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authorjiangyiwen <jiangyiwen@huawei.com>2014-04-03 14:47:13 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-04-03 16:20:57 -0700
commit43b10a20372d9a1c08391f33f1c8bd86179ddc5f (patch)
treeed5fd7ca5fd34c4d84393e7fb3d65b8512594382
parent7dc3e83901b342ea7fe36262329c3784f2937361 (diff)
downloadop-kernel-dev-43b10a20372d9a1c08391f33f1c8bd86179ddc5f.zip
op-kernel-dev-43b10a20372d9a1c08391f33f1c8bd86179ddc5f.tar.gz
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@huawei.com> Reviewed-by: Joseph Qi <joseph.qi@huawei.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Mark Fasheh <mfasheh@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/ocfs2/ocfs2.h2
-rw-r--r--fs/ocfs2/super.c2
-rw-r--r--fs/ocfs2/sysfile.c3
3 files changed, 7 insertions, 0 deletions
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index a780e20..8d64a97 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/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 --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index 888a145..1aecd62 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -2100,6 +2100,8 @@ 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;
}
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