fs/nfs/read.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/fs/nfs/read.c
   4  *
   5  * Block I/O for NFS
   6  *
   7  * Partial copy of Linus' read cache modifications to fs/nfs/file.c
   8  * modified for async RPC by [email protected]
   9  */
  10
  11 #include <linux/time.h>
  12 #include <linux/kernel.h>
  13 #include <linux/errno.h>
  14 #include <linux/fcntl.h>
  15 #include <linux/stat.h>
  16 #include <linux/mm.h>
  17 #include <linux/slab.h>
  18 #include <linux/task_io_accounting_ops.h>
  19 #include <linux/pagemap.h>
  20 #include <linux/sunrpc/clnt.h>
  21 #include <linux/nfs_fs.h>
  22 #include <linux/nfs_page.h>
  23 #include <linux/module.h>
  24
  25 #include "nfs4_fs.h"
  26 #include "internal.h"
  27 #include "iostat.h"
  28 #include "fscache.h"
  29 #include "pnfs.h"
  30 #include "nfstrace.h"
  31 #include "delegation.h"
  32
  33 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  34
  35 const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
  36 static const struct nfs_rw_ops nfs_rw_read_ops;
  37
  38 static struct kmem_cache *nfs_rdata_cachep;
  39
  40 static struct nfs_pgio_header *nfs_readhdr_alloc(void)
  41 {
  42         struct nfs_pgio_header *p = kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL);
  43
  44         if (p)
  45                 p->rw_mode = FMODE_READ;
  46         return p;
  47 }
  48
  49 static void nfs_readhdr_free(struct nfs_pgio_header *rhdr)
  50 {
  51         kfree(rhdr->res.scratch);
  52         kmem_cache_free(nfs_rdata_cachep, rhdr);
  53 }
  54
  55 static int nfs_return_empty_folio(struct folio *folio)
  56 {
  57         folio_zero_segment(folio, 0, folio_size(folio));
  58         folio_mark_uptodate(folio);
  59         folio_unlock(folio);
  60         return 0;
  61 }
  62
  63 void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
  64                               struct inode *inode, bool force_mds,
  65                               const struct nfs_pgio_completion_ops *compl_ops)
  66 {
  67         struct nfs_server *server = NFS_SERVER(inode);
  68         const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
  69
  70 #ifdef CONFIG_NFS_V4_1
  71         if (server->pnfs_curr_ld && !force_mds)
  72                 pg_ops = server->pnfs_curr_ld->pg_read_ops;
  73 #endif
  74         nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_read_ops,
  75                         server->rsize, 0);
  76 }
  77 EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
  78
  79 void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
  80 {
  81         struct nfs_pgio_mirror *pgm;
  82         unsigned long npages;
  83
  84         nfs_pageio_complete(pgio);
  85
  86         /* It doesn't make sense to do mirrored reads! */
  87         WARN_ON_ONCE(pgio->pg_mirror_count != 1);
  88
  89         pgm = &pgio->pg_mirrors[0];
  90         NFS_I(pgio->pg_inode)->read_io += pgm->pg_bytes_written;
  91         npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >> PAGE_SHIFT;
  92         nfs_add_stats(pgio->pg_inode, NFSIOS_READPAGES, npages);
  93 }
  94
  95
  96 void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio)
  97 {
  98         struct nfs_pgio_mirror *mirror;
  99
 100         if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
 101                 pgio->pg_ops->pg_cleanup(pgio);
 102
 103         pgio->pg_ops = &nfs_pgio_rw_ops;
 104
 105         /* read path should never have more than one mirror */
 106         WARN_ON_ONCE(pgio->pg_mirror_count != 1);
 107
 108         mirror = &pgio->pg_mirrors[0];
 109         mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize;
 110 }
 111 EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
 112
 113 bool nfs_read_alloc_scratch(struct nfs_pgio_header *hdr, size_t size)
 114 {
 115         WARN_ON(hdr->res.scratch != NULL);
 116         hdr->res.scratch = kmalloc(size, GFP_KERNEL);
 117         return hdr->res.scratch != NULL;
 118 }
 119 EXPORT_SYMBOL_GPL(nfs_read_alloc_scratch);
 120
 121 static void nfs_readpage_release(struct nfs_page *req, int error)
 122 {
 123         struct folio *folio = nfs_page_to_folio(req);
 124
 125         if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE))
 126                 if (nfs_netfs_folio_unlock(folio))
 127                         folio_unlock(folio);
 128
 129         nfs_release_request(req);
 130 }
 131
 132 static void nfs_page_group_set_uptodate(struct nfs_page *req)
 133 {
 134         if (nfs_page_group_sync_on_bit(req, PG_UPTODATE))
 135                 folio_mark_uptodate(nfs_page_to_folio(req));
 136 }
 137
 138 static void nfs_read_completion(struct nfs_pgio_header *hdr)
 139 {
 140         unsigned long bytes = 0;
 141         int error;
 142
 143         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 144                 goto out;
 145         while (!list_empty(&hdr->pages)) {
 146                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 147                 struct folio *folio = nfs_page_to_folio(req);
 148                 unsigned long start = req->wb_pgbase;
 149                 unsigned long end = req->wb_pgbase + req->wb_bytes;
 150
 151                 if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
 152                         /* note: regions of the page not covered by a
 153                          * request are zeroed in nfs_read_add_folio
 154                          */
 155                         if (bytes > hdr->good_bytes) {
 156                                 /* nothing in this request was good, so zero
 157                                  * the full extent of the request */
 158                                 folio_zero_segment(folio, start, end);
 159
 160                         } else if (hdr->good_bytes - bytes < req->wb_bytes) {
 161                                 /* part of this request has good bytes, but
 162                                  * not all. zero the bad bytes */
 163                                 start += hdr->good_bytes - bytes;
 164                                 WARN_ON(start < req->wb_pgbase);
 165                                 folio_zero_segment(folio, start, end);
 166                         }
 167                 }
 168                 error = 0;
 169                 bytes += req->wb_bytes;
 170                 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
 171                         if (bytes <= hdr->good_bytes)
 172                                 nfs_page_group_set_uptodate(req);
 173                         else {
 174                                 error = hdr->error;
 175                                 xchg(&nfs_req_openctx(req)->error, error);
 176                         }
 177                 } else
 178                         nfs_page_group_set_uptodate(req);
 179                 nfs_list_remove_request(req);
 180                 nfs_readpage_release(req, error);
 181         }
 182         nfs_netfs_read_completion(hdr);
 183
 184 out:
 185         hdr->release(hdr);
 186 }
 187
 188 static void nfs_initiate_read(struct nfs_pgio_header *hdr,
 189                               struct rpc_message *msg,
 190                               const struct nfs_rpc_ops *rpc_ops,
 191                               struct rpc_task_setup *task_setup_data, int how)
 192 {
 193         rpc_ops->read_setup(hdr, msg);
 194         nfs_netfs_initiate_read(hdr);
 195         trace_nfs_initiate_read(hdr);
 196 }
 197
 198 static void
 199 nfs_async_read_error(struct list_head *head, int error)
 200 {
 201         struct nfs_page *req;
 202
 203         while (!list_empty(head)) {
 204                 req = nfs_list_entry(head->next);
 205                 nfs_list_remove_request(req);
 206                 nfs_readpage_release(req, error);
 207         }
 208 }
 209
 210 const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
 211         .error_cleanup = nfs_async_read_error,
 212         .completion = nfs_read_completion,
 213 };
 214
 215 /*
 216  * This is the callback from RPC telling us whether a reply was
 217  * received or some error occurred (timeout or socket shutdown).
 218  */
 219 static int nfs_readpage_done(struct rpc_task *task,
 220                              struct nfs_pgio_header *hdr,
 221                              struct inode *inode)
 222 {
 223         int status = NFS_PROTO(inode)->read_done(task, hdr);
 224         if (status != 0)
 225                 return status;
 226
 227         nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
 228         trace_nfs_readpage_done(task, hdr);
 229
 230         if (task->tk_status == -ESTALE) {
 231                 nfs_set_inode_stale(inode);
 232                 nfs_mark_for_revalidate(inode);
 233         }
 234         return 0;
 235 }
 236
 237 static void nfs_readpage_retry(struct rpc_task *task,
 238                                struct nfs_pgio_header *hdr)
 239 {
 240         struct nfs_pgio_args *argp = &hdr->args;
 241         struct nfs_pgio_res  *resp = &hdr->res;
 242
 243         /* This is a short read! */
 244         nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD);
 245         trace_nfs_readpage_short(task, hdr);
 246
 247         /* Has the server at least made some progress? */
 248         if (resp->count == 0) {
 249                 nfs_set_pgio_error(hdr, -EIO, argp->offset);
 250                 return;
 251         }
 252
 253         /* For non rpc-based layout drivers, retry-through-MDS */
 254         if (!task->tk_ops) {
 255                 hdr->pnfs_error = -EAGAIN;
 256                 return;
 257         }
 258
 259         /* Yes, so retry the read at the end of the hdr */
 260         hdr->mds_offset += resp->count;
 261         argp->offset += resp->count;
 262         argp->pgbase += resp->count;
 263         argp->count -= resp->count;
 264         resp->count = 0;
 265         resp->eof = 0;
 266         rpc_restart_call_prepare(task);
 267 }
 268
 269 static void nfs_readpage_result(struct rpc_task *task,
 270                                 struct nfs_pgio_header *hdr)
 271 {
 272         if (hdr->res.eof) {
 273                 loff_t pos = hdr->args.offset + hdr->res.count;
 274                 unsigned int new = pos - hdr->io_start;
 275
 276                 if (hdr->good_bytes > new) {
 277                         hdr->good_bytes = new;
 278                         set_bit(NFS_IOHDR_EOF, &hdr->flags);
 279                         clear_bit(NFS_IOHDR_ERROR, &hdr->flags);
 280                 }
 281         } else if (hdr->res.count < hdr->args.count)
 282                 nfs_readpage_retry(task, hdr);
 283 }
 284
 285 int nfs_read_add_folio(struct nfs_pageio_descriptor *pgio,
 286                        struct nfs_open_context *ctx,
 287                        struct folio *folio)
 288 {
 289         struct inode *inode = folio->mapping->host;
 290         struct nfs_server *server = NFS_SERVER(inode);
 291         size_t fsize = folio_size(folio);
 292         unsigned int rsize = server->rsize;
 293         struct nfs_page *new;
 294         unsigned int len, aligned_len;
 295         int error;
 296
 297         len = nfs_folio_length(folio);
 298         if (len == 0)
 299                 return nfs_return_empty_folio(folio);
 300
 301         aligned_len = min_t(unsigned int, ALIGN(len, rsize), fsize);
 302
 303         new = nfs_page_create_from_folio(ctx, folio, 0, aligned_len);
 304         if (IS_ERR(new)) {
 305                 error = PTR_ERR(new);
 306                 if (nfs_netfs_folio_unlock(folio))
 307                         folio_unlock(folio);
 308                 goto out;
 309         }
 310
 311         if (len < fsize)
 312                 folio_zero_segment(folio, len, fsize);
 313         if (!nfs_pageio_add_request(pgio, new)) {
 314                 nfs_list_remove_request(new);
 315                 error = pgio->pg_error;
 316                 nfs_readpage_release(new, error);
 317                 goto out;
 318         }
 319         return 0;
 320 out:
 321         return error;
 322 }
 323
 324 /*
 325  * Actually read a folio over the wire.
 326  */
 327 static int nfs_do_read_folio(struct file *file, struct folio *folio)
 328 {
 329         struct inode *inode = file_inode(file);
 330         struct nfs_pageio_descriptor pgio;
 331         struct nfs_open_context *ctx;
 332         int ret;
 333
 334         ctx = get_nfs_open_context(nfs_file_open_context(file));
 335
 336         xchg(&ctx->error, 0);
 337         nfs_pageio_init_read(&pgio, inode, false,
 338                              &nfs_async_read_completion_ops);
 339
 340         ret = nfs_read_add_folio(&pgio, ctx, folio);
 341         if (ret)
 342                 goto out_put;
 343
 344         nfs_pageio_complete_read(&pgio);
 345         nfs_update_delegated_atime(inode);
 346         if (pgio.pg_error < 0) {
 347                 ret = pgio.pg_error;
 348                 goto out_put;
 349         }
 350
 351         ret = folio_wait_locked_killable(folio);
 352         if (!folio_test_uptodate(folio) && !ret)
 353                 ret = xchg(&ctx->error, 0);
 354
 355 out_put:
 356         put_nfs_open_context(ctx);
 357         return ret;
 358 }
 359
 360 /*
 361  * Synchronously read a folio.
 362  *
 363  * This is not heavily used as most users to try an asynchronous
 364  * large read through ->readahead first.
 365  */
 366 int nfs_read_folio(struct file *file, struct folio *folio)
 367 {
 368         struct inode *inode = file_inode(file);
 369         loff_t pos = folio_pos(folio);
 370         size_t len = folio_size(folio);
 371         int ret;
 372
 373         trace_nfs_aop_readpage(inode, pos, len);
 374         nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
 375         task_io_account_read(len);
 376
 377         /*
 378          * Try to flush any pending writes to the file..
 379          *
 380          * NOTE! Because we own the folio lock, there cannot
 381          * be any new pending writes generated at this point
 382          * for this folio (other folios can be written to).
 383          */
 384         ret = nfs_wb_folio(inode, folio);
 385         if (ret)
 386                 goto out_unlock;
 387         if (folio_test_uptodate(folio))
 388                 goto out_unlock;
 389
 390         ret = -ESTALE;
 391         if (NFS_STALE(inode))
 392                 goto out_unlock;
 393
 394         ret = nfs_netfs_read_folio(file, folio);
 395         if (ret)
 396                 ret = nfs_do_read_folio(file, folio);
 397 out:
 398         trace_nfs_aop_readpage_done(inode, pos, len, ret);
 399         return ret;
 400 out_unlock:
 401         folio_unlock(folio);
 402         goto out;
 403 }
 404
 405 void nfs_readahead(struct readahead_control *ractl)
 406 {
 407         struct nfs_pageio_descriptor pgio;
 408         struct nfs_open_context *ctx;
 409         unsigned int nr_pages = readahead_count(ractl);
 410         struct file *file = ractl->file;
 411         struct inode *inode = ractl->mapping->host;
 412         struct folio *folio;
 413         int ret;
 414
 415         trace_nfs_aop_readahead(inode, readahead_pos(ractl), nr_pages);
 416         nfs_inc_stats(inode, NFSIOS_VFSREADPAGES);
 417         task_io_account_read(readahead_length(ractl));
 418
 419         ret = -ESTALE;
 420         if (NFS_STALE(inode))
 421                 goto out;
 422
 423         ret = nfs_netfs_readahead(ractl);
 424         if (!ret)
 425                 goto out;
 426
 427         if (file == NULL) {
 428                 ret = -EBADF;
 429                 ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
 430                 if (ctx == NULL)
 431                         goto out;
 432         } else
 433                 ctx = get_nfs_open_context(nfs_file_open_context(file));
 434
 435         nfs_pageio_init_read(&pgio, inode, false,
 436                              &nfs_async_read_completion_ops);
 437
 438         while ((folio = readahead_folio(ractl)) != NULL) {
 439                 ret = nfs_read_add_folio(&pgio, ctx, folio);
 440                 if (ret)
 441                         break;
 442         }
 443
 444         nfs_pageio_complete_read(&pgio);
 445         nfs_update_delegated_atime(inode);
 446
 447         put_nfs_open_context(ctx);
 448 out:
 449         trace_nfs_aop_readahead_done(inode, nr_pages, ret);
 450 }
 451
 452 int __init nfs_init_readpagecache(void)
 453 {
 454         nfs_rdata_cachep = kmem_cache_create("nfs_read_data",
 455                                              sizeof(struct nfs_pgio_header),
 456                                              0, SLAB_HWCACHE_ALIGN,
 457                                              NULL);
 458         if (nfs_rdata_cachep == NULL)
 459                 return -ENOMEM;
 460
 461         return 0;
 462 }
 463
 464 void nfs_destroy_readpagecache(void)
 465 {
 466         kmem_cache_destroy(nfs_rdata_cachep);
 467 }
 468
 469 static const struct nfs_rw_ops nfs_rw_read_ops = {
 470         .rw_alloc_header        = nfs_readhdr_alloc,
 471         .rw_free_header         = nfs_readhdr_free,
 472         .rw_done                = nfs_readpage_done,
 473         .rw_result              = nfs_readpage_result,
 474         .rw_initiate            = nfs_initiate_read,
 475 };