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Linux/fs/nfs/fscache-index.c

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  1 /* NFS FS-Cache index structure definition
  2  *
  3  * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
  4  * Written by David Howells (dhowells@redhat.com)
  5  *
  6  * This program is free software; you can redistribute it and/or
  7  * modify it under the terms of the GNU General Public Licence
  8  * as published by the Free Software Foundation; either version
  9  * 2 of the Licence, or (at your option) any later version.
 10  */
 11 
 12 #include <linux/init.h>
 13 #include <linux/kernel.h>
 14 #include <linux/sched.h>
 15 #include <linux/mm.h>
 16 #include <linux/nfs_fs.h>
 17 #include <linux/nfs_fs_sb.h>
 18 #include <linux/in6.h>
 19 
 20 #include "internal.h"
 21 #include "fscache.h"
 22 
 23 #define NFSDBG_FACILITY         NFSDBG_FSCACHE
 24 
 25 /*
 26  * Define the NFS filesystem for FS-Cache.  Upon registration FS-Cache sticks
 27  * the cookie for the top-level index object for NFS into here.  The top-level
 28  * index can than have other cache objects inserted into it.
 29  */
 30 struct fscache_netfs nfs_fscache_netfs = {
 31         .name           = "nfs",
 32         .version        = 0,
 33 };
 34 
 35 /*
 36  * Register NFS for caching
 37  */
 38 int nfs_fscache_register(void)
 39 {
 40         return fscache_register_netfs(&nfs_fscache_netfs);
 41 }
 42 
 43 /*
 44  * Unregister NFS for caching
 45  */
 46 void nfs_fscache_unregister(void)
 47 {
 48         fscache_unregister_netfs(&nfs_fscache_netfs);
 49 }
 50 
 51 /*
 52  * Layout of the key for an NFS server cache object.
 53  */
 54 struct nfs_server_key {
 55         uint16_t        nfsversion;             /* NFS protocol version */
 56         uint16_t        family;                 /* address family */
 57         uint16_t        port;                   /* IP port */
 58         union {
 59                 struct in_addr  ipv4_addr;      /* IPv4 address */
 60                 struct in6_addr ipv6_addr;      /* IPv6 address */
 61         } addr[0];
 62 };
 63 
 64 /*
 65  * Generate a key to describe a server in the main NFS index
 66  * - We return the length of the key, or 0 if we can't generate one
 67  */
 68 static uint16_t nfs_server_get_key(const void *cookie_netfs_data,
 69                                    void *buffer, uint16_t bufmax)
 70 {
 71         const struct nfs_client *clp = cookie_netfs_data;
 72         const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) &clp->cl_addr;
 73         const struct sockaddr_in *sin = (struct sockaddr_in *) &clp->cl_addr;
 74         struct nfs_server_key *key = buffer;
 75         uint16_t len = sizeof(struct nfs_server_key);
 76 
 77         key->nfsversion = clp->rpc_ops->version;
 78         key->family = clp->cl_addr.ss_family;
 79 
 80         memset(key, 0, len);
 81 
 82         switch (clp->cl_addr.ss_family) {
 83         case AF_INET:
 84                 key->port = sin->sin_port;
 85                 key->addr[0].ipv4_addr = sin->sin_addr;
 86                 len += sizeof(key->addr[0].ipv4_addr);
 87                 break;
 88 
 89         case AF_INET6:
 90                 key->port = sin6->sin6_port;
 91                 key->addr[0].ipv6_addr = sin6->sin6_addr;
 92                 len += sizeof(key->addr[0].ipv6_addr);
 93                 break;
 94 
 95         default:
 96                 printk(KERN_WARNING "NFS: Unknown network family '%d'\n",
 97                        clp->cl_addr.ss_family);
 98                 len = 0;
 99                 break;
100         }
101 
102         return len;
103 }
104 
105 /*
106  * Define the server object for FS-Cache.  This is used to describe a server
107  * object to fscache_acquire_cookie().  It is keyed by the NFS protocol and
108  * server address parameters.
109  */
110 const struct fscache_cookie_def nfs_fscache_server_index_def = {
111         .name           = "NFS.server",
112         .type           = FSCACHE_COOKIE_TYPE_INDEX,
113         .get_key        = nfs_server_get_key,
114 };
115 
116 /*
117  * Generate a key to describe a superblock key in the main NFS index
118  */
119 static uint16_t nfs_super_get_key(const void *cookie_netfs_data,
120                                   void *buffer, uint16_t bufmax)
121 {
122         const struct nfs_fscache_key *key;
123         const struct nfs_server *nfss = cookie_netfs_data;
124         uint16_t len;
125 
126         key = nfss->fscache_key;
127         len = sizeof(key->key) + key->key.uniq_len;
128         if (len > bufmax) {
129                 len = 0;
130         } else {
131                 memcpy(buffer, &key->key, sizeof(key->key));
132                 memcpy(buffer + sizeof(key->key),
133                        key->key.uniquifier, key->key.uniq_len);
134         }
135 
136         return len;
137 }
138 
139 /*
140  * Define the superblock object for FS-Cache.  This is used to describe a
141  * superblock object to fscache_acquire_cookie().  It is keyed by all the NFS
142  * parameters that might cause a separate superblock.
143  */
144 const struct fscache_cookie_def nfs_fscache_super_index_def = {
145         .name           = "NFS.super",
146         .type           = FSCACHE_COOKIE_TYPE_INDEX,
147         .get_key        = nfs_super_get_key,
148 };
149 
150 /*
151  * Definition of the auxiliary data attached to NFS inode storage objects
152  * within the cache.
153  *
154  * The contents of this struct are recorded in the on-disk local cache in the
155  * auxiliary data attached to the data storage object backing an inode.  This
156  * permits coherency to be managed when a new inode binds to an already extant
157  * cache object.
158  */
159 struct nfs_fscache_inode_auxdata {
160         struct timespec mtime;
161         struct timespec ctime;
162         loff_t          size;
163         u64             change_attr;
164 };
165 
166 /*
167  * Generate a key to describe an NFS inode in an NFS server's index
168  */
169 static uint16_t nfs_fscache_inode_get_key(const void *cookie_netfs_data,
170                                           void *buffer, uint16_t bufmax)
171 {
172         const struct nfs_inode *nfsi = cookie_netfs_data;
173         uint16_t nsize;
174 
175         /* use the inode's NFS filehandle as the key */
176         nsize = nfsi->fh.size;
177         memcpy(buffer, nfsi->fh.data, nsize);
178         return nsize;
179 }
180 
181 /*
182  * Get certain file attributes from the netfs data
183  * - This function can be absent for an index
184  * - Not permitted to return an error
185  * - The netfs data from the cookie being used as the source is presented
186  */
187 static void nfs_fscache_inode_get_attr(const void *cookie_netfs_data,
188                                        uint64_t *size)
189 {
190         const struct nfs_inode *nfsi = cookie_netfs_data;
191 
192         *size = nfsi->vfs_inode.i_size;
193 }
194 
195 /*
196  * Get the auxiliary data from netfs data
197  * - This function can be absent if the index carries no state data
198  * - Should store the auxiliary data in the buffer
199  * - Should return the amount of amount stored
200  * - Not permitted to return an error
201  * - The netfs data from the cookie being used as the source is presented
202  */
203 static uint16_t nfs_fscache_inode_get_aux(const void *cookie_netfs_data,
204                                           void *buffer, uint16_t bufmax)
205 {
206         struct nfs_fscache_inode_auxdata auxdata;
207         const struct nfs_inode *nfsi = cookie_netfs_data;
208 
209         memset(&auxdata, 0, sizeof(auxdata));
210         auxdata.size = nfsi->vfs_inode.i_size;
211         auxdata.mtime = nfsi->vfs_inode.i_mtime;
212         auxdata.ctime = nfsi->vfs_inode.i_ctime;
213 
214         if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
215                 auxdata.change_attr = nfsi->vfs_inode.i_version;
216 
217         if (bufmax > sizeof(auxdata))
218                 bufmax = sizeof(auxdata);
219 
220         memcpy(buffer, &auxdata, bufmax);
221         return bufmax;
222 }
223 
224 /*
225  * Consult the netfs about the state of an object
226  * - This function can be absent if the index carries no state data
227  * - The netfs data from the cookie being used as the target is
228  *   presented, as is the auxiliary data
229  */
230 static
231 enum fscache_checkaux nfs_fscache_inode_check_aux(void *cookie_netfs_data,
232                                                   const void *data,
233                                                   uint16_t datalen)
234 {
235         struct nfs_fscache_inode_auxdata auxdata;
236         struct nfs_inode *nfsi = cookie_netfs_data;
237 
238         if (datalen != sizeof(auxdata))
239                 return FSCACHE_CHECKAUX_OBSOLETE;
240 
241         memset(&auxdata, 0, sizeof(auxdata));
242         auxdata.size = nfsi->vfs_inode.i_size;
243         auxdata.mtime = nfsi->vfs_inode.i_mtime;
244         auxdata.ctime = nfsi->vfs_inode.i_ctime;
245 
246         if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
247                 auxdata.change_attr = nfsi->vfs_inode.i_version;
248 
249         if (memcmp(data, &auxdata, datalen) != 0)
250                 return FSCACHE_CHECKAUX_OBSOLETE;
251 
252         return FSCACHE_CHECKAUX_OKAY;
253 }
254 
255 /*
256  * Indication from FS-Cache that the cookie is no longer cached
257  * - This function is called when the backing store currently caching a cookie
258  *   is removed
259  * - The netfs should use this to clean up any markers indicating cached pages
260  * - This is mandatory for any object that may have data
261  */
262 static void nfs_fscache_inode_now_uncached(void *cookie_netfs_data)
263 {
264         struct nfs_inode *nfsi = cookie_netfs_data;
265         struct pagevec pvec;
266         pgoff_t first;
267         int loop, nr_pages;
268 
269         pagevec_init(&pvec, 0);
270         first = 0;
271 
272         dprintk("NFS: nfs_inode_now_uncached: nfs_inode 0x%p\n", nfsi);
273 
274         for (;;) {
275                 /* grab a bunch of pages to unmark */
276                 nr_pages = pagevec_lookup(&pvec,
277                                           nfsi->vfs_inode.i_mapping,
278                                           first,
279                                           PAGEVEC_SIZE - pagevec_count(&pvec));
280                 if (!nr_pages)
281                         break;
282 
283                 for (loop = 0; loop < nr_pages; loop++)
284                         ClearPageFsCache(pvec.pages[loop]);
285 
286                 first = pvec.pages[nr_pages - 1]->index + 1;
287 
288                 pvec.nr = nr_pages;
289                 pagevec_release(&pvec);
290                 cond_resched();
291         }
292 }
293 
294 /*
295  * Get an extra reference on a read context.
296  * - This function can be absent if the completion function doesn't require a
297  *   context.
298  * - The read context is passed back to NFS in the event that a data read on the
299  *   cache fails with EIO - in which case the server must be contacted to
300  *   retrieve the data, which requires the read context for security.
301  */
302 static void nfs_fh_get_context(void *cookie_netfs_data, void *context)
303 {
304         get_nfs_open_context(context);
305 }
306 
307 /*
308  * Release an extra reference on a read context.
309  * - This function can be absent if the completion function doesn't require a
310  *   context.
311  */
312 static void nfs_fh_put_context(void *cookie_netfs_data, void *context)
313 {
314         if (context)
315                 put_nfs_open_context(context);
316 }
317 
318 /*
319  * Define the inode object for FS-Cache.  This is used to describe an inode
320  * object to fscache_acquire_cookie().  It is keyed by the NFS file handle for
321  * an inode.
322  *
323  * Coherency is managed by comparing the copies of i_size, i_mtime and i_ctime
324  * held in the cache auxiliary data for the data storage object with those in
325  * the inode struct in memory.
326  */
327 const struct fscache_cookie_def nfs_fscache_inode_object_def = {
328         .name           = "NFS.fh",
329         .type           = FSCACHE_COOKIE_TYPE_DATAFILE,
330         .get_key        = nfs_fscache_inode_get_key,
331         .get_attr       = nfs_fscache_inode_get_attr,
332         .get_aux        = nfs_fscache_inode_get_aux,
333         .check_aux      = nfs_fscache_inode_check_aux,
334         .now_uncached   = nfs_fscache_inode_now_uncached,
335         .get_context    = nfs_fh_get_context,
336         .put_context    = nfs_fh_put_context,
337 };
338 

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