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
  43#define PNFS_DEVICE_RETRY_TIMEOUT (120*HZ)
  44
  45static struct hlist_head nfs4_deviceid_cache[NFS4_DEVICE_ID_HASH_SIZE];
  46static DEFINE_SPINLOCK(nfs4_deviceid_lock);
  47
  48#ifdef NFS_DEBUG
  49void
  50nfs4_print_deviceid(const struct nfs4_deviceid *id)
  51{
  52        u32 *p = (u32 *)id;
  53
  54        dprintk("%s: device id= [%x%x%x%x]\n", __func__,
  55                p[0], p[1], p[2], p[3]);
  56}
  57EXPORT_SYMBOL_GPL(nfs4_print_deviceid);
  58#endif
  59
  60static inline u32
  61nfs4_deviceid_hash(const struct nfs4_deviceid *id)
  62{
  63        unsigned char *cptr = (unsigned char *)id->data;
  64        unsigned int nbytes = NFS4_DEVICEID4_SIZE;
  65        u32 x = 0;
  66
  67        while (nbytes--) {
  68                x *= 37;
  69                x += *cptr++;
  70        }
  71        return x & NFS4_DEVICE_ID_HASH_MASK;
  72}
  73
  74static struct nfs4_deviceid_node *
  75_lookup_deviceid(const struct pnfs_layoutdriver_type *ld,
  76                 const struct nfs_client *clp, const struct nfs4_deviceid *id,
  77                 long hash)
  78{
  79        struct nfs4_deviceid_node *d;
  80        struct hlist_node *n;
  81
  82        hlist_for_each_entry_rcu(d, n, &nfs4_deviceid_cache[hash], node)
  83                if (d->ld == ld && d->nfs_client == clp &&
  84                    !memcmp(&d->deviceid, id, sizeof(*id))) {
  85                        if (atomic_read(&d->ref))
  86                                return d;
  87                        else
  88                                continue;
  89                }
  90        return NULL;
  91}
  92
  93/*
  94 * Lookup a deviceid in cache and get a reference count on it if found
  95 *
  96 * @clp nfs_client associated with deviceid
  97 * @id deviceid to look up
  98 */
  99static struct nfs4_deviceid_node *
 100_find_get_deviceid(const struct pnfs_layoutdriver_type *ld,
 101                   const struct nfs_client *clp, const struct nfs4_deviceid *id,
 102                   long hash)
 103{
 104        struct nfs4_deviceid_node *d;
 105
 106        rcu_read_lock();
 107        d = _lookup_deviceid(ld, clp, id, hash);
 108        if (d != NULL)
 109                atomic_inc(&d->ref);
 110        rcu_read_unlock();
 111        return d;
 112}
 113
 114struct nfs4_deviceid_node *
 115nfs4_find_get_deviceid(const struct pnfs_layoutdriver_type *ld,
 116                       const struct nfs_client *clp, const struct nfs4_deviceid *id)
 117{
 118        return _find_get_deviceid(ld, clp, id, nfs4_deviceid_hash(id));
 119}
 120EXPORT_SYMBOL_GPL(nfs4_find_get_deviceid);
 121
 122/*
 123 * Remove a deviceid from cache
 124 *
 125 * @clp nfs_client associated with deviceid
 126 * @id the deviceid to unhash
 127 *
 128 * @ret the unhashed node, if found and dereferenced to zero, NULL otherwise.
 129 */
 130void
 131nfs4_delete_deviceid(const struct pnfs_layoutdriver_type *ld,
 132                         const struct nfs_client *clp, const struct nfs4_deviceid *id)
 133{
 134        struct nfs4_deviceid_node *d;
 135
 136        spin_lock(&nfs4_deviceid_lock);
 137        rcu_read_lock();
 138        d = _lookup_deviceid(ld, clp, id, nfs4_deviceid_hash(id));
 139        rcu_read_unlock();
 140        if (!d) {
 141                spin_unlock(&nfs4_deviceid_lock);
 142                return;
 143        }
 144        hlist_del_init_rcu(&d->node);
 145        spin_unlock(&nfs4_deviceid_lock);
 146        synchronize_rcu();
 147
 148        /* balance the initial ref set in pnfs_insert_deviceid */
 149        if (atomic_dec_and_test(&d->ref))
 150                d->ld->free_deviceid_node(d);
 151}
 152EXPORT_SYMBOL_GPL(nfs4_delete_deviceid);
 153
 154void
 155nfs4_init_deviceid_node(struct nfs4_deviceid_node *d,
 156                        const struct pnfs_layoutdriver_type *ld,
 157                        const struct nfs_client *nfs_client,
 158                        const struct nfs4_deviceid *id)
 159{
 160        INIT_HLIST_NODE(&d->node);
 161        INIT_HLIST_NODE(&d->tmpnode);
 162        d->ld = ld;
 163        d->nfs_client = nfs_client;
 164        d->flags = 0;
 165        d->deviceid = *id;
 166        atomic_set(&d->ref, 1);
 167}
 168EXPORT_SYMBOL_GPL(nfs4_init_deviceid_node);
 169
 170/*
 171 * Uniquely initialize and insert a deviceid node into cache
 172 *
 173 * @new new deviceid node
 174 *      Note that the caller must set up the following members:
 175 *        new->ld
 176 *        new->nfs_client
 177 *        new->deviceid
 178 *
 179 * @ret the inserted node, if none found, otherwise, the found entry.
 180 */
 181struct nfs4_deviceid_node *
 182nfs4_insert_deviceid_node(struct nfs4_deviceid_node *new)
 183{
 184        struct nfs4_deviceid_node *d;
 185        long hash;
 186
 187        spin_lock(&nfs4_deviceid_lock);
 188        hash = nfs4_deviceid_hash(&new->deviceid);
 189        d = _find_get_deviceid(new->ld, new->nfs_client, &new->deviceid, hash);
 190        if (d) {
 191                spin_unlock(&nfs4_deviceid_lock);
 192                return d;
 193        }
 194
 195        hlist_add_head_rcu(&new->node, &nfs4_deviceid_cache[hash]);
 196        spin_unlock(&nfs4_deviceid_lock);
 197        atomic_inc(&new->ref);
 198
 199        return new;
 200}
 201EXPORT_SYMBOL_GPL(nfs4_insert_deviceid_node);
 202
 203/*
 204 * Dereference a deviceid node and delete it when its reference count drops
 205 * to zero.
 206 *
 207 * @d deviceid node to put
 208 *
 209 * return true iff the node was deleted
 210 * Note that since the test for d->ref == 0 is sufficient to establish
 211 * that the node is no longer hashed in the global device id cache.
 212 */
 213bool
 214nfs4_put_deviceid_node(struct nfs4_deviceid_node *d)
 215{
 216        if (!atomic_dec_and_test(&d->ref))
 217                return false;
 218        d->ld->free_deviceid_node(d);
 219        return true;
 220}
 221EXPORT_SYMBOL_GPL(nfs4_put_deviceid_node);
 222
 223void
 224nfs4_mark_deviceid_unavailable(struct nfs4_deviceid_node *node)
 225{
 226        node->timestamp_unavailable = jiffies;
 227        set_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags);
 228}
 229EXPORT_SYMBOL_GPL(nfs4_mark_deviceid_unavailable);
 230
 231bool
 232nfs4_test_deviceid_unavailable(struct nfs4_deviceid_node *node)
 233{
 234        if (test_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags)) {
 235                unsigned long start, end;
 236
 237                end = jiffies;
 238                start = end - PNFS_DEVICE_RETRY_TIMEOUT;
 239                if (time_in_range(node->timestamp_unavailable, start, end))
 240                        return true;
 241                clear_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags);
 242        }
 243        return false;
 244}
 245EXPORT_SYMBOL_GPL(nfs4_test_deviceid_unavailable);
 246
 247static void
 248_deviceid_purge_client(const struct nfs_client *clp, long hash)
 249{
 250        struct nfs4_deviceid_node *d;
 251        struct hlist_node *n;
 252        HLIST_HEAD(tmp);
 253
 254        spin_lock(&nfs4_deviceid_lock);
 255        rcu_read_lock();
 256        hlist_for_each_entry_rcu(d, n, &nfs4_deviceid_cache[hash], node)
 257                if (d->nfs_client == clp && atomic_read(&d->ref)) {
 258                        hlist_del_init_rcu(&d->node);
 259                        hlist_add_head(&d->tmpnode, &tmp);
 260                }
 261        rcu_read_unlock();
 262        spin_unlock(&nfs4_deviceid_lock);
 263
 264        if (hlist_empty(&tmp))
 265                return;
 266
 267        synchronize_rcu();
 268        while (!hlist_empty(&tmp)) {
 269                d = hlist_entry(tmp.first, struct nfs4_deviceid_node, tmpnode);
 270                hlist_del(&d->tmpnode);
 271                if (atomic_dec_and_test(&d->ref))
 272                        d->ld->free_deviceid_node(d);
 273        }
 274}
 275
 276void
 277nfs4_deviceid_purge_client(const struct nfs_client *clp)
 278{
 279        long h;
 280
 281        if (!(clp->cl_exchange_flags & EXCHGID4_FLAG_USE_PNFS_MDS))
 282                return;
 283        for (h = 0; h < NFS4_DEVICE_ID_HASH_SIZE; h++)
 284                _deviceid_purge_client(clp, h);
 285}
 286
 287/*
 288 * Stop use of all deviceids associated with an nfs_client
 289 */
 290void
 291nfs4_deviceid_mark_client_invalid(struct nfs_client *clp)
 292{
 293        struct nfs4_deviceid_node *d;
 294        struct hlist_node *n;
 295        int i;
 296
 297        rcu_read_lock();
 298        for (i = 0; i < NFS4_DEVICE_ID_HASH_SIZE; i ++){
 299                hlist_for_each_entry_rcu(d, n, &nfs4_deviceid_cache[i], node)
 300                        if (d->nfs_client == clp)
 301                                set_bit(NFS_DEVICEID_INVALID, &d->flags);
 302        }
 303        rcu_read_unlock();
 304}
 305
 306
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