jiangyiwen
2014-Mar-14 01:55 UTC
[Ocfs2-devel] [PATCH] ocfs2: Avoid system inode ref in confusion by add mutex lock
The following case may lead to the same system inode ref in confusion.
A thread B thread
ocfs2_get_system_file_inode
->get_local_system_inode
->_ocfs2_get_system_file_inode
because of *arr == NULL,
ocfs2_get_system_file_inode
->get_local_system_inode
->_ocfs2_get_system_file_inode
gets first ref thru
_ocfs2_get_system_file_inode,
gets second ref thru igrab and
set *arr = inode
at the moment, B thread also gets
two refs, so lead to one more
inode ref.
So add mutex lock to avoid multi thread set two inode ref once at
the same time.
Reviewed-by: Joseph Qi <joseph.qi at huawei.com>
Signed-off-by: jiangyiwen <jiangyiwen at huawei.com>
---
fs/ocfs2/ocfs2.h | 2 ++
fs/ocfs2/super.c | 2 ++
fs/ocfs2/sysfile.c | 3 +++
3 files changed, 7 insertions(+)
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index 553f53c..975a70c 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -449,6 +449,8 @@ struct ocfs2_super
/* rb tree root for refcount lock. */
struct rb_root osb_rf_lock_tree;
struct ocfs2_refcount_tree *osb_ref_tree_lru;
+
+ struct mutex system_file_mutex;
};
#define OCFS2_SB(sb) ((struct ocfs2_super *)(sb)->s_fs_info)
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index 49d84f8..eb855a7 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -2123,6 +2123,8 @@ static int ocfs2_initialize_super(struct super_block *sb,
spin_lock_init(&osb->osb_xattr_lock);
ocfs2_init_steal_slots(osb);
+ mutex_init(&osb->system_file_mutex);
+
atomic_set(&osb->alloc_stats.moves, 0);
atomic_set(&osb->alloc_stats.local_data, 0);
atomic_set(&osb->alloc_stats.bitmap_data, 0);
diff --git a/fs/ocfs2/sysfile.c b/fs/ocfs2/sysfile.c
index f053688..af155c1 100644
--- a/fs/ocfs2/sysfile.c
+++ b/fs/ocfs2/sysfile.c
@@ -113,9 +113,11 @@ struct inode *ocfs2_get_system_file_inode(struct
ocfs2_super *osb,
} else
arr = get_local_system_inode(osb, type, slot);
+ mutex_lock(&osb->system_file_mutex);
if (arr && ((inode = *arr) != NULL)) {
/* get a ref in addition to the array ref */
inode = igrab(inode);
+ mutex_unlock(&osb->system_file_mutex);
BUG_ON(!inode);
return inode;
@@ -129,6 +131,7 @@ struct inode *ocfs2_get_system_file_inode(struct ocfs2_super
*osb,
*arr = igrab(inode);
BUG_ON(!*arr);
}
+ mutex_unlock(&osb->system_file_mutex);
return inode;
}
--
1.8.4.3
Andrew Morton
2014-Apr-01 21:36 UTC
[Ocfs2-devel] [PATCH] ocfs2: Avoid system inode ref in confusion by add mutex lock
On Fri, 14 Mar 2014 09:55:36 +0800 jiangyiwen <jiangyiwen at huawei.com> wrote:> The following case may lead to the same system inode ref in confusion. > > A thread B thread > ocfs2_get_system_file_inode > ->get_local_system_inode > ->_ocfs2_get_system_file_inode > because of *arr == NULL, > ocfs2_get_system_file_inode > ->get_local_system_inode > ->_ocfs2_get_system_file_inode > gets first ref thru > _ocfs2_get_system_file_inode, > gets second ref thru igrab and > set *arr = inode > at the moment, B thread also gets > two refs, so lead to one more > inode ref. > > So add mutex lock to avoid multi thread set two inode ref once at > the same time.Looks good to me. I queued it for 3.15-rc1. From: jiangyiwen <jiangyiwen at huawei.com> Subject: ocfs2: avoid system inode ref confusion by adding mutex lock The following case may lead to the same system inode ref in confusion. A thread B thread ocfs2_get_system_file_inode ->get_local_system_inode ->_ocfs2_get_system_file_inode because of *arr == NULL, ocfs2_get_system_file_inode ->get_local_system_inode ->_ocfs2_get_system_file_inode gets first ref thru _ocfs2_get_system_file_inode, gets second ref thru igrab and set *arr = inode at the moment, B thread also gets two refs, so lead to one more inode ref. So add mutex lock to avoid multi thread set two inode ref once at the same time. Signed-off-by: jiangyiwen <jiangyiwen at huawei.com> Reviewed-by: Joseph Qi <joseph.qi at huawei.com> Cc: Joel Becker <jlbec at evilplan.org> Cc: Mark Fasheh <mfasheh at suse.com> Signed-off-by: Andrew Morton <akpm at linux-foundation.org> --- fs/ocfs2/ocfs2.h | 2 ++ fs/ocfs2/super.c | 2 ++ fs/ocfs2/sysfile.c | 3 +++ 3 files changed, 7 insertions(+) diff -puN fs/ocfs2/ocfs2.h~ocfs2-avoid-system-inode-ref-confusion-by-adding-mutex-lock fs/ocfs2/ocfs2.h --- a/fs/ocfs2/ocfs2.h~ocfs2-avoid-system-inode-ref-confusion-by-adding-mutex-lock +++ a/fs/ocfs2/ocfs2.h @@ -446,6 +446,8 @@ struct ocfs2_super /* rb tree root for refcount lock. */ struct rb_root osb_rf_lock_tree; struct ocfs2_refcount_tree *osb_ref_tree_lru; + + struct mutex system_file_mutex; }; #define OCFS2_SB(sb) ((struct ocfs2_super *)(sb)->s_fs_info) diff -puN fs/ocfs2/super.c~ocfs2-avoid-system-inode-ref-confusion-by-adding-mutex-lock fs/ocfs2/super.c --- a/fs/ocfs2/super.c~ocfs2-avoid-system-inode-ref-confusion-by-adding-mutex-lock +++ a/fs/ocfs2/super.c @@ -2100,6 +2100,8 @@ static int ocfs2_initialize_super(struct spin_lock_init(&osb->osb_xattr_lock); ocfs2_init_steal_slots(osb); + mutex_init(&osb->system_file_mutex); + atomic_set(&osb->alloc_stats.moves, 0); atomic_set(&osb->alloc_stats.local_data, 0); atomic_set(&osb->alloc_stats.bitmap_data, 0); diff -puN fs/ocfs2/sysfile.c~ocfs2-avoid-system-inode-ref-confusion-by-adding-mutex-lock fs/ocfs2/sysfile.c --- a/fs/ocfs2/sysfile.c~ocfs2-avoid-system-inode-ref-confusion-by-adding-mutex-lock +++ a/fs/ocfs2/sysfile.c @@ -113,9 +113,11 @@ struct inode *ocfs2_get_system_file_inod } else arr = get_local_system_inode(osb, type, slot); + mutex_lock(&osb->system_file_mutex); if (arr && ((inode = *arr) != NULL)) { /* get a ref in addition to the array ref */ inode = igrab(inode); + mutex_unlock(&osb->system_file_mutex); BUG_ON(!inode); return inode; @@ -129,6 +131,7 @@ struct inode *ocfs2_get_system_file_inod *arr = igrab(inode); BUG_ON(!*arr); } + mutex_unlock(&osb->system_file_mutex); return inode; } _