fs/ceph/cache.c

   1 /*
   2  * Ceph cache definitions.
   3  *
   4  *  Copyright (C) 2013 by Adfin Solutions, Inc. All Rights Reserved.
   5  *  Written by Milosz Tanski (milosz@adfin.com)
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License version 2
   9  *  as published by the Free Software Foundation.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to:
  18  *  Free Software Foundation
  19  *  51 Franklin Street, Fifth Floor
  20  *  Boston, MA  02111-1301  USA
  21  *
  22  */
  23
  24 #include "super.h"
  25 #include "cache.h"
  26
  27 struct ceph_aux_inode {
  28         u64             version;
  29         struct timespec mtime;
  30 };
  31
  32 struct fscache_netfs ceph_cache_netfs = {
  33         .name           = "ceph",
  34         .version        = 0,
  35 };
  36
  37 static DEFINE_MUTEX(ceph_fscache_lock);
  38 static LIST_HEAD(ceph_fscache_list);
  39
  40 struct ceph_fscache_entry {
  41         struct list_head list;
  42         struct fscache_cookie *fscache;
  43         size_t uniq_len;
  44         /* The following members must be last */
  45         struct ceph_fsid fsid;
  46         char uniquifier[0];
  47 };
  48
  49 static const struct fscache_cookie_def ceph_fscache_fsid_object_def = {
  50         .name           = "CEPH.fsid",
  51         .type           = FSCACHE_COOKIE_TYPE_INDEX,
  52 };
  53
  54 int __init ceph_fscache_register(void)
  55 {
  56         return fscache_register_netfs(&ceph_cache_netfs);
  57 }
  58
  59 void ceph_fscache_unregister(void)
  60 {
  61         fscache_unregister_netfs(&ceph_cache_netfs);
  62 }
  63
  64 int ceph_fscache_register_fs(struct ceph_fs_client* fsc)
  65 {
  66         const struct ceph_fsid *fsid = &fsc->client->fsid;
  67         const char *fscache_uniq = fsc->mount_options->fscache_uniq;
  68         size_t uniq_len = fscache_uniq ? strlen(fscache_uniq) : 0;
  69         struct ceph_fscache_entry *ent;
  70         int err = 0;
  71
  72         mutex_lock(&ceph_fscache_lock);
  73         list_for_each_entry(ent, &ceph_fscache_list, list) {
  74                 if (memcmp(&ent->fsid, fsid, sizeof(*fsid)))
  75                         continue;
  76                 if (ent->uniq_len != uniq_len)
  77                         continue;
  78                 if (uniq_len && memcmp(ent->uniquifier, fscache_uniq, uniq_len))
  79                         continue;
  80
  81                 pr_err("fscache cookie already registered for fsid %pU\n", fsid);
  82                 pr_err("  use fsc=%%s mount option to specify a uniquifier\n");
  83                 err = -EBUSY;
  84                 goto out_unlock;
  85         }
  86
  87         ent = kzalloc(sizeof(*ent) + uniq_len, GFP_KERNEL);
  88         if (!ent) {
  89                 err = -ENOMEM;
  90                 goto out_unlock;
  91         }
  92
  93         memcpy(&ent->fsid, fsid, sizeof(*fsid));
  94         if (uniq_len > 0) {
  95                 memcpy(&ent->uniquifier, fscache_uniq, uniq_len);
  96                 ent->uniq_len = uniq_len;
  97         }
  98
  99         fsc->fscache = fscache_acquire_cookie(ceph_cache_netfs.primary_index,
 100                                               &ceph_fscache_fsid_object_def,
 101                                               &ent->fsid, sizeof(ent->fsid) + uniq_len,
 102                                               NULL, 0,
 103                                               fsc, 0, true);
 104
 105         if (fsc->fscache) {
 106                 ent->fscache = fsc->fscache;
 107                 list_add_tail(&ent->list, &ceph_fscache_list);
 108         } else {
 109                 kfree(ent);
 110                 pr_err("unable to register fscache cookie for fsid %pU\n",
 111                        fsid);
 112                 /* all other fs ignore this error */
 113         }
 114 out_unlock:
 115         mutex_unlock(&ceph_fscache_lock);
 116         return err;
 117 }
 118
 119 static enum fscache_checkaux ceph_fscache_inode_check_aux(
 120         void *cookie_netfs_data, const void *data, uint16_t dlen,
 121         loff_t object_size)
 122 {
 123         struct ceph_aux_inode aux;
 124         struct ceph_inode_info* ci = cookie_netfs_data;
 125         struct inode* inode = &ci->vfs_inode;
 126
 127         if (dlen != sizeof(aux) ||
 128             i_size_read(inode) != object_size)
 129                 return FSCACHE_CHECKAUX_OBSOLETE;
 130
 131         memset(&aux, 0, sizeof(aux));
 132         aux.version = ci->i_version;
 133         aux.mtime = inode->i_mtime;
 134
 135         if (memcmp(data, &aux, sizeof(aux)) != 0)
 136                 return FSCACHE_CHECKAUX_OBSOLETE;
 137
 138         dout("ceph inode 0x%p cached okay\n", ci);
 139         return FSCACHE_CHECKAUX_OKAY;
 140 }
 141
 142 static const struct fscache_cookie_def ceph_fscache_inode_object_def = {
 143         .name           = "CEPH.inode",
 144         .type           = FSCACHE_COOKIE_TYPE_DATAFILE,
 145         .check_aux      = ceph_fscache_inode_check_aux,
 146 };
 147
 148 void ceph_fscache_register_inode_cookie(struct inode *inode)
 149 {
 150         struct ceph_inode_info *ci = ceph_inode(inode);
 151         struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
 152         struct ceph_aux_inode aux;
 153
 154         /* No caching for filesystem */
 155         if (!fsc->fscache)
 156                 return;
 157
 158         /* Only cache for regular files that are read only */
 159         if (!S_ISREG(inode->i_mode))
 160                 return;
 161
 162         inode_lock_nested(inode, I_MUTEX_CHILD);
 163         if (!ci->fscache) {
 164                 memset(&aux, 0, sizeof(aux));
 165                 aux.version = ci->i_version;
 166                 aux.mtime = inode->i_mtime;
 167                 ci->fscache = fscache_acquire_cookie(fsc->fscache,
 168                                                      &ceph_fscache_inode_object_def,
 169                                                      &ci->i_vino, sizeof(ci->i_vino),
 170                                                      &aux, sizeof(aux),
 171                                                      ci, i_size_read(inode), false);
 172         }
 173         inode_unlock(inode);
 174 }
 175
 176 void ceph_fscache_unregister_inode_cookie(struct ceph_inode_info* ci)
 177 {
 178         struct fscache_cookie* cookie;
 179
 180         if ((cookie = ci->fscache) == NULL)
 181                 return;
 182
 183         ci->fscache = NULL;
 184
 185         fscache_uncache_all_inode_pages(cookie, &ci->vfs_inode);
 186         fscache_relinquish_cookie(cookie, &ci->i_vino, false);
 187 }
 188
 189 static bool ceph_fscache_can_enable(void *data)
 190 {
 191         struct inode *inode = data;
 192         return !inode_is_open_for_write(inode);
 193 }
 194
 195 void ceph_fscache_file_set_cookie(struct inode *inode, struct file *filp)
 196 {
 197         struct ceph_inode_info *ci = ceph_inode(inode);
 198
 199         if (!fscache_cookie_valid(ci->fscache))
 200                 return;
 201
 202         if (inode_is_open_for_write(inode)) {
 203                 dout("fscache_file_set_cookie %p %p disabling cache\n",
 204                      inode, filp);
 205                 fscache_disable_cookie(ci->fscache, &ci->i_vino, false);
 206                 fscache_uncache_all_inode_pages(ci->fscache, inode);
 207         } else {
 208                 fscache_enable_cookie(ci->fscache, &ci->i_vino, i_size_read(inode),
 209                                       ceph_fscache_can_enable, inode);
 210                 if (fscache_cookie_enabled(ci->fscache)) {
 211                         dout("fscache_file_set_cookie %p %p enabling cache\n",
 212                              inode, filp);
 213                 }
 214         }
 215 }
 216
 217 static void ceph_readpage_from_fscache_complete(struct page *page, void *data, int error)
 218 {
 219         if (!error)
 220                 SetPageUptodate(page);
 221
 222         unlock_page(page);
 223 }
 224
 225 static inline bool cache_valid(struct ceph_inode_info *ci)
 226 {
 227         return ci->i_fscache_gen == ci->i_rdcache_gen;
 228 }
 229
 230
 231 /* Atempt to read from the fscache,
 232  *
 233  * This function is called from the readpage_nounlock context. DO NOT attempt to
 234  * unlock the page here (or in the callback).
 235  */
 236 int ceph_readpage_from_fscache(struct inode *inode, struct page *page)
 237 {
 238         struct ceph_inode_info *ci = ceph_inode(inode);
 239         int ret;
 240
 241         if (!cache_valid(ci))
 242                 return -ENOBUFS;
 243
 244         ret = fscache_read_or_alloc_page(ci->fscache, page,
 245                                          ceph_readpage_from_fscache_complete, NULL,
 246                                          GFP_KERNEL);
 247
 248         switch (ret) {
 249                 case 0: /* Page found */
 250                         dout("page read submitted\n");
 251                         return 0;
 252                 case -ENOBUFS: /* Pages were not found, and can't be */
 253                 case -ENODATA: /* Pages were not found */
 254                         dout("page/inode not in cache\n");
 255                         return ret;
 256                 default:
 257                         dout("%s: unknown error ret = %i\n", __func__, ret);
 258                         return ret;
 259         }
 260 }
 261
 262 int ceph_readpages_from_fscache(struct inode *inode,
 263                                   struct address_space *mapping,
 264                                   struct list_head *pages,
 265                                   unsigned *nr_pages)
 266 {
 267         struct ceph_inode_info *ci = ceph_inode(inode);
 268         int ret;
 269
 270         if (!cache_valid(ci))
 271                 return -ENOBUFS;
 272
 273         ret = fscache_read_or_alloc_pages(ci->fscache, mapping, pages, nr_pages,
 274                                           ceph_readpage_from_fscache_complete,
 275                                           NULL, mapping_gfp_mask(mapping));
 276
 277         switch (ret) {
 278                 case 0: /* All pages found */
 279                         dout("all-page read submitted\n");
 280                         return 0;
 281                 case -ENOBUFS: /* Some pages were not found, and can't be */
 282                 case -ENODATA: /* some pages were not found */
 283                         dout("page/inode not in cache\n");
 284                         return ret;
 285                 default:
 286                         dout("%s: unknown error ret = %i\n", __func__, ret);
 287                         return ret;
 288         }
 289 }
 290
 291 void ceph_readpage_to_fscache(struct inode *inode, struct page *page)
 292 {
 293         struct ceph_inode_info *ci = ceph_inode(inode);
 294         int ret;
 295
 296         if (!PageFsCache(page))
 297                 return;
 298
 299         if (!cache_valid(ci))
 300                 return;
 301
 302         ret = fscache_write_page(ci->fscache, page, i_size_read(inode),
 303                                  GFP_KERNEL);
 304         if (ret)
 305                  fscache_uncache_page(ci->fscache, page);
 306 }
 307
 308 void ceph_invalidate_fscache_page(struct inode* inode, struct page *page)
 309 {
 310         struct ceph_inode_info *ci = ceph_inode(inode);
 311
 312         if (!PageFsCache(page))
 313                 return;
 314
 315         fscache_wait_on_page_write(ci->fscache, page);
 316         fscache_uncache_page(ci->fscache, page);
 317 }
 318
 319 void ceph_fscache_unregister_fs(struct ceph_fs_client* fsc)
 320 {
 321         if (fscache_cookie_valid(fsc->fscache)) {
 322                 struct ceph_fscache_entry *ent;
 323                 bool found = false;
 324
 325                 mutex_lock(&ceph_fscache_lock);
 326                 list_for_each_entry(ent, &ceph_fscache_list, list) {
 327                         if (ent->fscache == fsc->fscache) {
 328                                 list_del(&ent->list);
 329                                 kfree(ent);
 330                                 found = true;
 331                                 break;
 332                         }
 333                 }
 334                 WARN_ON_ONCE(!found);
 335                 mutex_unlock(&ceph_fscache_lock);
 336
 337                 __fscache_relinquish_cookie(fsc->fscache, NULL, false);
 338         }
 339         fsc->fscache = NULL;
 340 }
 341
 342 /*
 343  * caller should hold CEPH_CAP_FILE_{RD,CACHE}
 344  */
 345 void ceph_fscache_revalidate_cookie(struct ceph_inode_info *ci)
 346 {
 347         if (cache_valid(ci))
 348                 return;
 349
 350         /* resue i_truncate_mutex. There should be no pending
 351          * truncate while the caller holds CEPH_CAP_FILE_RD */
 352         mutex_lock(&ci->i_truncate_mutex);
 353         if (!cache_valid(ci)) {
 354                 if (fscache_check_consistency(ci->fscache, &ci->i_vino))
 355                         fscache_invalidate(ci->fscache);
 356                 spin_lock(&ci->i_ceph_lock);
 357                 ci->i_fscache_gen = ci->i_rdcache_gen;
 358                 spin_unlock(&ci->i_ceph_lock);
 359         }
 360         mutex_unlock(&ci->i_truncate_mutex);
 361 }