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 okir@monad.swb.de
   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
  32 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  33
  34 const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
  35 static const struct nfs_rw_ops nfs_rw_read_ops;
  36
  37 static struct kmem_cache *nfs_rdata_cachep;
  38
  39 static struct nfs_pgio_header *nfs_readhdr_alloc(void)
  40 {
  41         struct nfs_pgio_header *p = kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL);
  42
  43         if (p)
  44                 p->rw_mode = FMODE_READ;
  45         return p;
  46 }
  47
  48 static void nfs_readhdr_free(struct nfs_pgio_header *rhdr)
  49 {
  50         if (rhdr->res.scratch != NULL)
  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_error_is_fatal_on_server(error) && error != -ETIMEDOUT)
 126                 folio_set_error(folio);
 127         if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE))
 128                 if (nfs_netfs_folio_unlock(folio))
 129                         folio_unlock(folio);
 130
 131         nfs_release_request(req);
 132 }
 133
 134 static void nfs_page_group_set_uptodate(struct nfs_page *req)
 135 {
 136         if (nfs_page_group_sync_on_bit(req, PG_UPTODATE))
 137                 folio_mark_uptodate(nfs_page_to_folio(req));
 138 }
 139
 140 static void nfs_read_completion(struct nfs_pgio_header *hdr)
 141 {
 142         unsigned long bytes = 0;
 143         int error;
 144
 145         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 146                 goto out;
 147         while (!list_empty(&hdr->pages)) {
 148                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 149                 struct folio *folio = nfs_page_to_folio(req);
 150                 unsigned long start = req->wb_pgbase;
 151                 unsigned long end = req->wb_pgbase + req->wb_bytes;
 152
 153                 if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
 154                         /* note: regions of the page not covered by a
 155                          * request are zeroed in nfs_read_add_folio
 156                          */
 157                         if (bytes > hdr->good_bytes) {
 158                                 /* nothing in this request was good, so zero
 159                                  * the full extent of the request */
 160                                 folio_zero_segment(folio, start, end);
 161
 162                         } else if (hdr->good_bytes - bytes < req->wb_bytes) {
 163                                 /* part of this request has good bytes, but
 164                                  * not all. zero the bad bytes */
 165                                 start += hdr->good_bytes - bytes;
 166                                 WARN_ON(start < req->wb_pgbase);
 167                                 folio_zero_segment(folio, start, end);
 168                         }
 169                 }
 170                 error = 0;
 171                 bytes += req->wb_bytes;
 172                 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
 173                         if (bytes <= hdr->good_bytes)
 174                                 nfs_page_group_set_uptodate(req);
 175                         else {
 176                                 error = hdr->error;
 177                                 xchg(&nfs_req_openctx(req)->error, error);
 178                         }
 179                 } else
 180                         nfs_page_group_set_uptodate(req);
 181                 nfs_list_remove_request(req);
 182                 nfs_readpage_release(req, error);
 183         }
 184         nfs_netfs_read_completion(hdr);
 185
 186 out:
 187         hdr->release(hdr);
 188 }
 189
 190 static void nfs_initiate_read(struct nfs_pgio_header *hdr,
 191                               struct rpc_message *msg,
 192                               const struct nfs_rpc_ops *rpc_ops,
 193                               struct rpc_task_setup *task_setup_data, int how)
 194 {
 195         rpc_ops->read_setup(hdr, msg);
 196         nfs_netfs_initiate_read(hdr);
 197         trace_nfs_initiate_read(hdr);
 198 }
 199
 200 static void
 201 nfs_async_read_error(struct list_head *head, int error)
 202 {
 203         struct nfs_page *req;
 204
 205         while (!list_empty(head)) {
 206                 req = nfs_list_entry(head->next);
 207                 nfs_list_remove_request(req);
 208                 nfs_readpage_release(req, error);
 209         }
 210 }
 211
 212 const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
 213         .error_cleanup = nfs_async_read_error,
 214         .completion = nfs_read_completion,
 215 };
 216
 217 /*
 218  * This is the callback from RPC telling us whether a reply was
 219  * received or some error occurred (timeout or socket shutdown).
 220  */
 221 static int nfs_readpage_done(struct rpc_task *task,
 222                              struct nfs_pgio_header *hdr,
 223                              struct inode *inode)
 224 {
 225         int status = NFS_PROTO(inode)->read_done(task, hdr);
 226         if (status != 0)
 227                 return status;
 228
 229         nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
 230         trace_nfs_readpage_done(task, hdr);
 231
 232         if (task->tk_status == -ESTALE) {
 233                 nfs_set_inode_stale(inode);
 234                 nfs_mark_for_revalidate(inode);
 235         }
 236         return 0;
 237 }
 238
 239 static void nfs_readpage_retry(struct rpc_task *task,
 240                                struct nfs_pgio_header *hdr)
 241 {
 242         struct nfs_pgio_args *argp = &hdr->args;
 243         struct nfs_pgio_res  *resp = &hdr->res;
 244
 245         /* This is a short read! */
 246         nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD);
 247         trace_nfs_readpage_short(task, hdr);
 248
 249         /* Has the server at least made some progress? */
 250         if (resp->count == 0) {
 251                 nfs_set_pgio_error(hdr, -EIO, argp->offset);
 252                 return;
 253         }
 254
 255         /* For non rpc-based layout drivers, retry-through-MDS */
 256         if (!task->tk_ops) {
 257                 hdr->pnfs_error = -EAGAIN;
 258                 return;
 259         }
 260
 261         /* Yes, so retry the read at the end of the hdr */
 262         hdr->mds_offset += resp->count;
 263         argp->offset += resp->count;
 264         argp->pgbase += resp->count;
 265         argp->count -= resp->count;
 266         resp->count = 0;
 267         resp->eof = 0;
 268         rpc_restart_call_prepare(task);
 269 }
 270
 271 static void nfs_readpage_result(struct rpc_task *task,
 272                                 struct nfs_pgio_header *hdr)
 273 {
 274         if (hdr->res.eof) {
 275                 loff_t pos = hdr->args.offset + hdr->res.count;
 276                 unsigned int new = pos - hdr->io_start;
 277
 278                 if (hdr->good_bytes > new) {
 279                         hdr->good_bytes = new;
 280                         set_bit(NFS_IOHDR_EOF, &hdr->flags);
 281                         clear_bit(NFS_IOHDR_ERROR, &hdr->flags);
 282                 }
 283         } else if (hdr->res.count < hdr->args.count)
 284                 nfs_readpage_retry(task, hdr);
 285 }
 286
 287 int nfs_read_add_folio(struct nfs_pageio_descriptor *pgio,
 288                        struct nfs_open_context *ctx,
 289                        struct folio *folio)
 290 {
 291         struct inode *inode = folio_file_mapping(folio)->host;
 292         struct nfs_server *server = NFS_SERVER(inode);
 293         size_t fsize = folio_size(folio);
 294         unsigned int rsize = server->rsize;
 295         struct nfs_page *new;
 296         unsigned int len, aligned_len;
 297         int error;
 298
 299         len = nfs_folio_length(folio);
 300         if (len == 0)
 301                 return nfs_return_empty_folio(folio);
 302
 303         aligned_len = min_t(unsigned int, ALIGN(len, rsize), fsize);
 304
 305         new = nfs_page_create_from_folio(ctx, folio, 0, aligned_len);
 306         if (IS_ERR(new)) {
 307                 error = PTR_ERR(new);
 308                 if (nfs_netfs_folio_unlock(folio))
 309                         folio_unlock(folio);
 310                 goto out;
 311         }
 312
 313         if (len < fsize)
 314                 folio_zero_segment(folio, len, fsize);
 315         if (!nfs_pageio_add_request(pgio, new)) {
 316                 nfs_list_remove_request(new);
 317                 error = pgio->pg_error;
 318                 nfs_readpage_release(new, error);
 319                 goto out;
 320         }
 321         return 0;
 322 out:
 323         return error;
 324 }
 325
 326 /*
 327  * Read a page over NFS.
 328  * We read the page synchronously in the following case:
 329  *  -   The error flag is set for this page. This happens only when a
 330  *      previous async read operation failed.
 331  */
 332 int nfs_read_folio(struct file *file, struct folio *folio)
 333 {
 334         struct inode *inode = file_inode(file);
 335         struct nfs_pageio_descriptor pgio;
 336         struct nfs_open_context *ctx;
 337         int ret;
 338
 339         trace_nfs_aop_readpage(inode, folio);
 340         nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
 341         task_io_account_read(folio_size(folio));
 342
 343         /*
 344          * Try to flush any pending writes to the file..
 345          *
 346          * NOTE! Because we own the folio lock, there cannot
 347          * be any new pending writes generated at this point
 348          * for this folio (other folios can be written to).
 349          */
 350         ret = nfs_wb_folio(inode, folio);
 351         if (ret)
 352                 goto out_unlock;
 353         if (folio_test_uptodate(folio))
 354                 goto out_unlock;
 355
 356         ret = -ESTALE;
 357         if (NFS_STALE(inode))
 358                 goto out_unlock;
 359
 360         ret = nfs_netfs_read_folio(file, folio);
 361         if (!ret)
 362                 goto out;
 363
 364         ctx = get_nfs_open_context(nfs_file_open_context(file));
 365
 366         xchg(&ctx->error, 0);
 367         nfs_pageio_init_read(&pgio, inode, false,
 368                              &nfs_async_read_completion_ops);
 369
 370         ret = nfs_read_add_folio(&pgio, ctx, folio);
 371         if (ret)
 372                 goto out_put;
 373
 374         nfs_pageio_complete_read(&pgio);
 375         ret = pgio.pg_error < 0 ? pgio.pg_error : 0;
 376         if (!ret) {
 377                 ret = folio_wait_locked_killable(folio);
 378                 if (!folio_test_uptodate(folio) && !ret)
 379                         ret = xchg(&ctx->error, 0);
 380         }
 381 out_put:
 382         put_nfs_open_context(ctx);
 383 out:
 384         trace_nfs_aop_readpage_done(inode, folio, ret);
 385         return ret;
 386 out_unlock:
 387         folio_unlock(folio);
 388         goto out;
 389 }
 390
 391 void nfs_readahead(struct readahead_control *ractl)
 392 {
 393         struct nfs_pageio_descriptor pgio;
 394         struct nfs_open_context *ctx;
 395         unsigned int nr_pages = readahead_count(ractl);
 396         struct file *file = ractl->file;
 397         struct inode *inode = ractl->mapping->host;
 398         struct folio *folio;
 399         int ret;
 400
 401         trace_nfs_aop_readahead(inode, readahead_pos(ractl), nr_pages);
 402         nfs_inc_stats(inode, NFSIOS_VFSREADPAGES);
 403         task_io_account_read(readahead_length(ractl));
 404
 405         ret = -ESTALE;
 406         if (NFS_STALE(inode))
 407                 goto out;
 408
 409         ret = nfs_netfs_readahead(ractl);
 410         if (!ret)
 411                 goto out;
 412
 413         if (file == NULL) {
 414                 ret = -EBADF;
 415                 ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
 416                 if (ctx == NULL)
 417                         goto out;
 418         } else
 419                 ctx = get_nfs_open_context(nfs_file_open_context(file));
 420
 421         nfs_pageio_init_read(&pgio, inode, false,
 422                              &nfs_async_read_completion_ops);
 423
 424         while ((folio = readahead_folio(ractl)) != NULL) {
 425                 ret = nfs_read_add_folio(&pgio, ctx, folio);
 426                 if (ret)
 427                         break;
 428         }
 429
 430         nfs_pageio_complete_read(&pgio);
 431
 432         put_nfs_open_context(ctx);
 433 out:
 434         trace_nfs_aop_readahead_done(inode, nr_pages, ret);
 435 }
 436
 437 int __init nfs_init_readpagecache(void)
 438 {
 439         nfs_rdata_cachep = kmem_cache_create("nfs_read_data",
 440                                              sizeof(struct nfs_pgio_header),
 441                                              0, SLAB_HWCACHE_ALIGN,
 442                                              NULL);
 443         if (nfs_rdata_cachep == NULL)
 444                 return -ENOMEM;
 445
 446         return 0;
 447 }
 448
 449 void nfs_destroy_readpagecache(void)
 450 {
 451         kmem_cache_destroy(nfs_rdata_cachep);
 452 }
 453
 454 static const struct nfs_rw_ops nfs_rw_read_ops = {
 455         .rw_alloc_header        = nfs_readhdr_alloc,
 456         .rw_free_header         = nfs_readhdr_free,
 457         .rw_done                = nfs_readpage_done,
 458         .rw_result              = nfs_readpage_result,
 459         .rw_initiate            = nfs_initiate_read,
 460 };