staging: android: ashmem: lseek failed due to no FMODE_LSEEK.

vfs_llseek will check whether the file mode has
FMODE_LSEEK, no return failure. But ashmem can be
lseek, so add FMODE_LSEEK to ashmem file.

Comment From Greg Hackmann:
	ashmem_llseek() passes the llseek() call through to the backing
	shmem file.  91360b02ab48 ("ashmem: use vfs_llseek()") changed
	this from directly calling the file's llseek() op into a VFS
	layer call.  This also adds a check for the FMODE_LSEEK bit, so
	without that bit ashmem_llseek() now always fails with -ESPIPE.

Fixes: 91360b02ab48 ("ashmem: use vfs_llseek()")
Signed-off-by: Shuxiao Zhang <zhangshuxiao@xiaomi.com>
Tested-by: Greg Hackmann <ghackmann@google.com>
Cc: stable <stable@vger.kernel.org> # 3.18+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
index 7cbad0d45b9c8053dc77b7ec696966ed6318324d..6ba270e0494ddc689eb7be7a12eecc819bc1ac7b 100644 (file)
--- a/drivers/staging/android/ashmem.c
+++ b/drivers/staging/android/ashmem.c
@@ -409,6 +409,7 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
                        ret = PTR_ERR(vmfile);
                        goto out;
                }
+               vmfile->f_mode |= FMODE_LSEEK;
                asma->file = vmfile;
        }
        get_file(asma->file);