Re: reiser4-2.6.18-rc2-mm1: possible circular locking dependency detected in txn_end

[Alexander Zarochentsev <zam@namesys.com>]

On Tuesday 01 August 2006 01:29, Laurent Riffard wrote:
> Le 31.07.2006 21:55, Vladimir V. Saveliev a écrit :
> > Hello
> >
> > What kind of load did you run on reiser4 at that time?
>
> I just formatted a new 2GB Reiser4 FS, then I moved a whole ccache
> cache tree to this new FS (cache size was about 20~30 Mbytes).
> Something like:
>
> # mkfs.reiser4 /dev/vglinux1/ccache
> # mount -tauto -onoatime /dev/vglinux1/ccache /mnt/disk
> # mv ~laurent/.ccache/* /mnt/disk/

I was not able to reproduce it.  Can you please try the following patch?


lock validator friendly locking of new atom in 
atom_begin_and_assign_to_txnh and locking of two atoms.

Signed-off-by: Alexander Zarochentsev <zam@namesys.com>
---

 fs/reiser4/txnmgr.c |   14 ++++++++------
 fs/reiser4/txnmgr.h |   15 +++++++++++++++
 2 files changed, 23 insertions(+), 6 deletions(-)

Index: linux-2.6-git/fs/reiser4/txnmgr.c
===================================================================
--- linux-2.6-git.orig/fs/reiser4/txnmgr.c
+++ linux-2.6-git/fs/reiser4/txnmgr.c
@@ -730,10 +730,12 @@ static int atom_begin_and_assign_to_txnh
 	assert("jmacd-17", atom_isclean(atom));
 
         /*
-	 * do not use spin_lock_atom because we have broken lock ordering here
-	 * which is ok, as long as @atom is new and inaccessible for others.
+	 * lock ordering is broken here. It is ok, as long as @atom is new
+	 * and inaccessible for others. We can't use spin_lock_atom or
+	 * spin_lock(&atom->alock) because they care about locking
+	 * dependencies. spin_trylock_lock doesn't.
 	 */
-	spin_lock(&(atom->alock));
+	check_me("", spin_trylock_atom(atom));
 
 	/* add atom to the end of transaction manager's list of atoms */
 	list_add_tail(&atom->atom_link, &mgr->atoms_list);
@@ -749,7 +751,7 @@ static int atom_begin_and_assign_to_txnh
 	atom->super = reiser4_get_current_sb();
 	capture_assign_txnh_nolock(atom, txnh);
 
-	spin_unlock(&(atom->alock));
+	spin_unlock_atom(atom);
 	spin_unlock_txnh(txnh);
 
 	return -E_REPEAT;
@@ -2791,10 +2793,10 @@ static void lock_two_atoms(txn_atom * on
 	/* lock the atom with lesser address first */
 	if (one < two) {
 		spin_lock_atom(one);
-		spin_lock_atom(two);
+		spin_lock_atom_nested(two);
 	} else {
 		spin_lock_atom(two);
-		spin_lock_atom(one);
+		spin_lock_atom_nested(one);
 	}
 }
 
Index: linux-2.6-git/fs/reiser4/txnmgr.h
===================================================================
--- linux-2.6-git.orig/fs/reiser4/txnmgr.h
+++ linux-2.6-git/fs/reiser4/txnmgr.h
@@ -502,6 +502,7 @@ static inline void spin_lock_atom(txn_at
 {
 	/* check that spinlocks of lower priorities are not held */
 	assert("", (LOCK_CNT_NIL(spin_locked_txnh) &&
+		    LOCK_CNT_NIL(spin_locked_atom) &&
 		    LOCK_CNT_NIL(spin_locked_jnode) &&
 		    LOCK_CNT_NIL(spin_locked_zlock) &&
 		    LOCK_CNT_NIL(rw_locked_dk) &&
@@ -513,6 +514,20 @@ static inline void spin_lock_atom(txn_at
 	LOCK_CNT_INC(spin_locked);
 }
 
+static inline void spin_lock_atom_nested(txn_atom *atom)
+{
+	assert("", (LOCK_CNT_NIL(spin_locked_txnh) &&
+		    LOCK_CNT_NIL(spin_locked_jnode) &&
+		    LOCK_CNT_NIL(spin_locked_zlock) &&
+		    LOCK_CNT_NIL(rw_locked_dk) &&
+		    LOCK_CNT_NIL(rw_locked_tree)));
+
+	spin_lock_nested(&(atom->alock), SINGLE_DEPTH_NESTING);
+
+	LOCK_CNT_INC(spin_locked_atom);
+	LOCK_CNT_INC(spin_locked);
+}
+
 static inline int spin_trylock_atom(txn_atom *atom)
 {
 	if (spin_trylock(&(atom->alock))) {