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