[PATCH] [SMB3] Fix oops when creating symlinks on smb3

[Steve French]

When the protocol ops for create mf symlink was added
we were not checking for symlink support properly for SMB2/SMB3
mounts so could oops when mounted with mfsymlinks when try
to create symlink when on smb2/smb3 mounts rather than cifs
mount

I will add a followon patch for mfsymlinks for SMB3 but in the
meantime need to avoid this possible oops.

Signed-off-by: Steve French <smfrench-***@public.gmane.org>
Cc: <stable-***@public.gmane.org> # 3.14+
CC: Sachin Prabhu <sprabhu-H+wXaHxf7aLQT0dZR+***@public.gmane.org>
---
fs/cifs/link.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/link.c b/fs/cifs/link.c
index 68559fd..a5c2812 100644
--- a/fs/cifs/link.c
+++ b/fs/cifs/link.c
@@ -213,8 +213,12 @@ create_mf_symlink(const unsigned int xid, struct
cifs_tcon *tcon,
if (rc)
goto out;

- rc = tcon->ses->server->ops->create_mf_symlink(xid, tcon, cifs_sb,
- fromName, buf, &bytes_written);
+ if (tcon->ses->server->ops->create_mf_symlink)
+ rc = tcon->ses->server->ops->create_mf_symlink(xid, tcon,
+ cifs_sb, fromName, buf, &bytes_written);
+ else
+ rc = -EOPNOTSUPP;
+
if (rc)
goto out;

[Sachin Prabhu]

Post by Steve French
When the protocol ops for create mf symlink was added
we were not checking for symlink support properly for SMB2/SMB3
mounts so could oops when mounted with mfsymlinks when try
to create symlink when on smb2/smb3 mounts rather than cifs
mount
I will add a followon patch for mfsymlinks for SMB3 but in the
meantime need to avoid this possible oops.
---
fs/cifs/link.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/fs/cifs/link.c b/fs/cifs/link.c
index 68559fd..a5c2812 100644
--- a/fs/cifs/link.c
+++ b/fs/cifs/link.c
@@ -213,8 +213,12 @@ create_mf_symlink(const unsigned int xid, struct
cifs_tcon *tcon,
if (rc)
goto out;
- rc = tcon->ses->server->ops->create_mf_symlink(xid, tcon, cifs_sb,
- fromName, buf, &bytes_written);
+ if (tcon->ses->server->ops->create_mf_symlink)
+ rc = tcon->ses->server->ops->create_mf_symlink(xid, tcon,
+ cifs_sb, fromName, buf, &bytes_written);
+ else
+ rc = -EOPNOTSUPP;
+
if (rc)
goto out;

ACK-ed by: Sachin Prabhu <sprabhu-H+wXaHxf7aLQT0dZR+***@public.gmane.org>