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/task_io_accounting_ops.h> 19 #include <linux/pagemap.h> 20 #include <linux/sunrpc/clnt.h> 21 #include <linux/nfs_fs.h> 22 #include <linux/nfs_page.h> 23 #include <linux/module.h> 24 25 #include "nfs4_fs.h" 26 #include "internal.h" 27 #include "iostat.h" 28 #include "fscache.h" 29 #include "pnfs.h" 30 #include "nfstrace.h" 31 #include "delegation.h" 32 33 #define NFSDBG_FACILITY NFSDBG_PAGECACHE 34 35 const struct nfs_pgio_completion_ops nfs_async_read_completion_ops; 36 static const struct nfs_rw_ops nfs_rw_read_ops; 37 38 static struct kmem_cache *nfs_rdata_cachep; 39 40 static struct nfs_pgio_header *nfs_readhdr_alloc(void) 41 { 42 struct nfs_pgio_header *p = kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL); 43 44 if (p) 45 p->rw_mode = FMODE_READ; 46 return p; 47 } 48 49 static void nfs_readhdr_free(struct nfs_pgio_header *rhdr) 50 { 51 if (rhdr->res.scratch != NULL) 52 kfree(rhdr->res.scratch); 53 kmem_cache_free(nfs_rdata_cachep, rhdr); 54 } 55 56 static int nfs_return_empty_folio(struct folio *folio) 57 { 58 folio_zero_segment(folio, 0, folio_size(folio)); 59 folio_mark_uptodate(folio); 60 folio_unlock(folio); 61 return 0; 62 } 63 64 void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio, 65 struct inode *inode, bool force_mds, 66 const struct nfs_pgio_completion_ops *compl_ops) 67 { 68 struct nfs_server *server = NFS_SERVER(inode); 69 const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops; 70 71 #ifdef CONFIG_NFS_V4_1 72 if (server->pnfs_curr_ld && !force_mds) 73 pg_ops = server->pnfs_curr_ld->pg_read_ops; 74 #endif 75 nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_read_ops, 76 server->rsize, 0); 77 } 78 EXPORT_SYMBOL_GPL(nfs_pageio_init_read); 79 80 void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio) 81 { 82 struct nfs_pgio_mirror *pgm; 83 unsigned long npages; 84 85 nfs_pageio_complete(pgio); 86 87 /* It doesn't make sense to do mirrored reads! */ 88 WARN_ON_ONCE(pgio->pg_mirror_count != 1); 89 90 pgm = &pgio->pg_mirrors[0]; 91 NFS_I(pgio->pg_inode)->read_io += pgm->pg_bytes_written; 92 npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >> PAGE_SHIFT; 93 nfs_add_stats(pgio->pg_inode, NFSIOS_READPAGES, npages); 94 } 95 96 97 void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio) 98 { 99 struct nfs_pgio_mirror *mirror; 100 101 if (pgio->pg_ops && pgio->pg_ops->pg_cleanup) 102 pgio->pg_ops->pg_cleanup(pgio); 103 104 pgio->pg_ops = &nfs_pgio_rw_ops; 105 106 /* read path should never have more than one mirror */ 107 WARN_ON_ONCE(pgio->pg_mirror_count != 1); 108 109 mirror = &pgio->pg_mirrors[0]; 110 mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize; 111 } 112 EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds); 113 114 bool nfs_read_alloc_scratch(struct nfs_pgio_header *hdr, size_t size) 115 { 116 WARN_ON(hdr->res.scratch != NULL); 117 hdr->res.scratch = kmalloc(size, GFP_KERNEL); 118 return hdr->res.scratch != NULL; 119 } 120 EXPORT_SYMBOL_GPL(nfs_read_alloc_scratch); 121 122 static void nfs_readpage_release(struct nfs_page *req, int error) 123 { 124 struct folio *folio = nfs_page_to_folio(req); 125 126 if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) 127 if (nfs_netfs_folio_unlock(folio)) 128 folio_unlock(folio); 129 130 nfs_release_request(req); 131 } 132 133 static void nfs_page_group_set_uptodate(struct nfs_page *req) 134 { 135 if (nfs_page_group_sync_on_bit(req, PG_UPTODATE)) 136 folio_mark_uptodate(nfs_page_to_folio(req)); 137 } 138 139 static void nfs_read_completion(struct nfs_pgio_header *hdr) 140 { 141 unsigned long bytes = 0; 142 int error; 143 144 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) 145 goto out; 146 while (!list_empty(&hdr->pages)) { 147 struct nfs_page *req = nfs_list_entry(hdr->pages.next); 148 struct folio *folio = nfs_page_to_folio(req); 149 unsigned long start = req->wb_pgbase; 150 unsigned long end = req->wb_pgbase + req->wb_bytes; 151 152 if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) { 153 /* note: regions of the page not covered by a 154 * request are zeroed in nfs_read_add_folio 155 */ 156 if (bytes > hdr->good_bytes) { 157 /* nothing in this request was good, so zero 158 * the full extent of the request */ 159 folio_zero_segment(folio, start, end); 160 161 } else if (hdr->good_bytes - bytes < req->wb_bytes) { 162 /* part of this request has good bytes, but 163 * not all. zero the bad bytes */ 164 start += hdr->good_bytes - bytes; 165 WARN_ON(start < req->wb_pgbase); 166 folio_zero_segment(folio, start, end); 167 } 168 } 169 error = 0; 170 bytes += req->wb_bytes; 171 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) { 172 if (bytes <= hdr->good_bytes) 173 nfs_page_group_set_uptodate(req); 174 else { 175 error = hdr->error; 176 xchg(&nfs_req_openctx(req)->error, error); 177 } 178 } else 179 nfs_page_group_set_uptodate(req); 180 nfs_list_remove_request(req); 181 nfs_readpage_release(req, error); 182 } 183 nfs_netfs_read_completion(hdr); 184 185 out: 186 hdr->release(hdr); 187 } 188 189 static void nfs_initiate_read(struct nfs_pgio_header *hdr, 190 struct rpc_message *msg, 191 const struct nfs_rpc_ops *rpc_ops, 192 struct rpc_task_setup *task_setup_data, int how) 193 { 194 rpc_ops->read_setup(hdr, msg); 195 nfs_netfs_initiate_read(hdr); 196 trace_nfs_initiate_read(hdr); 197 } 198 199 static void 200 nfs_async_read_error(struct list_head *head, int error) 201 { 202 struct nfs_page *req; 203 204 while (!list_empty(head)) { 205 req = nfs_list_entry(head->next); 206 nfs_list_remove_request(req); 207 nfs_readpage_release(req, error); 208 } 209 } 210 211 const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = { 212 .error_cleanup = nfs_async_read_error, 213 .completion = nfs_read_completion, 214 }; 215 216 /* 217 * This is the callback from RPC telling us whether a reply was 218 * received or some error occurred (timeout or socket shutdown). 219 */ 220 static int nfs_readpage_done(struct rpc_task *task, 221 struct nfs_pgio_header *hdr, 222 struct inode *inode) 223 { 224 int status = NFS_PROTO(inode)->read_done(task, hdr); 225 if (status != 0) 226 return status; 227 228 nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count); 229 trace_nfs_readpage_done(task, hdr); 230 231 if (task->tk_status == -ESTALE) { 232 nfs_set_inode_stale(inode); 233 nfs_mark_for_revalidate(inode); 234 } 235 return 0; 236 } 237 238 static void nfs_readpage_retry(struct rpc_task *task, 239 struct nfs_pgio_header *hdr) 240 { 241 struct nfs_pgio_args *argp = &hdr->args; 242 struct nfs_pgio_res *resp = &hdr->res; 243 244 /* This is a short read! */ 245 nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD); 246 trace_nfs_readpage_short(task, hdr); 247 248 /* Has the server at least made some progress? */ 249 if (resp->count == 0) { 250 nfs_set_pgio_error(hdr, -EIO, argp->offset); 251 return; 252 } 253 254 /* For non rpc-based layout drivers, retry-through-MDS */ 255 if (!task->tk_ops) { 256 hdr->pnfs_error = -EAGAIN; 257 return; 258 } 259 260 /* Yes, so retry the read at the end of the hdr */ 261 hdr->mds_offset += resp->count; 262 argp->offset += resp->count; 263 argp->pgbase += resp->count; 264 argp->count -= resp->count; 265 resp->count = 0; 266 resp->eof = 0; 267 rpc_restart_call_prepare(task); 268 } 269 270 static void nfs_readpage_result(struct rpc_task *task, 271 struct nfs_pgio_header *hdr) 272 { 273 if (hdr->res.eof) { 274 loff_t pos = hdr->args.offset + hdr->res.count; 275 unsigned int new = pos - hdr->io_start; 276 277 if (hdr->good_bytes > new) { 278 hdr->good_bytes = new; 279 set_bit(NFS_IOHDR_EOF, &hdr->flags); 280 clear_bit(NFS_IOHDR_ERROR, &hdr->flags); 281 } 282 } else if (hdr->res.count < hdr->args.count) 283 nfs_readpage_retry(task, hdr); 284 } 285 286 int nfs_read_add_folio(struct nfs_pageio_descriptor *pgio, 287 struct nfs_open_context *ctx, 288 struct folio *folio) 289 { 290 struct inode *inode = folio->mapping->host; 291 struct nfs_server *server = NFS_SERVER(inode); 292 size_t fsize = folio_size(folio); 293 unsigned int rsize = server->rsize; 294 struct nfs_page *new; 295 unsigned int len, aligned_len; 296 int error; 297 298 len = nfs_folio_length(folio); 299 if (len == 0) 300 return nfs_return_empty_folio(folio); 301 302 aligned_len = min_t(unsigned int, ALIGN(len, rsize), fsize); 303 304 new = nfs_page_create_from_folio(ctx, folio, 0, aligned_len); 305 if (IS_ERR(new)) { 306 error = PTR_ERR(new); 307 if (nfs_netfs_folio_unlock(folio)) 308 folio_unlock(folio); 309 goto out; 310 } 311 312 if (len < fsize) 313 folio_zero_segment(folio, len, fsize); 314 if (!nfs_pageio_add_request(pgio, new)) { 315 nfs_list_remove_request(new); 316 error = pgio->pg_error; 317 nfs_readpage_release(new, error); 318 goto out; 319 } 320 return 0; 321 out: 322 return error; 323 } 324 325 /* 326 * Actually read a folio over the wire. 327 */ 328 static int nfs_do_read_folio(struct file *file, struct folio *folio) 329 { 330 struct inode *inode = file_inode(file); 331 struct nfs_pageio_descriptor pgio; 332 struct nfs_open_context *ctx; 333 int ret; 334 335 ctx = get_nfs_open_context(nfs_file_open_context(file)); 336 337 xchg(&ctx->error, 0); 338 nfs_pageio_init_read(&pgio, inode, false, 339 &nfs_async_read_completion_ops); 340 341 ret = nfs_read_add_folio(&pgio, ctx, folio); 342 if (ret) 343 goto out_put; 344 345 nfs_pageio_complete_read(&pgio); 346 nfs_update_delegated_atime(inode); 347 if (pgio.pg_error < 0) { 348 ret = pgio.pg_error; 349 goto out_put; 350 } 351 352 ret = folio_wait_locked_killable(folio); 353 if (!folio_test_uptodate(folio) && !ret) 354 ret = xchg(&ctx->error, 0); 355 356 out_put: 357 put_nfs_open_context(ctx); 358 return ret; 359 } 360 361 /* 362 * Synchronously read a folio. 363 * 364 * This is not heavily used as most users to try an asynchronous 365 * large read through ->readahead first. 366 */ 367 int nfs_read_folio(struct file *file, struct folio *folio) 368 { 369 struct inode *inode = file_inode(file); 370 loff_t pos = folio_pos(folio); 371 size_t len = folio_size(folio); 372 int ret; 373 374 trace_nfs_aop_readpage(inode, pos, len); 375 nfs_inc_stats(inode, NFSIOS_VFSREADPAGE); 376 task_io_account_read(len); 377 378 /* 379 * Try to flush any pending writes to the file.. 380 * 381 * NOTE! Because we own the folio lock, there cannot 382 * be any new pending writes generated at this point 383 * for this folio (other folios can be written to). 384 */ 385 ret = nfs_wb_folio(inode, folio); 386 if (ret) 387 goto out_unlock; 388 if (folio_test_uptodate(folio)) 389 goto out_unlock; 390 391 ret = -ESTALE; 392 if (NFS_STALE(inode)) 393 goto out_unlock; 394 395 ret = nfs_netfs_read_folio(file, folio); 396 if (ret) 397 ret = nfs_do_read_folio(file, folio); 398 out: 399 trace_nfs_aop_readpage_done(inode, pos, len, ret); 400 return ret; 401 out_unlock: 402 folio_unlock(folio); 403 goto out; 404 } 405 406 void nfs_readahead(struct readahead_control *ractl) 407 { 408 struct nfs_pageio_descriptor pgio; 409 struct nfs_open_context *ctx; 410 unsigned int nr_pages = readahead_count(ractl); 411 struct file *file = ractl->file; 412 struct inode *inode = ractl->mapping->host; 413 struct folio *folio; 414 int ret; 415 416 trace_nfs_aop_readahead(inode, readahead_pos(ractl), nr_pages); 417 nfs_inc_stats(inode, NFSIOS_VFSREADPAGES); 418 task_io_account_read(readahead_length(ractl)); 419 420 ret = -ESTALE; 421 if (NFS_STALE(inode)) 422 goto out; 423 424 ret = nfs_netfs_readahead(ractl); 425 if (!ret) 426 goto out; 427 428 if (file == NULL) { 429 ret = -EBADF; 430 ctx = nfs_find_open_context(inode, NULL, FMODE_READ); 431 if (ctx == NULL) 432 goto out; 433 } else 434 ctx = get_nfs_open_context(nfs_file_open_context(file)); 435 436 nfs_pageio_init_read(&pgio, inode, false, 437 &nfs_async_read_completion_ops); 438 439 while ((folio = readahead_folio(ractl)) != NULL) { 440 ret = nfs_read_add_folio(&pgio, ctx, folio); 441 if (ret) 442 break; 443 } 444 445 nfs_pageio_complete_read(&pgio); 446 nfs_update_delegated_atime(inode); 447 448 put_nfs_open_context(ctx); 449 out: 450 trace_nfs_aop_readahead_done(inode, nr_pages, ret); 451 } 452 453 int __init nfs_init_readpagecache(void) 454 { 455 nfs_rdata_cachep = kmem_cache_create("nfs_read_data", 456 sizeof(struct nfs_pgio_header), 457 0, SLAB_HWCACHE_ALIGN, 458 NULL); 459 if (nfs_rdata_cachep == NULL) 460 return -ENOMEM; 461 462 return 0; 463 } 464 465 void nfs_destroy_readpagecache(void) 466 { 467 kmem_cache_destroy(nfs_rdata_cachep); 468 } 469 470 static const struct nfs_rw_ops nfs_rw_read_ops = { 471 .rw_alloc_header = nfs_readhdr_alloc, 472 .rw_free_header = nfs_readhdr_free, 473 .rw_done = nfs_readpage_done, 474 .rw_result = nfs_readpage_result, 475 .rw_initiate = nfs_initiate_read, 476 }; 477