[PATCH] hugetlbfs: make BUG_ON(!inode) takes effect in hugetlbfs_setattr

[Miaohe Lin]

When we reach here with inode = NULL, we should have crashed as inode has
already been dereferenced via hstate_inode. In order to make BUG_ON(!inode)
takes effect, we should defer initializing hstate until we really need it.
Also do this for hugetlbfs_inode_info as it's only used when ia_valid is
verified with ATTR_SIZE.

Signed-off-by: Miaohe Lin <linmia...@huawei.com>
---
 fs/hugetlbfs/inode.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 740693d7f255..9b221b87fbea 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -755,10 +755,8 @@ static long hugetlbfs_fallocate(struct file *file, int 
mode, loff_t offset,
 static int hugetlbfs_setattr(struct dentry *dentry, struct iattr *attr)
 {
        struct inode *inode = d_inode(dentry);
-       struct hstate *h = hstate_inode(inode);
        int error;
        unsigned int ia_valid = attr->ia_valid;
-       struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
 
        BUG_ON(!inode);
 
@@ -767,6 +765,8 @@ static int hugetlbfs_setattr(struct dentry *dentry, struct 
iattr *attr)
                return error;
 
        if (ia_valid & ATTR_SIZE) {
+               struct hstate *h = hstate_inode(inode);
+               struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
                loff_t oldsize = inode->i_size;
                loff_t newsize = attr->ia_size;
 
-- 
2.19.1