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NFS: implement option checking when remounting NFS filesystems (resend)

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When remounting an NFS or NFS4 filesystem, the new NFS options are not
respected, yet the remount will still return success. This patch adds
a remount_fs sb op for NFS that checks any new nfs mount options against
the existing ones and fails the mount if any have changed.

This is only implemented for string-based mount options since doing
this with binary options isn't really feasible.

This is essentially the same as the original patch I sent out, but
adds a check to see if the addr= option has changed.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Jeff Layton 2008-06-10 15:38:39 -04:00 committed by Trond Myklebust
parent c2d946e55e
commit 48b605f83c
1 changed files with 76 additions and 0 deletions
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76
fs/nfs/super.c
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@ -207,6 +207,7 @@ static int nfs_xdev_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
static void nfs_kill_super(struct super_block *);
static void nfs_put_super(struct super_block *);
static int nfs_remount(struct super_block *sb, int *flags, char *raw_data);
static struct file_system_type nfs_fs_type = {
.owner = THIS_MODULE,
@ -234,6 +235,7 @@ static const struct super_operations nfs_sops = {
.umount_begin = nfs_umount_begin,
.show_options = nfs_show_options,
.show_stats = nfs_show_stats,
.remount_fs = nfs_remount,
};
#ifdef CONFIG_NFS_V4
@ -278,6 +280,7 @@ static const struct super_operations nfs4_sops = {
.umount_begin = nfs_umount_begin,
.show_options = nfs_show_options,
.show_stats = nfs_show_stats,
.remount_fs = nfs_remount,
};
#endif
@ -1396,6 +1399,79 @@ static int nfs_validate_mount_data(void *options,
return -EINVAL;
}
static int
nfs_compare_remount_data(struct nfs_server *nfss,
struct nfs_parsed_mount_data *data)
{
if (data->flags != nfss->flags ||
data->rsize != nfss->rsize ||
data->wsize != nfss->wsize ||
data->retrans != nfss->client->cl_timeout->to_retries ||
data->auth_flavors[0] != nfss->client->cl_auth->au_flavor ||
data->acregmin != nfss->acregmin / HZ ||
data->acregmax != nfss->acregmax / HZ ||
data->acdirmin != nfss->acdirmin / HZ ||
data->acdirmax != nfss->acdirmax / HZ ||
data->timeo != (10U * nfss->client->cl_timeout->to_initval / HZ) ||
data->nfs_server.addrlen != nfss->nfs_client->cl_addrlen ||
memcmp(&data->nfs_server.address, &nfss->nfs_client->cl_addr,
data->nfs_server.addrlen) != 0)
return -EINVAL;
return 0;
}
static int
nfs_remount(struct super_block *sb, int *flags, char *raw_data)
{
int error;
struct nfs_server *nfss = sb->s_fs_info;
struct nfs_parsed_mount_data *data;
struct nfs_mount_data *options = (struct nfs_mount_data *)raw_data;
struct nfs4_mount_data *options4 = (struct nfs4_mount_data *)raw_data;
/*
* Userspace mount programs that send binary options generally send
* them populated with default values. We have no way to know which
* ones were explicitly specified. Fall back to legacy behavior and
* just return success.
*/
if ((sb->s_type == &nfs4_fs_type && options4->version == 1) ||
(sb->s_type == &nfs_fs_type && options->version >= 1 &&
options->version <= 6))
return 0;
data = kzalloc(sizeof(*data), GFP_KERNEL);
if (data == NULL)
return -ENOMEM;
/* fill out struct with values from existing mount */
data->flags = nfss->flags;
data->rsize = nfss->rsize;
data->wsize = nfss->wsize;
data->retrans = nfss->client->cl_timeout->to_retries;
data->auth_flavors[0] = nfss->client->cl_auth->au_flavor;
data->acregmin = nfss->acregmin / HZ;
data->acregmax = nfss->acregmax / HZ;
data->acdirmin = nfss->acdirmin / HZ;
data->acdirmax = nfss->acdirmax / HZ;
data->timeo = 10U * nfss->client->cl_timeout->to_initval / HZ;
data->nfs_server.addrlen = nfss->nfs_client->cl_addrlen;
memcpy(&data->nfs_server.address, &nfss->nfs_client->cl_addr,
data->nfs_server.addrlen);
/* overwrite those values with any that were specified */
error = nfs_parse_mount_options((char *)options, data);
if (error < 0)
goto out;
/* compare new mount options with old ones */
error = nfs_compare_remount_data(nfss, data);
out:
kfree(data);
return error;
}
/*
* Initialise the common bits of the superblock
*/