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Commit 43b10a20 authored by jiangyiwen's avatar jiangyiwen Committed by Linus Torvalds
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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: default avatarjiangyiwen <jiangyiwen@huawei.com>
Reviewed-by: default avatarJoseph Qi <joseph.qi@huawei.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7dc3e839

fs/ocfs2/ocfs2.h

+2 −0
Original line number Diff line number Diff line
@@ -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)

fs/ocfs2/super.c

+2 −0
Original line number Diff line number Diff line
@@ -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);

fs/ocfs2/sysfile.c

+3 −0
Original line number Diff line number Diff line
@@ -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;

}