fs/nfs/nfs4super.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (c) 2012 Bryan Schumaker <bjschuma@netapp.com>
  */
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/mount.h>
 #include <linux/nfs4_mount.h>
 #include <linux/nfs_fs.h>
 #include "delegation.h"
 #include "internal.h"
 #include "nfs4_fs.h"
 #include "nfs4idmap.h"
 #include "dns_resolve.h"
 #include "pnfs.h"
 #include "nfs.h"

 #define NFSDBG_FACILITY		NFSDBG_VFS

 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc);
 static void nfs4_evict_inode(struct inode *inode);

 static const struct super_operations nfs4_sops = {
 	.alloc_inode	= nfs_alloc_inode,
 	.free_inode	= nfs_free_inode,
 	.write_inode	= nfs4_write_inode,
 	.drop_inode	= nfs_drop_inode,
 	.statfs		= nfs_statfs,
 	.evict_inode	= nfs4_evict_inode,
 	.umount_begin	= nfs_umount_begin,
 	.show_options	= nfs_show_options,
 	.show_devname	= nfs_show_devname,
 	.show_path	= nfs_show_path,
 	.show_stats	= nfs_show_stats,
 };

 struct nfs_subversion nfs_v4 = {
 	.owner		= THIS_MODULE,
 	.nfs_fs		= &nfs4_fs_type,
 	.rpc_vers	= &nfs_version4,
 	.rpc_ops	= &nfs_v4_clientops,
 	.sops		= &nfs4_sops,
 	.xattr		= nfs4_xattr_handlers,
 };

 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc)
 {
 	int ret = nfs_write_inode(inode, wbc);

 	if (ret == 0)
 		ret = pnfs_layoutcommit_inode(inode,
 				wbc->sync_mode == WB_SYNC_ALL);
 	return ret;
 }

 /*
  * Clean out any remaining NFSv4 state that might be left over due
  * to open() calls that passed nfs_atomic_lookup, but failed to call
  * nfs_open().
  */
 static void nfs4_evict_inode(struct inode *inode)
 {
 	truncate_inode_pages_final(&inode->i_data);
 	clear_inode(inode);
 	/* If we are holding a delegation, return and free it */
 	nfs_inode_evict_delegation(inode);
 	/* Note that above delegreturn would trigger pnfs return-on-close */
 	pnfs_return_layout(inode);
 	pnfs_destroy_layout(NFS_I(inode));
 	/* First call standard NFS clear_inode() code */
 	nfs_clear_inode(inode);
 	nfs4_xattr_cache_zap(inode);
 }

 struct nfs_referral_count {
 	struct list_head list;
 	const struct task_struct *task;
 	unsigned int referral_count;
 };

 static LIST_HEAD(nfs_referral_count_list);
 static DEFINE_SPINLOCK(nfs_referral_count_list_lock);

 static struct nfs_referral_count *nfs_find_referral_count(void)
 {
 	struct nfs_referral_count *p;

 	list_for_each_entry(p, &nfs_referral_count_list, list) {
 		if (p->task == current)
 			return p;
 	}
 	return NULL;
 }

 #define NFS_MAX_NESTED_REFERRALS 2

 static int nfs_referral_loop_protect(void)
 {
 	struct nfs_referral_count *p, *new;
 	int ret = -ENOMEM;

 	new = kmalloc(sizeof(*new), GFP_KERNEL);
 	if (!new)
 		goto out;
 	new->task = current;
 	new->referral_count = 1;

 	ret = 0;
 	spin_lock(&nfs_referral_count_list_lock);
 	p = nfs_find_referral_count();
 	if (p != NULL) {
 		if (p->referral_count >= NFS_MAX_NESTED_REFERRALS)
 			ret = -ELOOP;
 		else
 			p->referral_count++;
 	} else {
 		list_add(&new->list, &nfs_referral_count_list);
 		new = NULL;
 	}
 	spin_unlock(&nfs_referral_count_list_lock);
 	kfree(new);
 out:
 	return ret;
 }

 static void nfs_referral_loop_unprotect(void)
 {
 	struct nfs_referral_count *p;

 	spin_lock(&nfs_referral_count_list_lock);
 	p = nfs_find_referral_count();
 	p->referral_count--;
 	if (p->referral_count == 0)
 		list_del(&p->list);
 	else
 		p = NULL;
 	spin_unlock(&nfs_referral_count_list_lock);
 	kfree(p);
 }

 static int do_nfs4_mount(struct nfs_server *server,
 			 struct fs_context *fc,
 			 const char *hostname,
 			 const char *export_path)
 {
 	struct nfs_fs_context *root_ctx;
 	struct fs_context *root_fc;
 	struct vfsmount *root_mnt;
 	struct dentry *dentry;
 	size_t len;
 	int ret;

 	struct fs_parameter param = {
 		.key	= "source",
 		.type	= fs_value_is_string,
 		.dirfd	= -1,
 	};

 	if (IS_ERR(server))
 		return PTR_ERR(server);

 	root_fc = vfs_dup_fs_context(fc);
 	if (IS_ERR(root_fc)) {
 		nfs_free_server(server);
 		return PTR_ERR(root_fc);
 	}
 	kfree(root_fc->source);
 	root_fc->source = NULL;

 	root_ctx = nfs_fc2context(root_fc);
 	root_ctx->internal = true;
 	root_ctx->server = server;
 	/* We leave export_path unset as it's not used to find the root. */

 	len = strlen(hostname) + 5;
 	param.string = kmalloc(len, GFP_KERNEL);
 	if (param.string == NULL) {
 		put_fs_context(root_fc);
 		return -ENOMEM;
 	}

 	/* Does hostname needs to be enclosed in brackets? */
 	if (strchr(hostname, ':'))
 		param.size = snprintf(param.string, len, "[%s]:/", hostname);
 	else
 		param.size = snprintf(param.string, len, "%s:/", hostname);
 	ret = vfs_parse_fs_param(root_fc, &param);
 	kfree(param.string);
 	if (ret < 0) {
 		put_fs_context(root_fc);
 		return ret;
 	}
 	root_mnt = fc_mount(root_fc);
 	put_fs_context(root_fc);

 	if (IS_ERR(root_mnt))
 		return PTR_ERR(root_mnt);

 	ret = nfs_referral_loop_protect();
 	if (ret) {
 		mntput(root_mnt);
 		return ret;
 	}

 	dentry = mount_subtree(root_mnt, export_path);
 	nfs_referral_loop_unprotect();

 	if (IS_ERR(dentry))
 		return PTR_ERR(dentry);

 	fc->root = dentry;
 	return 0;
 }

 int nfs4_try_get_tree(struct fs_context *fc)
 {
 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
 	int err;

 	dfprintk(MOUNT, "--> nfs4_try_get_tree()\n");

 	/* We create a mount for the server's root, walk to the requested
 	 * location and then create another mount for that.
 	 */
 	err= do_nfs4_mount(nfs4_create_server(fc),
 			   fc, ctx->nfs_server.hostname,
 			   ctx->nfs_server.export_path);
 	if (err) {
 		nfs_errorf(fc, "NFS4: Couldn't follow remote path");
 		dfprintk(MOUNT, "<-- nfs4_try_get_tree() = %d [error]\n", err);
 	} else {
 		dfprintk(MOUNT, "<-- nfs4_try_get_tree() = 0\n");
 	}
 	return err;
 }

 /*
  * Create an NFS4 server record on referral traversal
  */
 int nfs4_get_referral_tree(struct fs_context *fc)
 {
 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
 	int err;

 	dprintk("--> nfs4_referral_mount()\n");

 	/* create a new volume representation */
 	err = do_nfs4_mount(nfs4_create_referral_server(fc),
 			    fc, ctx->nfs_server.hostname,
 			    ctx->nfs_server.export_path);
 	if (err) {
 		nfs_errorf(fc, "NFS4: Couldn't follow remote path");
 		dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = %d [error]\n", err);
 	} else {
 		dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = 0\n");
 	}
 	return err;
 }

 static int __init init_nfs_v4(void)
 {
 	int err;

 	err = nfs_dns_resolver_init();
 	if (err)
 		goto out;

 	err = nfs_idmap_init();
 	if (err)
 		goto out1;

 #ifdef CONFIG_NFS_V4_2
 	err = nfs4_xattr_cache_init();
 	if (err)
 		goto out2;
 #endif

 	err = nfs4_register_sysctl();
 	if (err)
 		goto out2;

 	register_nfs_version(&nfs_v4);
 	return 0;
 out2:
 	nfs_idmap_quit();
 out1:
 	nfs_dns_resolver_destroy();
 out:
 	return err;
 }

 static void __exit exit_nfs_v4(void)
 {
 	/* Not called in the _init(), conditionally loaded */
 	nfs4_pnfs_v3_ds_connect_unload();

 	unregister_nfs_version(&nfs_v4);
 #ifdef CONFIG_NFS_V4_2
 	nfs4_xattr_cache_exit();
 #endif
 	nfs4_unregister_sysctl();
 	nfs_idmap_quit();
 	nfs_dns_resolver_destroy();
 }

 MODULE_LICENSE("GPL");

 module_init(init_nfs_v4);
 module_exit(exit_nfs_v4);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Copyright (c) 2012 Bryan Schumaker <bjschuma@netapp.com>
	*/
	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/mount.h>
	#include <linux/nfs4_mount.h>
	#include <linux/nfs_fs.h>
	#include "delegation.h"
	#include "internal.h"
	#include "nfs4_fs.h"
	#include "nfs4idmap.h"
	#include "dns_resolve.h"
	#include "pnfs.h"
	#include "nfs.h"

	#define NFSDBG_FACILITY NFSDBG_VFS

	static int nfs4_write_inode(struct inode inode, struct writeback_control wbc);
	static void nfs4_evict_inode(struct inode *inode);

	static const struct super_operations nfs4_sops = {
	.alloc_inode = nfs_alloc_inode,
	.free_inode = nfs_free_inode,
	.write_inode = nfs4_write_inode,
	.drop_inode = nfs_drop_inode,
	.statfs = nfs_statfs,
	.evict_inode = nfs4_evict_inode,
	.umount_begin = nfs_umount_begin,
	.show_options = nfs_show_options,
	.show_devname = nfs_show_devname,
	.show_path = nfs_show_path,
	.show_stats = nfs_show_stats,
	};

	struct nfs_subversion nfs_v4 = {
	.owner = THIS_MODULE,
	.nfs_fs = &nfs4_fs_type,
	.rpc_vers = &nfs_version4,
	.rpc_ops = &nfs_v4_clientops,
	.sops = &nfs4_sops,
	.xattr = nfs4_xattr_handlers,
	};

	static int nfs4_write_inode(struct inode inode, struct writeback_control wbc)
	{
	int ret = nfs_write_inode(inode, wbc);

	if (ret == 0)
	ret = pnfs_layoutcommit_inode(inode,
	wbc->sync_mode == WB_SYNC_ALL);
	return ret;
	}

	/*
	* Clean out any remaining NFSv4 state that might be left over due
	* to open() calls that passed nfs_atomic_lookup, but failed to call
	* nfs_open().
	*/
	static void nfs4_evict_inode(struct inode *inode)
	{
	truncate_inode_pages_final(&inode->i_data);
	clear_inode(inode);
	/* If we are holding a delegation, return and free it */
	nfs_inode_evict_delegation(inode);
	/* Note that above delegreturn would trigger pnfs return-on-close */
	pnfs_return_layout(inode);
	pnfs_destroy_layout(NFS_I(inode));
	/* First call standard NFS clear_inode() code */
	nfs_clear_inode(inode);
	nfs4_xattr_cache_zap(inode);
	}

	struct nfs_referral_count {
	struct list_head list;
	const struct task_struct *task;
	unsigned int referral_count;
	};

	static LIST_HEAD(nfs_referral_count_list);
	static DEFINE_SPINLOCK(nfs_referral_count_list_lock);

	static struct nfs_referral_count *nfs_find_referral_count(void)
	{
	struct nfs_referral_count *p;

	list_for_each_entry(p, &nfs_referral_count_list, list) {
	if (p->task == current)
	return p;
	}
	return NULL;
	}

	#define NFS_MAX_NESTED_REFERRALS 2

	static int nfs_referral_loop_protect(void)
	{
	struct nfs_referral_count p, new;
	int ret = -ENOMEM;

	new = kmalloc(sizeof(*new), GFP_KERNEL);
	if (!new)
	goto out;
	new->task = current;
	new->referral_count = 1;

	ret = 0;
	spin_lock(&nfs_referral_count_list_lock);
	p = nfs_find_referral_count();
	if (p != NULL) {
	if (p->referral_count >= NFS_MAX_NESTED_REFERRALS)
	ret = -ELOOP;
	else
	p->referral_count++;
	} else {
	list_add(&new->list, &nfs_referral_count_list);
	new = NULL;
	}
	spin_unlock(&nfs_referral_count_list_lock);
	kfree(new);
	out:
	return ret;
	}

	static void nfs_referral_loop_unprotect(void)
	{
	struct nfs_referral_count *p;

	spin_lock(&nfs_referral_count_list_lock);
	p = nfs_find_referral_count();
	p->referral_count--;
	if (p->referral_count == 0)
	list_del(&p->list);
	else
	p = NULL;
	spin_unlock(&nfs_referral_count_list_lock);
	kfree(p);
	}

	static int do_nfs4_mount(struct nfs_server *server,
	struct fs_context *fc,
	const char *hostname,
	const char *export_path)
	{
	struct nfs_fs_context *root_ctx;
	struct fs_context *root_fc;
	struct vfsmount *root_mnt;
	struct dentry *dentry;
	size_t len;
	int ret;

	struct fs_parameter param = {
	.key = "source",
	.type = fs_value_is_string,
	.dirfd = -1,
	};

	if (IS_ERR(server))
	return PTR_ERR(server);

	root_fc = vfs_dup_fs_context(fc);
	if (IS_ERR(root_fc)) {
	nfs_free_server(server);
	return PTR_ERR(root_fc);
	}
	kfree(root_fc->source);
	root_fc->source = NULL;

	root_ctx = nfs_fc2context(root_fc);
	root_ctx->internal = true;
	root_ctx->server = server;
	/* We leave export_path unset as it's not used to find the root. */

	len = strlen(hostname) + 5;
	param.string = kmalloc(len, GFP_KERNEL);
	if (param.string == NULL) {
	put_fs_context(root_fc);
	return -ENOMEM;
	}

	/* Does hostname needs to be enclosed in brackets? */
	if (strchr(hostname, ':'))
	param.size = snprintf(param.string, len, "[%s]:/", hostname);
	else
	param.size = snprintf(param.string, len, "%s:/", hostname);
	ret = vfs_parse_fs_param(root_fc, &param);
	kfree(param.string);
	if (ret < 0) {
	put_fs_context(root_fc);
	return ret;
	}
	root_mnt = fc_mount(root_fc);
	put_fs_context(root_fc);

	if (IS_ERR(root_mnt))
	return PTR_ERR(root_mnt);

	ret = nfs_referral_loop_protect();
	if (ret) {
	mntput(root_mnt);
	return ret;
	}

	dentry = mount_subtree(root_mnt, export_path);
	nfs_referral_loop_unprotect();

	if (IS_ERR(dentry))
	return PTR_ERR(dentry);

	fc->root = dentry;
	return 0;
	}

	int nfs4_try_get_tree(struct fs_context *fc)
	{
	struct nfs_fs_context *ctx = nfs_fc2context(fc);
	int err;

	dfprintk(MOUNT, "--> nfs4_try_get_tree()\n");

	/* We create a mount for the server's root, walk to the requested
	* location and then create another mount for that.
	*/
	err= do_nfs4_mount(nfs4_create_server(fc),
	fc, ctx->nfs_server.hostname,
	ctx->nfs_server.export_path);
	if (err) {
	nfs_errorf(fc, "NFS4: Couldn't follow remote path");
	dfprintk(MOUNT, "<-- nfs4_try_get_tree() = %d [error]\n", err);
	} else {
	dfprintk(MOUNT, "<-- nfs4_try_get_tree() = 0\n");
	}
	return err;
	}

	/*
	* Create an NFS4 server record on referral traversal
	*/
	int nfs4_get_referral_tree(struct fs_context *fc)
	{
	struct nfs_fs_context *ctx = nfs_fc2context(fc);
	int err;

	dprintk("--> nfs4_referral_mount()\n");

	/* create a new volume representation */
	err = do_nfs4_mount(nfs4_create_referral_server(fc),
	fc, ctx->nfs_server.hostname,
	ctx->nfs_server.export_path);
	if (err) {
	nfs_errorf(fc, "NFS4: Couldn't follow remote path");
	dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = %d [error]\n", err);
	} else {
	dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = 0\n");
	}
	return err;
	}

	static int __init init_nfs_v4(void)
	{
	int err;

	err = nfs_dns_resolver_init();
	if (err)
	goto out;

	err = nfs_idmap_init();
	if (err)
	goto out1;

	#ifdef CONFIG_NFS_V4_2
	err = nfs4_xattr_cache_init();
	if (err)
	goto out2;
	#endif

	err = nfs4_register_sysctl();
	if (err)
	goto out2;

	register_nfs_version(&nfs_v4);
	return 0;
	out2:
	nfs_idmap_quit();
	out1:
	nfs_dns_resolver_destroy();
	out:
	return err;
	}

	static void __exit exit_nfs_v4(void)
	{
	/* Not called in the _init(), conditionally loaded */
	nfs4_pnfs_v3_ds_connect_unload();

	unregister_nfs_version(&nfs_v4);
	#ifdef CONFIG_NFS_V4_2
	nfs4_xattr_cache_exit();
	#endif
	nfs4_unregister_sysctl();
	nfs_idmap_quit();
	nfs_dns_resolver_destroy();
	}

	MODULE_LICENSE("GPL");

	module_init(init_nfs_v4);
	module_exit(exit_nfs_v4);