ocfs2: avoid system inode ref confusion by adding mutex lock (43b10a20) · Commits · 戴 / test

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>

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;
		}

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