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_fscache_write_page(inode, page);
 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         rpc_ops->read_setup(hdr, msg);
 198         trace_nfs_initiate_read(hdr);
 199 }
 200
 201 static void
 202 nfs_async_read_error(struct list_head *head, int error)
 203 {
 204         struct nfs_page *req;
 205
 206         while (!list_empty(head)) {
 207                 req = nfs_list_entry(head->next);
 208                 nfs_list_remove_request(req);
 209                 nfs_readpage_release(req, error);
 210         }
 211 }
 212
 213 static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
 214         .error_cleanup = nfs_async_read_error,
 215         .completion = nfs_read_completion,
 216 };
 217
 218 /*
 219  * This is the callback from RPC telling us whether a reply was
 220  * received or some error occurred (timeout or socket shutdown).
 221  */
 222 static int nfs_readpage_done(struct rpc_task *task,
 223                              struct nfs_pgio_header *hdr,
 224                              struct inode *inode)
 225 {
 226         int status = NFS_PROTO(inode)->read_done(task, hdr);
 227         if (status != 0)
 228                 return status;
 229
 230         nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
 231         trace_nfs_readpage_done(task, hdr);
 232
 233         if (task->tk_status == -ESTALE) {
 234                 nfs_set_inode_stale(inode);
 235                 nfs_mark_for_revalidate(inode);
 236         }
 237         return 0;
 238 }
 239
 240 static void nfs_readpage_retry(struct rpc_task *task,
 241                                struct nfs_pgio_header *hdr)
 242 {
 243         struct nfs_pgio_args *argp = &hdr->args;
 244         struct nfs_pgio_res  *resp = &hdr->res;
 245
 246         /* This is a short read! */
 247         nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD);
 248         trace_nfs_readpage_short(task, hdr);
 249
 250         /* Has the server at least made some progress? */
 251         if (resp->count == 0) {
 252                 nfs_set_pgio_error(hdr, -EIO, argp->offset);
 253                 return;
 254         }
 255
 256         /* For non rpc-based layout drivers, retry-through-MDS */
 257         if (!task->tk_ops) {
 258                 hdr->pnfs_error = -EAGAIN;
 259                 return;
 260         }
 261
 262         /* Yes, so retry the read at the end of the hdr */
 263         hdr->mds_offset += resp->count;
 264         argp->offset += resp->count;
 265         argp->pgbase += resp->count;
 266         argp->count -= resp->count;
 267         resp->count = 0;
 268         resp->eof = 0;
 269         rpc_restart_call_prepare(task);
 270 }
 271
 272 static void nfs_readpage_result(struct rpc_task *task,
 273                                 struct nfs_pgio_header *hdr)
 274 {
 275         if (hdr->res.eof) {
 276                 loff_t pos = hdr->args.offset + hdr->res.count;
 277                 unsigned int new = pos - hdr->io_start;
 278
 279                 if (hdr->good_bytes > new) {
 280                         hdr->good_bytes = new;
 281                         set_bit(NFS_IOHDR_EOF, &hdr->flags);
 282                         clear_bit(NFS_IOHDR_ERROR, &hdr->flags);
 283                 }
 284         } else if (hdr->res.count < hdr->args.count)
 285                 nfs_readpage_retry(task, hdr);
 286 }
 287
 288 static int
 289 readpage_async_filler(struct nfs_readdesc *desc, struct page *page)
 290 {
 291         struct inode *inode = page_file_mapping(page)->host;
 292         unsigned int rsize = NFS_SERVER(inode)->rsize;
 293         struct nfs_page *new;
 294         unsigned int len, aligned_len;
 295         int error;
 296
 297         len = nfs_page_length(page);
 298         if (len == 0)
 299                 return nfs_return_empty_page(page);
 300
 301         aligned_len = min_t(unsigned int, ALIGN(len, rsize), PAGE_SIZE);
 302
 303         if (!IS_SYNC(page->mapping->host)) {
 304                 error = nfs_fscache_read_page(page->mapping->host, page);
 305                 if (error == 0)
 306                         goto out_unlock;
 307         }
 308
 309         new = nfs_create_request(desc->ctx, page, 0, aligned_len);
 310         if (IS_ERR(new))
 311                 goto out_error;
 312
 313         if (len < PAGE_SIZE)
 314                 zero_user_segment(page, len, PAGE_SIZE);
 315         if (!nfs_pageio_add_request(&desc->pgio, new)) {
 316                 nfs_list_remove_request(new);
 317                 error = desc->pgio.pg_error;
 318                 nfs_readpage_release(new, error);
 319                 goto out;
 320         }
 321         return 0;
 322 out_error:
 323         error = PTR_ERR(new);
 324 out_unlock:
 325         unlock_page(page);
 326 out:
 327         return error;
 328 }
 329
 330 /*
 331  * Read a page over NFS.
 332  * We read the page synchronously in the following case:
 333  *  -   The error flag is set for this page. This happens only when a
 334  *      previous async read operation failed.
 335  */
 336 int nfs_readpage(struct file *file, struct page *page)
 337 {
 338         struct nfs_readdesc desc;
 339         struct inode *inode = page_file_mapping(page)->host;
 340         int ret;
 341
 342         trace_nfs_aop_readpage(inode, page);
 343         nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
 344
 345         /*
 346          * Try to flush any pending writes to the file..
 347          *
 348          * NOTE! Because we own the page lock, there cannot
 349          * be any new pending writes generated at this point
 350          * for this page (other pages can be written to).
 351          */
 352         ret = nfs_wb_page(inode, page);
 353         if (ret)
 354                 goto out_unlock;
 355         if (PageUptodate(page))
 356                 goto out_unlock;
 357
 358         ret = -ESTALE;
 359         if (NFS_STALE(inode))
 360                 goto out_unlock;
 361
 362         if (file == NULL) {
 363                 ret = -EBADF;
 364                 desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
 365                 if (desc.ctx == NULL)
 366                         goto out_unlock;
 367         } else
 368                 desc.ctx = get_nfs_open_context(nfs_file_open_context(file));
 369
 370         xchg(&desc.ctx->error, 0);
 371         nfs_pageio_init_read(&desc.pgio, inode, false,
 372                              &nfs_async_read_completion_ops);
 373
 374         ret = readpage_async_filler(&desc, page);
 375         if (ret)
 376                 goto out;
 377
 378         nfs_pageio_complete_read(&desc.pgio);
 379         ret = desc.pgio.pg_error < 0 ? desc.pgio.pg_error : 0;
 380         if (!ret) {
 381                 ret = wait_on_page_locked_killable(page);
 382                 if (!PageUptodate(page) && !ret)
 383                         ret = xchg(&desc.ctx->error, 0);
 384         }
 385 out:
 386         put_nfs_open_context(desc.ctx);
 387         trace_nfs_aop_readpage_done(inode, page, ret);
 388         return ret;
 389 out_unlock:
 390         unlock_page(page);
 391         trace_nfs_aop_readpage_done(inode, page, ret);
 392         return ret;
 393 }
 394
 395 void nfs_readahead(struct readahead_control *ractl)
 396 {
 397         unsigned int nr_pages = readahead_count(ractl);
 398         struct file *file = ractl->file;
 399         struct nfs_readdesc desc;
 400         struct inode *inode = ractl->mapping->host;
 401         struct page *page;
 402         int ret;
 403
 404         trace_nfs_aop_readahead(inode, readahead_pos(ractl), nr_pages);
 405         nfs_inc_stats(inode, NFSIOS_VFSREADPAGES);
 406
 407         ret = -ESTALE;
 408         if (NFS_STALE(inode))
 409                 goto out;
 410
 411         if (file == NULL) {
 412                 ret = -EBADF;
 413                 desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
 414                 if (desc.ctx == NULL)
 415                         goto out;
 416         } else
 417                 desc.ctx = get_nfs_open_context(nfs_file_open_context(file));
 418
 419         nfs_pageio_init_read(&desc.pgio, inode, false,
 420                              &nfs_async_read_completion_ops);
 421
 422         while ((page = readahead_page(ractl)) != NULL) {
 423                 ret = readpage_async_filler(&desc, page);
 424                 put_page(page);
 425                 if (ret)
 426                         break;
 427         }
 428
 429         nfs_pageio_complete_read(&desc.pgio);
 430
 431         put_nfs_open_context(desc.ctx);
 432 out:
 433         trace_nfs_aop_readahead_done(inode, nr_pages, ret);
 434 }
 435
 436 int __init nfs_init_readpagecache(void)
 437 {
 438         nfs_rdata_cachep = kmem_cache_create("nfs_read_data",
 439                                              sizeof(struct nfs_pgio_header),
 440                                              0, SLAB_HWCACHE_ALIGN,
 441                                              NULL);
 442         if (nfs_rdata_cachep == NULL)
 443                 return -ENOMEM;
 444
 445         return 0;
 446 }
 447
 448 void nfs_destroy_readpagecache(void)
 449 {
 450         kmem_cache_destroy(nfs_rdata_cachep);
 451 }
 452
 453 static const struct nfs_rw_ops nfs_rw_read_ops = {
 454         .rw_alloc_header        = nfs_readhdr_alloc,
 455         .rw_free_header         = nfs_readhdr_free,
 456         .rw_done                = nfs_readpage_done,
 457         .rw_result              = nfs_readpage_result,
 458         .rw_initiate            = nfs_initiate_read,
 459 };