linux/fs/nfs/pnfs_dev.c
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   1/*
   2 *  Device operations for the pnfs client.
   3 *
   4 *  Copyright (c) 2002
   5 *  The Regents of the University of Michigan
   6 *  All Rights Reserved
   7 *
   8 *  Dean Hildebrand <dhildebz@umich.edu>
   9 *  Garth Goodson   <Garth.Goodson@netapp.com>
  10 *
  11 *  Permission is granted to use, copy, create derivative works, and
  12 *  redistribute this software and such derivative works for any purpose,
  13 *  so long as the name of the University of Michigan is not used in
  14 *  any advertising or publicity pertaining to the use or distribution
  15 *  of this software without specific, written prior authorization. If
  16 *  the above copyright notice or any other identification of the
  17 *  University of Michigan is included in any copy of any portion of
  18 *  this software, then the disclaimer below must also be included.
  19 *
  20 *  This software is provided as is, without representation or warranty
  21 *  of any kind either express or implied, including without limitation
  22 *  the implied warranties of merchantability, fitness for a particular
  23 *  purpose, or noninfringement.  The Regents of the University of
  24 *  Michigan shall not be liable for any damages, including special,
  25 *  indirect, incidental, or consequential damages, with respect to any
  26 *  claim arising out of or in connection with the use of the software,
  27 *  even if it has been or is hereafter advised of the possibility of
  28 *  such damages.
  29 */
  30
  31#include <linux/export.h>
  32#include "pnfs.h"
  33
  34#define NFSDBG_FACILITY         NFSDBG_PNFS
  35
  36/*
  37 * Device ID RCU cache. A device ID is unique per server and layout type.
  38 */
  39#define NFS4_DEVICE_ID_HASH_BITS        5
  40#define NFS4_DEVICE_ID_HASH_SIZE        (1 << NFS4_DEVICE_ID_HASH_BITS)
  41#define NFS4_DEVICE_ID_HASH_MASK        (NFS4_DEVICE_ID_HASH_SIZE - 1)
  42
  43static struct hlist_head nfs4_deviceid_cache[NFS4_DEVICE_ID_HASH_SIZE];
  44static DEFINE_SPINLOCK(nfs4_deviceid_lock);
  45
  46#ifdef NFS_DEBUG
  47void
  48nfs4_print_deviceid(const struct nfs4_deviceid *id)
  49{
  50        u32 *p = (u32 *)id;
  51
  52        dprintk("%s: device id= [%x%x%x%x]\n", __func__,
  53                p[0], p[1], p[2], p[3]);
  54}
  55EXPORT_SYMBOL_GPL(nfs4_print_deviceid);
  56#endif
  57
  58static inline u32
  59nfs4_deviceid_hash(const struct nfs4_deviceid *id)
  60{
  61        unsigned char *cptr = (unsigned char *)id->data;
  62        unsigned int nbytes = NFS4_DEVICEID4_SIZE;
  63        u32 x = 0;
  64
  65        while (nbytes--) {
  66                x *= 37;
  67                x += *cptr++;
  68        }
  69        return x & NFS4_DEVICE_ID_HASH_MASK;
  70}
  71
  72static struct nfs4_deviceid_node *
  73_lookup_deviceid(const struct pnfs_layoutdriver_type *ld,
  74                 const struct nfs_client *clp, const struct nfs4_deviceid *id,
  75                 long hash)
  76{
  77        struct nfs4_deviceid_node *d;
  78        struct hlist_node *n;
  79
  80        hlist_for_each_entry_rcu(d, n, &nfs4_deviceid_cache[hash], node)
  81                if (d->ld == ld && d->nfs_client == clp &&
  82                    !memcmp(&d->deviceid, id, sizeof(*id))) {
  83                        if (atomic_read(&d->ref))
  84                                return d;
  85                        else
  86                                continue;
  87                }
  88        return NULL;
  89}
  90
  91/*
  92 * Lookup a deviceid in cache and get a reference count on it if found
  93 *
  94 * @clp nfs_client associated with deviceid
  95 * @id deviceid to look up
  96 */
  97static struct nfs4_deviceid_node *
  98_find_get_deviceid(const struct pnfs_layoutdriver_type *ld,
  99                   const struct nfs_client *clp, const struct nfs4_deviceid *id,
 100                   long hash)
 101{
 102        struct nfs4_deviceid_node *d;
 103
 104        rcu_read_lock();
 105        d = _lookup_deviceid(ld, clp, id, hash);
 106        if (d != NULL)
 107                atomic_inc(&d->ref);
 108        rcu_read_unlock();
 109        return d;
 110}
 111
 112struct nfs4_deviceid_node *
 113nfs4_find_get_deviceid(const struct pnfs_layoutdriver_type *ld,
 114                       const struct nfs_client *clp, const struct nfs4_deviceid *id)
 115{
 116        return _find_get_deviceid(ld, clp, id, nfs4_deviceid_hash(id));
 117}
 118EXPORT_SYMBOL_GPL(nfs4_find_get_deviceid);
 119
 120/*
 121 * Remove a deviceid from cache
 122 *
 123 * @clp nfs_client associated with deviceid
 124 * @id the deviceid to unhash
 125 *
 126 * @ret the unhashed node, if found and dereferenced to zero, NULL otherwise.
 127 */
 128void
 129nfs4_delete_deviceid(const struct pnfs_layoutdriver_type *ld,
 130                         const struct nfs_client *clp, const struct nfs4_deviceid *id)
 131{
 132        struct nfs4_deviceid_node *d;
 133
 134        spin_lock(&nfs4_deviceid_lock);
 135        rcu_read_lock();
 136        d = _lookup_deviceid(ld, clp, id, nfs4_deviceid_hash(id));
 137        rcu_read_unlock();
 138        if (!d) {
 139                spin_unlock(&nfs4_deviceid_lock);
 140                return;
 141        }
 142        hlist_del_init_rcu(&d->node);
 143        spin_unlock(&nfs4_deviceid_lock);
 144        synchronize_rcu();
 145
 146        /* balance the initial ref set in pnfs_insert_deviceid */
 147        if (atomic_dec_and_test(&d->ref))
 148                d->ld->free_deviceid_node(d);
 149}
 150EXPORT_SYMBOL_GPL(nfs4_delete_deviceid);
 151
 152void
 153nfs4_init_deviceid_node(struct nfs4_deviceid_node *d,
 154                        const struct pnfs_layoutdriver_type *ld,
 155                        const struct nfs_client *nfs_client,
 156                        const struct nfs4_deviceid *id)
 157{
 158        INIT_HLIST_NODE(&d->node);
 159        INIT_HLIST_NODE(&d->tmpnode);
 160        d->ld = ld;
 161        d->nfs_client = nfs_client;
 162        d->flags = 0;
 163        d->deviceid = *id;
 164        atomic_set(&d->ref, 1);
 165}
 166EXPORT_SYMBOL_GPL(nfs4_init_deviceid_node);
 167
 168/*
 169 * Uniquely initialize and insert a deviceid node into cache
 170 *
 171 * @new new deviceid node
 172 *      Note that the caller must set up the following members:
 173 *        new->ld
 174 *        new->nfs_client
 175 *        new->deviceid
 176 *
 177 * @ret the inserted node, if none found, otherwise, the found entry.
 178 */
 179struct nfs4_deviceid_node *
 180nfs4_insert_deviceid_node(struct nfs4_deviceid_node *new)
 181{
 182        struct nfs4_deviceid_node *d;
 183        long hash;
 184
 185        spin_lock(&nfs4_deviceid_lock);
 186        hash = nfs4_deviceid_hash(&new->deviceid);
 187        d = _find_get_deviceid(new->ld, new->nfs_client, &new->deviceid, hash);
 188        if (d) {
 189                spin_unlock(&nfs4_deviceid_lock);
 190                return d;
 191        }
 192
 193        hlist_add_head_rcu(&new->node, &nfs4_deviceid_cache[hash]);
 194        spin_unlock(&nfs4_deviceid_lock);
 195        atomic_inc(&new->ref);
 196
 197        return new;
 198}
 199EXPORT_SYMBOL_GPL(nfs4_insert_deviceid_node);
 200
 201/*
 202 * Dereference a deviceid node and delete it when its reference count drops
 203 * to zero.
 204 *
 205 * @d deviceid node to put
 206 *
 207 * return true iff the node was deleted
 208 * Note that since the test for d->ref == 0 is sufficient to establish
 209 * that the node is no longer hashed in the global device id cache.
 210 */
 211bool
 212nfs4_put_deviceid_node(struct nfs4_deviceid_node *d)
 213{
 214        if (!atomic_dec_and_test(&d->ref))
 215                return false;
 216        d->ld->free_deviceid_node(d);
 217        return true;
 218}
 219EXPORT_SYMBOL_GPL(nfs4_put_deviceid_node);
 220
 221static void
 222_deviceid_purge_client(const struct nfs_client *clp, long hash)
 223{
 224        struct nfs4_deviceid_node *d;
 225        struct hlist_node *n;
 226        HLIST_HEAD(tmp);
 227
 228        spin_lock(&nfs4_deviceid_lock);
 229        rcu_read_lock();
 230        hlist_for_each_entry_rcu(d, n, &nfs4_deviceid_cache[hash], node)
 231                if (d->nfs_client == clp && atomic_read(&d->ref)) {
 232                        hlist_del_init_rcu(&d->node);
 233                        hlist_add_head(&d->tmpnode, &tmp);
 234                }
 235        rcu_read_unlock();
 236        spin_unlock(&nfs4_deviceid_lock);
 237
 238        if (hlist_empty(&tmp))
 239                return;
 240
 241        synchronize_rcu();
 242        while (!hlist_empty(&tmp)) {
 243                d = hlist_entry(tmp.first, struct nfs4_deviceid_node, tmpnode);
 244                hlist_del(&d->tmpnode);
 245                if (atomic_dec_and_test(&d->ref))
 246                        d->ld->free_deviceid_node(d);
 247        }
 248}
 249
 250void
 251nfs4_deviceid_purge_client(const struct nfs_client *clp)
 252{
 253        long h;
 254
 255        if (!(clp->cl_exchange_flags & EXCHGID4_FLAG_USE_PNFS_MDS))
 256                return;
 257        for (h = 0; h < NFS4_DEVICE_ID_HASH_SIZE; h++)
 258                _deviceid_purge_client(clp, h);
 259}
 260
 261/*
 262 * Stop use of all deviceids associated with an nfs_client
 263 */
 264void
 265nfs4_deviceid_mark_client_invalid(struct nfs_client *clp)
 266{
 267        struct nfs4_deviceid_node *d;
 268        struct hlist_node *n;
 269        int i;
 270
 271        rcu_read_lock();
 272        for (i = 0; i < NFS4_DEVICE_ID_HASH_SIZE; i ++){
 273                hlist_for_each_entry_rcu(d, n, &nfs4_deviceid_cache[i], node)
 274                        if (d->nfs_client == clp)
 275                                set_bit(NFS_DEVICEID_INVALID, &d->flags);
 276        }
 277        rcu_read_unlock();
 278}
 279
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