NFS: Error when mounting the same filesystem with different options
Unless the user sets the NFS_MOUNT_NOSHAREDCACHE mount flag, we should
return EBUSY if the filesystem is already mounted on a superblock that
has set conflicting mount options.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 1b555cd..a2b1af8 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -1317,7 +1317,9 @@
{
struct nfs_server *server = data, *old = NFS_SB(sb);
- if (old->nfs_client != server->nfs_client)
+ if (memcmp(&old->nfs_client->cl_addr,
+ &server->nfs_client->cl_addr,
+ sizeof(old->nfs_client->cl_addr)) != 0)
return 0;
/* Note: NFS_MOUNT_UNSHARED == NFS4_MOUNT_UNSHARED */
if (old->flags & NFS_MOUNT_UNSHARED)
@@ -1327,6 +1329,39 @@
return 1;
}
+#define NFS_MS_MASK (MS_RDONLY|MS_NOSUID|MS_NODEV|MS_NOEXEC|MS_SYNCHRONOUS)
+
+static int nfs_compare_mount_options(const struct super_block *s, const struct nfs_server *b, int flags)
+{
+ const struct nfs_server *a = s->s_fs_info;
+ const struct rpc_clnt *clnt_a = a->client;
+ const struct rpc_clnt *clnt_b = b->client;
+
+ if ((s->s_flags & NFS_MS_MASK) != (flags & NFS_MS_MASK))
+ goto Ebusy;
+ if (a->nfs_client != b->nfs_client)
+ goto Ebusy;
+ if (a->flags != b->flags)
+ goto Ebusy;
+ if (a->wsize != b->wsize)
+ goto Ebusy;
+ if (a->rsize != b->rsize)
+ goto Ebusy;
+ if (a->acregmin != b->acregmin)
+ goto Ebusy;
+ if (a->acregmax != b->acregmax)
+ goto Ebusy;
+ if (a->acdirmin != b->acdirmin)
+ goto Ebusy;
+ if (a->acdirmax != b->acdirmax)
+ goto Ebusy;
+ if (clnt_a->cl_auth->au_flavor != clnt_b->cl_auth->au_flavor)
+ goto Ebusy;
+ return 0;
+Ebusy:
+ return -EBUSY;
+}
+
static int nfs_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt)
{
@@ -1361,8 +1396,11 @@
}
if (s->s_fs_info != server) {
+ error = nfs_compare_mount_options(s, server, flags);
nfs_free_server(server);
server = NULL;
+ if (error < 0)
+ goto error_splat_super;
}
if (!s->s_root) {
@@ -1442,8 +1480,11 @@
}
if (s->s_fs_info != server) {
+ error = nfs_compare_mount_options(s, server, flags);
nfs_free_server(server);
server = NULL;
+ if (error < 0)
+ goto error_splat_super;
}
if (!s->s_root) {