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 #ifdef NFS_DEBUG
  47 void
  48 nfs4_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 }
  55 EXPORT_SYMBOL_GPL(nfs4_print_deviceid);
  56 #endif
  57
  58 static inline u32
  59 nfs4_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
  72 static 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  */
  97 static 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
 112 struct nfs4_deviceid_node *
 113 nfs4_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 }
 118 EXPORT_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  */
 128 void
 129 nfs4_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 }
 150 EXPORT_SYMBOL_GPL(nfs4_delete_deviceid);
 151
 152 void
 153 nfs4_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 }
 166 EXPORT_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  */
 179 struct nfs4_deviceid_node *
 180 nfs4_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 }
 199 EXPORT_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  */
 211 bool
 212 nfs4_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 }
 219 EXPORT_SYMBOL_GPL(nfs4_put_deviceid_node);
 220
 221 static 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
 250 void
 251 nfs4_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  */
 264 void
 265 nfs4_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 }