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https://github.com/edk2-porting/linux-next.git
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f30a6ea0f3
Setting nfs_mountpoint_expiry_timeout() to a negative value stops mountpoint expiration, while setting it to a positive value restarts the scheduler. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
364 lines
9.2 KiB
C
364 lines
9.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* linux/fs/nfs/namespace.c
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*
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* Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
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* - Modified by David Howells <dhowells@redhat.com>
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*
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* NFS namespace
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*/
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#include <linux/module.h>
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#include <linux/dcache.h>
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#include <linux/gfp.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/nfs_fs.h>
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#include <linux/string.h>
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#include <linux/sunrpc/clnt.h>
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#include <linux/vfs.h>
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#include <linux/sunrpc/gss_api.h>
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#include "internal.h"
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#include "nfs.h"
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#define NFSDBG_FACILITY NFSDBG_VFS
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static void nfs_expire_automounts(struct work_struct *work);
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static LIST_HEAD(nfs_automount_list);
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static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
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int nfs_mountpoint_expiry_timeout = 500 * HZ;
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/*
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* nfs_path - reconstruct the path given an arbitrary dentry
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* @base - used to return pointer to the end of devname part of path
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* @dentry - pointer to dentry
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* @buffer - result buffer
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* @buflen - length of buffer
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* @flags - options (see below)
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*
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* Helper function for constructing the server pathname
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* by arbitrary hashed dentry.
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*
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* This is mainly for use in figuring out the path on the
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* server side when automounting on top of an existing partition
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* and in generating /proc/mounts and friends.
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*
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* Supported flags:
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* NFS_PATH_CANONICAL: ensure there is exactly one slash after
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* the original device (export) name
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* (if unset, the original name is returned verbatim)
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*/
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char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen,
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unsigned flags)
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{
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char *end;
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int namelen;
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unsigned seq;
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const char *base;
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rename_retry:
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end = buffer+buflen;
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*--end = '\0';
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buflen--;
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seq = read_seqbegin(&rename_lock);
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rcu_read_lock();
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while (1) {
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spin_lock(&dentry->d_lock);
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if (IS_ROOT(dentry))
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break;
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namelen = dentry->d_name.len;
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buflen -= namelen + 1;
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if (buflen < 0)
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goto Elong_unlock;
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end -= namelen;
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memcpy(end, dentry->d_name.name, namelen);
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*--end = '/';
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spin_unlock(&dentry->d_lock);
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dentry = dentry->d_parent;
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}
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if (read_seqretry(&rename_lock, seq)) {
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spin_unlock(&dentry->d_lock);
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rcu_read_unlock();
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goto rename_retry;
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}
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if ((flags & NFS_PATH_CANONICAL) && *end != '/') {
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if (--buflen < 0) {
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spin_unlock(&dentry->d_lock);
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rcu_read_unlock();
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goto Elong;
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}
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*--end = '/';
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}
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*p = end;
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base = dentry->d_fsdata;
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if (!base) {
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spin_unlock(&dentry->d_lock);
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rcu_read_unlock();
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WARN_ON(1);
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return end;
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}
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namelen = strlen(base);
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if (*end == '/') {
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/* Strip off excess slashes in base string */
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while (namelen > 0 && base[namelen - 1] == '/')
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namelen--;
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}
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buflen -= namelen;
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if (buflen < 0) {
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spin_unlock(&dentry->d_lock);
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rcu_read_unlock();
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goto Elong;
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}
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end -= namelen;
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memcpy(end, base, namelen);
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spin_unlock(&dentry->d_lock);
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rcu_read_unlock();
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return end;
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Elong_unlock:
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spin_unlock(&dentry->d_lock);
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rcu_read_unlock();
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if (read_seqretry(&rename_lock, seq))
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goto rename_retry;
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Elong:
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return ERR_PTR(-ENAMETOOLONG);
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}
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EXPORT_SYMBOL_GPL(nfs_path);
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/*
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* nfs_d_automount - Handle crossing a mountpoint on the server
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* @path - The mountpoint
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*
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* When we encounter a mountpoint on the server, we want to set up
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* a mountpoint on the client too, to prevent inode numbers from
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* colliding, and to allow "df" to work properly.
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* On NFSv4, we also want to allow for the fact that different
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* filesystems may be migrated to different servers in a failover
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* situation, and that different filesystems may want to use
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* different security flavours.
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*/
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struct vfsmount *nfs_d_automount(struct path *path)
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{
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struct nfs_fs_context *ctx;
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struct fs_context *fc;
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struct vfsmount *mnt = ERR_PTR(-ENOMEM);
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struct nfs_server *server = NFS_SERVER(d_inode(path->dentry));
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struct nfs_client *client = server->nfs_client;
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int timeout = READ_ONCE(nfs_mountpoint_expiry_timeout);
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int ret;
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if (IS_ROOT(path->dentry))
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return ERR_PTR(-ESTALE);
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/* Open a new filesystem context, transferring parameters from the
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* parent superblock, including the network namespace.
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*/
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fc = fs_context_for_submount(path->mnt->mnt_sb->s_type, path->dentry);
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if (IS_ERR(fc))
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return ERR_CAST(fc);
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ctx = nfs_fc2context(fc);
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ctx->clone_data.dentry = path->dentry;
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ctx->clone_data.sb = path->dentry->d_sb;
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ctx->clone_data.fattr = nfs_alloc_fattr();
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if (!ctx->clone_data.fattr)
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goto out_fc;
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if (fc->net_ns != client->cl_net) {
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put_net(fc->net_ns);
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fc->net_ns = get_net(client->cl_net);
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}
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/* for submounts we want the same server; referrals will reassign */
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memcpy(&ctx->nfs_server.address, &client->cl_addr, client->cl_addrlen);
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ctx->nfs_server.addrlen = client->cl_addrlen;
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ctx->nfs_server.port = server->port;
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ctx->version = client->rpc_ops->version;
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ctx->minorversion = client->cl_minorversion;
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ctx->nfs_mod = client->cl_nfs_mod;
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__module_get(ctx->nfs_mod->owner);
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ret = client->rpc_ops->submount(fc, server);
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if (ret < 0) {
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mnt = ERR_PTR(ret);
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goto out_fc;
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}
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up_write(&fc->root->d_sb->s_umount);
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mnt = vfs_create_mount(fc);
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if (IS_ERR(mnt))
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goto out_fc;
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mntget(mnt); /* prevent immediate expiration */
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if (timeout <= 0)
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goto out_fc;
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mnt_set_expiry(mnt, &nfs_automount_list);
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schedule_delayed_work(&nfs_automount_task, timeout);
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out_fc:
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put_fs_context(fc);
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return mnt;
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}
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static int
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nfs_namespace_getattr(const struct path *path, struct kstat *stat,
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u32 request_mask, unsigned int query_flags)
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{
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if (NFS_FH(d_inode(path->dentry))->size != 0)
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return nfs_getattr(path, stat, request_mask, query_flags);
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generic_fillattr(d_inode(path->dentry), stat);
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return 0;
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}
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static int
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nfs_namespace_setattr(struct dentry *dentry, struct iattr *attr)
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{
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if (NFS_FH(d_inode(dentry))->size != 0)
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return nfs_setattr(dentry, attr);
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return -EACCES;
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}
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const struct inode_operations nfs_mountpoint_inode_operations = {
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.getattr = nfs_getattr,
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.setattr = nfs_setattr,
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};
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const struct inode_operations nfs_referral_inode_operations = {
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.getattr = nfs_namespace_getattr,
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.setattr = nfs_namespace_setattr,
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};
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static void nfs_expire_automounts(struct work_struct *work)
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{
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struct list_head *list = &nfs_automount_list;
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int timeout = READ_ONCE(nfs_mountpoint_expiry_timeout);
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mark_mounts_for_expiry(list);
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if (!list_empty(list) && timeout > 0)
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schedule_delayed_work(&nfs_automount_task, timeout);
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}
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void nfs_release_automount_timer(void)
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{
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if (list_empty(&nfs_automount_list))
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cancel_delayed_work(&nfs_automount_task);
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}
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/**
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* nfs_do_submount - set up mountpoint when crossing a filesystem boundary
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* @fc: pointer to struct nfs_fs_context
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*
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*/
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int nfs_do_submount(struct fs_context *fc)
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{
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struct nfs_fs_context *ctx = nfs_fc2context(fc);
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struct dentry *dentry = ctx->clone_data.dentry;
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struct nfs_server *server;
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char *buffer, *p;
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int ret;
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/* create a new volume representation */
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server = ctx->nfs_mod->rpc_ops->clone_server(NFS_SB(ctx->clone_data.sb),
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ctx->mntfh,
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ctx->clone_data.fattr,
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ctx->selected_flavor);
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if (IS_ERR(server))
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return PTR_ERR(server);
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ctx->server = server;
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buffer = kmalloc(4096, GFP_USER);
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if (!buffer)
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return -ENOMEM;
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ctx->internal = true;
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ctx->clone_data.inherited_bsize = ctx->clone_data.sb->s_blocksize_bits;
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p = nfs_devname(dentry, buffer, 4096);
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if (IS_ERR(p)) {
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nfs_errorf(fc, "NFS: Couldn't determine submount pathname");
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ret = PTR_ERR(p);
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} else {
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ret = vfs_parse_fs_string(fc, "source", p, buffer + 4096 - p);
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if (!ret)
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ret = vfs_get_tree(fc);
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}
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kfree(buffer);
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return ret;
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}
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EXPORT_SYMBOL_GPL(nfs_do_submount);
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int nfs_submount(struct fs_context *fc, struct nfs_server *server)
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{
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struct nfs_fs_context *ctx = nfs_fc2context(fc);
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struct dentry *dentry = ctx->clone_data.dentry;
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struct dentry *parent = dget_parent(dentry);
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int err;
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/* Look it up again to get its attributes */
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err = server->nfs_client->rpc_ops->lookup(d_inode(parent), dentry,
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ctx->mntfh, ctx->clone_data.fattr,
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NULL);
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dput(parent);
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if (err != 0)
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return err;
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ctx->selected_flavor = server->client->cl_auth->au_flavor;
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return nfs_do_submount(fc);
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}
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EXPORT_SYMBOL_GPL(nfs_submount);
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static int param_set_nfs_timeout(const char *val, const struct kernel_param *kp)
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{
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long num;
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int ret;
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if (!val)
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return -EINVAL;
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ret = kstrtol(val, 0, &num);
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if (ret)
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return -EINVAL;
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if (num > 0) {
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if (num >= INT_MAX / HZ)
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num = INT_MAX;
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else
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num *= HZ;
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*((int *)kp->arg) = num;
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if (!list_empty(&nfs_automount_list))
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mod_delayed_work(system_wq, &nfs_automount_task, num);
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} else {
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*((int *)kp->arg) = -1*HZ;
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cancel_delayed_work(&nfs_automount_task);
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}
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return 0;
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}
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static int param_get_nfs_timeout(char *buffer, const struct kernel_param *kp)
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{
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long num = *((int *)kp->arg);
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if (num > 0) {
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if (num >= INT_MAX - (HZ - 1))
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num = INT_MAX / HZ;
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else
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num = (num + (HZ - 1)) / HZ;
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} else
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num = -1;
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return scnprintf(buffer, PAGE_SIZE, "%li\n", num);
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}
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static const struct kernel_param_ops param_ops_nfs_timeout = {
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.set = param_set_nfs_timeout,
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.get = param_get_nfs_timeout,
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};
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#define param_check_nfs_timeout(name, p) __param_check(name, p, int);
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module_param(nfs_mountpoint_expiry_timeout, nfs_timeout, 0644);
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MODULE_PARM_DESC(nfs_mountpoint_expiry_timeout,
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"Set the NFS automounted mountpoint timeout value (seconds)."
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"Values <= 0 turn expiration off.");
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