tmpfs: truncate prealloc blocks past i_size

[firefly-linux-kernel-4.4.55.git] / mm / shmem.c

diff --git a/mm/shmem.c b/mm/shmem.c
index 7f6e2f88912285989eaa3341787180d512f3e43f..4caf8ed24d6586e32ab910f28f945c01cef6373b 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -569,7 +569,7 @@ static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
                        i_size_write(inode, newsize);
                        inode->i_ctime = inode->i_mtime = CURRENT_TIME;
                }
-               if (newsize < oldsize) {
+               if (newsize <= oldsize) {
                        loff_t holebegin = round_up(newsize, PAGE_SIZE);
                        unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
                        shmem_truncate_range(inode, newsize, (loff_t)-1);
@@ -2475,24 +2475,23 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s
        return 0;
 }
 
-static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
+static const char *shmem_follow_link(struct dentry *dentry, void **cookie)
 {
        struct page *page = NULL;
        int error = shmem_getpage(d_inode(dentry), 0, &page, SGP_READ, NULL);
-       nd_set_link(nd, error ? ERR_PTR(error) : kmap(page));
-       if (page)
-               unlock_page(page);
-       return page;
+       if (error)
+               return ERR_PTR(error);
+       unlock_page(page);
+       *cookie = page;
+       return kmap(page);
 }
 
-static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
+static void shmem_put_link(struct inode *unused, void *cookie)
 {
-       if (!IS_ERR(nd_get_link(nd))) {
-               struct page *page = cookie;
-               kunmap(page);
-               mark_page_accessed(page);
-               page_cache_release(page);
-       }
+       struct page *page = cookie;
+       kunmap(page);
+       mark_page_accessed(page);
+       page_cache_release(page);
 }
 
 #ifdef CONFIG_TMPFS_XATTR
@@ -3396,7 +3395,13 @@ int shmem_zero_setup(struct vm_area_struct *vma)
        struct file *file;
        loff_t size = vma->vm_end - vma->vm_start;
 
-       file = shmem_file_setup("dev/zero", size, vma->vm_flags);
+       /*
+        * Cloning a new file under mmap_sem leads to a lock ordering conflict
+        * between XFS directory reading and selinux: since this file is only
+        * accessible to the user through its mapping, use S_PRIVATE flag to
+        * bypass file security, in the same way as shmem_kernel_file_setup().
+        */
+       file = __shmem_file_setup("dev/zero", size, vma->vm_flags, S_PRIVATE);
        if (IS_ERR(file))
                return PTR_ERR(file);