On 02/09/2011 01:25 AM, Boaz Harrosh wrote:
On 02/08/2011 06:57 PM, Aneesh Kumar K. V wrote:
On Mon, 07 Feb 2011 15:14:40 +0200, Boaz Harrosh<bharrosh@xxxxxxxxxxx> wrote:
On 02/05/2011 11:01 AM, Tao Ma wrote:
From: Tao Ma<boyu.mt@xxxxxxxxxx>
In fa0d7e3, we use rcu free inode instead of freeing the inode
directly. It causes a problem when we rmmod immediately after
we umount the volume[1].
So we need to call synchronize_rcu after we kill_sb so that
the inode is freed before we do rmmod. The idea is inspired
by Chris Mason[2]. I tested with ext4 by umount+rmmod and it
doesn't show any error by now.
1. http://marc.info/?l=linux-fsdevel&m=129680863330185&w=2
2. http://marc.info/?l=linux-fsdevel&m=129684698713709&w=2
Cc: Nick Piggin<npiggin@xxxxxxxxx>
Cc: Al Viro<viro@xxxxxxxxxxxxxxxxxx>
Cc: Chris Mason<chris.mason@xxxxxxxxxx>
Cc: Boaz Harrosh<bharrosh@xxxxxxxxxxx>
Signed-off-by: Tao Ma<boyu.mt@xxxxxxxxxx>
---
fs/super.c | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/fs/super.c b/fs/super.c
index 74e149e..315bce9 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -177,6 +177,13 @@ void deactivate_locked_super(struct super_block *s)
struct file_system_type *fs = s->s_type;
if (atomic_dec_and_test(&s->s_active)) {
fs->kill_sb(s);
+ /*
+ * We need to synchronize rcu here so that
+ * the delayed rcu inode free can be executed
+ * before we put_super.
+ * https://bugzilla.kernel.org/show_bug.cgi?id=27652
+ */
+ synchronize_rcu();
put_filesystem(fs);
put_super(s);
} else {
<>
http://lwn.net/Articles/217484/ explains how to wait for rcu callback to finish
-aneesh
Yes thanks Aneesh, rcu_barrier does the trick
---
From: Boaz Harrosh<bharrosh@xxxxxxxxxxx>
In fa0d7e3, we use rcu free inode instead of freeing the inode
directly. It causes a problem when we rmmod immediately after
we umount the volume[1].
So we need to call rcu_barrier after we kill_sb so that
the inode is freed before we do rmmod. The idea is inspired
by Aneesh Kumar. rcu_barrier will wait for all callbacks
to end before preceding. The original patch was done by
Tao Ma, but synchronize_rcu() is not enough here.
1. http://marc.info/?l=linux-fsdevel&m=129680863330185&w=2
2. http://marc.info/?l=linux-fsdevel&m=129684698713709&w=2
Cc: Nick Piggin<npiggin@xxxxxxxxx>
Cc: Al Viro<viro@xxxxxxxxxxxxxxxxxx>
Cc: Chris Mason<chris.mason@xxxxxxxxxx>
Cc: Tao Ma<boyu.mt@xxxxxxxxxx>
Signed-off-by: Boaz Harrosh<bharrosh@xxxxxxxxxxx>
It works now in my ext4 test box. Thanks for your work.
Tested-by: Tao Ma <boyu.mt@xxxxxxxxxx>
---
git diff --stat -p -M fs/super.c
fs/super.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/fs/super.c b/fs/super.c
index 74e149e..5fd4ec9 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -177,6 +177,13 @@ void deactivate_locked_super(struct super_block *s)
struct file_system_type *fs = s->s_type;
if (atomic_dec_and_test(&s->s_active)) {
fs->kill_sb(s);
+ /*
+ * We need to synchronize rcu here so that
+ * the delayed rcu inode free can be executed
+ * before we put_super.
+ * https://bugzilla.kernel.org/show_bug.cgi?id=27652
+ */
+ rcu_barrier();
put_filesystem(fs);
put_super(s);
} else {
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