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/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
  53 int nfs_return_empty_page(struct page *page)
  54 {
  55         zero_user(page, 0, PAGE_SIZE);
  56         SetPageUptodate(page);
  57         unlock_page(page);
  58         return 0;
  59 }
  60
  61 void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
  62                               struct inode *inode, bool force_mds,
  63                               const struct nfs_pgio_completion_ops *compl_ops)
  64 {
  65         struct nfs_server *server = NFS_SERVER(inode);
  66         const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
  67
  68 #ifdef CONFIG_NFS_V4_1
  69         if (server->pnfs_curr_ld && !force_mds)
  70                 pg_ops = server->pnfs_curr_ld->pg_read_ops;
  71 #endif
  72         nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_read_ops,
  73                         server->rsize, 0);
  74 }
  75 EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
  76
  77 static void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio,
  78                                      struct inode *inode)
  79 {
  80         struct nfs_pgio_mirror *pgm;
  81         unsigned long npages;
  82
  83         nfs_pageio_complete(pgio);
  84
  85         /* It doesn't make sense to do mirrored reads! */
  86         WARN_ON_ONCE(pgio->pg_mirror_count != 1);
  87
  88         pgm = &pgio->pg_mirrors[0];
  89         NFS_I(inode)->read_io += pgm->pg_bytes_written;
  90         npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >> PAGE_SHIFT;
  91         nfs_add_stats(inode, NFSIOS_READPAGES, npages);
  92 }
  93
  94
  95 void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio)
  96 {
  97         struct nfs_pgio_mirror *mirror;
  98
  99         if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
 100                 pgio->pg_ops->pg_cleanup(pgio);
 101
 102         pgio->pg_ops = &nfs_pgio_rw_ops;
 103
 104         /* read path should never have more than one mirror */
 105         WARN_ON_ONCE(pgio->pg_mirror_count != 1);
 106
 107         mirror = &pgio->pg_mirrors[0];
 108         mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize;
 109 }
 110 EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
 111
 112 static void nfs_readpage_release(struct nfs_page *req, int error)
 113 {
 114         struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
 115         struct page *page = req->wb_page;
 116
 117         dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id,
 118                 (unsigned long long)NFS_FILEID(inode), req->wb_bytes,
 119                 (long long)req_offset(req));
 120
 121         if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT)
 122                 SetPageError(page);
 123         if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) {
 124                 struct address_space *mapping = page_file_mapping(page);
 125
 126                 if (PageUptodate(page))
 127                         nfs_readpage_to_fscache(inode, page, 0);
 128                 else if (!PageError(page) && !PagePrivate(page))
 129                         generic_error_remove_page(mapping, page);
 130                 unlock_page(page);
 131         }
 132         nfs_release_request(req);
 133 }
 134
 135 struct nfs_readdesc {
 136         struct nfs_pageio_descriptor pgio;
 137         struct nfs_open_context *ctx;
 138 };
 139
 140 static void nfs_page_group_set_uptodate(struct nfs_page *req)
 141 {
 142         if (nfs_page_group_sync_on_bit(req, PG_UPTODATE))
 143                 SetPageUptodate(req->wb_page);
 144 }
 145
 146 static void nfs_read_completion(struct nfs_pgio_header *hdr)
 147 {
 148         unsigned long bytes = 0;
 149         int error;
 150
 151         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 152                 goto out;
 153         while (!list_empty(&hdr->pages)) {
 154                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 155                 struct page *page = req->wb_page;
 156                 unsigned long start = req->wb_pgbase;
 157                 unsigned long end = req->wb_pgbase + req->wb_bytes;
 158
 159                 if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
 160                         /* note: regions of the page not covered by a
 161                          * request are zeroed in readpage_async_filler */
 162                         if (bytes > hdr->good_bytes) {
 163                                 /* nothing in this request was good, so zero
 164                                  * the full extent of the request */
 165                                 zero_user_segment(page, start, end);
 166
 167                         } else if (hdr->good_bytes - bytes < req->wb_bytes) {
 168                                 /* part of this request has good bytes, but
 169                                  * not all. zero the bad bytes */
 170                                 start += hdr->good_bytes - bytes;
 171                                 WARN_ON(start < req->wb_pgbase);
 172                                 zero_user_segment(page, start, end);
 173                         }
 174                 }
 175                 error = 0;
 176                 bytes += req->wb_bytes;
 177                 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
 178                         if (bytes <= hdr->good_bytes)
 179                                 nfs_page_group_set_uptodate(req);
 180                         else {
 181                                 error = hdr->error;
 182                                 xchg(&nfs_req_openctx(req)->error, error);
 183                         }
 184                 } else
 185                         nfs_page_group_set_uptodate(req);
 186                 nfs_list_remove_request(req);
 187                 nfs_readpage_release(req, error);
 188         }
 189 out:
 190         hdr->release(hdr);
 191 }
 192
 193 static void nfs_initiate_read(struct nfs_pgio_header *hdr,
 194                               struct rpc_message *msg,
 195                               const struct nfs_rpc_ops *rpc_ops,
 196                               struct rpc_task_setup *task_setup_data, int how)
 197 {
 198         struct inode *inode = hdr->inode;
 199         int swap_flags = IS_SWAPFILE(inode) ? NFS_RPC_SWAPFLAGS : 0;
 200
 201         task_setup_data->flags |= swap_flags;
 202         rpc_ops->read_setup(hdr, msg);
 203         trace_nfs_initiate_read(hdr);
 204 }
 205
 206 static void
 207 nfs_async_read_error(struct list_head *head, int error)
 208 {
 209         struct nfs_page *req;
 210
 211         while (!list_empty(head)) {
 212                 req = nfs_list_entry(head->next);
 213                 nfs_list_remove_request(req);
 214                 nfs_readpage_release(req, error);
 215         }
 216 }
 217
 218 static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
 219         .error_cleanup = nfs_async_read_error,
 220         .completion = nfs_read_completion,
 221 };
 222
 223 /*
 224  * This is the callback from RPC telling us whether a reply was
 225  * received or some error occurred (timeout or socket shutdown).
 226  */
 227 static int nfs_readpage_done(struct rpc_task *task,
 228                              struct nfs_pgio_header *hdr,
 229                              struct inode *inode)
 230 {
 231         int status = NFS_PROTO(inode)->read_done(task, hdr);
 232         if (status != 0)
 233                 return status;
 234
 235         nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
 236         trace_nfs_readpage_done(task, hdr);
 237
 238         if (task->tk_status == -ESTALE) {
 239                 nfs_set_inode_stale(inode);
 240                 nfs_mark_for_revalidate(inode);
 241         }
 242         return 0;
 243 }
 244
 245 static void nfs_readpage_retry(struct rpc_task *task,
 246                                struct nfs_pgio_header *hdr)
 247 {
 248         struct nfs_pgio_args *argp = &hdr->args;
 249         struct nfs_pgio_res  *resp = &hdr->res;
 250
 251         /* This is a short read! */
 252         nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD);
 253         trace_nfs_readpage_short(task, hdr);
 254
 255         /* Has the server at least made some progress? */
 256         if (resp->count == 0) {
 257                 nfs_set_pgio_error(hdr, -EIO, argp->offset);
 258                 return;
 259         }
 260
 261         /* For non rpc-based layout drivers, retry-through-MDS */
 262         if (!task->tk_ops) {
 263                 hdr->pnfs_error = -EAGAIN;
 264                 return;
 265         }
 266
 267         /* Yes, so retry the read at the end of the hdr */
 268         hdr->mds_offset += resp->count;
 269         argp->offset += resp->count;
 270         argp->pgbase += resp->count;
 271         argp->count -= resp->count;
 272         resp->count = 0;
 273         resp->eof = 0;
 274         rpc_restart_call_prepare(task);
 275 }
 276
 277 static void nfs_readpage_result(struct rpc_task *task,
 278                                 struct nfs_pgio_header *hdr)
 279 {
 280         if (hdr->res.eof) {
 281                 loff_t pos = hdr->args.offset + hdr->res.count;
 282                 unsigned int new = pos - hdr->io_start;
 283
 284                 if (hdr->good_bytes > new) {
 285                         hdr->good_bytes = new;
 286                         set_bit(NFS_IOHDR_EOF, &hdr->flags);
 287                         clear_bit(NFS_IOHDR_ERROR, &hdr->flags);
 288                 }
 289         } else if (hdr->res.count < hdr->args.count)
 290                 nfs_readpage_retry(task, hdr);
 291 }
 292
 293 static int
 294 readpage_async_filler(void *data, struct page *page)
 295 {
 296         struct nfs_readdesc *desc = data;
 297         struct nfs_page *new;
 298         unsigned int len;
 299         int error;
 300
 301         len = nfs_page_length(page);
 302         if (len == 0)
 303                 return nfs_return_empty_page(page);
 304
 305         new = nfs_create_request(desc->ctx, page, 0, len);
 306         if (IS_ERR(new))
 307                 goto out_error;
 308
 309         if (len < PAGE_SIZE)
 310                 zero_user_segment(page, len, PAGE_SIZE);
 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         unlock_page(page);
 321 out:
 322         return error;
 323 }
 324
 325 /*
 326  * Read a page over NFS.
 327  * We read the page synchronously in the following case:
 328  *  -   The error flag is set for this page. This happens only when a
 329  *      previous async read operation failed.
 330  */
 331 int nfs_readpage(struct file *file, struct page *page)
 332 {
 333         struct nfs_readdesc desc;
 334         struct inode *inode = page_file_mapping(page)->host;
 335         int ret;
 336
 337         dprintk("NFS: nfs_readpage (%p %ld@%lu)\n",
 338                 page, PAGE_SIZE, page_index(page));
 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 page lock, there cannot
 345          * be any new pending writes generated at this point
 346          * for this page (other pages can be written to).
 347          */
 348         ret = nfs_wb_page(inode, page);
 349         if (ret)
 350                 goto out_unlock;
 351         if (PageUptodate(page))
 352                 goto out_unlock;
 353
 354         ret = -ESTALE;
 355         if (NFS_STALE(inode))
 356                 goto out_unlock;
 357
 358         if (file == NULL) {
 359                 ret = -EBADF;
 360                 desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
 361                 if (desc.ctx == NULL)
 362                         goto out_unlock;
 363         } else
 364                 desc.ctx = get_nfs_open_context(nfs_file_open_context(file));
 365
 366         if (!IS_SYNC(inode)) {
 367                 ret = nfs_readpage_from_fscache(desc.ctx, inode, page);
 368                 if (ret == 0)
 369                         goto out;
 370         }
 371
 372         xchg(&desc.ctx->error, 0);
 373         nfs_pageio_init_read(&desc.pgio, inode, false,
 374                              &nfs_async_read_completion_ops);
 375
 376         ret = readpage_async_filler(&desc, page);
 377
 378         if (!ret)
 379                 nfs_pageio_complete_read(&desc.pgio, inode);
 380
 381         ret = desc.pgio.pg_error < 0 ? desc.pgio.pg_error : 0;
 382         if (!ret) {
 383                 ret = wait_on_page_locked_killable(page);
 384                 if (!PageUptodate(page) && !ret)
 385                         ret = xchg(&desc.ctx->error, 0);
 386         }
 387 out:
 388         put_nfs_open_context(desc.ctx);
 389         return ret;
 390 out_unlock:
 391         unlock_page(page);
 392         return ret;
 393 }
 394
 395 int nfs_readpages(struct file *file, struct address_space *mapping,
 396                 struct list_head *pages, unsigned nr_pages)
 397 {
 398         struct nfs_readdesc desc;
 399         struct inode *inode = mapping->host;
 400         int ret;
 401
 402         dprintk("NFS: nfs_readpages (%s/%Lu %d)\n",
 403                         inode->i_sb->s_id,
 404                         (unsigned long long)NFS_FILEID(inode),
 405                         nr_pages);
 406         nfs_inc_stats(inode, NFSIOS_VFSREADPAGES);
 407
 408         ret = -ESTALE;
 409         if (NFS_STALE(inode))
 410                 goto out;
 411
 412         if (file == NULL) {
 413                 ret = -EBADF;
 414                 desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
 415                 if (desc.ctx == NULL)
 416                         goto out;
 417         } else
 418                 desc.ctx = get_nfs_open_context(nfs_file_open_context(file));
 419
 420         /* attempt to read as many of the pages as possible from the cache
 421          * - this returns -ENOBUFS immediately if the cookie is negative
 422          */
 423         ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping,
 424                                          pages, &nr_pages);
 425         if (ret == 0)
 426                 goto read_complete; /* all pages were read */
 427
 428         nfs_pageio_init_read(&desc.pgio, inode, false,
 429                              &nfs_async_read_completion_ops);
 430
 431         ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
 432
 433         nfs_pageio_complete_read(&desc.pgio, inode);
 434
 435 read_complete:
 436         put_nfs_open_context(desc.ctx);
 437 out:
 438         return ret;
 439 }
 440
 441 int __init nfs_init_readpagecache(void)
 442 {
 443         nfs_rdata_cachep = kmem_cache_create("nfs_read_data",
 444                                              sizeof(struct nfs_pgio_header),
 445                                              0, SLAB_HWCACHE_ALIGN,
 446                                              NULL);
 447         if (nfs_rdata_cachep == NULL)
 448                 return -ENOMEM;
 449
 450         return 0;
 451 }
 452
 453 void nfs_destroy_readpagecache(void)
 454 {
 455         kmem_cache_destroy(nfs_rdata_cachep);
 456 }
 457
 458 static const struct nfs_rw_ops nfs_rw_read_ops = {
 459         .rw_alloc_header        = nfs_readhdr_alloc,
 460         .rw_free_header         = nfs_readhdr_free,
 461         .rw_done                = nfs_readpage_done,
 462         .rw_result              = nfs_readpage_result,
 463         .rw_initiate            = nfs_initiate_read,
 464 };