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         if (rhdr->res.scratch != NULL)
  52                 kfree(rhdr->res.scratch);
  53         kmem_cache_free(nfs_rdata_cachep, rhdr);
  54 }
  55
  56 static int nfs_return_empty_folio(struct folio *folio)
  57 {
  58         folio_zero_segment(folio, 0, folio_size(folio));
  59         folio_mark_uptodate(folio);
  60         folio_unlock(folio);
  61         return 0;
  62 }
  63
  64 void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
  65                               struct inode *inode, bool force_mds,
  66                               const struct nfs_pgio_completion_ops *compl_ops)
  67 {
  68         struct nfs_server *server = NFS_SERVER(inode);
  69         const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
  70
  71 #ifdef CONFIG_NFS_V4_1
  72         if (server->pnfs_curr_ld && !force_mds)
  73                 pg_ops = server->pnfs_curr_ld->pg_read_ops;
  74 #endif
  75         nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_read_ops,
  76                         server->rsize, 0);
  77 }
  78 EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
  79
  80 void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
  81 {
  82         struct nfs_pgio_mirror *pgm;
  83         unsigned long npages;
  84
  85         nfs_pageio_complete(pgio);
  86
  87         /* It doesn't make sense to do mirrored reads! */
  88         WARN_ON_ONCE(pgio->pg_mirror_count != 1);
  89
  90         pgm = &pgio->pg_mirrors[0];
  91         NFS_I(pgio->pg_inode)->read_io += pgm->pg_bytes_written;
  92         npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >> PAGE_SHIFT;
  93         nfs_add_stats(pgio->pg_inode, NFSIOS_READPAGES, npages);
  94 }
  95
  96
  97 void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio)
  98 {
  99         struct nfs_pgio_mirror *mirror;
 100
 101         if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
 102                 pgio->pg_ops->pg_cleanup(pgio);
 103
 104         pgio->pg_ops = &nfs_pgio_rw_ops;
 105
 106         /* read path should never have more than one mirror */
 107         WARN_ON_ONCE(pgio->pg_mirror_count != 1);
 108
 109         mirror = &pgio->pg_mirrors[0];
 110         mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize;
 111 }
 112 EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
 113
 114 bool nfs_read_alloc_scratch(struct nfs_pgio_header *hdr, size_t size)
 115 {
 116         WARN_ON(hdr->res.scratch != NULL);
 117         hdr->res.scratch = kmalloc(size, GFP_KERNEL);
 118         return hdr->res.scratch != NULL;
 119 }
 120 EXPORT_SYMBOL_GPL(nfs_read_alloc_scratch);
 121
 122 static void nfs_readpage_release(struct nfs_page *req, int error)
 123 {
 124         struct folio *folio = nfs_page_to_folio(req);
 125
 126         if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE))
 127                 if (nfs_netfs_folio_unlock(folio))
 128                         folio_unlock(folio);
 129
 130         nfs_release_request(req);
 131 }
 132
 133 static void nfs_page_group_set_uptodate(struct nfs_page *req)
 134 {
 135         if (nfs_page_group_sync_on_bit(req, PG_UPTODATE))
 136                 folio_mark_uptodate(nfs_page_to_folio(req));
 137 }
 138
 139 static void nfs_read_completion(struct nfs_pgio_header *hdr)
 140 {
 141         unsigned long bytes = 0;
 142         int error;
 143
 144         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 145                 goto out;
 146         while (!list_empty(&hdr->pages)) {
 147                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 148                 struct folio *folio = nfs_page_to_folio(req);
 149                 unsigned long start = req->wb_pgbase;
 150                 unsigned long end = req->wb_pgbase + req->wb_bytes;
 151
 152                 if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
 153                         /* note: regions of the page not covered by a
 154                          * request are zeroed in nfs_read_add_folio
 155                          */
 156                         if (bytes > hdr->good_bytes) {
 157                                 /* nothing in this request was good, so zero
 158                                  * the full extent of the request */
 159                                 folio_zero_segment(folio, start, end);
 160
 161                         } else if (hdr->good_bytes - bytes < req->wb_bytes) {
 162                                 /* part of this request has good bytes, but
 163                                  * not all. zero the bad bytes */
 164                                 start += hdr->good_bytes - bytes;
 165                                 WARN_ON(start < req->wb_pgbase);
 166                                 folio_zero_segment(folio, start, end);
 167                         }
 168                 }
 169                 error = 0;
 170                 bytes += req->wb_bytes;
 171                 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
 172                         if (bytes <= hdr->good_bytes)
 173                                 nfs_page_group_set_uptodate(req);
 174                         else {
 175                                 error = hdr->error;
 176                                 xchg(&nfs_req_openctx(req)->error, error);
 177                         }
 178                 } else
 179                         nfs_page_group_set_uptodate(req);
 180                 nfs_list_remove_request(req);
 181                 nfs_readpage_release(req, error);
 182         }
 183         nfs_netfs_read_completion(hdr);
 184
 185 out:
 186         hdr->release(hdr);
 187 }
 188
 189 static void nfs_initiate_read(struct nfs_pgio_header *hdr,
 190                               struct rpc_message *msg,
 191                               const struct nfs_rpc_ops *rpc_ops,
 192                               struct rpc_task_setup *task_setup_data, int how)
 193 {
 194         rpc_ops->read_setup(hdr, msg);
 195         nfs_netfs_initiate_read(hdr);
 196         trace_nfs_initiate_read(hdr);
 197 }
 198
 199 static void
 200 nfs_async_read_error(struct list_head *head, int error)
 201 {
 202         struct nfs_page *req;
 203
 204         while (!list_empty(head)) {
 205                 req = nfs_list_entry(head->next);
 206                 nfs_list_remove_request(req);
 207                 nfs_readpage_release(req, error);
 208         }
 209 }
 210
 211 const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
 212         .error_cleanup = nfs_async_read_error,
 213         .completion = nfs_read_completion,
 214 };
 215
 216 /*
 217  * This is the callback from RPC telling us whether a reply was
 218  * received or some error occurred (timeout or socket shutdown).
 219  */
 220 static int nfs_readpage_done(struct rpc_task *task,
 221                              struct nfs_pgio_header *hdr,
 222                              struct inode *inode)
 223 {
 224         int status = NFS_PROTO(inode)->read_done(task, hdr);
 225         if (status != 0)
 226                 return status;
 227
 228         nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
 229         trace_nfs_readpage_done(task, hdr);
 230
 231         if (task->tk_status == -ESTALE) {
 232                 nfs_set_inode_stale(inode);
 233                 nfs_mark_for_revalidate(inode);
 234         }
 235         return 0;
 236 }
 237
 238 static void nfs_readpage_retry(struct rpc_task *task,
 239                                struct nfs_pgio_header *hdr)
 240 {
 241         struct nfs_pgio_args *argp = &hdr->args;
 242         struct nfs_pgio_res  *resp = &hdr->res;
 243
 244         /* This is a short read! */
 245         nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD);
 246         trace_nfs_readpage_short(task, hdr);
 247
 248         /* Has the server at least made some progress? */
 249         if (resp->count == 0) {
 250                 nfs_set_pgio_error(hdr, -EIO, argp->offset);
 251                 return;
 252         }
 253
 254         /* For non rpc-based layout drivers, retry-through-MDS */
 255         if (!task->tk_ops) {
 256                 hdr->pnfs_error = -EAGAIN;
 257                 return;
 258         }
 259
 260         /* Yes, so retry the read at the end of the hdr */
 261         hdr->mds_offset += resp->count;
 262         argp->offset += resp->count;
 263         argp->pgbase += resp->count;
 264         argp->count -= resp->count;
 265         resp->count = 0;
 266         resp->eof = 0;
 267         rpc_restart_call_prepare(task);
 268 }
 269
 270 static void nfs_readpage_result(struct rpc_task *task,
 271                                 struct nfs_pgio_header *hdr)
 272 {
 273         if (hdr->res.eof) {
 274                 loff_t pos = hdr->args.offset + hdr->res.count;
 275                 unsigned int new = pos - hdr->io_start;
 276
 277                 if (hdr->good_bytes > new) {
 278                         hdr->good_bytes = new;
 279                         set_bit(NFS_IOHDR_EOF, &hdr->flags);
 280                         clear_bit(NFS_IOHDR_ERROR, &hdr->flags);
 281                 }
 282         } else if (hdr->res.count < hdr->args.count)
 283                 nfs_readpage_retry(task, hdr);
 284 }
 285
 286 int nfs_read_add_folio(struct nfs_pageio_descriptor *pgio,
 287                        struct nfs_open_context *ctx,
 288                        struct folio *folio)
 289 {
 290         struct inode *inode = folio->mapping->host;
 291         struct nfs_server *server = NFS_SERVER(inode);
 292         size_t fsize = folio_size(folio);
 293         unsigned int rsize = server->rsize;
 294         struct nfs_page *new;
 295         unsigned int len, aligned_len;
 296         int error;
 297
 298         len = nfs_folio_length(folio);
 299         if (len == 0)
 300                 return nfs_return_empty_folio(folio);
 301
 302         aligned_len = min_t(unsigned int, ALIGN(len, rsize), fsize);
 303
 304         new = nfs_page_create_from_folio(ctx, folio, 0, aligned_len);
 305         if (IS_ERR(new)) {
 306                 error = PTR_ERR(new);
 307                 if (nfs_netfs_folio_unlock(folio))
 308                         folio_unlock(folio);
 309                 goto out;
 310         }
 311
 312         if (len < fsize)
 313                 folio_zero_segment(folio, len, fsize);
 314         if (!nfs_pageio_add_request(pgio, new)) {
 315                 nfs_list_remove_request(new);
 316                 error = pgio->pg_error;
 317                 nfs_readpage_release(new, error);
 318                 goto out;
 319         }
 320         return 0;
 321 out:
 322         return error;
 323 }
 324
 325 /*
 326  * Actually read a folio over the wire.
 327  */
 328 static int nfs_do_read_folio(struct file *file, struct folio *folio)
 329 {
 330         struct inode *inode = file_inode(file);
 331         struct nfs_pageio_descriptor pgio;
 332         struct nfs_open_context *ctx;
 333         int ret;
 334
 335         ctx = get_nfs_open_context(nfs_file_open_context(file));
 336
 337         xchg(&ctx->error, 0);
 338         nfs_pageio_init_read(&pgio, inode, false,
 339                              &nfs_async_read_completion_ops);
 340
 341         ret = nfs_read_add_folio(&pgio, ctx, folio);
 342         if (ret)
 343                 goto out_put;
 344
 345         nfs_pageio_complete_read(&pgio);
 346         nfs_update_delegated_atime(inode);
 347         if (pgio.pg_error < 0) {
 348                 ret = pgio.pg_error;
 349                 goto out_put;
 350         }
 351
 352         ret = folio_wait_locked_killable(folio);
 353         if (!folio_test_uptodate(folio) && !ret)
 354                 ret = xchg(&ctx->error, 0);
 355
 356 out_put:
 357         put_nfs_open_context(ctx);
 358         return ret;
 359 }
 360
 361 /*
 362  * Synchronously read a folio.
 363  *
 364  * This is not heavily used as most users to try an asynchronous
 365  * large read through ->readahead first.
 366  */
 367 int nfs_read_folio(struct file *file, struct folio *folio)
 368 {
 369         struct inode *inode = file_inode(file);
 370         loff_t pos = folio_pos(folio);
 371         size_t len = folio_size(folio);
 372         int ret;
 373
 374         trace_nfs_aop_readpage(inode, pos, len);
 375         nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
 376         task_io_account_read(len);
 377
 378         /*
 379          * Try to flush any pending writes to the file..
 380          *
 381          * NOTE! Because we own the folio lock, there cannot
 382          * be any new pending writes generated at this point
 383          * for this folio (other folios can be written to).
 384          */
 385         ret = nfs_wb_folio(inode, folio);
 386         if (ret)
 387                 goto out_unlock;
 388         if (folio_test_uptodate(folio))
 389                 goto out_unlock;
 390
 391         ret = -ESTALE;
 392         if (NFS_STALE(inode))
 393                 goto out_unlock;
 394
 395         ret = nfs_netfs_read_folio(file, folio);
 396         if (ret)
 397                 ret = nfs_do_read_folio(file, folio);
 398 out:
 399         trace_nfs_aop_readpage_done(inode, pos, len, ret);
 400         return ret;
 401 out_unlock:
 402         folio_unlock(folio);
 403         goto out;
 404 }
 405
 406 void nfs_readahead(struct readahead_control *ractl)
 407 {
 408         struct nfs_pageio_descriptor pgio;
 409         struct nfs_open_context *ctx;
 410         unsigned int nr_pages = readahead_count(ractl);
 411         struct file *file = ractl->file;
 412         struct inode *inode = ractl->mapping->host;
 413         struct folio *folio;
 414         int ret;
 415
 416         trace_nfs_aop_readahead(inode, readahead_pos(ractl), nr_pages);
 417         nfs_inc_stats(inode, NFSIOS_VFSREADPAGES);
 418         task_io_account_read(readahead_length(ractl));
 419
 420         ret = -ESTALE;
 421         if (NFS_STALE(inode))
 422                 goto out;
 423
 424         ret = nfs_netfs_readahead(ractl);
 425         if (!ret)
 426                 goto out;
 427
 428         if (file == NULL) {
 429                 ret = -EBADF;
 430                 ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
 431                 if (ctx == NULL)
 432                         goto out;
 433         } else
 434                 ctx = get_nfs_open_context(nfs_file_open_context(file));
 435
 436         nfs_pageio_init_read(&pgio, inode, false,
 437                              &nfs_async_read_completion_ops);
 438
 439         while ((folio = readahead_folio(ractl)) != NULL) {
 440                 ret = nfs_read_add_folio(&pgio, ctx, folio);
 441                 if (ret)
 442                         break;
 443         }
 444
 445         nfs_pageio_complete_read(&pgio);
 446         nfs_update_delegated_atime(inode);
 447
 448         put_nfs_open_context(ctx);
 449 out:
 450         trace_nfs_aop_readahead_done(inode, nr_pages, ret);
 451 }
 452
 453 int __init nfs_init_readpagecache(void)
 454 {
 455         nfs_rdata_cachep = kmem_cache_create("nfs_read_data",
 456                                              sizeof(struct nfs_pgio_header),
 457                                              0, SLAB_HWCACHE_ALIGN,
 458                                              NULL);
 459         if (nfs_rdata_cachep == NULL)
 460                 return -ENOMEM;
 461
 462         return 0;
 463 }
 464
 465 void nfs_destroy_readpagecache(void)
 466 {
 467         kmem_cache_destroy(nfs_rdata_cachep);
 468 }
 469
 470 static const struct nfs_rw_ops nfs_rw_read_ops = {
 471         .rw_alloc_header        = nfs_readhdr_alloc,
 472         .rw_free_header         = nfs_readhdr_free,
 473         .rw_done                = nfs_readpage_done,
 474         .rw_result              = nfs_readpage_result,
 475         .rw_initiate            = nfs_initiate_read,
 476 };