From 2f502839e85ab265f03f25f30d6463154aee5473 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Wed, 18 Jul 2018 15:44:42 +0200 Subject: [PATCH] ovl: add ovl_mmap() Implement stacked mmap. Signed-off-by: Miklos Szeredi --- fs/overlayfs/file.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index 8adddee93418..4c8bf77e048f 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -255,6 +255,37 @@ static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync) return ret; } +static int ovl_mmap(struct file *file, struct vm_area_struct *vma) +{ + struct file *realfile = file->private_data; + const struct cred *old_cred; + int ret; + + if (!realfile->f_op->mmap) + return -ENODEV; + + if (WARN_ON(file != vma->vm_file)) + return -EIO; + + vma->vm_file = get_file(realfile); + + old_cred = ovl_override_creds(file_inode(file)->i_sb); + ret = call_mmap(vma->vm_file, vma); + revert_creds(old_cred); + + if (ret) { + /* Drop reference count from new vm_file value */ + fput(realfile); + } else { + /* Drop reference count from previous vm_file value */ + fput(file); + } + + ovl_file_accessed(file); + + return ret; +} + const struct file_operations ovl_file_operations = { .open = ovl_open, .release = ovl_release, @@ -262,4 +293,5 @@ const struct file_operations ovl_file_operations = { .read_iter = ovl_read_iter, .write_iter = ovl_write_iter, .fsync = ovl_fsync, + .mmap = ovl_mmap, };