlx4_en_dev *mdev)
 	}
 }
 
+#define MLX4_EN_WRAP_AROUND_SEC	10UL
+/* By scheduling the overflow check every 5 seconds, we have a reasonably
+ * good chance we wont miss a wrap around.
+ * TOTO: Use a timer instead of a work queue to increase the guarantee.
+ */
+#define MLX4_EN_OVERFLOW_PERIOD (MLX4_EN_WRAP_AROUND_SEC * HZ / 2)
+
 void mlx4_en_ptp_overflow_check(struct mlx4_en_dev *mdev)
 {
 	bool timeout = time_is_before_jiffies(mdev->last_overflow_check +
-					      mdev->overflow_period);
+					      MLX4_EN_OVERFLOW_PERIOD);
 	unsigned long flags;
 
 	if (timeout) {
@@ -236,7 +243,6 @@ static const struct ptp_clock_info mlx4_en_ptp_clock_info = {
 	.enable		= mlx4_en_phc_enable,
 };
 
-#define MLX4_EN_WRAP_AROUND_SEC	10ULL
 
 /* This function calculates the max shift that enables the user range
  * of MLX4_EN_WRAP_AROUND_SEC values in the cycles register.
@@ -258,7 +264,6 @@ void mlx4_en_init_timestamp(struct mlx4_en_dev *mdev)
 {
 	struct mlx4_dev *dev = mdev->dev;
 	unsigned long flags;
-	u64 ns, zero = 0;
 
 	/* mlx4_en_init_timestamp is called for each netdev.
 	 * mdev->ptp_clock is common for all ports, skip initialization if
@@ -282,13 +287,6 @@ void mlx4_en_init_timestamp(struct mlx4_en_dev *mdev)
 			 ktime_to_ns(ktime_get_real()));
 	write_unlock_irqrestore(&mdev->clock_lock, flags);
 
-	/* Calculate period in seconds to call the overflow watchdog - to make
-	 * sure counter is checked at least once every wrap around.
-	 */
-	ns = cyclecounter_cyc2ns(&mdev->cycles, mdev->cycles.mask, zero, &zero);
-	do_div(ns, NSEC_PER_SEC / 2 / HZ);
-	mdev->overflow_period = ns;
-
 	/* Configure the PHC */
 	mdev->ptp_clock_info = mlx4_en_ptp_clock_info;
 	snprintf(mdev->ptp_clock_info.name, 16, "mlx4 ptp");
diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
index c41f15102ae0..10aa6544cf4d 100644
--- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
+++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
@@ -409,7 +409,6 @@ struct mlx4_en_dev {
 	struct cyclecounter	cycles;
 	struct timecounter	clock;
 	unsigned long		last_overflow_check;
-	unsigned long		overflow_period;
 	struct ptp_clock	*ptp_clock;
 	struct ptp_clock_info	ptp_clock_info;
 	struct notifier_block	nb;
-- 
2.11.0

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#1738681 — [PATCH review for 4.4 14/26] crypto: xts - Add ECB dependency

From: Milan Broz <gmazyland@gmail.com>

[ Upstream commit 12cb3a1c4184f891d965d1f39f8cfcc9ef617647 ]

Since the
   commit f1c131b45410a202eb45cc55980a7a9e4e4b4f40
   crypto: xts - Convert to skcipher
the XTS mode is based on ECB, so the mode must select
ECB otherwise it can fail to initialize.

Signed-off-by: Milan Broz <gmazyland@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
---
 crypto/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/crypto/Kconfig b/crypto/Kconfig
index 7240821137fd..617bf4a7da56 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -343,6 +343,7 @@ config CRYPTO_XTS
 	select CRYPTO_BLKCIPHER
 	select CRYPTO_MANAGER
 	select CRYPTO_GF128MUL
+	select CRYPTO_ECB
 	help
 	  XTS: IEEE1619/D16 narrow block cipher use with aes-xts-plain,
 	  key size 256, 384 or 512 bits. This implementation currently
-- 
2.11.0

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#1738683 — [PATCH review for 4.4 15/26] ocfs2/dlmglue: prepare tracking logic to avoid recursive cluster lock

From: Eric Ren <zren@suse.com>

[ Upstream commit 439a36b8ef38657f765b80b775e2885338d72451 ]

We are in the situation that we have to avoid recursive cluster locking,
but there is no way to check if a cluster lock has been taken by a precess
already.

Mostly, we can avoid recursive locking by writing code carefully.
However, we found that it's very hard to handle the routines that are
invoked directly by vfs code.  For instance:

  const struct inode_operations ocfs2_file_iops = {
      .permission     = ocfs2_permission,
      .get_acl        = ocfs2_iop_get_acl,
      .set_acl        = ocfs2_iop_set_acl,
  };

Both ocfs2_permission() and ocfs2_iop_get_acl() call ocfs2_inode_lock(PR):

  do_sys_open
   may_open
    inode_permission
     ocfs2_permission
      ocfs2_inode_lock() <=== first time
       generic_permission
        get_acl
         ocfs2_iop_get_acl
  	ocfs2_inode_lock() <=== recursive one

A deadlock will occur if a remote EX request comes in between two of
ocfs2_inode_lock().  Briefly describe how the deadlock is formed:

On one hand, OCFS2_LOCK_BLOCKED flag of this lockres is set in
BAST(ocfs2_generic_handle_bast) when downconvert is started on behalf of
the remote EX lock request.  Another hand, the recursive cluster lock
(the second one) will be blocked in in __ocfs2_cluster_lock() because of
OCFS2_LOCK_BLOCKED.  But, the downconvert never complete, why? because
there is no chance for the first cluster lock on this node to be
unlocked - we block ourselves in the code path.

The idea to fix this issue is mostly taken from gfs2 code.

1. introduce a new field: struct ocfs2_lock_res.l_holders, to keep track
   of the processes' pid who has taken the cluster lock of this lock
   resource;

2. introduce a new flag for ocfs2_inode_lock_full:
   OCFS2_META_LOCK_GETBH; it means just getting back disk inode bh for
   us if we've got cluster lock.

3. export a helper: ocfs2_is_locked_by_me() is used to check if we have
   got the cluster lock in the upper code path.

The tracking logic should be used by some of the ocfs2 vfs's callbacks,
to solve the recursive locking issue cuased by the fact that vfs
routines can call into each other.

The performance penalty of processing the holder list should only be
seen at a few cases where the tracking logic is used, such as get/set
acl.

You may ask what if the first time we got a PR lock, and the second time
we want a EX lock? fortunately, this case never happens in the real
world, as far as I can see, including permission check,
(get|set)_(acl|attr), and the gfs2 code also do so.

[sfr@canb.auug.org.au remove some inlines]
Link: http://lkml.kernel.org/r/20170117100948.11657-2-zren@suse.com
Signed-off-by: Eric Ren <zren@suse.com>
Reviewed-by: Junxiao Bi <junxiao.bi@oracle.com>
Reviewed-by: Joseph Qi <jiangqi903@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Mark Fasheh <mfasheh@versity.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>

Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
---
 fs/ocfs2/dlmglue.c | 105 +++++++++++++++++++++++++++++++++++++++++++++++++++--
 fs/ocfs2/dlmglue.h |  18 +++++++++
 fs/ocfs2/ocfs2.h   |   1 +
 3 files changed, 121 insertions(+), 3 deletions(-)

diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 60a5f1548cd9..555b57a16499 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -531,6 +531,7 @@ void ocfs2_lock_res_init_once(struct ocfs2_lock_res *res)
 	init_waitqueue_head(&res->l_event);
 	INIT_LIST_HEAD(&res->l_blocked_list);
 	INIT_LIST_HEAD(&res->l_mask_waiters);
+	INIT_LIST_HEAD(&res->l_holders);
 }
 
 void ocfs2_inode_lock_res_init(struct ocfs2_lock_res *res,
@@ -748,6 +749,50 @@ void ocfs2_lock_res_free(struct ocfs2_lock_res *res)
 	res->l_flags = 0UL;
 }
 
+/*
+ * Keep a list of processes who have interest in a lockres.
+ * Note: this is now only uesed for check recursive cluster locking.
+ */
+static inline void ocfs2_add_holder(struct ocfs2_lock_res *lockres,
+				   struct ocfs2_lock_holder *oh)
+{
+	INIT_LIST_HEAD(&oh->oh_list);
+	oh->oh_owner_pid = get_pid(task_pid(current));
+
+	spin_lock(&lockres->l_lock);
+	list_add_tail(&oh->oh_list, &lockres->l_holders);
+	spin_unlock(&lockres->l_lock);
+}
+
+static inline void ocfs2_remove_holder(struct ocfs2_lock_res *lockres,
+				       struct ocfs2_lock_holder *oh)
+{
+	spin_lock(&lockres->l_lock);
+	list_del(&oh->oh_list);
+	spin_unlock(&lockres->l_lock);
+
+	put_pid(oh->oh_owner_pid);
+}
+
+static inline int ocfs2_is_locked_by_me(struct ocfs2_lock_res *lockres)
+{
+	struct ocfs2_lock_holder *oh;
+	struct pid *pid;
+
+	/* look in the list of holders for one with the current task as owner */
+	spin_lock(&lockres->l_lock);
+	pid = task_pid(current);
+	list_for_each_entry(oh, &lockres->l_holders, oh_list) {
+		if (oh->oh_owner_pid == pid) {
+			spin_unlock(&lockres->l_lock);
+			return 1;
+		}
+	}
+	spin_unlock(&lockres->l_lock);
+
+	return 0;
+}
+
 static inline void ocfs2_inc_holders(struct ocfs2_lock_res *lockres,
 				     int level)
 {
@@ -2343,8 +2388,9 @@ int ocfs2_inode_lock_full_nested(struct inode *inode,
 		goto getbh;
 	}
 
-	if (ocfs2_mount_local(osb))
-		goto local;
+	if ((arg_flags & OCFS2_META_LOCK_GETBH) ||
+	    ocfs2_mount_local(osb))
+		goto update;
 
 	if (!(arg_flags & OCFS2_META_LOCK_RECOVERY))
 		ocfs2_wait_for_recovery(osb);
@@ -2373,7 +2419,7 @@ int ocfs2_inode_lock_full_nested(struct inode *inode,
 	if (!(arg_flags & OCFS2_META_LOCK_RECOVERY))
 		ocfs2_wait_for_recovery(osb);
 
-local:
+update:
 	/*
 	 * We only see this flag if we're being called from
 	 * ocfs2_read_locked_inode(). It means we're locking an inode
@@ -2515,6 +2561,59 @@ void ocfs2_inode_unlock(struct inode *inode,
 		ocfs2_cluster_unlock(OCFS2_SB(inode->i_sb), lockres, level);
 }
 
+/*
+ * This _tracker variantes are introduced to deal with the recursive cluster
+ * locking issue. The idea is to keep track of a lock holder on the stack of
+ * the current process. If there's a lock holder on the stack, we know the
+ * task context is already protected by cluster locking. Currently, they're
+ * used in some VFS entry routines.
+ *
+ * return < 0 on error, return == 0 if there's no lock holder on the stack
+ * before this call, return == 1 if this call would be a recursive locking.
+ */
+int ocfs2_inode_lock_tracker(struct inode *inode,
+			     struct buffer_head **ret_bh,
+			     int ex,
+			     struct ocfs2_lock_holder *oh)
+{
+	int status;
+	int arg_flags = 0, has_locked;
+	struct ocfs2_lock_res *lockres;
+
+	lockres = &OCFS2_I(inode)->ip_inode_lockres;
+	has_locked = ocfs2_is_locked_by_me(lockres);
+	/* Just get buffer head if the cluster lock has been taken */
+	if (has_locked)
+		arg_flags = OCFS2_META_LOCK_GETBH;
+
+	if (likely(!has_locked || ret_bh)) {
+		status = ocfs2_inode_lock_full(inode, ret_bh, ex, arg_flags);
+		if (status < 0) {
+			if (status != -ENOENT)
+				mlog_errno(status);
+			return status;
+		}
+	}
+	if (!has_locked)
+		ocfs2_add_holder(lockres, oh);
+
+	return has_locked;
+}
+
+void ocfs2_inode_unlock_tracker(struct inode *inode,
+				int ex,
+				struct ocfs2_lock_holder *oh,
+				int had_lock)
+{
+	struct ocfs2_lock_res *lockres;
+
+	lockres = &OCFS2_I(inode)->ip_inode_lockres;
+	if (!had_lock) {
+		ocfs2_remove_holder(lockres, oh);
+		ocfs2_inode_unlock(inode, ex);
+	}
+}
+
 int ocfs2_orphan_scan_lock(struct ocfs2_super *osb, u32 *seqno)
 {
 	struct ocfs2_lock_res *lockres;
diff --git a/fs/ocfs2/dlmglue.h b/fs/ocfs2/dlmglue.h
index d293a22c32c5..a7fc18ba0dc1 100644
--- a/fs/ocfs2/dlmglue.h
+++ b/fs/ocfs2/dlmglue.h
@@ -70,6 +70,11 @@ struct ocfs2_orphan_scan_lvb {
 	__be32	lvb_os_seqno;
 };
 
+struct ocfs2_lock_holder {
+	struct list_head oh_list;
+	struct pid *oh_owner_pid;
+};
+
 /* ocfs2_inode_lock_full() 'arg_flags' flags */
 /* don't wait on recovery. */
 #define OCFS2_META_LOCK_RECOVERY	(0x01)
@@ -77,6 +82,8 @@ struct ocfs2_orphan_scan_lvb {
 #define OCFS2_META_LOCK_NOQUEUE		(0x02)
 /* don't block waiting for the downconvert thread, instead return -EAGAIN */
 #define OCFS2_LOCK_NONBLOCK		(0x04)
+/* just get back disk inode bh if we've got cluster lock. */
+#define OCFS2_META_LOCK_GETBH		(0x08)
 
 /* Locking subclasses of inode cluster lock */
 enum {
@@ -170,4 +177,15 @@ void ocfs2_put_dlm_debug(struct ocfs2_dlm_debug *dlm_debug);
 
 /* To set the locking protocol on module initialization */
 void ocfs2_set_locking_protocol(void);
+
+/* The _tracker pair is used to avoid cluster recursive locking */
+int ocfs2_inode_lock_tracker(struct inode *inode,
+			     struct buffer_head **ret_bh,
+			     int ex,
+			     struct ocfs2_lock_holder *oh);
+void ocfs2_inode_unlock_tracker(struct inode *inode,
+				int ex,
+				struct ocfs2_lock_holder *oh,
+				int had_lock);
+
 #endif	/* DLMGLUE_H */
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index 7a0126267847..2495066a9ca3 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -172,6 +172,7 @@ struct ocfs2_lock_res {
 
 	struct list_head         l_blocked_list;
 	struct list_head         l_mask_waiters;
+	struct list_head	 l_holders;
 
 	unsigned long		 l_flags;
 	char                     l_name[OCFS2_LOCK_ID_MAX_LEN];
-- 
2.11.0

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