fs/9p/cache.c

   1 /*
   2  * V9FS cache definitions.
   3  *
   4  *  Copyright (C) 2009 by Abhishek Kulkarni <adkulkar@umail.iu.edu>
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License version 2
   8  *  as published by the Free Software Foundation.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, write to:
  17  *  Free Software Foundation
  18  *  51 Franklin Street, Fifth Floor
  19  *  Boston, MA  02111-1301  USA
  20  *
  21  */
  22
  23 #include <linux/jiffies.h>
  24 #include <linux/file.h>
  25 #include <linux/slab.h>
  26 #include <linux/stat.h>
  27 #include <linux/sched.h>
  28 #include <linux/fs.h>
  29 #include <net/9p/9p.h>
  30
  31 #include "v9fs.h"
  32 #include "cache.h"
  33
  34 #define CACHETAG_LEN  11
  35
  36 struct fscache_netfs v9fs_cache_netfs = {
  37         .name           = "9p",
  38         .version        = 0,
  39 };
  40
  41 /**
  42  * v9fs_random_cachetag - Generate a random tag to be associated
  43  *                        with a new cache session.
  44  *
  45  * The value of jiffies is used for a fairly randomly cache tag.
  46  */
  47
  48 static
  49 int v9fs_random_cachetag(struct v9fs_session_info *v9ses)
  50 {
  51         v9ses->cachetag = kmalloc(CACHETAG_LEN, GFP_KERNEL);
  52         if (!v9ses->cachetag)
  53                 return -ENOMEM;
  54
  55         return scnprintf(v9ses->cachetag, CACHETAG_LEN, "%lu", jiffies);
  56 }
  57
  58 static uint16_t v9fs_cache_session_get_key(const void *cookie_netfs_data,
  59                                            void *buffer, uint16_t bufmax)
  60 {
  61         struct v9fs_session_info *v9ses;
  62         uint16_t klen = 0;
  63
  64         v9ses = (struct v9fs_session_info *)cookie_netfs_data;
  65         P9_DPRINTK(P9_DEBUG_FSC, "session %p buf %p size %u", v9ses,
  66                    buffer, bufmax);
  67
  68         if (v9ses->cachetag)
  69                 klen = strlen(v9ses->cachetag);
  70
  71         if (klen > bufmax)
  72                 return 0;
  73
  74         memcpy(buffer, v9ses->cachetag, klen);
  75         P9_DPRINTK(P9_DEBUG_FSC, "cache session tag %s", v9ses->cachetag);
  76         return klen;
  77 }
  78
  79 const struct fscache_cookie_def v9fs_cache_session_index_def = {
  80         .name           = "9P.session",
  81         .type           = FSCACHE_COOKIE_TYPE_INDEX,
  82         .get_key        = v9fs_cache_session_get_key,
  83 };
  84
  85 void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
  86 {
  87         /* If no cache session tag was specified, we generate a random one. */
  88         if (!v9ses->cachetag)
  89                 v9fs_random_cachetag(v9ses);
  90
  91         v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
  92                                                 &v9fs_cache_session_index_def,
  93                                                 v9ses);
  94         P9_DPRINTK(P9_DEBUG_FSC, "session %p get cookie %p", v9ses,
  95                    v9ses->fscache);
  96 }
  97
  98 void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)
  99 {
 100         P9_DPRINTK(P9_DEBUG_FSC, "session %p put cookie %p", v9ses,
 101                    v9ses->fscache);
 102         fscache_relinquish_cookie(v9ses->fscache, 0);
 103         v9ses->fscache = NULL;
 104 }
 105
 106
 107 static uint16_t v9fs_cache_inode_get_key(const void *cookie_netfs_data,
 108                                          void *buffer, uint16_t bufmax)
 109 {
 110         const struct v9fs_inode *v9inode = cookie_netfs_data;
 111         memcpy(buffer, &v9inode->fscache_key->path,
 112                sizeof(v9inode->fscache_key->path));
 113         P9_DPRINTK(P9_DEBUG_FSC, "inode %p get key %llu", &v9inode->vfs_inode,
 114                    v9inode->fscache_key->path);
 115         return sizeof(v9inode->fscache_key->path);
 116 }
 117
 118 static void v9fs_cache_inode_get_attr(const void *cookie_netfs_data,
 119                                       uint64_t *size)
 120 {
 121         const struct v9fs_inode *v9inode = cookie_netfs_data;
 122         *size = i_size_read(&v9inode->vfs_inode);
 123
 124         P9_DPRINTK(P9_DEBUG_FSC, "inode %p get attr %llu", &v9inode->vfs_inode,
 125                    *size);
 126 }
 127
 128 static uint16_t v9fs_cache_inode_get_aux(const void *cookie_netfs_data,
 129                                          void *buffer, uint16_t buflen)
 130 {
 131         const struct v9fs_inode *v9inode = cookie_netfs_data;
 132         memcpy(buffer, &v9inode->fscache_key->version,
 133                sizeof(v9inode->fscache_key->version));
 134         P9_DPRINTK(P9_DEBUG_FSC, "inode %p get aux %u", &v9inode->vfs_inode,
 135                    v9inode->fscache_key->version);
 136         return sizeof(v9inode->fscache_key->version);
 137 }
 138
 139 static enum
 140 fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,
 141                                             const void *buffer,
 142                                             uint16_t buflen)
 143 {
 144         const struct v9fs_inode *v9inode = cookie_netfs_data;
 145
 146         if (buflen != sizeof(v9inode->fscache_key->version))
 147                 return FSCACHE_CHECKAUX_OBSOLETE;
 148
 149         if (memcmp(buffer, &v9inode->fscache_key->version,
 150                    sizeof(v9inode->fscache_key->version)))
 151                 return FSCACHE_CHECKAUX_OBSOLETE;
 152
 153         return FSCACHE_CHECKAUX_OKAY;
 154 }
 155
 156 static void v9fs_cache_inode_now_uncached(void *cookie_netfs_data)
 157 {
 158         struct v9fs_inode *v9inode = cookie_netfs_data;
 159         struct pagevec pvec;
 160         pgoff_t first;
 161         int loop, nr_pages;
 162
 163         pagevec_init(&pvec, 0);
 164         first = 0;
 165
 166         for (;;) {
 167                 nr_pages = pagevec_lookup(&pvec, v9inode->vfs_inode.i_mapping,
 168                                           first,
 169                                           PAGEVEC_SIZE - pagevec_count(&pvec));
 170                 if (!nr_pages)
 171                         break;
 172
 173                 for (loop = 0; loop < nr_pages; loop++)
 174                         ClearPageFsCache(pvec.pages[loop]);
 175
 176                 first = pvec.pages[nr_pages - 1]->index + 1;
 177
 178                 pvec.nr = nr_pages;
 179                 pagevec_release(&pvec);
 180                 cond_resched();
 181         }
 182 }
 183
 184 const struct fscache_cookie_def v9fs_cache_inode_index_def = {
 185         .name           = "9p.inode",
 186         .type           = FSCACHE_COOKIE_TYPE_DATAFILE,
 187         .get_key        = v9fs_cache_inode_get_key,
 188         .get_attr       = v9fs_cache_inode_get_attr,
 189         .get_aux        = v9fs_cache_inode_get_aux,
 190         .check_aux      = v9fs_cache_inode_check_aux,
 191         .now_uncached   = v9fs_cache_inode_now_uncached,
 192 };
 193
 194 void v9fs_cache_inode_get_cookie(struct inode *inode)
 195 {
 196         struct v9fs_inode *v9inode;
 197         struct v9fs_session_info *v9ses;
 198
 199         if (!S_ISREG(inode->i_mode))
 200                 return;
 201
 202         v9inode = V9FS_I(inode);
 203         if (v9inode->fscache)
 204                 return;
 205
 206         v9ses = v9fs_inode2v9ses(inode);
 207         v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
 208                                                   &v9fs_cache_inode_index_def,
 209                                                   v9inode);
 210
 211         P9_DPRINTK(P9_DEBUG_FSC, "inode %p get cookie %p", inode,
 212                    v9inode->fscache);
 213 }
 214
 215 void v9fs_cache_inode_put_cookie(struct inode *inode)
 216 {
 217         struct v9fs_inode *v9inode = V9FS_I(inode);
 218
 219         if (!v9inode->fscache)
 220                 return;
 221         P9_DPRINTK(P9_DEBUG_FSC, "inode %p put cookie %p", inode,
 222                    v9inode->fscache);
 223
 224         fscache_relinquish_cookie(v9inode->fscache, 0);
 225         v9inode->fscache = NULL;
 226 }
 227
 228 void v9fs_cache_inode_flush_cookie(struct inode *inode)
 229 {
 230         struct v9fs_inode *v9inode = V9FS_I(inode);
 231
 232         if (!v9inode->fscache)
 233                 return;
 234         P9_DPRINTK(P9_DEBUG_FSC, "inode %p flush cookie %p", inode,
 235                    v9inode->fscache);
 236
 237         fscache_relinquish_cookie(v9inode->fscache, 1);
 238         v9inode->fscache = NULL;
 239 }
 240
 241 void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)
 242 {
 243         struct v9fs_inode *v9inode = V9FS_I(inode);
 244         struct p9_fid *fid;
 245
 246         if (!v9inode->fscache)
 247                 return;
 248
 249         spin_lock(&v9inode->fscache_lock);
 250         fid = filp->private_data;
 251         if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
 252                 v9fs_cache_inode_flush_cookie(inode);
 253         else
 254                 v9fs_cache_inode_get_cookie(inode);
 255
 256         spin_unlock(&v9inode->fscache_lock);
 257 }
 258
 259 void v9fs_cache_inode_reset_cookie(struct inode *inode)
 260 {
 261         struct v9fs_inode *v9inode = V9FS_I(inode);
 262         struct v9fs_session_info *v9ses;
 263         struct fscache_cookie *old;
 264
 265         if (!v9inode->fscache)
 266                 return;
 267
 268         old = v9inode->fscache;
 269
 270         spin_lock(&v9inode->fscache_lock);
 271         fscache_relinquish_cookie(v9inode->fscache, 1);
 272
 273         v9ses = v9fs_inode2v9ses(inode);
 274         v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
 275                                                   &v9fs_cache_inode_index_def,
 276                                                   v9inode);
 277         P9_DPRINTK(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p",
 278                    inode, old, v9inode->fscache);
 279
 280         spin_unlock(&v9inode->fscache_lock);
 281 }
 282
 283 int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)
 284 {
 285         struct inode *inode = page->mapping->host;
 286         struct v9fs_inode *v9inode = V9FS_I(inode);
 287
 288         BUG_ON(!v9inode->fscache);
 289
 290         return fscache_maybe_release_page(v9inode->fscache, page, gfp);
 291 }
 292
 293 void __v9fs_fscache_invalidate_page(struct page *page)
 294 {
 295         struct inode *inode = page->mapping->host;
 296         struct v9fs_inode *v9inode = V9FS_I(inode);
 297
 298         BUG_ON(!v9inode->fscache);
 299
 300         if (PageFsCache(page)) {
 301                 fscache_wait_on_page_write(v9inode->fscache, page);
 302                 BUG_ON(!PageLocked(page));
 303                 fscache_uncache_page(v9inode->fscache, page);
 304         }
 305 }
 306
 307 static void v9fs_vfs_readpage_complete(struct page *page, void *data,
 308                                        int error)
 309 {
 310         if (!error)
 311                 SetPageUptodate(page);
 312
 313         unlock_page(page);
 314 }
 315
 316 /**
 317  * __v9fs_readpage_from_fscache - read a page from cache
 318  *
 319  * Returns 0 if the pages are in cache and a BIO is submitted,
 320  * 1 if the pages are not in cache and -error otherwise.
 321  */
 322
 323 int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page)
 324 {
 325         int ret;
 326         const struct v9fs_inode *v9inode = V9FS_I(inode);
 327
 328         P9_DPRINTK(P9_DEBUG_FSC, "inode %p page %p", inode, page);
 329         if (!v9inode->fscache)
 330                 return -ENOBUFS;
 331
 332         ret = fscache_read_or_alloc_page(v9inode->fscache,
 333                                          page,
 334                                          v9fs_vfs_readpage_complete,
 335                                          NULL,
 336                                          GFP_KERNEL);
 337         switch (ret) {
 338         case -ENOBUFS:
 339         case -ENODATA:
 340                 P9_DPRINTK(P9_DEBUG_FSC, "page/inode not in cache %d", ret);
 341                 return 1;
 342         case 0:
 343                 P9_DPRINTK(P9_DEBUG_FSC, "BIO submitted");
 344                 return ret;
 345         default:
 346                 P9_DPRINTK(P9_DEBUG_FSC, "ret %d", ret);
 347                 return ret;
 348         }
 349 }
 350
 351 /**
 352  * __v9fs_readpages_from_fscache - read multiple pages from cache
 353  *
 354  * Returns 0 if the pages are in cache and a BIO is submitted,
 355  * 1 if the pages are not in cache and -error otherwise.
 356  */
 357
 358 int __v9fs_readpages_from_fscache(struct inode *inode,
 359                                   struct address_space *mapping,
 360                                   struct list_head *pages,
 361                                   unsigned *nr_pages)
 362 {
 363         int ret;
 364         const struct v9fs_inode *v9inode = V9FS_I(inode);
 365
 366         P9_DPRINTK(P9_DEBUG_FSC, "inode %p pages %u", inode, *nr_pages);
 367         if (!v9inode->fscache)
 368                 return -ENOBUFS;
 369
 370         ret = fscache_read_or_alloc_pages(v9inode->fscache,
 371                                           mapping, pages, nr_pages,
 372                                           v9fs_vfs_readpage_complete,
 373                                           NULL,
 374                                           mapping_gfp_mask(mapping));
 375         switch (ret) {
 376         case -ENOBUFS:
 377         case -ENODATA:
 378                 P9_DPRINTK(P9_DEBUG_FSC, "pages/inodes not in cache %d", ret);
 379                 return 1;
 380         case 0:
 381                 BUG_ON(!list_empty(pages));
 382                 BUG_ON(*nr_pages != 0);
 383                 P9_DPRINTK(P9_DEBUG_FSC, "BIO submitted");
 384                 return ret;
 385         default:
 386                 P9_DPRINTK(P9_DEBUG_FSC, "ret %d", ret);
 387                 return ret;
 388         }
 389 }
 390
 391 /**
 392  * __v9fs_readpage_to_fscache - write a page to the cache
 393  *
 394  */
 395
 396 void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)
 397 {
 398         int ret;
 399         const struct v9fs_inode *v9inode = V9FS_I(inode);
 400
 401         P9_DPRINTK(P9_DEBUG_FSC, "inode %p page %p", inode, page);
 402         ret = fscache_write_page(v9inode->fscache, page, GFP_KERNEL);
 403         P9_DPRINTK(P9_DEBUG_FSC, "ret =  %d", ret);
 404         if (ret != 0)
 405                 v9fs_uncache_page(inode, page);
 406 }
 407
 408 /*
 409  * wait for a page to complete writing to the cache
 410  */
 411 void __v9fs_fscache_wait_on_page_write(struct inode *inode, struct page *page)
 412 {
 413         const struct v9fs_inode *v9inode = V9FS_I(inode);
 414         P9_DPRINTK(P9_DEBUG_FSC, "inode %p page %p", inode, page);
 415         if (PageFsCache(page))
 416                 fscache_wait_on_page_write(v9inode->fscache, page);
 417 }