e571cbf1a4
The NFSv4 and NFSv4.1 protocols both allow for the redirection of a client from one server to another in order to support filesystem migration and replication. For full protocol support, we need to add the ability to convert a DNS host name into an IP address that we can feed to the RPC client. We'll reuse the sunrpc cache, now that it has been converted to work with rpc_pipefs. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
141 lines
3.3 KiB
C
141 lines
3.3 KiB
C
/*
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* linux/fs/nfs/cache_lib.c
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*
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* Helper routines for the NFS client caches
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*
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* Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com>
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*/
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#include <linux/kmod.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/sunrpc/cache.h>
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#include <linux/sunrpc/rpc_pipe_fs.h>
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#include "cache_lib.h"
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#define NFS_CACHE_UPCALL_PATHLEN 256
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#define NFS_CACHE_UPCALL_TIMEOUT 15
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static char nfs_cache_getent_prog[NFS_CACHE_UPCALL_PATHLEN] =
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"/sbin/nfs_cache_getent";
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static unsigned long nfs_cache_getent_timeout = NFS_CACHE_UPCALL_TIMEOUT;
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module_param_string(cache_getent, nfs_cache_getent_prog,
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sizeof(nfs_cache_getent_prog), 0600);
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MODULE_PARM_DESC(cache_getent, "Path to the client cache upcall program");
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module_param_named(cache_getent_timeout, nfs_cache_getent_timeout, ulong, 0600);
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MODULE_PARM_DESC(cache_getent_timeout, "Timeout (in seconds) after which "
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"the cache upcall is assumed to have failed");
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int nfs_cache_upcall(struct cache_detail *cd, char *entry_name)
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{
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static char *envp[] = { "HOME=/",
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"TERM=linux",
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"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
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NULL
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};
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char *argv[] = {
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nfs_cache_getent_prog,
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cd->name,
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entry_name,
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NULL
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};
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int ret = -EACCES;
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if (nfs_cache_getent_prog[0] == '\0')
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goto out;
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ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
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/*
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* Disable the upcall mechanism if we're getting an ENOENT or
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* EACCES error. The admin can re-enable it on the fly by using
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* sysfs to set the 'cache_getent' parameter once the problem
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* has been fixed.
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*/
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if (ret == -ENOENT || ret == -EACCES)
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nfs_cache_getent_prog[0] = '\0';
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out:
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return ret > 0 ? 0 : ret;
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}
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/*
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* Deferred request handling
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*/
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void nfs_cache_defer_req_put(struct nfs_cache_defer_req *dreq)
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{
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if (atomic_dec_and_test(&dreq->count))
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kfree(dreq);
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}
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static void nfs_dns_cache_revisit(struct cache_deferred_req *d, int toomany)
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{
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struct nfs_cache_defer_req *dreq;
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dreq = container_of(d, struct nfs_cache_defer_req, deferred_req);
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complete_all(&dreq->completion);
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nfs_cache_defer_req_put(dreq);
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}
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static struct cache_deferred_req *nfs_dns_cache_defer(struct cache_req *req)
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{
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struct nfs_cache_defer_req *dreq;
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dreq = container_of(req, struct nfs_cache_defer_req, req);
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dreq->deferred_req.revisit = nfs_dns_cache_revisit;
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atomic_inc(&dreq->count);
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return &dreq->deferred_req;
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}
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struct nfs_cache_defer_req *nfs_cache_defer_req_alloc(void)
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{
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struct nfs_cache_defer_req *dreq;
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dreq = kzalloc(sizeof(*dreq), GFP_KERNEL);
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if (dreq) {
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init_completion(&dreq->completion);
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atomic_set(&dreq->count, 1);
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dreq->req.defer = nfs_dns_cache_defer;
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}
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return dreq;
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}
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int nfs_cache_wait_for_upcall(struct nfs_cache_defer_req *dreq)
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{
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if (wait_for_completion_timeout(&dreq->completion,
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nfs_cache_getent_timeout * HZ) == 0)
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return -ETIMEDOUT;
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return 0;
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}
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int nfs_cache_register(struct cache_detail *cd)
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{
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struct nameidata nd;
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struct vfsmount *mnt;
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int ret;
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mnt = rpc_get_mount();
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if (IS_ERR(mnt))
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return PTR_ERR(mnt);
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ret = vfs_path_lookup(mnt->mnt_root, mnt, "/cache", 0, &nd);
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if (ret)
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goto err;
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ret = sunrpc_cache_register_pipefs(nd.path.dentry,
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cd->name, 0600, cd);
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path_put(&nd.path);
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if (!ret)
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return ret;
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err:
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rpc_put_mount();
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return ret;
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}
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void nfs_cache_unregister(struct cache_detail *cd)
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{
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sunrpc_cache_unregister_pipefs(cd);
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rpc_put_mount();
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}
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