fs/nfs/nfs4super.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Copyright (c) 2012 Bryan Schumaker <bjschuma@netapp.com>
0004  */
0005 #include <linux/init.h>
0006 #include <linux/module.h>
0007 #include <linux/mount.h>
0008 #include <linux/nfs4_mount.h>
0009 #include <linux/nfs_fs.h>
0010 #include <linux/nfs_ssc.h>
0011 #include "delegation.h"
0012 #include "internal.h"
0013 #include "nfs4_fs.h"
0014 #include "nfs4idmap.h"
0015 #include "dns_resolve.h"
0016 #include "pnfs.h"
0017 #include "nfs.h"
0018
0019 #define NFSDBG_FACILITY     NFSDBG_VFS
0020
0021 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc);
0022 static void nfs4_evict_inode(struct inode *inode);
0023
0024 static const struct super_operations nfs4_sops = {
0025     .alloc_inode    = nfs_alloc_inode,
0026     .free_inode = nfs_free_inode,
0027     .write_inode    = nfs4_write_inode,
0028     .drop_inode = nfs_drop_inode,
0029     .statfs     = nfs_statfs,
0030     .evict_inode    = nfs4_evict_inode,
0031     .umount_begin   = nfs_umount_begin,
0032     .show_options   = nfs_show_options,
0033     .show_devname   = nfs_show_devname,
0034     .show_path  = nfs_show_path,
0035     .show_stats = nfs_show_stats,
0036 };
0037
0038 struct nfs_subversion nfs_v4 = {
0039     .owner      = THIS_MODULE,
0040     .nfs_fs     = &nfs4_fs_type,
0041     .rpc_vers   = &nfs_version4,
0042     .rpc_ops    = &nfs_v4_clientops,
0043     .sops       = &nfs4_sops,
0044     .xattr      = nfs4_xattr_handlers,
0045 };
0046
0047 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc)
0048 {
0049     int ret = nfs_write_inode(inode, wbc);
0050
0051     if (ret == 0)
0052         ret = pnfs_layoutcommit_inode(inode,
0053                 wbc->sync_mode == WB_SYNC_ALL);
0054     return ret;
0055 }
0056
0057 /*
0058  * Clean out any remaining NFSv4 state that might be left over due
0059  * to open() calls that passed nfs_atomic_lookup, but failed to call
0060  * nfs_open().
0061  */
0062 static void nfs4_evict_inode(struct inode *inode)
0063 {
0064     truncate_inode_pages_final(&inode->i_data);
0065     clear_inode(inode);
0066     /* If we are holding a delegation, return and free it */
0067     nfs_inode_evict_delegation(inode);
0068     /* Note that above delegreturn would trigger pnfs return-on-close */
0069     pnfs_return_layout(inode);
0070     pnfs_destroy_layout_final(NFS_I(inode));
0071     /* First call standard NFS clear_inode() code */
0072     nfs_clear_inode(inode);
0073     nfs4_xattr_cache_zap(inode);
0074 }
0075
0076 struct nfs_referral_count {
0077     struct list_head list;
0078     const struct task_struct *task;
0079     unsigned int referral_count;
0080 };
0081
0082 static LIST_HEAD(nfs_referral_count_list);
0083 static DEFINE_SPINLOCK(nfs_referral_count_list_lock);
0084
0085 static struct nfs_referral_count *nfs_find_referral_count(void)
0086 {
0087     struct nfs_referral_count *p;
0088
0089     list_for_each_entry(p, &nfs_referral_count_list, list) {
0090         if (p->task == current)
0091             return p;
0092     }
0093     return NULL;
0094 }
0095
0096 #define NFS_MAX_NESTED_REFERRALS 2
0097
0098 static int nfs_referral_loop_protect(void)
0099 {
0100     struct nfs_referral_count *p, *new;
0101     int ret = -ENOMEM;
0102
0103     new = kmalloc(sizeof(*new), GFP_KERNEL);
0104     if (!new)
0105         goto out;
0106     new->task = current;
0107     new->referral_count = 1;
0108
0109     ret = 0;
0110     spin_lock(&nfs_referral_count_list_lock);
0111     p = nfs_find_referral_count();
0112     if (p != NULL) {
0113         if (p->referral_count >= NFS_MAX_NESTED_REFERRALS)
0114             ret = -ELOOP;
0115         else
0116             p->referral_count++;
0117     } else {
0118         list_add(&new->list, &nfs_referral_count_list);
0119         new = NULL;
0120     }
0121     spin_unlock(&nfs_referral_count_list_lock);
0122     kfree(new);
0123 out:
0124     return ret;
0125 }
0126
0127 static void nfs_referral_loop_unprotect(void)
0128 {
0129     struct nfs_referral_count *p;
0130
0131     spin_lock(&nfs_referral_count_list_lock);
0132     p = nfs_find_referral_count();
0133     p->referral_count--;
0134     if (p->referral_count == 0)
0135         list_del(&p->list);
0136     else
0137         p = NULL;
0138     spin_unlock(&nfs_referral_count_list_lock);
0139     kfree(p);
0140 }
0141
0142 static int do_nfs4_mount(struct nfs_server *server,
0143              struct fs_context *fc,
0144              const char *hostname,
0145              const char *export_path)
0146 {
0147     struct nfs_fs_context *root_ctx;
0148     struct fs_context *root_fc;
0149     struct vfsmount *root_mnt;
0150     struct dentry *dentry;
0151     size_t len;
0152     int ret;
0153
0154     struct fs_parameter param = {
0155         .key    = "source",
0156         .type   = fs_value_is_string,
0157         .dirfd  = -1,
0158     };
0159
0160     if (IS_ERR(server))
0161         return PTR_ERR(server);
0162
0163     root_fc = vfs_dup_fs_context(fc);
0164     if (IS_ERR(root_fc)) {
0165         nfs_free_server(server);
0166         return PTR_ERR(root_fc);
0167     }
0168     kfree(root_fc->source);
0169     root_fc->source = NULL;
0170
0171     root_ctx = nfs_fc2context(root_fc);
0172     root_ctx->internal = true;
0173     root_ctx->server = server;
0174     /* We leave export_path unset as it's not used to find the root. */
0175
0176     len = strlen(hostname) + 5;
0177     param.string = kmalloc(len, GFP_KERNEL);
0178     if (param.string == NULL) {
0179         put_fs_context(root_fc);
0180         return -ENOMEM;
0181     }
0182
0183     /* Does hostname needs to be enclosed in brackets? */
0184     if (strchr(hostname, ':'))
0185         param.size = snprintf(param.string, len, "[%s]:/", hostname);
0186     else
0187         param.size = snprintf(param.string, len, "%s:/", hostname);
0188     ret = vfs_parse_fs_param(root_fc, &param);
0189     kfree(param.string);
0190     if (ret < 0) {
0191         put_fs_context(root_fc);
0192         return ret;
0193     }
0194     root_mnt = fc_mount(root_fc);
0195     put_fs_context(root_fc);
0196
0197     if (IS_ERR(root_mnt))
0198         return PTR_ERR(root_mnt);
0199
0200     ret = nfs_referral_loop_protect();
0201     if (ret) {
0202         mntput(root_mnt);
0203         return ret;
0204     }
0205
0206     dentry = mount_subtree(root_mnt, export_path);
0207     nfs_referral_loop_unprotect();
0208
0209     if (IS_ERR(dentry))
0210         return PTR_ERR(dentry);
0211
0212     fc->root = dentry;
0213     return 0;
0214 }
0215
0216 int nfs4_try_get_tree(struct fs_context *fc)
0217 {
0218     struct nfs_fs_context *ctx = nfs_fc2context(fc);
0219     int err;
0220
0221     dfprintk(MOUNT, "--> nfs4_try_get_tree()\n");
0222
0223     /* We create a mount for the server's root, walk to the requested
0224      * location and then create another mount for that.
0225      */
0226     err= do_nfs4_mount(nfs4_create_server(fc),
0227                fc, ctx->nfs_server.hostname,
0228                ctx->nfs_server.export_path);
0229     if (err) {
0230         nfs_ferrorf(fc, MOUNT, "NFS4: Couldn't follow remote path");
0231         dfprintk(MOUNT, "<-- nfs4_try_get_tree() = %d [error]\n", err);
0232     } else {
0233         dfprintk(MOUNT, "<-- nfs4_try_get_tree() = 0\n");
0234     }
0235     return err;
0236 }
0237
0238 /*
0239  * Create an NFS4 server record on referral traversal
0240  */
0241 int nfs4_get_referral_tree(struct fs_context *fc)
0242 {
0243     struct nfs_fs_context *ctx = nfs_fc2context(fc);
0244     int err;
0245
0246     dprintk("--> nfs4_referral_mount()\n");
0247
0248     /* create a new volume representation */
0249     err = do_nfs4_mount(nfs4_create_referral_server(fc),
0250                 fc, ctx->nfs_server.hostname,
0251                 ctx->nfs_server.export_path);
0252     if (err) {
0253         nfs_ferrorf(fc, MOUNT, "NFS4: Couldn't follow remote path");
0254         dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = %d [error]\n", err);
0255     } else {
0256         dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = 0\n");
0257     }
0258     return err;
0259 }
0260
0261 static int __init init_nfs_v4(void)
0262 {
0263     int err;
0264
0265     err = nfs_dns_resolver_init();
0266     if (err)
0267         goto out;
0268
0269     err = nfs_idmap_init();
0270     if (err)
0271         goto out1;
0272
0273 #ifdef CONFIG_NFS_V4_2
0274     err = nfs4_xattr_cache_init();
0275     if (err)
0276         goto out2;
0277 #endif
0278
0279     err = nfs4_register_sysctl();
0280     if (err)
0281         goto out2;
0282
0283 #ifdef CONFIG_NFS_V4_2
0284     nfs42_ssc_register_ops();
0285 #endif
0286     register_nfs_version(&nfs_v4);
0287     return 0;
0288 out2:
0289     nfs_idmap_quit();
0290 out1:
0291     nfs_dns_resolver_destroy();
0292 out:
0293     return err;
0294 }
0295
0296 static void __exit exit_nfs_v4(void)
0297 {
0298     /* Not called in the _init(), conditionally loaded */
0299     nfs4_pnfs_v3_ds_connect_unload();
0300
0301     unregister_nfs_version(&nfs_v4);
0302 #ifdef CONFIG_NFS_V4_2
0303     nfs4_xattr_cache_exit();
0304     nfs42_ssc_unregister_ops();
0305 #endif
0306     nfs4_unregister_sysctl();
0307     nfs_idmap_quit();
0308     nfs_dns_resolver_destroy();
0309 }
0310
0311 MODULE_LICENSE("GPL");
0312
0313 module_init(init_nfs_v4);
0314 module_exit(exit_nfs_v4);