nilfs2: missing a read lock for segment writer in nilfs_attach_checkpoint()
'ns_cno' of structure 'the_nilfs' must be protected from segment
writer, in other words, the caller of nilfs_get_checkpoint should hold
read lock for nilfs->ns_segctor_sem. This patch adds the lock/unlock
operations in nilfs_attach_checkpoint() when calling
nilfs_cpfile_get_checkpoint().
Signed-off-by: Zhang Qiang <zhangqiang.buaa@gmail.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 8e2ec43..151964f 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -416,8 +416,10 @@
if (unlikely(err))
goto failed;
+ down_read(&nilfs->ns_segctor_sem);
err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, cno, 0, &raw_cp,
&bh_cp);
+ up_read(&nilfs->ns_segctor_sem);
if (unlikely(err)) {
if (err == -ENOENT || err == -EINVAL) {
printk(KERN_ERR