memfd: update inode size during mmap()

1 files changed, 4 insertions, 5 deletions

diff --git a/memfd.c b/memfd.c
index 5998359e9b5..d9d92d95d88 100644
--- a/memfd.c
+++ b/memfd.c
@@ -227,6 +227,7 @@ static int kdbus_memfd_mmap(struct file *file, struct vm_area_struct *vma)
 
 	if (vma->vm_flags & VM_WRITE) {
 		size_t size;
+		struct inode *inode;
 
 		/*
 		 * Deny a writable mapping to a sealed file.
@@ -244,11 +245,9 @@ static int kdbus_memfd_mmap(struct file *file, struct vm_area_struct *vma)
 		/* extend the size of the shmem file to the size of the mapping */
 		size = (vma->vm_end - vma->vm_start) +
 		       (vma->vm_pgoff << PAGE_SHIFT);
-		if (size > PAGE_ALIGN(i_size_read(file_inode(mf->fp)))) {
-			ret = vfs_truncate(&mf->fp->f_path, size);
-			if (ret < 0)
-				goto exit;
-		}
+		inode = file_inode(mf->fp);
+		if (size > PAGE_ALIGN(i_size_read(inode)))
+			i_size_write(inode, size);
 	}
 
 	/* replace the anoymous inode file with our shmem file */