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 goto out; 309 } 310 311 if (len < fsize) 312 folio_zero_segment(folio, len, fsize); 313 if (!nfs_pageio_add_request(pgio, new)) { 314 nfs_list_remove_request(new); 315 error = pgio->pg_error; 316 nfs_readpage_release(new, error); 317 goto out; 318 } 319 return 0; 320 out: 321 return error; 322 } 323 324 /* 325 * Read a page over NFS. 326 * We read the page synchronously in the following case: 327 * - The error flag is set for this page. This happens only when a 328 * previous async read operation failed. 329 */ 330 int nfs_read_folio(struct file *file, struct folio *folio) 331 { 332 struct inode *inode = file_inode(file); 333 struct nfs_pageio_descriptor pgio; 334 struct nfs_open_context *ctx; 335 int ret; 336 337 trace_nfs_aop_readpage(inode, folio); 338 nfs_inc_stats(inode, NFSIOS_VFSREADPAGE); 339 task_io_account_read(folio_size(folio)); 340 341 /* 342 * Try to flush any pending writes to the file.. 343 * 344 * NOTE! Because we own the folio lock, there cannot 345 * be any new pending writes generated at this point 346 * for this folio (other folios can be written to). 347 */ 348 ret = nfs_wb_folio(inode, folio); 349 if (ret) 350 goto out_unlock; 351 if (folio_test_uptodate(folio)) 352 goto out_unlock; 353 354 ret = -ESTALE; 355 if (NFS_STALE(inode)) 356 goto out_unlock; 357 358 ret = nfs_netfs_read_folio(file, folio); 359 if (!ret) 360 goto out; 361 362 ctx = get_nfs_open_context(nfs_file_open_context(file)); 363 364 xchg(&ctx->error, 0); 365 nfs_pageio_init_read(&pgio, inode, false, 366 &nfs_async_read_completion_ops); 367 368 ret = nfs_read_add_folio(&pgio, ctx, folio); 369 if (ret) 370 goto out_put; 371 372 nfs_pageio_complete_read(&pgio); 373 ret = pgio.pg_error < 0 ? pgio.pg_error : 0; 374 if (!ret) { 375 ret = folio_wait_locked_killable(folio); 376 if (!folio_test_uptodate(folio) && !ret) 377 ret = xchg(&ctx->error, 0); 378 } 379 out_put: 380 put_nfs_open_context(ctx); 381 out: 382 trace_nfs_aop_readpage_done(inode, folio, ret); 383 return ret; 384 out_unlock: 385 folio_unlock(folio); 386 goto out; 387 } 388 389 void nfs_readahead(struct readahead_control *ractl) 390 { 391 struct nfs_pageio_descriptor pgio; 392 struct nfs_open_context *ctx; 393 unsigned int nr_pages = readahead_count(ractl); 394 struct file *file = ractl->file; 395 struct inode *inode = ractl->mapping->host; 396 struct folio *folio; 397 int ret; 398 399 trace_nfs_aop_readahead(inode, readahead_pos(ractl), nr_pages); 400 nfs_inc_stats(inode, NFSIOS_VFSREADPAGES); 401 task_io_account_read(readahead_length(ractl)); 402 403 ret = -ESTALE; 404 if (NFS_STALE(inode)) 405 goto out; 406 407 ret = nfs_netfs_readahead(ractl); 408 if (!ret) 409 goto out; 410 411 if (file == NULL) { 412 ret = -EBADF; 413 ctx = nfs_find_open_context(inode, NULL, FMODE_READ); 414 if (ctx == NULL) 415 goto out; 416 } else 417 ctx = get_nfs_open_context(nfs_file_open_context(file)); 418 419 nfs_pageio_init_read(&pgio, inode, false, 420 &nfs_async_read_completion_ops); 421 422 while ((folio = readahead_folio(ractl)) != NULL) { 423 ret = nfs_read_add_folio(&pgio, ctx, folio); 424 if (ret) 425 break; 426 } 427 428 nfs_pageio_complete_read(&pgio); 429 430 put_nfs_open_context(ctx); 431 out: 432 trace_nfs_aop_readahead_done(inode, nr_pages, ret); 433 } 434 435 int __init nfs_init_readpagecache(void) 436 { 437 nfs_rdata_cachep = kmem_cache_create("nfs_read_data", 438 sizeof(struct nfs_pgio_header), 439 0, SLAB_HWCACHE_ALIGN, 440 NULL); 441 if (nfs_rdata_cachep == NULL) 442 return -ENOMEM; 443 444 return 0; 445 } 446 447 void nfs_destroy_readpagecache(void) 448 { 449 kmem_cache_destroy(nfs_rdata_cachep); 450 } 451 452 static const struct nfs_rw_ops nfs_rw_read_ops = { 453 .rw_alloc_header = nfs_readhdr_alloc, 454 .rw_free_header = nfs_readhdr_free, 455 .rw_done = nfs_readpage_done, 456 .rw_result = nfs_readpage_result, 457 .rw_initiate = nfs_initiate_read, 458 }; 459