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 void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio)
  78 {
  79         struct nfs_pgio_mirror *mirror;
  80
  81         if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
  82                 pgio->pg_ops->pg_cleanup(pgio);
  83
  84         pgio->pg_ops = &nfs_pgio_rw_ops;
  85
  86         /* read path should never have more than one mirror */
  87         WARN_ON_ONCE(pgio->pg_mirror_count != 1);
  88
  89         mirror = &pgio->pg_mirrors[0];
  90         mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize;
  91 }
  92 EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
  93
  94 static void nfs_readpage_release(struct nfs_page *req, int error)
  95 {
  96         struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
  97         struct page *page = req->wb_page;
  98
  99         dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id,
 100                 (unsigned long long)NFS_FILEID(inode), req->wb_bytes,
 101                 (long long)req_offset(req));
 102
 103         if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT)
 104                 SetPageError(page);
 105         if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) {
 106                 struct address_space *mapping = page_file_mapping(page);
 107
 108                 if (PageUptodate(page))
 109                         nfs_readpage_to_fscache(inode, page, 0);
 110                 else if (!PageError(page) && !PagePrivate(page))
 111                         generic_error_remove_page(mapping, page);
 112                 unlock_page(page);
 113         }
 114         nfs_release_request(req);
 115 }
 116
 117 int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
 118                        struct page *page)
 119 {
 120         struct nfs_page *new;
 121         unsigned int len;
 122         struct nfs_pageio_descriptor pgio;
 123         struct nfs_pgio_mirror *pgm;
 124
 125         len = nfs_page_length(page);
 126         if (len == 0)
 127                 return nfs_return_empty_page(page);
 128         new = nfs_create_request(ctx, page, 0, len);
 129         if (IS_ERR(new)) {
 130                 unlock_page(page);
 131                 return PTR_ERR(new);
 132         }
 133         if (len < PAGE_SIZE)
 134                 zero_user_segment(page, len, PAGE_SIZE);
 135
 136         nfs_pageio_init_read(&pgio, inode, false,
 137                              &nfs_async_read_completion_ops);
 138         if (!nfs_pageio_add_request(&pgio, new)) {
 139                 nfs_list_remove_request(new);
 140                 nfs_readpage_release(new, pgio.pg_error);
 141         }
 142         nfs_pageio_complete(&pgio);
 143
 144         /* It doesn't make sense to do mirrored reads! */
 145         WARN_ON_ONCE(pgio.pg_mirror_count != 1);
 146
 147         pgm = &pgio.pg_mirrors[0];
 148         NFS_I(inode)->read_io += pgm->pg_bytes_written;
 149
 150         return pgio.pg_error < 0 ? pgio.pg_error : 0;
 151 }
 152
 153 static void nfs_page_group_set_uptodate(struct nfs_page *req)
 154 {
 155         if (nfs_page_group_sync_on_bit(req, PG_UPTODATE))
 156                 SetPageUptodate(req->wb_page);
 157 }
 158
 159 static void nfs_read_completion(struct nfs_pgio_header *hdr)
 160 {
 161         unsigned long bytes = 0;
 162         int error;
 163
 164         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 165                 goto out;
 166         while (!list_empty(&hdr->pages)) {
 167                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 168                 struct page *page = req->wb_page;
 169                 unsigned long start = req->wb_pgbase;
 170                 unsigned long end = req->wb_pgbase + req->wb_bytes;
 171
 172                 if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
 173                         /* note: regions of the page not covered by a
 174                          * request are zeroed in nfs_readpage_async /
 175                          * readpage_async_filler */
 176                         if (bytes > hdr->good_bytes) {
 177                                 /* nothing in this request was good, so zero
 178                                  * the full extent of the request */
 179                                 zero_user_segment(page, start, end);
 180
 181                         } else if (hdr->good_bytes - bytes < req->wb_bytes) {
 182                                 /* part of this request has good bytes, but
 183                                  * not all. zero the bad bytes */
 184                                 start += hdr->good_bytes - bytes;
 185                                 WARN_ON(start < req->wb_pgbase);
 186                                 zero_user_segment(page, start, end);
 187                         }
 188                 }
 189                 error = 0;
 190                 bytes += req->wb_bytes;
 191                 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
 192                         if (bytes <= hdr->good_bytes)
 193                                 nfs_page_group_set_uptodate(req);
 194                         else {
 195                                 error = hdr->error;
 196                                 xchg(&nfs_req_openctx(req)->error, error);
 197                         }
 198                 } else
 199                         nfs_page_group_set_uptodate(req);
 200                 nfs_list_remove_request(req);
 201                 nfs_readpage_release(req, error);
 202         }
 203 out:
 204         hdr->release(hdr);
 205 }
 206
 207 static void nfs_initiate_read(struct nfs_pgio_header *hdr,
 208                               struct rpc_message *msg,
 209                               const struct nfs_rpc_ops *rpc_ops,
 210                               struct rpc_task_setup *task_setup_data, int how)
 211 {
 212         struct inode *inode = hdr->inode;
 213         int swap_flags = IS_SWAPFILE(inode) ? NFS_RPC_SWAPFLAGS : 0;
 214
 215         task_setup_data->flags |= swap_flags;
 216         rpc_ops->read_setup(hdr, msg);
 217         trace_nfs_initiate_read(hdr);
 218 }
 219
 220 static void
 221 nfs_async_read_error(struct list_head *head, int error)
 222 {
 223         struct nfs_page *req;
 224
 225         while (!list_empty(head)) {
 226                 req = nfs_list_entry(head->next);
 227                 nfs_list_remove_request(req);
 228                 nfs_readpage_release(req, error);
 229         }
 230 }
 231
 232 static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
 233         .error_cleanup = nfs_async_read_error,
 234         .completion = nfs_read_completion,
 235 };
 236
 237 /*
 238  * This is the callback from RPC telling us whether a reply was
 239  * received or some error occurred (timeout or socket shutdown).
 240  */
 241 static int nfs_readpage_done(struct rpc_task *task,
 242                              struct nfs_pgio_header *hdr,
 243                              struct inode *inode)
 244 {
 245         int status = NFS_PROTO(inode)->read_done(task, hdr);
 246         if (status != 0)
 247                 return status;
 248
 249         nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
 250         trace_nfs_readpage_done(task, hdr);
 251
 252         if (task->tk_status == -ESTALE) {
 253                 nfs_set_inode_stale(inode);
 254                 nfs_mark_for_revalidate(inode);
 255         }
 256         return 0;
 257 }
 258
 259 static void nfs_readpage_retry(struct rpc_task *task,
 260                                struct nfs_pgio_header *hdr)
 261 {
 262         struct nfs_pgio_args *argp = &hdr->args;
 263         struct nfs_pgio_res  *resp = &hdr->res;
 264
 265         /* This is a short read! */
 266         nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD);
 267         /* Has the server at least made some progress? */
 268         if (resp->count == 0) {
 269                 nfs_set_pgio_error(hdr, -EIO, argp->offset);
 270                 return;
 271         }
 272
 273         /* For non rpc-based layout drivers, retry-through-MDS */
 274         if (!task->tk_ops) {
 275                 hdr->pnfs_error = -EAGAIN;
 276                 return;
 277         }
 278
 279         /* Yes, so retry the read at the end of the hdr */
 280         hdr->mds_offset += resp->count;
 281         argp->offset += resp->count;
 282         argp->pgbase += resp->count;
 283         argp->count -= resp->count;
 284         resp->count = 0;
 285         resp->eof = 0;
 286         rpc_restart_call_prepare(task);
 287 }
 288
 289 static void nfs_readpage_result(struct rpc_task *task,
 290                                 struct nfs_pgio_header *hdr)
 291 {
 292         if (hdr->res.eof) {
 293                 loff_t pos = hdr->args.offset + hdr->res.count;
 294                 unsigned int new = pos - hdr->io_start;
 295
 296                 if (hdr->good_bytes > new) {
 297                         hdr->good_bytes = new;
 298                         set_bit(NFS_IOHDR_EOF, &hdr->flags);
 299                         clear_bit(NFS_IOHDR_ERROR, &hdr->flags);
 300                 }
 301         } else if (hdr->res.count < hdr->args.count)
 302                 nfs_readpage_retry(task, hdr);
 303 }
 304
 305 /*
 306  * Read a page over NFS.
 307  * We read the page synchronously in the following case:
 308  *  -   The error flag is set for this page. This happens only when a
 309  *      previous async read operation failed.
 310  */
 311 int nfs_readpage(struct file *file, struct page *page)
 312 {
 313         struct nfs_open_context *ctx;
 314         struct inode *inode = page_file_mapping(page)->host;
 315         int             error;
 316
 317         dprintk("NFS: nfs_readpage (%p %ld@%lu)\n",
 318                 page, PAGE_SIZE, page_index(page));
 319         nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
 320         nfs_add_stats(inode, NFSIOS_READPAGES, 1);
 321
 322         /*
 323          * Try to flush any pending writes to the file..
 324          *
 325          * NOTE! Because we own the page lock, there cannot
 326          * be any new pending writes generated at this point
 327          * for this page (other pages can be written to).
 328          */
 329         error = nfs_wb_page(inode, page);
 330         if (error)
 331                 goto out_unlock;
 332         if (PageUptodate(page))
 333                 goto out_unlock;
 334
 335         error = -ESTALE;
 336         if (NFS_STALE(inode))
 337                 goto out_unlock;
 338
 339         if (file == NULL) {
 340                 error = -EBADF;
 341                 ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
 342                 if (ctx == NULL)
 343                         goto out_unlock;
 344         } else
 345                 ctx = get_nfs_open_context(nfs_file_open_context(file));
 346
 347         if (!IS_SYNC(inode)) {
 348                 error = nfs_readpage_from_fscache(ctx, inode, page);
 349                 if (error == 0)
 350                         goto out;
 351         }
 352
 353         xchg(&ctx->error, 0);
 354         error = nfs_readpage_async(ctx, inode, page);
 355         if (!error) {
 356                 error = wait_on_page_locked_killable(page);
 357                 if (!PageUptodate(page) && !error)
 358                         error = xchg(&ctx->error, 0);
 359         }
 360 out:
 361         put_nfs_open_context(ctx);
 362         return error;
 363 out_unlock:
 364         unlock_page(page);
 365         return error;
 366 }
 367
 368 struct nfs_readdesc {
 369         struct nfs_pageio_descriptor *pgio;
 370         struct nfs_open_context *ctx;
 371 };
 372
 373 static int
 374 readpage_async_filler(void *data, struct page *page)
 375 {
 376         struct nfs_readdesc *desc = (struct nfs_readdesc *)data;
 377         struct nfs_page *new;
 378         unsigned int len;
 379         int error;
 380
 381         len = nfs_page_length(page);
 382         if (len == 0)
 383                 return nfs_return_empty_page(page);
 384
 385         new = nfs_create_request(desc->ctx, page, 0, len);
 386         if (IS_ERR(new))
 387                 goto out_error;
 388
 389         if (len < PAGE_SIZE)
 390                 zero_user_segment(page, len, PAGE_SIZE);
 391         if (!nfs_pageio_add_request(desc->pgio, new)) {
 392                 nfs_list_remove_request(new);
 393                 error = desc->pgio->pg_error;
 394                 nfs_readpage_release(new, error);
 395                 goto out;
 396         }
 397         return 0;
 398 out_error:
 399         error = PTR_ERR(new);
 400         unlock_page(page);
 401 out:
 402         return error;
 403 }
 404
 405 int nfs_readpages(struct file *filp, struct address_space *mapping,
 406                 struct list_head *pages, unsigned nr_pages)
 407 {
 408         struct nfs_pageio_descriptor pgio;
 409         struct nfs_pgio_mirror *pgm;
 410         struct nfs_readdesc desc = {
 411                 .pgio = &pgio,
 412         };
 413         struct inode *inode = mapping->host;
 414         unsigned long npages;
 415         int ret = -ESTALE;
 416
 417         dprintk("NFS: nfs_readpages (%s/%Lu %d)\n",
 418                         inode->i_sb->s_id,
 419                         (unsigned long long)NFS_FILEID(inode),
 420                         nr_pages);
 421         nfs_inc_stats(inode, NFSIOS_VFSREADPAGES);
 422
 423         if (NFS_STALE(inode))
 424                 goto out;
 425
 426         if (filp == NULL) {
 427                 desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
 428                 if (desc.ctx == NULL)
 429                         return -EBADF;
 430         } else
 431                 desc.ctx = get_nfs_open_context(nfs_file_open_context(filp));
 432
 433         /* attempt to read as many of the pages as possible from the cache
 434          * - this returns -ENOBUFS immediately if the cookie is negative
 435          */
 436         ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping,
 437                                          pages, &nr_pages);
 438         if (ret == 0)
 439                 goto read_complete; /* all pages were read */
 440
 441         nfs_pageio_init_read(&pgio, inode, false,
 442                              &nfs_async_read_completion_ops);
 443
 444         ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
 445         nfs_pageio_complete(&pgio);
 446
 447         /* It doesn't make sense to do mirrored reads! */
 448         WARN_ON_ONCE(pgio.pg_mirror_count != 1);
 449
 450         pgm = &pgio.pg_mirrors[0];
 451         NFS_I(inode)->read_io += pgm->pg_bytes_written;
 452         npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >>
 453                  PAGE_SHIFT;
 454         nfs_add_stats(inode, NFSIOS_READPAGES, npages);
 455 read_complete:
 456         put_nfs_open_context(desc.ctx);
 457 out:
 458         return ret;
 459 }
 460
 461 int __init nfs_init_readpagecache(void)
 462 {
 463         nfs_rdata_cachep = kmem_cache_create("nfs_read_data",
 464                                              sizeof(struct nfs_pgio_header),
 465                                              0, SLAB_HWCACHE_ALIGN,
 466                                              NULL);
 467         if (nfs_rdata_cachep == NULL)
 468                 return -ENOMEM;
 469
 470         return 0;
 471 }
 472
 473 void nfs_destroy_readpagecache(void)
 474 {
 475         kmem_cache_destroy(nfs_rdata_cachep);
 476 }
 477
 478 static const struct nfs_rw_ops nfs_rw_read_ops = {
 479         .rw_alloc_header        = nfs_readhdr_alloc,
 480         .rw_free_header         = nfs_readhdr_free,
 481         .rw_done                = nfs_readpage_done,
 482         .rw_result              = nfs_readpage_result,
 483         .rw_initiate            = nfs_initiate_read,
 484 };