When generic_write_checks() returns zero, it means that
iov_iter_count() is zero, and there is no work to do.
Simply return success like all other filesystems do, rather than
proceeding down the write path, which today yields an -EFAULT in
generic_perform_write() via the
(fault_in_iov_iter_readable(i, bytes) == bytes) check when bytes
== 0.
Reported-by: Noah <kernel-org-10@xxxxxxxxxxx>
Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
---
diff --git a/fs/exfat/file.c b/fs/exfat/file.c
index 05b51e721783..807349d8ea05 100644
--- a/fs/exfat/file.c
+++ b/fs/exfat/file.c
@@ -587,7 +587,7 @@ static ssize_t exfat_file_write_iter(struct kiocb *iocb, struct iov_iter *iter)
valid_size = ei->valid_size;
ret = generic_write_checks(iocb, iter);
- if (ret < 0)
+ if (ret <= 0)
goto unlock;
if (iocb->ki_flags & IOCB_DIRECT) {
