fs/nfs/pnfs_dev.c

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