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Commit 926dd8a6 authored by Jan Schmidt's avatar Jan Schmidt
Browse files

Btrfs: add missing spin_lock for insertion into tree mod log 



tree_mod_alloc calls __get_tree_mod_seq and must acquire a spinlock before
doing so.

Signed-off-by: default avatarJan Schmidt <list.btrfs@jan-o-sch.net>
parent 3301958b

fs/btrfs/ctree.c

+18 −5
Original line number Diff line number Diff line
@@ -455,11 +455,11 @@ unlock: 
	return ret;

}



int tree_mod_alloc(struct btrfs_fs_info *fs_info, gfp_t flags,

static inline int tree_mod_alloc(struct btrfs_fs_info *fs_info, gfp_t flags,

				 struct tree_mod_elem **tm_ret)

{

	struct tree_mod_elem *tm;

	u64 seq = 0;

	int seq;



	smp_mb();

	if (list_empty(&fs_info->tree_mod_seq_list))
@@ -469,9 +469,22 @@ int tree_mod_alloc(struct btrfs_fs_info *fs_info, gfp_t flags, 
	if (!tm)

		return -ENOMEM;



	tm->elem.flags = 0;

	spin_lock(&fs_info->tree_mod_seq_lock);

	if (list_empty(&fs_info->tree_mod_seq_list)) {

		/*

		 * someone emptied the list while we were waiting for the lock.

		 * we must not add to the list, because no blocker exists. items

		 * are removed from the list only when the existing blocker is

		 * removed from the list.

		 */

		kfree(tm);

		seq = 0;

	} else {

		__get_tree_mod_seq(fs_info, &tm->elem);

		seq = tm->elem.seq;

	tm->elem.flags = 0;

	}

	spin_unlock(&fs_info->tree_mod_seq_lock);



	return seq;

}