From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Andr=C3=A9=20Fabian=20Silva=20Delgado?= Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- fs/nfs/namespace.c | 289 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 289 insertions(+) create mode 100644 fs/nfs/namespace.c (limited to 'fs/nfs/namespace.c') diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c new file mode 100644 index 000000000..c8162c660 --- /dev/null +++ b/fs/nfs/namespace.c @@ -0,0 +1,289 @@ +/* + * linux/fs/nfs/namespace.c + * + * Copyright (C) 2005 Trond Myklebust + * - Modified by David Howells + * + * NFS namespace + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "internal.h" + +#define NFSDBG_FACILITY NFSDBG_VFS + +static void nfs_expire_automounts(struct work_struct *work); + +static LIST_HEAD(nfs_automount_list); +static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts); +int nfs_mountpoint_expiry_timeout = 500 * HZ; + +/* + * nfs_path - reconstruct the path given an arbitrary dentry + * @base - used to return pointer to the end of devname part of path + * @dentry - pointer to dentry + * @buffer - result buffer + * @buflen - length of buffer + * @flags - options (see below) + * + * Helper function for constructing the server pathname + * by arbitrary hashed dentry. + * + * This is mainly for use in figuring out the path on the + * server side when automounting on top of an existing partition + * and in generating /proc/mounts and friends. + * + * Supported flags: + * NFS_PATH_CANONICAL: ensure there is exactly one slash after + * the original device (export) name + * (if unset, the original name is returned verbatim) + */ +char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen, + unsigned flags) +{ + char *end; + int namelen; + unsigned seq; + const char *base; + +rename_retry: + end = buffer+buflen; + *--end = '\0'; + buflen--; + + seq = read_seqbegin(&rename_lock); + rcu_read_lock(); + while (1) { + spin_lock(&dentry->d_lock); + if (IS_ROOT(dentry)) + break; + namelen = dentry->d_name.len; + buflen -= namelen + 1; + if (buflen < 0) + goto Elong_unlock; + end -= namelen; + memcpy(end, dentry->d_name.name, namelen); + *--end = '/'; + spin_unlock(&dentry->d_lock); + dentry = dentry->d_parent; + } + if (read_seqretry(&rename_lock, seq)) { + spin_unlock(&dentry->d_lock); + rcu_read_unlock(); + goto rename_retry; + } + if ((flags & NFS_PATH_CANONICAL) && *end != '/') { + if (--buflen < 0) { + spin_unlock(&dentry->d_lock); + rcu_read_unlock(); + goto Elong; + } + *--end = '/'; + } + *p = end; + base = dentry->d_fsdata; + if (!base) { + spin_unlock(&dentry->d_lock); + rcu_read_unlock(); + WARN_ON(1); + return end; + } + namelen = strlen(base); + if (flags & NFS_PATH_CANONICAL) { + /* Strip off excess slashes in base string */ + while (namelen > 0 && base[namelen - 1] == '/') + namelen--; + } + buflen -= namelen; + if (buflen < 0) { + spin_unlock(&dentry->d_lock); + rcu_read_unlock(); + goto Elong; + } + end -= namelen; + memcpy(end, base, namelen); + spin_unlock(&dentry->d_lock); + rcu_read_unlock(); + return end; +Elong_unlock: + spin_unlock(&dentry->d_lock); + rcu_read_unlock(); + if (read_seqretry(&rename_lock, seq)) + goto rename_retry; +Elong: + return ERR_PTR(-ENAMETOOLONG); +} +EXPORT_SYMBOL_GPL(nfs_path); + +/* + * nfs_d_automount - Handle crossing a mountpoint on the server + * @path - The mountpoint + * + * When we encounter a mountpoint on the server, we want to set up + * a mountpoint on the client too, to prevent inode numbers from + * colliding, and to allow "df" to work properly. + * On NFSv4, we also want to allow for the fact that different + * filesystems may be migrated to different servers in a failover + * situation, and that different filesystems may want to use + * different security flavours. + */ +struct vfsmount *nfs_d_automount(struct path *path) +{ + struct vfsmount *mnt; + struct nfs_server *server = NFS_SERVER(d_inode(path->dentry)); + struct nfs_fh *fh = NULL; + struct nfs_fattr *fattr = NULL; + + dprintk("--> nfs_d_automount()\n"); + + mnt = ERR_PTR(-ESTALE); + if (IS_ROOT(path->dentry)) + goto out_nofree; + + mnt = ERR_PTR(-ENOMEM); + fh = nfs_alloc_fhandle(); + fattr = nfs_alloc_fattr(); + if (fh == NULL || fattr == NULL) + goto out; + + dprintk("%s: enter\n", __func__); + + mnt = server->nfs_client->rpc_ops->submount(server, path->dentry, fh, fattr); + if (IS_ERR(mnt)) + goto out; + + dprintk("%s: done, success\n", __func__); + mntget(mnt); /* prevent immediate expiration */ + mnt_set_expiry(mnt, &nfs_automount_list); + schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout); + +out: + nfs_free_fattr(fattr); + nfs_free_fhandle(fh); +out_nofree: + if (IS_ERR(mnt)) + dprintk("<-- %s(): error %ld\n", __func__, PTR_ERR(mnt)); + else + dprintk("<-- %s() = %p\n", __func__, mnt); + return mnt; +} + +static int +nfs_namespace_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat) +{ + if (NFS_FH(d_inode(dentry))->size != 0) + return nfs_getattr(mnt, dentry, stat); + generic_fillattr(d_inode(dentry), stat); + return 0; +} + +static int +nfs_namespace_setattr(struct dentry *dentry, struct iattr *attr) +{ + if (NFS_FH(d_inode(dentry))->size != 0) + return nfs_setattr(dentry, attr); + return -EACCES; +} + +const struct inode_operations nfs_mountpoint_inode_operations = { + .getattr = nfs_getattr, + .setattr = nfs_setattr, +}; + +const struct inode_operations nfs_referral_inode_operations = { + .getattr = nfs_namespace_getattr, + .setattr = nfs_namespace_setattr, +}; + +static void nfs_expire_automounts(struct work_struct *work) +{ + struct list_head *list = &nfs_automount_list; + + mark_mounts_for_expiry(list); + if (!list_empty(list)) + schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout); +} + +void nfs_release_automount_timer(void) +{ + if (list_empty(&nfs_automount_list)) + cancel_delayed_work(&nfs_automount_task); +} + +/* + * Clone a mountpoint of the appropriate type + */ +static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server, + const char *devname, + struct nfs_clone_mount *mountdata) +{ + return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata); +} + +/** + * nfs_do_submount - set up mountpoint when crossing a filesystem boundary + * @dentry - parent directory + * @fh - filehandle for new root dentry + * @fattr - attributes for new root inode + * @authflavor - security flavor to use when performing the mount + * + */ +struct vfsmount *nfs_do_submount(struct dentry *dentry, struct nfs_fh *fh, + struct nfs_fattr *fattr, rpc_authflavor_t authflavor) +{ + struct nfs_clone_mount mountdata = { + .sb = dentry->d_sb, + .dentry = dentry, + .fh = fh, + .fattr = fattr, + .authflavor = authflavor, + }; + struct vfsmount *mnt = ERR_PTR(-ENOMEM); + char *page = (char *) __get_free_page(GFP_USER); + char *devname; + + dprintk("--> nfs_do_submount()\n"); + + dprintk("%s: submounting on %pd2\n", __func__, + dentry); + if (page == NULL) + goto out; + devname = nfs_devname(dentry, page, PAGE_SIZE); + mnt = (struct vfsmount *)devname; + if (IS_ERR(devname)) + goto free_page; + mnt = nfs_do_clone_mount(NFS_SB(dentry->d_sb), devname, &mountdata); +free_page: + free_page((unsigned long)page); +out: + dprintk("%s: done\n", __func__); + + dprintk("<-- nfs_do_submount() = %p\n", mnt); + return mnt; +} +EXPORT_SYMBOL_GPL(nfs_do_submount); + +struct vfsmount *nfs_submount(struct nfs_server *server, struct dentry *dentry, + struct nfs_fh *fh, struct nfs_fattr *fattr) +{ + int err; + struct dentry *parent = dget_parent(dentry); + + /* Look it up again to get its attributes */ + err = server->nfs_client->rpc_ops->lookup(d_inode(parent), &dentry->d_name, fh, fattr, NULL); + dput(parent); + if (err != 0) + return ERR_PTR(err); + + return nfs_do_submount(dentry, fh, fattr, server->client->cl_auth->au_flavor); +} +EXPORT_SYMBOL_GPL(nfs_submount); -- cgit v1.2.3