ANDROID: sdcardfs: fix ->llseek to update upper and lower offset
Adapted from wrapfs
commit 1d1d23a47baa ("Wrapfs: fix ->llseek to update upper and lower
offsets")
Fixes bug: xfstests generic/257. f_pos consistently is required by and
only by dir_ops->wrapfs_readdir, main_ops is not affected.
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: I360a1368ac37ea8966910a58972b81504031d437
diff --git a/fs/sdcardfs/file.c b/fs/sdcardfs/file.c
index 41a550f..f49df7a 100644
--- a/fs/sdcardfs/file.c
+++ b/fs/sdcardfs/file.c
@@ -316,6 +316,29 @@
return err;
}
+/*
+ * Sdcardfs cannot use generic_file_llseek as ->llseek, because it would
+ * only set the offset of the upper file. So we have to implement our
+ * own method to set both the upper and lower file offsets
+ * consistently.
+ */
+static loff_t sdcardfs_file_llseek(struct file *file, loff_t offset, int whence)
+{
+ int err;
+ struct file *lower_file;
+
+ err = generic_file_llseek(file, offset, whence);
+ if (err < 0)
+ goto out;
+
+ lower_file = sdcardfs_lower_file(file);
+ err = generic_file_llseek(lower_file, offset, whence);
+
+out:
+ return err;
+}
+
+
const struct file_operations sdcardfs_main_fops = {
.llseek = generic_file_llseek,
.read = sdcardfs_read,
@@ -334,7 +357,7 @@
/* trimmed directory options */
const struct file_operations sdcardfs_dir_fops = {
- .llseek = generic_file_llseek,
+ .llseek = sdcardfs_file_llseek,
.read = generic_read_dir,
.iterate = sdcardfs_readdir,
.unlocked_ioctl = sdcardfs_unlocked_ioctl,