Implement stacked writes.
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
---
fs/overlayfs/file.c | 39 +++++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index bbc40a14acf8..a7af56861aa5 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -195,9 +195,48 @@ static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter)
return ret;
}
+static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
+{
+ struct file *file = iocb->ki_filp;
+ struct inode *inode = file_inode(file);
+ struct fd real;
+ const struct cred *old_cred;
+ ssize_t ret;
+
+ if (!iov_iter_count(iter))
+ return 0;
+
+ inode_lock(inode);
+ /* Update mode */
+ ovl_copyattr(ovl_inode_real(inode), inode);
+ ret = file_remove_privs(file);
+ if (ret)
+ goto out_unlock;
+
+ ret = ovl_real_fdget(file, &real);
+ if (ret)
+ goto out_unlock;
+
+ old_cred = ovl_override_creds(file_inode(file)->i_sb);
+ ret = vfs_iter_write(real.file, iter, &iocb->ki_pos,
+ ovl_iocb_to_rwf(iocb));
+ revert_creds(old_cred);
+
+ /* Update size */
+ ovl_copyattr(ovl_inode_real(inode), inode);
+
+ fdput(real);
+
+out_unlock:
+ inode_unlock(inode);
+
+ return ret;
+}
+
const struct file_operations ovl_file_operations = {
.open = ovl_open,
.release = ovl_release,
.llseek = ovl_llseek,
.read_iter = ovl_read_iter,
+ .write_iter = ovl_write_iter,
};
--
2.14.3
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