ceph: check zero length in ceph_sync_read()

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index fec9ddcf1528..c66d4b436437 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -423,6 +423,9 @@ static ssize_t ceph_sync_read(struct kiocb *iocb, struct iov_iter *i,
         dout("sync_read on file %p %llu~%u %s\n", file, off,
              (unsigned)len,
              (file->f_flags & O_DIRECT) ? "O_DIRECT" : "");
+
+        if (!len)
+                return 0;
         /*
          * flush any page cache pages in this range.  this
          * will make concurrent normal and sync io slow,