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/pagemap.h>
  19 #include <linux/sunrpc/clnt.h>
  20 #include <linux/nfs_fs.h>
  21 #include <linux/nfs_page.h>
  22 #include <linux/module.h>
  23
  24 #include "nfs4_fs.h"
  25 #include "internal.h"
  26 #include "iostat.h"
  27 #include "fscache.h"
  28 #include "pnfs.h"
  29 #include "nfstrace.h"
  30
  31 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  32
  33 static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
  34 static const struct nfs_rw_ops nfs_rw_read_ops;
  35
  36 static struct kmem_cache *nfs_rdata_cachep;
  37
  38 static struct nfs_pgio_header *nfs_readhdr_alloc(void)
  39 {
  40         struct nfs_pgio_header *p = kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL);
  41
  42         if (p)
  43                 p->rw_mode = FMODE_READ;
  44         return p;
  45 }
  46
  47 static void nfs_readhdr_free(struct nfs_pgio_header *rhdr)
  48 {
  49         kmem_cache_free(nfs_rdata_cachep, rhdr);
  50 }
  51
  52 static int nfs_return_empty_folio(struct folio *folio)
  53 {
  54         folio_zero_segment(folio, 0, folio_size(folio));
  55         folio_mark_uptodate(folio);
  56         folio_unlock(folio);
  57         return 0;
  58 }
  59
  60 void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
  61                               struct inode *inode, bool force_mds,
  62                               const struct nfs_pgio_completion_ops *compl_ops)
  63 {
  64         struct nfs_server *server = NFS_SERVER(inode);
  65         const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
  66
  67 #ifdef CONFIG_NFS_V4_1
  68         if (server->pnfs_curr_ld && !force_mds)
  69                 pg_ops = server->pnfs_curr_ld->pg_read_ops;
  70 #endif
  71         nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_read_ops,
  72                         server->rsize, 0);
  73 }
  74 EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
  75
  76 static void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
  77 {
  78         struct nfs_pgio_mirror *pgm;
  79         unsigned long npages;
  80
  81         nfs_pageio_complete(pgio);
  82
  83         /* It doesn't make sense to do mirrored reads! */
  84         WARN_ON_ONCE(pgio->pg_mirror_count != 1);
  85
  86         pgm = &pgio->pg_mirrors[0];
  87         NFS_I(pgio->pg_inode)->read_io += pgm->pg_bytes_written;
  88         npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >> PAGE_SHIFT;
  89         nfs_add_stats(pgio->pg_inode, NFSIOS_READPAGES, npages);
  90 }
  91
  92
  93 void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio)
  94 {
  95         struct nfs_pgio_mirror *mirror;
  96
  97         if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
  98                 pgio->pg_ops->pg_cleanup(pgio);
  99
 100         pgio->pg_ops = &nfs_pgio_rw_ops;
 101
 102         /* read path should never have more than one mirror */
 103         WARN_ON_ONCE(pgio->pg_mirror_count != 1);
 104
 105         mirror = &pgio->pg_mirrors[0];
 106         mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize;
 107 }
 108 EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
 109
 110 static void nfs_readpage_release(struct nfs_page *req, int error)
 111 {
 112         struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
 113         struct folio *folio = nfs_page_to_folio(req);
 114
 115         dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id,
 116                 (unsigned long long)NFS_FILEID(inode), req->wb_bytes,
 117                 (long long)req_offset(req));
 118
 119         if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT)
 120                 folio_set_error(folio);
 121         if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) {
 122                 if (folio_test_uptodate(folio))
 123                         nfs_fscache_write_page(inode, &folio->page);
 124                 folio_unlock(folio);
 125         }
 126         nfs_release_request(req);
 127 }
 128
 129 struct nfs_readdesc {
 130         struct nfs_pageio_descriptor pgio;
 131         struct nfs_open_context *ctx;
 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 readpage_async_filler */
 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 out:
 184         hdr->release(hdr);
 185 }
 186
 187 static void nfs_initiate_read(struct nfs_pgio_header *hdr,
 188                               struct rpc_message *msg,
 189                               const struct nfs_rpc_ops *rpc_ops,
 190                               struct rpc_task_setup *task_setup_data, int how)
 191 {
 192         rpc_ops->read_setup(hdr, msg);
 193         trace_nfs_initiate_read(hdr);
 194 }
 195
 196 static void
 197 nfs_async_read_error(struct list_head *head, int error)
 198 {
 199         struct nfs_page *req;
 200
 201         while (!list_empty(head)) {
 202                 req = nfs_list_entry(head->next);
 203                 nfs_list_remove_request(req);
 204                 nfs_readpage_release(req, error);
 205         }
 206 }
 207
 208 static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
 209         .error_cleanup = nfs_async_read_error,
 210         .completion = nfs_read_completion,
 211 };
 212
 213 /*
 214  * This is the callback from RPC telling us whether a reply was
 215  * received or some error occurred (timeout or socket shutdown).
 216  */
 217 static int nfs_readpage_done(struct rpc_task *task,
 218                              struct nfs_pgio_header *hdr,
 219                              struct inode *inode)
 220 {
 221         int status = NFS_PROTO(inode)->read_done(task, hdr);
 222         if (status != 0)
 223                 return status;
 224
 225         nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
 226         trace_nfs_readpage_done(task, hdr);
 227
 228         if (task->tk_status == -ESTALE) {
 229                 nfs_set_inode_stale(inode);
 230                 nfs_mark_for_revalidate(inode);
 231         }
 232         return 0;
 233 }
 234
 235 static void nfs_readpage_retry(struct rpc_task *task,
 236                                struct nfs_pgio_header *hdr)
 237 {
 238         struct nfs_pgio_args *argp = &hdr->args;
 239         struct nfs_pgio_res  *resp = &hdr->res;
 240
 241         /* This is a short read! */
 242         nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD);
 243         trace_nfs_readpage_short(task, hdr);
 244
 245         /* Has the server at least made some progress? */
 246         if (resp->count == 0) {
 247                 nfs_set_pgio_error(hdr, -EIO, argp->offset);
 248                 return;
 249         }
 250
 251         /* For non rpc-based layout drivers, retry-through-MDS */
 252         if (!task->tk_ops) {
 253                 hdr->pnfs_error = -EAGAIN;
 254                 return;
 255         }
 256
 257         /* Yes, so retry the read at the end of the hdr */
 258         hdr->mds_offset += resp->count;
 259         argp->offset += resp->count;
 260         argp->pgbase += resp->count;
 261         argp->count -= resp->count;
 262         resp->count = 0;
 263         resp->eof = 0;
 264         rpc_restart_call_prepare(task);
 265 }
 266
 267 static void nfs_readpage_result(struct rpc_task *task,
 268                                 struct nfs_pgio_header *hdr)
 269 {
 270         if (hdr->res.eof) {
 271                 loff_t pos = hdr->args.offset + hdr->res.count;
 272                 unsigned int new = pos - hdr->io_start;
 273
 274                 if (hdr->good_bytes > new) {
 275                         hdr->good_bytes = new;
 276                         set_bit(NFS_IOHDR_EOF, &hdr->flags);
 277                         clear_bit(NFS_IOHDR_ERROR, &hdr->flags);
 278                 }
 279         } else if (hdr->res.count < hdr->args.count)
 280                 nfs_readpage_retry(task, hdr);
 281 }
 282
 283 static int readpage_async_filler(struct nfs_readdesc *desc, struct folio *folio)
 284 {
 285         struct inode *inode = folio_file_mapping(folio)->host;
 286         struct nfs_server *server = NFS_SERVER(inode);
 287         size_t fsize = folio_size(folio);
 288         unsigned int rsize = server->rsize;
 289         struct nfs_page *new;
 290         unsigned int len, aligned_len;
 291         int error;
 292
 293         len = nfs_folio_length(folio);
 294         if (len == 0)
 295                 return nfs_return_empty_folio(folio);
 296
 297         aligned_len = min_t(unsigned int, ALIGN(len, rsize), fsize);
 298
 299         if (!IS_SYNC(inode)) {
 300                 error = nfs_fscache_read_page(inode, &folio->page);
 301                 if (error == 0)
 302                         goto out_unlock;
 303         }
 304
 305         new = nfs_page_create_from_folio(desc->ctx, folio, 0, aligned_len);
 306         if (IS_ERR(new))
 307                 goto out_error;
 308
 309         if (len < fsize)
 310                 folio_zero_segment(folio, len, fsize);
 311         if (!nfs_pageio_add_request(&desc->pgio, new)) {
 312                 nfs_list_remove_request(new);
 313                 error = desc->pgio.pg_error;
 314                 nfs_readpage_release(new, error);
 315                 goto out;
 316         }
 317         return 0;
 318 out_error:
 319         error = PTR_ERR(new);
 320 out_unlock:
 321         folio_unlock(folio);
 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 nfs_readdesc desc;
 335         struct inode *inode = file_inode(file);
 336         int ret;
 337
 338         trace_nfs_aop_readpage(inode, folio);
 339         nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
 340
 341         /*
 342          * Try to flush any pending writes to the file..
 343          *
 344          * NOTE! Because we own the folio lock, there cannot
 345          * be any new pending writes generated at this point
 346          * for this folio (other folios can be written to).
 347          */
 348         ret = nfs_wb_folio(inode, folio);
 349         if (ret)
 350                 goto out_unlock;
 351         if (folio_test_uptodate(folio))
 352                 goto out_unlock;
 353
 354         ret = -ESTALE;
 355         if (NFS_STALE(inode))
 356                 goto out_unlock;
 357
 358         desc.ctx = get_nfs_open_context(nfs_file_open_context(file));
 359
 360         xchg(&desc.ctx->error, 0);
 361         nfs_pageio_init_read(&desc.pgio, inode, false,
 362                              &nfs_async_read_completion_ops);
 363
 364         ret = readpage_async_filler(&desc, folio);
 365         if (ret)
 366                 goto out;
 367
 368         nfs_pageio_complete_read(&desc.pgio);
 369         ret = desc.pgio.pg_error < 0 ? desc.pgio.pg_error : 0;
 370         if (!ret) {
 371                 ret = folio_wait_locked_killable(folio);
 372                 if (!folio_test_uptodate(folio) && !ret)
 373                         ret = xchg(&desc.ctx->error, 0);
 374         }
 375 out:
 376         put_nfs_open_context(desc.ctx);
 377         trace_nfs_aop_readpage_done(inode, folio, ret);
 378         return ret;
 379 out_unlock:
 380         folio_unlock(folio);
 381         trace_nfs_aop_readpage_done(inode, folio, ret);
 382         return ret;
 383 }
 384
 385 void nfs_readahead(struct readahead_control *ractl)
 386 {
 387         unsigned int nr_pages = readahead_count(ractl);
 388         struct file *file = ractl->file;
 389         struct nfs_readdesc desc;
 390         struct inode *inode = ractl->mapping->host;
 391         struct folio *folio;
 392         int ret;
 393
 394         trace_nfs_aop_readahead(inode, readahead_pos(ractl), nr_pages);
 395         nfs_inc_stats(inode, NFSIOS_VFSREADPAGES);
 396
 397         ret = -ESTALE;
 398         if (NFS_STALE(inode))
 399                 goto out;
 400
 401         if (file == NULL) {
 402                 ret = -EBADF;
 403                 desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
 404                 if (desc.ctx == NULL)
 405                         goto out;
 406         } else
 407                 desc.ctx = get_nfs_open_context(nfs_file_open_context(file));
 408
 409         nfs_pageio_init_read(&desc.pgio, inode, false,
 410                              &nfs_async_read_completion_ops);
 411
 412         while ((folio = readahead_folio(ractl)) != NULL) {
 413                 ret = readpage_async_filler(&desc, folio);
 414                 if (ret)
 415                         break;
 416         }
 417
 418         nfs_pageio_complete_read(&desc.pgio);
 419
 420         put_nfs_open_context(desc.ctx);
 421 out:
 422         trace_nfs_aop_readahead_done(inode, nr_pages, ret);
 423 }
 424
 425 int __init nfs_init_readpagecache(void)
 426 {
 427         nfs_rdata_cachep = kmem_cache_create("nfs_read_data",
 428                                              sizeof(struct nfs_pgio_header),
 429                                              0, SLAB_HWCACHE_ALIGN,
 430                                              NULL);
 431         if (nfs_rdata_cachep == NULL)
 432                 return -ENOMEM;
 433
 434         return 0;
 435 }
 436
 437 void nfs_destroy_readpagecache(void)
 438 {
 439         kmem_cache_destroy(nfs_rdata_cachep);
 440 }
 441
 442 static const struct nfs_rw_ops nfs_rw_read_ops = {
 443         .rw_alloc_header        = nfs_readhdr_alloc,
 444         .rw_free_header         = nfs_readhdr_free,
 445         .rw_done                = nfs_readpage_done,
 446         .rw_result              = nfs_readpage_result,
 447         .rw_initiate            = nfs_initiate_read,
 448 };