ANDROID: sdcardfs: add read_iter/write_iter opeations

Adapted from wrapfs
commit f398bf6a7377 ("Wrapfs: add read_iter/write_iter opeations")

Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
Signed-off-by: Mengyang Li <li.mengyang@stonybrook.edu>
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Bug: 35766959
Change-Id: I2b3de59c9682fc705bf21df0de6df81e76fd2e40

diff --git a/fs/sdcardfs/file.c b/fs/sdcardfs/file.c
index f49df7a..c0146e0 100644 (file)
--- a/fs/sdcardfs/file.c
+++ b/fs/sdcardfs/file.c
@@ -338,6 +338,52 @@ out:
        return err;
 }
 
+/*
+ * Sdcardfs read_iter, redirect modified iocb to lower read_iter
+ */
+ssize_t sdcardfs_read_iter(struct kiocb *iocb, struct iov_iter *iter)
+{
+       int err;
+       struct file *file = iocb->ki_filp, *lower_file;
+
+       lower_file = sdcardfs_lower_file(file);
+       if (!lower_file->f_op->read_iter) {
+               err = -EINVAL;
+               goto out;
+       }
+
+       get_file(lower_file); /* prevent lower_file from being released */
+       iocb->ki_filp = lower_file;
+       err = lower_file->f_op->read_iter(iocb, iter);
+       /* ? wait IO finish to update atime as ecryptfs ? */
+       iocb->ki_filp = file;
+       fput(lower_file);
+out:
+       return err;
+}
+
+/*
+ * Sdcardfs write_iter, redirect modified iocb to lower write_iter
+ */
+ssize_t sdcardfs_write_iter(struct kiocb *iocb, struct iov_iter *iter)
+{
+       int err;
+       struct file *file = iocb->ki_filp, *lower_file;
+
+       lower_file = sdcardfs_lower_file(file);
+       if (!lower_file->f_op->write_iter) {
+               err = -EINVAL;
+               goto out;
+       }
+
+       get_file(lower_file); /* prevent lower_file from being released */
+       iocb->ki_filp = lower_file;
+       err = lower_file->f_op->write_iter(iocb, iter);
+       iocb->ki_filp = file;
+       fput(lower_file);
+out:
+       return err;
+}
 
 const struct file_operations sdcardfs_main_fops = {
        .llseek         = generic_file_llseek,
@@ -353,6 +399,8 @@ const struct file_operations sdcardfs_main_fops = {
        .release        = sdcardfs_file_release,
        .fsync          = sdcardfs_fsync,
        .fasync         = sdcardfs_fasync,
+       .read_iter      = sdcardfs_read_iter,
+       .write_iter     = sdcardfs_write_iter,
 };
 
 /* trimmed directory options */