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>

diff --git a/fs/nilfs2/cpfile.c b/fs/nilfs2/cpfile.c
index aec942c..1c6cfb5 100644 (file)
--- a/fs/nilfs2/cpfile.c
+++ b/fs/nilfs2/cpfile.c
@@ -815,8 +815,10 @@ int nilfs_cpfile_is_snapshot(struct inode *cpfile, __u64 cno)
        void *kaddr;
        int ret;
 
-       if (cno == 0)
-               return -ENOENT; /* checkpoint number 0 is invalid */
+       /* CP number is invalid if it's zero or larger than the
+       largest exist one.*/
+       if (cno == 0 || cno >= nilfs_mdt_cno(cpfile))
+               return -ENOENT;
        down_read(&NILFS_MDT(cpfile)->mi_sem);
 
        ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);
@@ -824,7 +826,10 @@ int nilfs_cpfile_is_snapshot(struct inode *cpfile, __u64 cno)
                goto out;
        kaddr = kmap_atomic(bh->b_page, KM_USER0);
        cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
-       ret = nilfs_checkpoint_snapshot(cp);
+       if (nilfs_checkpoint_invalid(cp))
+               ret = -ENOENT;
+       else
+               ret = nilfs_checkpoint_snapshot(cp);
        kunmap_atomic(kaddr, KM_USER0);
        brelse(bh);
 

diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 019752f..50284ad 100644 (file)
--- 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 "