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 de981370fbc5d596de3d419062c0977829602af7..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);
@@ -2451,6 +2451,7 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s
                        return -ENOMEM;
                }
                inode->i_op = &shmem_short_symlink_operations;
+               inode->i_link = info->symlink;
        } else {
                error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
                if (error) {
@@ -2474,30 +2475,23 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s
        return 0;
 }
 
-static void *shmem_follow_short_symlink(struct dentry *dentry, struct nameidata *nd)
-{
-       nd_set_link(nd, SHMEM_I(d_inode(dentry))->symlink);
-       return NULL;
-}
-
-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
@@ -2642,7 +2636,7 @@ static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
 
 static const struct inode_operations shmem_short_symlink_operations = {
        .readlink       = generic_readlink,
-       .follow_link    = shmem_follow_short_symlink,
+       .follow_link    = simple_follow_link,
 #ifdef CONFIG_TMPFS_XATTR
        .setxattr       = shmem_setxattr,
        .getxattr       = shmem_getxattr,
@@ -3401,7 +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);