[PATCH 4.10 010/110] staging: android: ashmem: lseek failed due to no FMODE_LSEEK.

[Greg Kroah-Hartman]

4.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Shuxiao Zhang <zhangshux...@xiaomi.com>

commit 97fbfef6bd597888485b653175fb846c6998b60c upstream.

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 <zhangshux...@xiaomi.com>
Tested-by: Greg Hackmann <ghackm...@google.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/staging/android/ashmem.c |    1 +
 1 file changed, 1 insertion(+)

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