Commit 275a5d24 authored by Trond Myklebust's avatar Trond Myklebust
Browse files

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: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent 75180df2

fs/nfs/super.c

+42 −1
Original line number Diff line number Diff line
@@ -1317,7 +1317,9 @@ static int nfs_compare_super(struct super_block *sb, void *data) 
{

	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 @@ static int nfs_compare_super(struct super_block *sb, void *data) 
	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 @@ static int nfs_get_sb(struct file_system_type *fs_type, 
	}



	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 @@ static int nfs_xdev_get_sb(struct file_system_type *fs_type, int flags, 
	}



	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) {