linux/fs/ceph/cache.c
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   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
  27struct ceph_aux_inode {
  28        struct timespec mtime;
  29        loff_t          size;
  30};
  31
  32struct fscache_netfs ceph_cache_netfs = {
  33        .name           = "ceph",
  34        .version        = 0,
  35};
  36
  37static uint16_t ceph_fscache_session_get_key(const void *cookie_netfs_data,
  38                                             void *buffer, uint16_t maxbuf)
  39{
  40        const struct ceph_fs_client* fsc = cookie_netfs_data;
  41        uint16_t klen;
  42
  43        klen = sizeof(fsc->client->fsid);
  44        if (klen > maxbuf)
  45                return 0;
  46
  47        memcpy(buffer, &fsc->client->fsid, klen);
  48        return klen;
  49}
  50
  51static const struct fscache_cookie_def ceph_fscache_fsid_object_def = {
  52        .name           = "CEPH.fsid",
  53        .type           = FSCACHE_COOKIE_TYPE_INDEX,
  54        .get_key        = ceph_fscache_session_get_key,
  55};
  56
  57int ceph_fscache_register(void)
  58{
  59        return fscache_register_netfs(&ceph_cache_netfs);
  60}
  61
  62void ceph_fscache_unregister(void)
  63{
  64        fscache_unregister_netfs(&ceph_cache_netfs);
  65}
  66
  67int ceph_fscache_register_fs(struct ceph_fs_client* fsc)
  68{
  69        fsc->fscache = fscache_acquire_cookie(ceph_cache_netfs.primary_index,
  70                                              &ceph_fscache_fsid_object_def,
  71                                              fsc, true);
  72
  73        if (fsc->fscache == NULL) {
  74                pr_err("Unable to resgister fsid: %p fscache cookie", fsc);
  75                return 0;
  76        }
  77
  78        fsc->revalidate_wq = alloc_workqueue("ceph-revalidate", 0, 1);
  79        if (fsc->revalidate_wq == NULL)
  80                return -ENOMEM;
  81
  82        return 0;
  83}
  84
  85static uint16_t ceph_fscache_inode_get_key(const void *cookie_netfs_data,
  86                                           void *buffer, uint16_t maxbuf)
  87{
  88        const struct ceph_inode_info* ci = cookie_netfs_data;
  89        uint16_t klen;
  90
  91        /* use ceph virtual inode (id + snaphot) */
  92        klen = sizeof(ci->i_vino);
  93        if (klen > maxbuf)
  94                return 0;
  95
  96        memcpy(buffer, &ci->i_vino, klen);
  97        return klen;
  98}
  99
 100static uint16_t ceph_fscache_inode_get_aux(const void *cookie_netfs_data,
 101                                           void *buffer, uint16_t bufmax)
 102{
 103        struct ceph_aux_inode aux;
 104        const struct ceph_inode_info* ci = cookie_netfs_data;
 105        const struct inode* inode = &ci->vfs_inode;
 106
 107        memset(&aux, 0, sizeof(aux));
 108        aux.mtime = inode->i_mtime;
 109        aux.size = inode->i_size;
 110
 111        memcpy(buffer, &aux, sizeof(aux));
 112
 113        return sizeof(aux);
 114}
 115
 116static void ceph_fscache_inode_get_attr(const void *cookie_netfs_data,
 117                                        uint64_t *size)
 118{
 119        const struct ceph_inode_info* ci = cookie_netfs_data;
 120        const struct inode* inode = &ci->vfs_inode;
 121
 122        *size = inode->i_size;
 123}
 124
 125static enum fscache_checkaux ceph_fscache_inode_check_aux(
 126        void *cookie_netfs_data, const void *data, uint16_t dlen)
 127{
 128        struct ceph_aux_inode aux;
 129        struct ceph_inode_info* ci = cookie_netfs_data;
 130        struct inode* inode = &ci->vfs_inode;
 131
 132        if (dlen != sizeof(aux))
 133                return FSCACHE_CHECKAUX_OBSOLETE;
 134
 135        memset(&aux, 0, sizeof(aux));
 136        aux.mtime = inode->i_mtime;
 137        aux.size = inode->i_size;
 138
 139        if (memcmp(data, &aux, sizeof(aux)) != 0)
 140                return FSCACHE_CHECKAUX_OBSOLETE;
 141
 142        dout("ceph inode 0x%p cached okay", ci);
 143        return FSCACHE_CHECKAUX_OKAY;
 144}
 145
 146static void ceph_fscache_inode_now_uncached(void* cookie_netfs_data)
 147{
 148        struct ceph_inode_info* ci = cookie_netfs_data;
 149        struct pagevec pvec;
 150        pgoff_t first;
 151        int loop, nr_pages;
 152
 153        pagevec_init(&pvec, 0);
 154        first = 0;
 155
 156        dout("ceph inode 0x%p now uncached", ci);
 157
 158        while (1) {
 159                nr_pages = pagevec_lookup(&pvec, ci->vfs_inode.i_mapping, first,
 160                                          PAGEVEC_SIZE - pagevec_count(&pvec));
 161
 162                if (!nr_pages)
 163                        break;
 164
 165                for (loop = 0; loop < nr_pages; loop++)
 166                        ClearPageFsCache(pvec.pages[loop]);
 167
 168                first = pvec.pages[nr_pages - 1]->index + 1;
 169
 170                pvec.nr = nr_pages;
 171                pagevec_release(&pvec);
 172                cond_resched();
 173        }
 174}
 175
 176static const struct fscache_cookie_def ceph_fscache_inode_object_def = {
 177        .name           = "CEPH.inode",
 178        .type           = FSCACHE_COOKIE_TYPE_DATAFILE,
 179        .get_key        = ceph_fscache_inode_get_key,
 180        .get_attr       = ceph_fscache_inode_get_attr,
 181        .get_aux        = ceph_fscache_inode_get_aux,
 182        .check_aux      = ceph_fscache_inode_check_aux,
 183        .now_uncached   = ceph_fscache_inode_now_uncached,
 184};
 185
 186void ceph_fscache_register_inode_cookie(struct ceph_fs_client* fsc,
 187                                        struct ceph_inode_info* ci)
 188{
 189        struct inode* inode = &ci->vfs_inode;
 190
 191        /* No caching for filesystem */
 192        if (fsc->fscache == NULL)
 193                return;
 194
 195        /* Only cache for regular files that are read only */
 196        if ((ci->vfs_inode.i_mode & S_IFREG) == 0)
 197                return;
 198
 199        /* Avoid multiple racing open requests */
 200        mutex_lock(&inode->i_mutex);
 201
 202        if (ci->fscache)
 203                goto done;
 204
 205        ci->fscache = fscache_acquire_cookie(fsc->fscache,
 206                                             &ceph_fscache_inode_object_def,
 207                                             ci, true);
 208        fscache_check_consistency(ci->fscache);
 209done:
 210        mutex_unlock(&inode->i_mutex);
 211
 212}
 213
 214void ceph_fscache_unregister_inode_cookie(struct ceph_inode_info* ci)
 215{
 216        struct fscache_cookie* cookie;
 217
 218        if ((cookie = ci->fscache) == NULL)
 219                return;
 220
 221        ci->fscache = NULL;
 222
 223        fscache_uncache_all_inode_pages(cookie, &ci->vfs_inode);
 224        fscache_relinquish_cookie(cookie, 0);
 225}
 226
 227static void ceph_vfs_readpage_complete(struct page *page, void *data, int error)
 228{
 229        if (!error)
 230                SetPageUptodate(page);
 231}
 232
 233static void ceph_vfs_readpage_complete_unlock(struct page *page, void *data, int error)
 234{
 235        if (!error)
 236                SetPageUptodate(page);
 237
 238        unlock_page(page);
 239}
 240
 241static inline int cache_valid(struct ceph_inode_info *ci)
 242{
 243        return ((ceph_caps_issued(ci) & CEPH_CAP_FILE_CACHE) &&
 244                (ci->i_fscache_gen == ci->i_rdcache_gen));
 245}
 246
 247
 248/* Atempt to read from the fscache,
 249 *
 250 * This function is called from the readpage_nounlock context. DO NOT attempt to
 251 * unlock the page here (or in the callback).
 252 */
 253int ceph_readpage_from_fscache(struct inode *inode, struct page *page)
 254{
 255        struct ceph_inode_info *ci = ceph_inode(inode);
 256        int ret;
 257
 258        if (!cache_valid(ci))
 259                return -ENOBUFS;
 260
 261        ret = fscache_read_or_alloc_page(ci->fscache, page,
 262                                         ceph_vfs_readpage_complete, NULL,
 263                                         GFP_KERNEL);
 264
 265        switch (ret) {
 266                case 0: /* Page found */
 267                        dout("page read submitted\n");
 268                        return 0;
 269                case -ENOBUFS: /* Pages were not found, and can't be */
 270                case -ENODATA: /* Pages were not found */
 271                        dout("page/inode not in cache\n");
 272                        return ret;
 273                default:
 274                        dout("%s: unknown error ret = %i\n", __func__, ret);
 275                        return ret;
 276        }
 277}
 278
 279int ceph_readpages_from_fscache(struct inode *inode,
 280                                  struct address_space *mapping,
 281                                  struct list_head *pages,
 282                                  unsigned *nr_pages)
 283{
 284        struct ceph_inode_info *ci = ceph_inode(inode);
 285        int ret;
 286
 287        if (!cache_valid(ci))
 288                return -ENOBUFS;
 289
 290        ret = fscache_read_or_alloc_pages(ci->fscache, mapping, pages, nr_pages,
 291                                          ceph_vfs_readpage_complete_unlock,
 292                                          NULL, mapping_gfp_mask(mapping));
 293
 294        switch (ret) {
 295                case 0: /* All pages found */
 296                        dout("all-page read submitted\n");
 297                        return 0;
 298                case -ENOBUFS: /* Some pages were not found, and can't be */
 299                case -ENODATA: /* some pages were not found */
 300                        dout("page/inode not in cache\n");
 301                        return ret;
 302                default:
 303                        dout("%s: unknown error ret = %i\n", __func__, ret);
 304                        return ret;
 305        }
 306}
 307
 308void ceph_readpage_to_fscache(struct inode *inode, struct page *page)
 309{
 310        struct ceph_inode_info *ci = ceph_inode(inode);
 311        int ret;
 312
 313        if (!PageFsCache(page))
 314                return;
 315
 316        if (!cache_valid(ci))
 317                return;
 318
 319        ret = fscache_write_page(ci->fscache, page, GFP_KERNEL);
 320        if (ret)
 321                 fscache_uncache_page(ci->fscache, page);
 322}
 323
 324void ceph_invalidate_fscache_page(struct inode* inode, struct page *page)
 325{
 326        struct ceph_inode_info *ci = ceph_inode(inode);
 327
 328        if (!PageFsCache(page))
 329                return;
 330
 331        fscache_wait_on_page_write(ci->fscache, page);
 332        fscache_uncache_page(ci->fscache, page);
 333}
 334
 335void ceph_fscache_unregister_fs(struct ceph_fs_client* fsc)
 336{
 337        if (fsc->revalidate_wq)
 338                destroy_workqueue(fsc->revalidate_wq);
 339
 340        fscache_relinquish_cookie(fsc->fscache, 0);
 341        fsc->fscache = NULL;
 342}
 343
 344static void ceph_revalidate_work(struct work_struct *work)
 345{
 346        int issued;
 347        u32 orig_gen;
 348        struct ceph_inode_info *ci = container_of(work, struct ceph_inode_info,
 349                                                  i_revalidate_work);
 350        struct inode *inode = &ci->vfs_inode;
 351
 352        spin_lock(&ci->i_ceph_lock);
 353        issued = __ceph_caps_issued(ci, NULL);
 354        orig_gen = ci->i_rdcache_gen;
 355        spin_unlock(&ci->i_ceph_lock);
 356
 357        if (!(issued & CEPH_CAP_FILE_CACHE)) {
 358                dout("revalidate_work lost cache before validation %p\n",
 359                     inode);
 360                goto out;
 361        }
 362
 363        if (!fscache_check_consistency(ci->fscache))
 364                fscache_invalidate(ci->fscache);
 365
 366        spin_lock(&ci->i_ceph_lock);
 367        /* Update the new valid generation (backwards sanity check too) */
 368        if (orig_gen > ci->i_fscache_gen) {
 369                ci->i_fscache_gen = orig_gen;
 370        }
 371        spin_unlock(&ci->i_ceph_lock);
 372
 373out:
 374        iput(&ci->vfs_inode);
 375}
 376
 377void ceph_queue_revalidate(struct inode *inode)
 378{
 379        struct ceph_fs_client *fsc = ceph_sb_to_client(inode->i_sb);
 380        struct ceph_inode_info *ci = ceph_inode(inode);
 381
 382        if (fsc->revalidate_wq == NULL || ci->fscache == NULL)
 383                return;
 384
 385        ihold(inode);
 386
 387        if (queue_work(ceph_sb_to_client(inode->i_sb)->revalidate_wq,
 388                       &ci->i_revalidate_work)) {
 389                dout("ceph_queue_revalidate %p\n", inode);
 390        } else {
 391                dout("ceph_queue_revalidate %p failed\n)", inode);
 392                iput(inode);
 393        }
 394}
 395
 396void ceph_fscache_inode_init(struct ceph_inode_info *ci)
 397{
 398        ci->fscache = NULL;
 399        /* The first load is verifed cookie open time */
 400        ci->i_fscache_gen = 1;
 401        INIT_WORK(&ci->i_revalidate_work, ceph_revalidate_work);
 402}
 403