1 files changed, 786 insertions, 0 deletions

diff --git a/fs/9p/v9fs.c b/fs/9p/v9fs.c
new file mode 100644
index 000000000..274c51571
--- /dev/null
+++ b/fs/9p/v9fs.c
@@ -0,0 +1,786 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  This file contains functions assisting in mapping VFS to 9P2000
+ *
+ *  Copyright (C) 2004-2008 by Eric Van Hensbergen <ericvh@gmail.com>
+ *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/sched.h>
+#include <linux/cred.h>
+#include <linux/fs_parser.h>
+#include <linux/fs_context.h>
+#include <linux/slab.h>
+#include <linux/seq_file.h>
+#include <net/9p/9p.h>
+#include <net/9p/client.h>
+#include <net/9p/transport.h>
+#include "v9fs.h"
+#include "v9fs_vfs.h"
+#include "cache.h"
+
+/* cache=loose default negative dentry retention time is 24hours */
+#define CACHE_LOOSE_NDENTRY_TIMEOUT_DEFAULT (24 * 60 * 60 * 1000)
+
+static DEFINE_SPINLOCK(v9fs_sessionlist_lock);
+static LIST_HEAD(v9fs_sessionlist);
+struct kmem_cache *v9fs_inode_cache;
+
+/*
+ * Option Parsing (code inspired by NFS code)
+ *  NOTE: each transport will parse its own options
+ */
+
+enum {
+	/* Mount-point source, we need to handle this explicitly because
+	 * the code below accepts unknown args and the vfs layer only handles
+	 * source if we rejected it as EINVAL */
+	Opt_source,
+	/* Options that take integer arguments */
+	Opt_debug, Opt_dfltuid, Opt_dfltgid, Opt_afid, Opt_negtimeout,
+	/* String options */
+	Opt_uname, Opt_remotename, Opt_cache, Opt_cachetag,
+	/* Options that take no arguments */
+	Opt_nodevmap, Opt_noxattr, Opt_directio, Opt_ignoreqv,
+	/* Access options */
+	Opt_access, Opt_posixacl,
+	/* Lock timeout option */
+	Opt_locktimeout,
+
+	/* Client options */
+	Opt_msize, Opt_trans, Opt_legacy, Opt_version,
+
+	/* fd transport options */
+	/* Options that take integer arguments */
+	Opt_rfdno, Opt_wfdno,
+	/* Options that take no arguments */
+
+	/* rdma transport options */
+	/* Options that take integer arguments */
+	Opt_rq_depth, Opt_sq_depth, Opt_timeout,
+
+	/* Options for both fd and rdma transports */
+	Opt_port, Opt_privport,
+};
+
+static const struct constant_table p9_versions[] = {
+	{ "9p2000",	p9_proto_legacy },
+	{ "9p2000.u",	p9_proto_2000u },
+	{ "9p2000.L",	p9_proto_2000L },
+	{}
+};
+
+/*
+ * This structure contains all parameters used for the core code,
+ * the client, and all the transports.
+ */
+const struct fs_parameter_spec v9fs_param_spec[] = {
+	fsparam_string	("source",	Opt_source),
+	fsparam_u32hex	("debug",	Opt_debug),
+	fsparam_uid	("dfltuid",	Opt_dfltuid),
+	fsparam_gid	("dfltgid",	Opt_dfltgid),
+	fsparam_u32	("afid",	Opt_afid),
+	fsparam_string	("uname",	Opt_uname),
+	fsparam_string	("aname",	Opt_remotename),
+	fsparam_flag	("nodevmap",	Opt_nodevmap),
+	fsparam_flag	("noxattr",	Opt_noxattr),
+	fsparam_flag	("directio",	Opt_directio),
+	fsparam_flag	("ignoreqv",	Opt_ignoreqv),
+	fsparam_string	("cache",	Opt_cache),
+	fsparam_string	("cachetag",	Opt_cachetag),
+	fsparam_string	("access",	Opt_access),
+	fsparam_flag	("posixacl",	Opt_posixacl),
+	fsparam_u32	("locktimeout",	Opt_locktimeout),
+	fsparam_s32	("negtimeout",	Opt_negtimeout),
+
+	/* client options */
+	fsparam_u32	("msize",	Opt_msize),
+	fsparam_flag	("noextend",	Opt_legacy),
+	fsparam_string	("trans",	Opt_trans),
+	fsparam_enum	("version",	Opt_version, p9_versions),
+
+	/* fd transport options */
+	fsparam_u32	("rfdno",	Opt_rfdno),
+	fsparam_u32	("wfdno",	Opt_wfdno),
+
+	/* rdma transport options */
+	fsparam_u32	("sq",		Opt_sq_depth),
+	fsparam_u32	("rq",		Opt_rq_depth),
+	fsparam_u32	("timeout",	Opt_timeout),
+
+	/* fd and rdma transprt options */
+	fsparam_u32	("port",	Opt_port),
+	fsparam_flag	("privport",	Opt_privport),
+	{}
+};
+
+/* Interpret mount options for cache mode */
+static int get_cache_mode(char *s)
+{
+	int version = -EINVAL;
+
+	if (!strcmp(s, "loose")) {
+		version = CACHE_SC_LOOSE;
+		p9_debug(P9_DEBUG_9P, "Cache mode: loose\n");
+	} else if (!strcmp(s, "fscache")) {
+		version = CACHE_SC_FSCACHE;
+		p9_debug(P9_DEBUG_9P, "Cache mode: fscache\n");
+	} else if (!strcmp(s, "mmap")) {
+		version = CACHE_SC_MMAP;
+		p9_debug(P9_DEBUG_9P, "Cache mode: mmap\n");
+	} else if (!strcmp(s, "readahead")) {
+		version = CACHE_SC_READAHEAD;
+		p9_debug(P9_DEBUG_9P, "Cache mode: readahead\n");
+	} else if (!strcmp(s, "none")) {
+		version = CACHE_SC_NONE;
+		p9_debug(P9_DEBUG_9P, "Cache mode: none\n");
+	} else if (kstrtoint(s, 0, &version) != 0) {
+		version = -EINVAL;
+		pr_info("Unknown Cache mode or invalid value %s\n", s);
+	}
+	return version;
+}
+
+/*
+ * Display the mount options in /proc/mounts.
+ */
+int v9fs_show_options(struct seq_file *m, struct dentry *root)
+{
+	struct v9fs_session_info *v9ses = root->d_sb->s_fs_info;
+
+	if (v9ses->debug)
+		seq_printf(m, ",debug=%#x", v9ses->debug);
+	if (!uid_eq(v9ses->dfltuid, V9FS_DEFUID))
+		seq_printf(m, ",dfltuid=%u",
+			   from_kuid_munged(&init_user_ns, v9ses->dfltuid));
+	if (!gid_eq(v9ses->dfltgid, V9FS_DEFGID))
+		seq_printf(m, ",dfltgid=%u",
+			   from_kgid_munged(&init_user_ns, v9ses->dfltgid));
+	if (v9ses->afid != ~0)
+		seq_printf(m, ",afid=%u", v9ses->afid);
+	if (v9ses->flags & V9FS_NDENTRY_TIMEOUT_SET)
+		seq_printf(m, ",negtimeout=%d",
+			   (int)v9ses->ndentry_timeout_ms);
+	if (strcmp(v9ses->uname, V9FS_DEFUSER) != 0)
+		seq_printf(m, ",uname=%s", v9ses->uname);
+	if (strcmp(v9ses->aname, V9FS_DEFANAME) != 0)
+		seq_printf(m, ",aname=%s", v9ses->aname);
+	if (v9ses->nodev)
+		seq_puts(m, ",nodevmap");
+	if (v9ses->cache)
+		seq_printf(m, ",cache=%#x", v9ses->cache);
+#ifdef CONFIG_9P_FSCACHE
+	if (v9ses->cachetag && (v9ses->cache & CACHE_FSCACHE))
+		seq_printf(m, ",cachetag=%s", v9ses->cachetag);
+#endif
+
+	switch (v9ses->flags & V9FS_ACCESS_MASK) {
+	case V9FS_ACCESS_USER:
+		seq_puts(m, ",access=user");
+		break;
+	case V9FS_ACCESS_ANY:
+		seq_puts(m, ",access=any");
+		break;
+	case V9FS_ACCESS_CLIENT:
+		seq_puts(m, ",access=client");
+		break;
+	case V9FS_ACCESS_SINGLE:
+		seq_printf(m, ",access=%u",
+			   from_kuid_munged(&init_user_ns, v9ses->uid));
+		break;
+	}
+
+	if (v9ses->flags & V9FS_IGNORE_QV)
+		seq_puts(m, ",ignoreqv");
+	if (v9ses->flags & V9FS_DIRECT_IO)
+		seq_puts(m, ",directio");
+	if (v9ses->flags & V9FS_POSIX_ACL)
+		seq_puts(m, ",posixacl");
+
+	if (v9ses->flags & V9FS_NO_XATTR)
+		seq_puts(m, ",noxattr");
+
+	return p9_show_client_options(m, v9ses->clnt);
+}
+
+/**
+ * v9fs_parse_param - parse a mount option into the filesystem context
+ * @fc: the filesystem context
+ * @param: the parameter to parse
+ *
+ * Return 0 upon success, -ERRNO upon failure.
+ */
+int v9fs_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+	struct v9fs_context *ctx = fc->fs_private;
+	struct fs_parse_result result;
+	char *s;
+	int r;
+	int opt;
+	struct p9_client_opts	*clnt = &ctx->client_opts;
+	struct p9_fd_opts	*fd_opts = &ctx->fd_opts;
+	struct p9_rdma_opts	*rdma_opts = &ctx->rdma_opts;
+	struct p9_session_opts	*session_opts = &ctx->session_opts;
+
+	opt = fs_parse(fc, v9fs_param_spec, param, &result);
+	if (opt < 0) {
+		/*
+		 * We might like to report bad mount options here, but
+		 * traditionally 9p has ignored unknown mount options
+		 */
+		if (opt == -ENOPARAM)
+			return 0;
+
+		return opt;
+	}
+
+	switch (opt) {
+	case Opt_source:
+		if (fc->source) {
+			pr_info("p9: multiple sources not supported\n");
+			return -EINVAL;
+		}
+		fc->source = param->string;
+		param->string = NULL;
+		break;
+	case Opt_debug:
+		session_opts->debug = result.uint_32;
+#ifdef CONFIG_NET_9P_DEBUG
+		p9_debug_level = result.uint_32;
+#endif
+		break;
+
+	case Opt_dfltuid:
+		session_opts->dfltuid = result.uid;
+		break;
+	case Opt_dfltgid:
+		session_opts->dfltgid = result.gid;
+		break;
+	case Opt_afid:
+		session_opts->afid = result.uint_32;
+		break;
+	case Opt_uname:
+		kfree(session_opts->uname);
+		session_opts->uname = param->string;
+		param->string = NULL;
+		break;
+	case Opt_remotename:
+		kfree(session_opts->aname);
+		session_opts->aname = param->string;
+		param->string = NULL;
+		break;
+	case Opt_nodevmap:
+		session_opts->nodev = 1;
+		break;
+	case Opt_noxattr:
+		session_opts->flags |= V9FS_NO_XATTR;
+		break;
+	case Opt_directio:
+		session_opts->flags |= V9FS_DIRECT_IO;
+		break;
+	case Opt_ignoreqv:
+		session_opts->flags |= V9FS_IGNORE_QV;
+		break;
+	case Opt_cachetag:
+#ifdef CONFIG_9P_FSCACHE
+		kfree(session_opts->cachetag);
+		session_opts->cachetag = param->string;
+		param->string = NULL;
+#endif
+		break;
+	case Opt_cache:
+		r = get_cache_mode(param->string);
+		if (r < 0)
+			return r;
+		session_opts->cache = r;
+		break;
+	case Opt_access:
+		s = param->string;
+		session_opts->flags &= ~V9FS_ACCESS_MASK;
+		if (strcmp(s, "user") == 0) {
+			session_opts->flags |= V9FS_ACCESS_USER;
+		} else if (strcmp(s, "any") == 0) {
+			session_opts->flags |= V9FS_ACCESS_ANY;
+		} else if (strcmp(s, "client") == 0) {
+			session_opts->flags |= V9FS_ACCESS_CLIENT;
+		} else {
+			uid_t uid;
+
+			session_opts->flags |= V9FS_ACCESS_SINGLE;
+			r = kstrtouint(s, 10, &uid);
+			if (r) {
+				pr_info("Unknown access argument %s: %d\n",
+					param->string, r);
+				return r;
+			}
+			session_opts->uid = make_kuid(current_user_ns(), uid);
+			if (!uid_valid(session_opts->uid)) {
+				pr_info("Unknown uid %s\n", s);
+				return -EINVAL;
+			}
+		}
+		break;
+
+	case Opt_posixacl:
+#ifdef CONFIG_9P_FS_POSIX_ACL
+		session_opts->flags |= V9FS_POSIX_ACL;
+#else
+		p9_debug(P9_DEBUG_ERROR,
+			 "Not defined CONFIG_9P_FS_POSIX_ACL. Ignoring posixacl option\n");
+#endif
+		break;
+
+	case Opt_locktimeout:
+		if (result.uint_32 < 1) {
+			p9_debug(P9_DEBUG_ERROR,
+				 "locktimeout must be a greater than zero integer.\n");
+			return -EINVAL;
+		}
+		session_opts->session_lock_timeout = (long)result.uint_32 * HZ;
+		break;
+
+	case Opt_negtimeout:
+		session_opts->flags |= V9FS_NDENTRY_TIMEOUT_SET;
+		if (result.int_32 < 0) {
+			session_opts->ndentry_timeout_ms =
+				NDENTRY_TIMEOUT_NEVER;
+		} else {
+			session_opts->ndentry_timeout_ms = result.int_32;
+		}
+		break;
+
+	/* Options for client */
+	case Opt_msize:
+		if (result.uint_32 < 4096) {
+			p9_debug(P9_DEBUG_ERROR, "msize should be at least 4k\n");
+			return -EINVAL;
+		}
+		if (result.uint_32 > INT_MAX) {
+			p9_debug(P9_DEBUG_ERROR, "msize too big\n");
+			return -EINVAL;
+		}
+		clnt->msize = result.uint_32;
+		break;
+	case Opt_trans:
+		v9fs_put_trans(clnt->trans_mod);
+		clnt->trans_mod = v9fs_get_trans_by_name(param->string);
+		if (!clnt->trans_mod) {
+			pr_info("Could not find request transport: %s\n",
+				param->string);
+			return -EINVAL;
+		}
+		break;
+	case Opt_legacy:
+		clnt->proto_version = p9_proto_legacy;
+		break;
+	case Opt_version:
+		clnt->proto_version = result.uint_32;
+		p9_debug(P9_DEBUG_9P, "Protocol version: %s\n", param->string);
+		break;
+	/* Options for fd transport */
+	case Opt_rfdno:
+		fd_opts->rfd = result.uint_32;
+		break;
+	case Opt_wfdno:
+		fd_opts->wfd = result.uint_32;
+		break;
+	/* Options for rdma transport */
+	case Opt_sq_depth:
+		rdma_opts->sq_depth = result.uint_32;
+		break;
+	case Opt_rq_depth:
+		rdma_opts->rq_depth = result.uint_32;
+		break;
+	case Opt_timeout:
+		rdma_opts->timeout = result.uint_32;
+		break;
+	/* Options for both fd and rdma transports */
+	case Opt_port:
+		fd_opts->port = result.uint_32;
+		rdma_opts->port = result.uint_32;
+		break;
+	case Opt_privport:
+		fd_opts->privport = true;
+		rdma_opts->port = true;
+		break;
+	}
+
+	return 0;
+}
+
+static void v9fs_apply_options(struct v9fs_session_info *v9ses,
+		  struct fs_context *fc)
+{
+	struct v9fs_context	*ctx = fc->fs_private;
+
+	v9ses->debug = ctx->session_opts.debug;
+	v9ses->dfltuid = ctx->session_opts.dfltuid;
+	v9ses->dfltgid = ctx->session_opts.dfltgid;
+	v9ses->afid = ctx->session_opts.afid;
+	v9ses->uname = ctx->session_opts.uname;
+	ctx->session_opts.uname = NULL;
+	v9ses->aname = ctx->session_opts.aname;
+	ctx->session_opts.aname = NULL;
+	v9ses->nodev = ctx->session_opts.nodev;
+	/*
+	 * Note that we must |= flags here as session_init already
+	 * set basic flags. This adds in flags from parsed options.
+	 * Default access flags must be cleared if session options
+	 * changes them to avoid mangling the setting.
+	 */
+	if (ctx->session_opts.flags & V9FS_ACCESS_MASK)
+		v9ses->flags &= ~V9FS_ACCESS_MASK;
+	v9ses->flags |= ctx->session_opts.flags;
+#ifdef CONFIG_9P_FSCACHE
+	v9ses->cachetag = ctx->session_opts.cachetag;
+	ctx->session_opts.cachetag = NULL;
+#endif
+	v9ses->cache = ctx->session_opts.cache;
+	v9ses->uid = ctx->session_opts.uid;
+	v9ses->session_lock_timeout = ctx->session_opts.session_lock_timeout;
+	v9ses->ndentry_timeout_ms = ctx->session_opts.ndentry_timeout_ms;
+
+	/* If negative dentry timeout has not been overridden set default for
+	 * cache=loose
+	 */
+	if (!(v9ses->flags & V9FS_NDENTRY_TIMEOUT_SET) &&
+	    (v9ses->cache & CACHE_LOOSE))
+		v9ses->ndentry_timeout_ms = CACHE_LOOSE_NDENTRY_TIMEOUT_DEFAULT;
+}
+
+/**
+ * v9fs_session_init - initialize session
+ * @v9ses: session information structure
+ * @fc: the filesystem mount context
+ *
+ */
+
+struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,
+		  struct fs_context *fc)
+{
+	struct p9_fid *fid;
+	int rc = -ENOMEM;
+
+	init_rwsem(&v9ses->rename_sem);
+
+	v9ses->clnt = p9_client_create(fc);
+	if (IS_ERR(v9ses->clnt)) {
+		rc = PTR_ERR(v9ses->clnt);
+		p9_debug(P9_DEBUG_ERROR, "problem initializing 9p client\n");
+		goto err_names;
+	}
+
+	/*
+	 * Initialize flags on the real v9ses. v9fs_apply_options below
+	 * will |= the additional flags from parsed options.
+	 */
+	v9ses->flags = V9FS_ACCESS_USER;
+
+	if (p9_is_proto_dotl(v9ses->clnt)) {
+		v9ses->flags = V9FS_ACCESS_CLIENT;
+		v9ses->flags |= V9FS_PROTO_2000L;
+	} else if (p9_is_proto_dotu(v9ses->clnt)) {
+		v9ses->flags |= V9FS_PROTO_2000U;
+	}
+
+	v9fs_apply_options(v9ses, fc);
+
+	v9ses->maxdata = v9ses->clnt->msize - P9_IOHDRSZ;
+
+	if (!v9fs_proto_dotl(v9ses) &&
+	    ((v9ses->flags & V9FS_ACCESS_MASK) == V9FS_ACCESS_CLIENT)) {
+		/*
+		 * We support ACCESS_CLIENT only for dotl.
+		 * Fall back to ACCESS_USER
+		 */
+		v9ses->flags &= ~V9FS_ACCESS_MASK;
+		v9ses->flags |= V9FS_ACCESS_USER;
+	}
+	/* FIXME: for legacy mode, fall back to V9FS_ACCESS_ANY */
+	if (!(v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses)) &&
+		((v9ses->flags&V9FS_ACCESS_MASK) == V9FS_ACCESS_USER)) {
+
+		v9ses->flags &= ~V9FS_ACCESS_MASK;
+		v9ses->flags |= V9FS_ACCESS_ANY;
+		v9ses->uid = INVALID_UID;
+	}
+	if (!v9fs_proto_dotl(v9ses) ||
+		!((v9ses->flags & V9FS_ACCESS_MASK) == V9FS_ACCESS_CLIENT)) {
+		/*
+		 * We support ACL checks on client only if the protocol is
+		 * 9P2000.L and access is V9FS_ACCESS_CLIENT.
+		 */
+		v9ses->flags &= ~V9FS_ACL_MASK;
+	}
+
+	fid = p9_client_attach(v9ses->clnt, NULL, v9ses->uname, INVALID_UID,
+							v9ses->aname);
+	if (IS_ERR(fid)) {
+		rc = PTR_ERR(fid);
+		p9_debug(P9_DEBUG_ERROR, "cannot attach\n");
+		goto err_clnt;
+	}
+
+	if ((v9ses->flags & V9FS_ACCESS_MASK) == V9FS_ACCESS_SINGLE)
+		fid->uid = v9ses->uid;
+	else
+		fid->uid = INVALID_UID;
+
+#ifdef CONFIG_9P_FSCACHE
+	/* register the session for caching */
+	if (v9ses->cache & CACHE_FSCACHE) {
+		rc = v9fs_cache_session_get_cookie(v9ses, fc->source);
+		if (rc < 0)
+			goto err_clnt;
+	}
+#endif
+	spin_lock(&v9fs_sessionlist_lock);
+	list_add(&v9ses->slist, &v9fs_sessionlist);
+	spin_unlock(&v9fs_sessionlist_lock);
+
+	return fid;
+
+err_clnt:
+#ifdef CONFIG_9P_FSCACHE
+	kfree(v9ses->cachetag);
+#endif
+	p9_client_destroy(v9ses->clnt);
+err_names:
+	kfree(v9ses->uname);
+	kfree(v9ses->aname);
+	return ERR_PTR(rc);
+}
+
+/**
+ * v9fs_session_close - shutdown a session
+ * @v9ses: session information structure
+ *
+ */
+
+void v9fs_session_close(struct v9fs_session_info *v9ses)
+{
+	if (v9ses->clnt) {
+		p9_client_destroy(v9ses->clnt);
+		v9ses->clnt = NULL;
+	}
+
+#ifdef CONFIG_9P_FSCACHE
+	fscache_relinquish_volume(v9fs_session_cache(v9ses), NULL, false);
+	kfree(v9ses->cachetag);
+#endif
+	kfree(v9ses->uname);
+	kfree(v9ses->aname);
+
+	spin_lock(&v9fs_sessionlist_lock);
+	list_del(&v9ses->slist);
+	spin_unlock(&v9fs_sessionlist_lock);
+}
+
+/**
+ * v9fs_session_cancel - terminate a session
+ * @v9ses: session to terminate
+ *
+ * mark transport as disconnected and cancel all pending requests.
+ */
+
+void v9fs_session_cancel(struct v9fs_session_info *v9ses)
+{
+	p9_debug(P9_DEBUG_ERROR, "cancel session %p\n", v9ses);
+	p9_client_disconnect(v9ses->clnt);
+}
+
+/**
+ * v9fs_session_begin_cancel - Begin terminate of a session
+ * @v9ses: session to terminate
+ *
+ * After this call we don't allow any request other than clunk.
+ */
+
+void v9fs_session_begin_cancel(struct v9fs_session_info *v9ses)
+{
+	p9_debug(P9_DEBUG_ERROR, "begin cancel session %p\n", v9ses);
+	p9_client_begin_disconnect(v9ses->clnt);
+}
+
+static struct kobject *v9fs_kobj;
+
+#ifdef CONFIG_9P_FSCACHE
+/*
+ * List caches associated with a session
+ */
+static ssize_t caches_show(struct kobject *kobj,
+			   struct kobj_attribute *attr,
+			   char *buf)
+{
+	ssize_t n = 0, count = 0, limit = PAGE_SIZE;
+	struct v9fs_session_info *v9ses;
+
+	spin_lock(&v9fs_sessionlist_lock);
+	list_for_each_entry(v9ses, &v9fs_sessionlist, slist) {
+		if (v9ses->cachetag) {
+			n = snprintf(buf + count, limit, "%s\n", v9ses->cachetag);
+			if (n < 0) {
+				count = n;
+				break;
+			}
+
+			count += n;
+			limit -= n;
+		}
+	}
+
+	spin_unlock(&v9fs_sessionlist_lock);
+	return count;
+}
+
+static struct kobj_attribute v9fs_attr_cache = __ATTR_RO(caches);
+#endif /* CONFIG_9P_FSCACHE */
+
+static struct attribute *v9fs_attrs[] = {
+#ifdef CONFIG_9P_FSCACHE
+	&v9fs_attr_cache.attr,
+#endif
+	NULL,
+};
+
+static const struct attribute_group v9fs_attr_group = {
+	.attrs = v9fs_attrs,
+};
+
+/**
+ * v9fs_sysfs_init - Initialize the v9fs sysfs interface
+ *
+ */
+
+static int __init v9fs_sysfs_init(void)
+{
+	int ret;
+
+	v9fs_kobj = kobject_create_and_add("9p", fs_kobj);
+	if (!v9fs_kobj)
+		return -ENOMEM;
+
+	ret = sysfs_create_group(v9fs_kobj, &v9fs_attr_group);
+	if (ret) {
+		kobject_put(v9fs_kobj);
+		return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * v9fs_sysfs_cleanup - Unregister the v9fs sysfs interface
+ *
+ */
+
+static void v9fs_sysfs_cleanup(void)
+{
+	sysfs_remove_group(v9fs_kobj, &v9fs_attr_group);
+	kobject_put(v9fs_kobj);
+}
+
+static void v9fs_inode_init_once(void *foo)
+{
+	struct v9fs_inode *v9inode = (struct v9fs_inode *)foo;
+
+	memset(&v9inode->qid, 0, sizeof(v9inode->qid));
+	inode_init_once(&v9inode->netfs.inode);
+}
+
+/**
+ * v9fs_init_inode_cache - initialize a cache for 9P
+ * Returns 0 on success.
+ */
+static int v9fs_init_inode_cache(void)
+{
+	v9fs_inode_cache = kmem_cache_create("v9fs_inode_cache",
+					  sizeof(struct v9fs_inode),
+					  0, (SLAB_RECLAIM_ACCOUNT|
+					      SLAB_ACCOUNT),
+					  v9fs_inode_init_once);
+	if (!v9fs_inode_cache)
+		return -ENOMEM;
+
+	return 0;
+}
+
+/**
+ * v9fs_destroy_inode_cache - destroy the cache of 9P inode
+ *
+ */
+static void v9fs_destroy_inode_cache(void)
+{
+	/*
+	 * Make sure all delayed rcu free inodes are flushed before we
+	 * destroy cache.
+	 */
+	rcu_barrier();
+	kmem_cache_destroy(v9fs_inode_cache);
+}
+
+/**
+ * init_v9fs - Initialize module
+ *
+ */
+
+static int __init init_v9fs(void)
+{
+	int err;
+
+	pr_info("Installing v9fs 9p2000 file system support\n");
+	/* TODO: Setup list of registered transport modules */
+
+	err = v9fs_init_inode_cache();
+	if (err < 0) {
+		pr_err("Failed to register v9fs for caching\n");
+		return err;
+	}
+
+	err = v9fs_sysfs_init();
+	if (err < 0) {
+		pr_err("Failed to register with sysfs\n");
+		goto out_cache;
+	}
+	err = register_filesystem(&v9fs_fs_type);
+	if (err < 0) {
+		pr_err("Failed to register filesystem\n");
+		goto out_sysfs_cleanup;
+	}
+
+	return 0;
+
+out_sysfs_cleanup:
+	v9fs_sysfs_cleanup();
+
+out_cache:
+	v9fs_destroy_inode_cache();
+
+	return err;
+}
+
+/**
+ * exit_v9fs - shutdown module
+ *
+ */
+
+static void __exit exit_v9fs(void)
+{
+	v9fs_sysfs_cleanup();
+	v9fs_destroy_inode_cache();
+	unregister_filesystem(&v9fs_fs_type);
+}
+
+module_init(init_v9fs)
+module_exit(exit_v9fs)
+
+MODULE_AUTHOR("Latchesar Ionkov <lucho@ionkov.net>");
+MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
+MODULE_AUTHOR("Ron Minnich <rminnich@lanl.gov>");
+MODULE_DESCRIPTION("9P Client File System");
+MODULE_LICENSE("GPL");