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 "pnfs.h"
  32
  33 #define NFSDBG_FACILITY         NFSDBG_PNFS
  34
  35 /*
  36  * Device ID RCU cache. A device ID is unique per server and layout type.
  37  */
  38 #define NFS4_DEVICE_ID_HASH_BITS        5
  39 #define NFS4_DEVICE_ID_HASH_SIZE        (1 << NFS4_DEVICE_ID_HASH_BITS)
  40 #define NFS4_DEVICE_ID_HASH_MASK        (NFS4_DEVICE_ID_HASH_SIZE - 1)
  41
  42 static struct hlist_head nfs4_deviceid_cache[NFS4_DEVICE_ID_HASH_SIZE];
  43 static DEFINE_SPINLOCK(nfs4_deviceid_lock);
  44
  45 void
  46 nfs4_print_deviceid(const struct nfs4_deviceid *id)
  47 {
  48         u32 *p = (u32 *)id;
  49
  50         dprintk("%s: device id= [%x%x%x%x]\n", __func__,
  51                 p[0], p[1], p[2], p[3]);
  52 }
  53 EXPORT_SYMBOL_GPL(nfs4_print_deviceid);
  54
  55 static inline u32
  56 nfs4_deviceid_hash(const struct nfs4_deviceid *id)
  57 {
  58         unsigned char *cptr = (unsigned char *)id->data;
  59         unsigned int nbytes = NFS4_DEVICEID4_SIZE;
  60         u32 x = 0;
  61
  62         while (nbytes--) {
  63                 x *= 37;
  64                 x += *cptr++;
  65         }
  66         return x & NFS4_DEVICE_ID_HASH_MASK;
  67 }
  68
  69 static struct nfs4_deviceid_node *
  70 _lookup_deviceid(const struct pnfs_layoutdriver_type *ld,
  71                  const struct nfs_client *clp, const struct nfs4_deviceid *id,
  72                  long hash)
  73 {
  74         struct nfs4_deviceid_node *d;
  75         struct hlist_node *n;
  76
  77         hlist_for_each_entry_rcu(d, n, &nfs4_deviceid_cache[hash], node)
  78                 if (d->ld == ld && d->nfs_client == clp &&
  79                     !memcmp(&d->deviceid, id, sizeof(*id))) {
  80                         if (atomic_read(&d->ref))
  81                                 return d;
  82                         else
  83                                 continue;
  84                 }
  85         return NULL;
  86 }
  87
  88 /*
  89  * Lookup a deviceid in cache and get a reference count on it if found
  90  *
  91  * @clp nfs_client associated with deviceid
  92  * @id deviceid to look up
  93  */
  94 struct nfs4_deviceid_node *
  95 _find_get_deviceid(const struct pnfs_layoutdriver_type *ld,
  96                    const struct nfs_client *clp, const struct nfs4_deviceid *id,
  97                    long hash)
  98 {
  99         struct nfs4_deviceid_node *d;
 100
 101         rcu_read_lock();
 102         d = _lookup_deviceid(ld, clp, id, hash);
 103         if (d && !atomic_inc_not_zero(&d->ref))
 104                 d = NULL;
 105         rcu_read_unlock();
 106         return d;
 107 }
 108
 109 struct nfs4_deviceid_node *
 110 nfs4_find_get_deviceid(const struct pnfs_layoutdriver_type *ld,
 111                        const struct nfs_client *clp, const struct nfs4_deviceid *id)
 112 {
 113         return _find_get_deviceid(ld, clp, id, nfs4_deviceid_hash(id));
 114 }
 115 EXPORT_SYMBOL_GPL(nfs4_find_get_deviceid);
 116
 117 /*
 118  * Unhash and put deviceid
 119  *
 120  * @clp nfs_client associated with deviceid
 121  * @id the deviceid to unhash
 122  *
 123  * @ret the unhashed node, if found and dereferenced to zero, NULL otherwise.
 124  */
 125 struct nfs4_deviceid_node *
 126 nfs4_unhash_put_deviceid(const struct pnfs_layoutdriver_type *ld,
 127                          const struct nfs_client *clp, const struct nfs4_deviceid *id)
 128 {
 129         struct nfs4_deviceid_node *d;
 130
 131         spin_lock(&nfs4_deviceid_lock);
 132         rcu_read_lock();
 133         d = _lookup_deviceid(ld, clp, id, nfs4_deviceid_hash(id));
 134         rcu_read_unlock();
 135         if (!d) {
 136                 spin_unlock(&nfs4_deviceid_lock);
 137                 return NULL;
 138         }
 139         hlist_del_init_rcu(&d->node);
 140         spin_unlock(&nfs4_deviceid_lock);
 141         synchronize_rcu();
 142
 143         /* balance the initial ref set in pnfs_insert_deviceid */
 144         if (atomic_dec_and_test(&d->ref))
 145                 return d;
 146
 147         return NULL;
 148 }
 149 EXPORT_SYMBOL_GPL(nfs4_unhash_put_deviceid);
 150
 151 /*
 152  * Delete a deviceid from cache
 153  *
 154  * @clp struct nfs_client qualifying the deviceid
 155  * @id deviceid to delete
 156  */
 157 void
 158 nfs4_delete_deviceid(const struct pnfs_layoutdriver_type *ld,
 159                      const struct nfs_client *clp, const struct nfs4_deviceid *id)
 160 {
 161         struct nfs4_deviceid_node *d;
 162
 163         d = nfs4_unhash_put_deviceid(ld, clp, id);
 164         if (!d)
 165                 return;
 166         d->ld->free_deviceid_node(d);
 167 }
 168 EXPORT_SYMBOL_GPL(nfs4_delete_deviceid);
 169
 170 void
 171 nfs4_init_deviceid_node(struct nfs4_deviceid_node *d,
 172                         const struct pnfs_layoutdriver_type *ld,
 173                         const struct nfs_client *nfs_client,
 174                         const struct nfs4_deviceid *id)
 175 {
 176         INIT_HLIST_NODE(&d->node);
 177         d->ld = ld;
 178         d->nfs_client = nfs_client;
 179         d->deviceid = *id;
 180         atomic_set(&d->ref, 1);
 181 }
 182 EXPORT_SYMBOL_GPL(nfs4_init_deviceid_node);
 183
 184 /*
 185  * Uniquely initialize and insert a deviceid node into cache
 186  *
 187  * @new new deviceid node
 188  *      Note that the caller must set up the following members:
 189  *        new->ld
 190  *        new->nfs_client
 191  *        new->deviceid
 192  *
 193  * @ret the inserted node, if none found, otherwise, the found entry.
 194  */
 195 struct nfs4_deviceid_node *
 196 nfs4_insert_deviceid_node(struct nfs4_deviceid_node *new)
 197 {
 198         struct nfs4_deviceid_node *d;
 199         long hash;
 200
 201         spin_lock(&nfs4_deviceid_lock);
 202         hash = nfs4_deviceid_hash(&new->deviceid);
 203         d = _find_get_deviceid(new->ld, new->nfs_client, &new->deviceid, hash);
 204         if (d) {
 205                 spin_unlock(&nfs4_deviceid_lock);
 206                 return d;
 207         }
 208
 209         hlist_add_head_rcu(&new->node, &nfs4_deviceid_cache[hash]);
 210         spin_unlock(&nfs4_deviceid_lock);
 211
 212         return new;
 213 }
 214 EXPORT_SYMBOL_GPL(nfs4_insert_deviceid_node);
 215
 216 /*
 217  * Dereference a deviceid node and delete it when its reference count drops
 218  * to zero.
 219  *
 220  * @d deviceid node to put
 221  *
 222  * @ret true iff the node was deleted
 223  */
 224 bool
 225 nfs4_put_deviceid_node(struct nfs4_deviceid_node *d)
 226 {
 227         if (!atomic_dec_and_lock(&d->ref, &nfs4_deviceid_lock))
 228                 return false;
 229         hlist_del_init_rcu(&d->node);
 230         spin_unlock(&nfs4_deviceid_lock);
 231         synchronize_rcu();
 232         d->ld->free_deviceid_node(d);
 233         return true;
 234 }
 235 EXPORT_SYMBOL_GPL(nfs4_put_deviceid_node);
 236
 237 static void
 238 _deviceid_purge_client(const struct nfs_client *clp, long hash)
 239 {
 240         struct nfs4_deviceid_node *d;
 241         struct hlist_node *n, *next;
 242         HLIST_HEAD(tmp);
 243
 244         rcu_read_lock();
 245         hlist_for_each_entry_rcu(d, n, &nfs4_deviceid_cache[hash], node)
 246                 if (d->nfs_client == clp && atomic_read(&d->ref)) {
 247                         hlist_del_init_rcu(&d->node);
 248                         hlist_add_head(&d->node, &tmp);
 249                 }
 250         rcu_read_unlock();
 251
 252         if (hlist_empty(&tmp))
 253                 return;
 254
 255         synchronize_rcu();
 256         hlist_for_each_entry_safe(d, n, next, &tmp, node)
 257                 if (atomic_dec_and_test(&d->ref))
 258                         d->ld->free_deviceid_node(d);
 259 }
 260
 261 void
 262 nfs4_deviceid_purge_client(const struct nfs_client *clp)
 263 {
 264         long h;
 265
 266         spin_lock(&nfs4_deviceid_lock);
 267         for (h = 0; h < NFS4_DEVICE_ID_HASH_SIZE; h++)
 268                 _deviceid_purge_client(clp, h);
 269         spin_unlock(&nfs4_deviceid_lock);
 270 }