root/fs/ceph/cache.c

DEFINITIONS

1. ceph_fscache_register
2. ceph_fscache_unregister
3. ceph_fscache_register_fs
4. ceph_fscache_inode_check_aux
5. ceph_fscache_register_inode_cookie
6. ceph_fscache_unregister_inode_cookie
7. ceph_fscache_can_enable
8. ceph_fscache_file_set_cookie
9. ceph_readpage_from_fscache_complete
10. cache_valid
11. ceph_readpage_from_fscache
12. ceph_readpages_from_fscache
13. ceph_readpage_to_fscache
14. ceph_invalidate_fscache_page
15. ceph_fscache_unregister_fs
16. ceph_fscache_revalidate_cookie

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Ceph cache definitions.
   4  *
   5  *  Copyright (C) 2013 by Adfin Solutions, Inc. All Rights Reserved.
   6  *  Written by Milosz Tanski (milosz@adfin.com)
   7  */
   8 
   9 #include <linux/ceph/ceph_debug.h>
  10 
  11 #include "super.h"
  12 #include "cache.h"
  13 
  14 struct ceph_aux_inode {
  15         u64     version;
  16         u64     mtime_sec;
  17         u64     mtime_nsec;
  18 };
  19 
  20 struct fscache_netfs ceph_cache_netfs = {
  21         .name           = "ceph",
  22         .version        = 0,
  23 };
  24 
  25 static DEFINE_MUTEX(ceph_fscache_lock);
  26 static LIST_HEAD(ceph_fscache_list);
  27 
  28 struct ceph_fscache_entry {
  29         struct list_head list;
  30         struct fscache_cookie *fscache;
  31         size_t uniq_len;
  32         /* The following members must be last */
  33         struct ceph_fsid fsid;
  34         char uniquifier[0];
  35 };
  36 
  37 static const struct fscache_cookie_def ceph_fscache_fsid_object_def = {
  38         .name           = "CEPH.fsid",
  39         .type           = FSCACHE_COOKIE_TYPE_INDEX,
  40 };
  41 
  42 int __init ceph_fscache_register(void)
  43 {
  44         return fscache_register_netfs(&ceph_cache_netfs);
  45 }
  46 
  47 void ceph_fscache_unregister(void)
  48 {
  49         fscache_unregister_netfs(&ceph_cache_netfs);
  50 }
  51 
  52 int ceph_fscache_register_fs(struct ceph_fs_client* fsc)
  53 {
  54         const struct ceph_fsid *fsid = &fsc->client->fsid;
  55         const char *fscache_uniq = fsc->mount_options->fscache_uniq;
  56         size_t uniq_len = fscache_uniq ? strlen(fscache_uniq) : 0;
  57         struct ceph_fscache_entry *ent;
  58         int err = 0;
  59 
  60         mutex_lock(&ceph_fscache_lock);
  61         list_for_each_entry(ent, &ceph_fscache_list, list) {
  62                 if (memcmp(&ent->fsid, fsid, sizeof(*fsid)))
  63                         continue;
  64                 if (ent->uniq_len != uniq_len)
  65                         continue;
  66                 if (uniq_len && memcmp(ent->uniquifier, fscache_uniq, uniq_len))
  67                         continue;
  68 
  69                 pr_err("fscache cookie already registered for fsid %pU\n", fsid);
  70                 pr_err("  use fsc=%%s mount option to specify a uniquifier\n");
  71                 err = -EBUSY;
  72                 goto out_unlock;
  73         }
  74 
  75         ent = kzalloc(sizeof(*ent) + uniq_len, GFP_KERNEL);
  76         if (!ent) {
  77                 err = -ENOMEM;
  78                 goto out_unlock;
  79         }
  80 
  81         memcpy(&ent->fsid, fsid, sizeof(*fsid));
  82         if (uniq_len > 0) {
  83                 memcpy(&ent->uniquifier, fscache_uniq, uniq_len);
  84                 ent->uniq_len = uniq_len;
  85         }
  86 
  87         fsc->fscache = fscache_acquire_cookie(ceph_cache_netfs.primary_index,
  88                                               &ceph_fscache_fsid_object_def,
  89                                               &ent->fsid, sizeof(ent->fsid) + uniq_len,
  90                                               NULL, 0,
  91                                               fsc, 0, true);
  92 
  93         if (fsc->fscache) {
  94                 ent->fscache = fsc->fscache;
  95                 list_add_tail(&ent->list, &ceph_fscache_list);
  96         } else {
  97                 kfree(ent);
  98                 pr_err("unable to register fscache cookie for fsid %pU\n",
  99                        fsid);
 100                 /* all other fs ignore this error */
 101         }
 102 out_unlock:
 103         mutex_unlock(&ceph_fscache_lock);
 104         return err;
 105 }
 106 
 107 static enum fscache_checkaux ceph_fscache_inode_check_aux(
 108         void *cookie_netfs_data, const void *data, uint16_t dlen,
 109         loff_t object_size)
 110 {
 111         struct ceph_aux_inode aux;
 112         struct ceph_inode_info* ci = cookie_netfs_data;
 113         struct inode* inode = &ci->vfs_inode;
 114 
 115         if (dlen != sizeof(aux) ||
 116             i_size_read(inode) != object_size)
 117                 return FSCACHE_CHECKAUX_OBSOLETE;
 118 
 119         memset(&aux, 0, sizeof(aux));
 120         aux.version = ci->i_version;
 121         aux.mtime_sec = inode->i_mtime.tv_sec;
 122         aux.mtime_nsec = inode->i_mtime.tv_nsec;
 123 
 124         if (memcmp(data, &aux, sizeof(aux)) != 0)
 125                 return FSCACHE_CHECKAUX_OBSOLETE;
 126 
 127         dout("ceph inode 0x%p cached okay\n", ci);
 128         return FSCACHE_CHECKAUX_OKAY;
 129 }
 130 
 131 static const struct fscache_cookie_def ceph_fscache_inode_object_def = {
 132         .name           = "CEPH.inode",
 133         .type           = FSCACHE_COOKIE_TYPE_DATAFILE,
 134         .check_aux      = ceph_fscache_inode_check_aux,
 135 };
 136 
 137 void ceph_fscache_register_inode_cookie(struct inode *inode)
 138 {
 139         struct ceph_inode_info *ci = ceph_inode(inode);
 140         struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
 141         struct ceph_aux_inode aux;
 142 
 143         /* No caching for filesystem */
 144         if (!fsc->fscache)
 145                 return;
 146 
 147         /* Only cache for regular files that are read only */
 148         if (!S_ISREG(inode->i_mode))
 149                 return;
 150 
 151         inode_lock_nested(inode, I_MUTEX_CHILD);
 152         if (!ci->fscache) {
 153                 memset(&aux, 0, sizeof(aux));
 154                 aux.version = ci->i_version;
 155                 aux.mtime_sec = inode->i_mtime.tv_sec;
 156                 aux.mtime_nsec = inode->i_mtime.tv_nsec;
 157                 ci->fscache = fscache_acquire_cookie(fsc->fscache,
 158                                                      &ceph_fscache_inode_object_def,
 159                                                      &ci->i_vino, sizeof(ci->i_vino),
 160                                                      &aux, sizeof(aux),
 161                                                      ci, i_size_read(inode), false);
 162         }
 163         inode_unlock(inode);
 164 }
 165 
 166 void ceph_fscache_unregister_inode_cookie(struct ceph_inode_info* ci)
 167 {
 168         struct fscache_cookie* cookie;
 169 
 170         if ((cookie = ci->fscache) == NULL)
 171                 return;
 172 
 173         ci->fscache = NULL;
 174 
 175         fscache_uncache_all_inode_pages(cookie, &ci->vfs_inode);
 176         fscache_relinquish_cookie(cookie, &ci->i_vino, false);
 177 }
 178 
 179 static bool ceph_fscache_can_enable(void *data)
 180 {
 181         struct inode *inode = data;
 182         return !inode_is_open_for_write(inode);
 183 }
 184 
 185 void ceph_fscache_file_set_cookie(struct inode *inode, struct file *filp)
 186 {
 187         struct ceph_inode_info *ci = ceph_inode(inode);
 188 
 189         if (!fscache_cookie_valid(ci->fscache))
 190                 return;
 191 
 192         if (inode_is_open_for_write(inode)) {
 193                 dout("fscache_file_set_cookie %p %p disabling cache\n",
 194                      inode, filp);
 195                 fscache_disable_cookie(ci->fscache, &ci->i_vino, false);
 196                 fscache_uncache_all_inode_pages(ci->fscache, inode);
 197         } else {
 198                 fscache_enable_cookie(ci->fscache, &ci->i_vino, i_size_read(inode),
 199                                       ceph_fscache_can_enable, inode);
 200                 if (fscache_cookie_enabled(ci->fscache)) {
 201                         dout("fscache_file_set_cookie %p %p enabling cache\n",
 202                              inode, filp);
 203                 }
 204         }
 205 }
 206 
 207 static void ceph_readpage_from_fscache_complete(struct page *page, void *data, int error)
 208 {
 209         if (!error)
 210                 SetPageUptodate(page);
 211 
 212         unlock_page(page);
 213 }
 214 
 215 static inline bool cache_valid(struct ceph_inode_info *ci)
 216 {
 217         return ci->i_fscache_gen == ci->i_rdcache_gen;
 218 }
 219 
 220 
 221 /* Atempt to read from the fscache,
 222  *
 223  * This function is called from the readpage_nounlock context. DO NOT attempt to
 224  * unlock the page here (or in the callback).
 225  */
 226 int ceph_readpage_from_fscache(struct inode *inode, struct page *page)
 227 {
 228         struct ceph_inode_info *ci = ceph_inode(inode);
 229         int ret;
 230 
 231         if (!cache_valid(ci))
 232                 return -ENOBUFS;
 233 
 234         ret = fscache_read_or_alloc_page(ci->fscache, page,
 235                                          ceph_readpage_from_fscache_complete, NULL,
 236                                          GFP_KERNEL);
 237 
 238         switch (ret) {
 239                 case 0: /* Page found */
 240                         dout("page read submitted\n");
 241                         return 0;
 242                 case -ENOBUFS: /* Pages were not found, and can't be */
 243                 case -ENODATA: /* Pages were not found */
 244                         dout("page/inode not in cache\n");
 245                         return ret;
 246                 default:
 247                         dout("%s: unknown error ret = %i\n", __func__, ret);
 248                         return ret;
 249         }
 250 }
 251 
 252 int ceph_readpages_from_fscache(struct inode *inode,
 253                                   struct address_space *mapping,
 254                                   struct list_head *pages,
 255                                   unsigned *nr_pages)
 256 {
 257         struct ceph_inode_info *ci = ceph_inode(inode);
 258         int ret;
 259 
 260         if (!cache_valid(ci))
 261                 return -ENOBUFS;
 262 
 263         ret = fscache_read_or_alloc_pages(ci->fscache, mapping, pages, nr_pages,
 264                                           ceph_readpage_from_fscache_complete,
 265                                           NULL, mapping_gfp_mask(mapping));
 266 
 267         switch (ret) {
 268                 case 0: /* All pages found */
 269                         dout("all-page read submitted\n");
 270                         return 0;
 271                 case -ENOBUFS: /* Some pages were not found, and can't be */
 272                 case -ENODATA: /* some pages were not found */
 273                         dout("page/inode not in cache\n");
 274                         return ret;
 275                 default:
 276                         dout("%s: unknown error ret = %i\n", __func__, ret);
 277                         return ret;
 278         }
 279 }
 280 
 281 void ceph_readpage_to_fscache(struct inode *inode, struct page *page)
 282 {
 283         struct ceph_inode_info *ci = ceph_inode(inode);
 284         int ret;
 285 
 286         if (!PageFsCache(page))
 287                 return;
 288 
 289         if (!cache_valid(ci))
 290                 return;
 291 
 292         ret = fscache_write_page(ci->fscache, page, i_size_read(inode),
 293                                  GFP_KERNEL);
 294         if (ret)
 295                  fscache_uncache_page(ci->fscache, page);
 296 }
 297 
 298 void ceph_invalidate_fscache_page(struct inode* inode, struct page *page)
 299 {
 300         struct ceph_inode_info *ci = ceph_inode(inode);
 301 
 302         if (!PageFsCache(page))
 303                 return;
 304 
 305         fscache_wait_on_page_write(ci->fscache, page);
 306         fscache_uncache_page(ci->fscache, page);
 307 }
 308 
 309 void ceph_fscache_unregister_fs(struct ceph_fs_client* fsc)
 310 {
 311         if (fscache_cookie_valid(fsc->fscache)) {
 312                 struct ceph_fscache_entry *ent;
 313                 bool found = false;
 314 
 315                 mutex_lock(&ceph_fscache_lock);
 316                 list_for_each_entry(ent, &ceph_fscache_list, list) {
 317                         if (ent->fscache == fsc->fscache) {
 318                                 list_del(&ent->list);
 319                                 kfree(ent);
 320                                 found = true;
 321                                 break;
 322                         }
 323                 }
 324                 WARN_ON_ONCE(!found);
 325                 mutex_unlock(&ceph_fscache_lock);
 326 
 327                 __fscache_relinquish_cookie(fsc->fscache, NULL, false);
 328         }
 329         fsc->fscache = NULL;
 330 }
 331 
 332 /*
 333  * caller should hold CEPH_CAP_FILE_{RD,CACHE}
 334  */
 335 void ceph_fscache_revalidate_cookie(struct ceph_inode_info *ci)
 336 {
 337         if (cache_valid(ci))
 338                 return;
 339 
 340         /* resue i_truncate_mutex. There should be no pending
 341          * truncate while the caller holds CEPH_CAP_FILE_RD */
 342         mutex_lock(&ci->i_truncate_mutex);
 343         if (!cache_valid(ci)) {
 344                 if (fscache_check_consistency(ci->fscache, &ci->i_vino))
 345                         fscache_invalidate(ci->fscache);
 346                 spin_lock(&ci->i_ceph_lock);
 347                 ci->i_fscache_gen = ci->i_rdcache_gen;
 348                 spin_unlock(&ci->i_ceph_lock);
 349         }
 350         mutex_unlock(&ci->i_truncate_mutex);
 351 }