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 {
  79         struct nfs_pgio_mirror *pgm;
  80         unsigned long npages;
  81
  82         nfs_pageio_complete(pgio);
  83
  84         /* It doesn't make sense to do mirrored reads! */
  85         WARN_ON_ONCE(pgio->pg_mirror_count != 1);
  86
  87         pgm = &pgio->pg_mirrors[0];
  88         NFS_I(pgio->pg_inode)->read_io += pgm->pg_bytes_written;
  89         npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >> PAGE_SHIFT;
  90         nfs_add_stats(pgio->pg_inode, NFSIOS_READPAGES, npages);
  91 }
  92
  93
  94 void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio)
  95 {
  96         struct nfs_pgio_mirror *mirror;
  97
  98         if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
  99                 pgio->pg_ops->pg_cleanup(pgio);
 100
 101         pgio->pg_ops = &nfs_pgio_rw_ops;
 102
 103         /* read path should never have more than one mirror */
 104         WARN_ON_ONCE(pgio->pg_mirror_count != 1);
 105
 106         mirror = &pgio->pg_mirrors[0];
 107         mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize;
 108 }
 109 EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
 110
 111 static void nfs_readpage_release(struct nfs_page *req, int error)
 112 {
 113         struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
 114         struct page *page = req->wb_page;
 115
 116         dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id,
 117                 (unsigned long long)NFS_FILEID(inode), req->wb_bytes,
 118                 (long long)req_offset(req));
 119
 120         if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT)
 121                 SetPageError(page);
 122         if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) {
 123                 struct address_space *mapping = page_file_mapping(page);
 124
 125                 if (PageUptodate(page))
 126                         nfs_readpage_to_fscache(inode, page, 0);
 127                 else if (!PageError(page) && !PagePrivate(page))
 128                         generic_error_remove_page(mapping, page);
 129                 unlock_page(page);
 130         }
 131         nfs_release_request(req);
 132 }
 133
 134 struct nfs_readdesc {
 135         struct nfs_pageio_descriptor pgio;
 136         struct nfs_open_context *ctx;
 137 };
 138
 139 static void nfs_page_group_set_uptodate(struct nfs_page *req)
 140 {
 141         if (nfs_page_group_sync_on_bit(req, PG_UPTODATE))
 142                 SetPageUptodate(req->wb_page);
 143 }
 144
 145 static void nfs_read_completion(struct nfs_pgio_header *hdr)
 146 {
 147         unsigned long bytes = 0;
 148         int error;
 149
 150         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 151                 goto out;
 152         while (!list_empty(&hdr->pages)) {
 153                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 154                 struct page *page = req->wb_page;
 155                 unsigned long start = req->wb_pgbase;
 156                 unsigned long end = req->wb_pgbase + req->wb_bytes;
 157
 158                 if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
 159                         /* note: regions of the page not covered by a
 160                          * request are zeroed in readpage_async_filler */
 161                         if (bytes > hdr->good_bytes) {
 162                                 /* nothing in this request was good, so zero
 163                                  * the full extent of the request */
 164                                 zero_user_segment(page, start, end);
 165
 166                         } else if (hdr->good_bytes - bytes < req->wb_bytes) {
 167                                 /* part of this request has good bytes, but
 168                                  * not all. zero the bad bytes */
 169                                 start += hdr->good_bytes - bytes;
 170                                 WARN_ON(start < req->wb_pgbase);
 171                                 zero_user_segment(page, start, end);
 172                         }
 173                 }
 174                 error = 0;
 175                 bytes += req->wb_bytes;
 176                 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
 177                         if (bytes <= hdr->good_bytes)
 178                                 nfs_page_group_set_uptodate(req);
 179                         else {
 180                                 error = hdr->error;
 181                                 xchg(&nfs_req_openctx(req)->error, error);
 182                         }
 183                 } else
 184                         nfs_page_group_set_uptodate(req);
 185                 nfs_list_remove_request(req);
 186                 nfs_readpage_release(req, error);
 187         }
 188 out:
 189         hdr->release(hdr);
 190 }
 191
 192 static void nfs_initiate_read(struct nfs_pgio_header *hdr,
 193                               struct rpc_message *msg,
 194                               const struct nfs_rpc_ops *rpc_ops,
 195                               struct rpc_task_setup *task_setup_data, int how)
 196 {
 197         struct inode *inode = hdr->inode;
 198         int swap_flags = IS_SWAPFILE(inode) ? NFS_RPC_SWAPFLAGS : 0;
 199
 200         task_setup_data->flags |= swap_flags;
 201         rpc_ops->read_setup(hdr, msg);
 202         trace_nfs_initiate_read(hdr);
 203 }
 204
 205 static void
 206 nfs_async_read_error(struct list_head *head, int error)
 207 {
 208         struct nfs_page *req;
 209
 210         while (!list_empty(head)) {
 211                 req = nfs_list_entry(head->next);
 212                 nfs_list_remove_request(req);
 213                 nfs_readpage_release(req, error);
 214         }
 215 }
 216
 217 static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
 218         .error_cleanup = nfs_async_read_error,
 219         .completion = nfs_read_completion,
 220 };
 221
 222 /*
 223  * This is the callback from RPC telling us whether a reply was
 224  * received or some error occurred (timeout or socket shutdown).
 225  */
 226 static int nfs_readpage_done(struct rpc_task *task,
 227                              struct nfs_pgio_header *hdr,
 228                              struct inode *inode)
 229 {
 230         int status = NFS_PROTO(inode)->read_done(task, hdr);
 231         if (status != 0)
 232                 return status;
 233
 234         nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
 235         trace_nfs_readpage_done(task, hdr);
 236
 237         if (task->tk_status == -ESTALE) {
 238                 nfs_set_inode_stale(inode);
 239                 nfs_mark_for_revalidate(inode);
 240         }
 241         return 0;
 242 }
 243
 244 static void nfs_readpage_retry(struct rpc_task *task,
 245                                struct nfs_pgio_header *hdr)
 246 {
 247         struct nfs_pgio_args *argp = &hdr->args;
 248         struct nfs_pgio_res  *resp = &hdr->res;
 249
 250         /* This is a short read! */
 251         nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD);
 252         trace_nfs_readpage_short(task, hdr);
 253
 254         /* Has the server at least made some progress? */
 255         if (resp->count == 0) {
 256                 nfs_set_pgio_error(hdr, -EIO, argp->offset);
 257                 return;
 258         }
 259
 260         /* For non rpc-based layout drivers, retry-through-MDS */
 261         if (!task->tk_ops) {
 262                 hdr->pnfs_error = -EAGAIN;
 263                 return;
 264         }
 265
 266         /* Yes, so retry the read at the end of the hdr */
 267         hdr->mds_offset += resp->count;
 268         argp->offset += resp->count;
 269         argp->pgbase += resp->count;
 270         argp->count -= resp->count;
 271         resp->count = 0;
 272         resp->eof = 0;
 273         rpc_restart_call_prepare(task);
 274 }
 275
 276 static void nfs_readpage_result(struct rpc_task *task,
 277                                 struct nfs_pgio_header *hdr)
 278 {
 279         if (hdr->res.eof) {
 280                 loff_t pos = hdr->args.offset + hdr->res.count;
 281                 unsigned int new = pos - hdr->io_start;
 282
 283                 if (hdr->good_bytes > new) {
 284                         hdr->good_bytes = new;
 285                         set_bit(NFS_IOHDR_EOF, &hdr->flags);
 286                         clear_bit(NFS_IOHDR_ERROR, &hdr->flags);
 287                 }
 288         } else if (hdr->res.count < hdr->args.count)
 289                 nfs_readpage_retry(task, hdr);
 290 }
 291
 292 static int
 293 readpage_async_filler(void *data, struct page *page)
 294 {
 295         struct nfs_readdesc *desc = data;
 296         struct nfs_page *new;
 297         unsigned int len;
 298         int error;
 299
 300         len = nfs_page_length(page);
 301         if (len == 0)
 302                 return nfs_return_empty_page(page);
 303
 304         new = nfs_create_request(desc->ctx, page, 0, len);
 305         if (IS_ERR(new))
 306                 goto out_error;
 307
 308         if (len < PAGE_SIZE)
 309                 zero_user_segment(page, len, PAGE_SIZE);
 310         if (!nfs_pageio_add_request(&desc->pgio, new)) {
 311                 nfs_list_remove_request(new);
 312                 error = desc->pgio.pg_error;
 313                 nfs_readpage_release(new, error);
 314                 goto out;
 315         }
 316         return 0;
 317 out_error:
 318         error = PTR_ERR(new);
 319         unlock_page(page);
 320 out:
 321         return error;
 322 }
 323
 324 /*
 325  * Read a page over NFS.
 326  * We read the page synchronously in the following case:
 327  *  -   The error flag is set for this page. This happens only when a
 328  *      previous async read operation failed.
 329  */
 330 int nfs_readpage(struct file *file, struct page *page)
 331 {
 332         struct nfs_readdesc desc;
 333         struct inode *inode = page_file_mapping(page)->host;
 334         int ret;
 335
 336         dprintk("NFS: nfs_readpage (%p %ld@%lu)\n",
 337                 page, PAGE_SIZE, page_index(page));
 338         nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
 339
 340         /*
 341          * Try to flush any pending writes to the file..
 342          *
 343          * NOTE! Because we own the page lock, there cannot
 344          * be any new pending writes generated at this point
 345          * for this page (other pages can be written to).
 346          */
 347         ret = nfs_wb_page(inode, page);
 348         if (ret)
 349                 goto out_unlock;
 350         if (PageUptodate(page))
 351                 goto out_unlock;
 352
 353         ret = -ESTALE;
 354         if (NFS_STALE(inode))
 355                 goto out_unlock;
 356
 357         if (file == NULL) {
 358                 ret = -EBADF;
 359                 desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
 360                 if (desc.ctx == NULL)
 361                         goto out_unlock;
 362         } else
 363                 desc.ctx = get_nfs_open_context(nfs_file_open_context(file));
 364
 365         xchg(&desc.ctx->error, 0);
 366         if (!IS_SYNC(inode)) {
 367                 ret = nfs_readpage_from_fscache(desc.ctx, inode, page);
 368                 if (ret == 0)
 369                         goto out_wait;
 370         }
 371
 372         nfs_pageio_init_read(&desc.pgio, inode, false,
 373                              &nfs_async_read_completion_ops);
 374
 375         ret = readpage_async_filler(&desc, page);
 376         if (ret)
 377                 goto out;
 378
 379         nfs_pageio_complete_read(&desc.pgio);
 380         ret = desc.pgio.pg_error < 0 ? desc.pgio.pg_error : 0;
 381 out_wait:
 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);
 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 };