nilfs2: add more check routines in mount process

nilfs2: Add more safeguard routines and protections in mount process,
which also makes nilfs2 report consistency error messages when
checkpoint number is invalid.

Signed-off-by: Zhu Yanhai <zhu.yanhai@gmail.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

1 files changed, 6 insertions, 1 deletions

diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 019752f7d2da..50284add7880 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -792,10 +792,15 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent,
 
         if (sb->s_flags & MS_RDONLY) {
                 if (nilfs_test_opt(sbi, SNAPSHOT)) {
+                        down_read(&nilfs->ns_segctor_sem);
                         err = nilfs_cpfile_is_snapshot(nilfs->ns_cpfile,
                                                        sbi->s_snapshot_cno);
-                        if (err < 0)
+                        up_read(&nilfs->ns_segctor_sem);
+                        if (err < 0) {
+                                if (err == -ENOENT)
+                                        err = -EINVAL;
                                 goto failed_sbi;
+                        }
                         if (!err) {
                                 printk(KERN_ERR
                                        "NILFS: The specified checkpoint is "