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