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 kmem_cache_free(nfs_rdata_cachep, rhdr); 51 } 52 53 static int nfs_return_empty_folio(struct folio *folio) 54 { 55 folio_zero_segment(folio, 0, folio_size(folio)); 56 folio_mark_uptodate(folio); 57 folio_unlock(folio); 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_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 folio *folio = nfs_page_to_folio(req); 114 115 if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT) 116 folio_set_error(folio); 117 if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) 118 if (nfs_netfs_folio_unlock(folio)) 119 folio_unlock(folio); 120 121 nfs_release_request(req); 122 } 123 124 static void nfs_page_group_set_uptodate(struct nfs_page *req) 125 { 126 if (nfs_page_group_sync_on_bit(req, PG_UPTODATE)) 127 folio_mark_uptodate(nfs_page_to_folio(req)); 128 } 129 130 static void nfs_read_completion(struct nfs_pgio_header *hdr) 131 { 132 unsigned long bytes = 0; 133 int error; 134 135 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) 136 goto out; 137 while (!list_empty(&hdr->pages)) { 138 struct nfs_page *req = nfs_list_entry(hdr->pages.next); 139 struct folio *folio = nfs_page_to_folio(req); 140 unsigned long start = req->wb_pgbase; 141 unsigned long end = req->wb_pgbase + req->wb_bytes; 142 143 if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) { 144 /* note: regions of the page not covered by a 145 * request are zeroed in nfs_read_add_folio 146 */ 147 if (bytes > hdr->good_bytes) { 148 /* nothing in this request was good, so zero 149 * the full extent of the request */ 150 folio_zero_segment(folio, start, end); 151 152 } else if (hdr->good_bytes - bytes < req->wb_bytes) { 153 /* part of this request has good bytes, but 154 * not all. zero the bad bytes */ 155 start += hdr->good_bytes - bytes; 156 WARN_ON(start < req->wb_pgbase); 157 folio_zero_segment(folio, start, end); 158 } 159 } 160 error = 0; 161 bytes += req->wb_bytes; 162 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) { 163 if (bytes <= hdr->good_bytes) 164 nfs_page_group_set_uptodate(req); 165 else { 166 error = hdr->error; 167 xchg(&nfs_req_openctx(req)->error, error); 168 } 169 } else 170 nfs_page_group_set_uptodate(req); 171 nfs_list_remove_request(req); 172 nfs_readpage_release(req, error); 173 } 174 nfs_netfs_read_completion(hdr); 175 176 out: 177 hdr->release(hdr); 178 } 179 180 static void nfs_initiate_read(struct nfs_pgio_header *hdr, 181 struct rpc_message *msg, 182 const struct nfs_rpc_ops *rpc_ops, 183 struct rpc_task_setup *task_setup_data, int how) 184 { 185 rpc_ops->read_setup(hdr, msg); 186 nfs_netfs_initiate_read(hdr); 187 trace_nfs_initiate_read(hdr); 188 } 189 190 static void 191 nfs_async_read_error(struct list_head *head, int error) 192 { 193 struct nfs_page *req; 194 195 while (!list_empty(head)) { 196 req = nfs_list_entry(head->next); 197 nfs_list_remove_request(req); 198 nfs_readpage_release(req, error); 199 } 200 } 201 202 const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = { 203 .error_cleanup = nfs_async_read_error, 204 .completion = nfs_read_completion, 205 }; 206 207 /* 208 * This is the callback from RPC telling us whether a reply was 209 * received or some error occurred (timeout or socket shutdown). 210 */ 211 static int nfs_readpage_done(struct rpc_task *task, 212 struct nfs_pgio_header *hdr, 213 struct inode *inode) 214 { 215 int status = NFS_PROTO(inode)->read_done(task, hdr); 216 if (status != 0) 217 return status; 218 219 nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count); 220 trace_nfs_readpage_done(task, hdr); 221 222 if (task->tk_status == -ESTALE) { 223 nfs_set_inode_stale(inode); 224 nfs_mark_for_revalidate(inode); 225 } 226 return 0; 227 } 228 229 static void nfs_readpage_retry(struct rpc_task *task, 230 struct nfs_pgio_header *hdr) 231 { 232 struct nfs_pgio_args *argp = &hdr->args; 233 struct nfs_pgio_res *resp = &hdr->res; 234 235 /* This is a short read! */ 236 nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD); 237 trace_nfs_readpage_short(task, hdr); 238 239 /* Has the server at least made some progress? */ 240 if (resp->count == 0) { 241 nfs_set_pgio_error(hdr, -EIO, argp->offset); 242 return; 243 } 244 245 /* For non rpc-based layout drivers, retry-through-MDS */ 246 if (!task->tk_ops) { 247 hdr->pnfs_error = -EAGAIN; 248 return; 249 } 250 251 /* Yes, so retry the read at the end of the hdr */ 252 hdr->mds_offset += resp->count; 253 argp->offset += resp->count; 254 argp->pgbase += resp->count; 255 argp->count -= resp->count; 256 resp->count = 0; 257 resp->eof = 0; 258 rpc_restart_call_prepare(task); 259 } 260 261 static void nfs_readpage_result(struct rpc_task *task, 262 struct nfs_pgio_header *hdr) 263 { 264 if (hdr->res.eof) { 265 loff_t pos = hdr->args.offset + hdr->res.count; 266 unsigned int new = pos - hdr->io_start; 267 268 if (hdr->good_bytes > new) { 269 hdr->good_bytes = new; 270 set_bit(NFS_IOHDR_EOF, &hdr->flags); 271 clear_bit(NFS_IOHDR_ERROR, &hdr->flags); 272 } 273 } else if (hdr->res.count < hdr->args.count) 274 nfs_readpage_retry(task, hdr); 275 } 276 277 int nfs_read_add_folio(struct nfs_pageio_descriptor *pgio, 278 struct nfs_open_context *ctx, 279 struct folio *folio) 280 { 281 struct inode *inode = folio_file_mapping(folio)->host; 282 struct nfs_server *server = NFS_SERVER(inode); 283 size_t fsize = folio_size(folio); 284 unsigned int rsize = server->rsize; 285 struct nfs_page *new; 286 unsigned int len, aligned_len; 287 int error; 288 289 len = nfs_folio_length(folio); 290 if (len == 0) 291 return nfs_return_empty_folio(folio); 292 293 aligned_len = min_t(unsigned int, ALIGN(len, rsize), fsize); 294 295 new = nfs_page_create_from_folio(ctx, folio, 0, aligned_len); 296 if (IS_ERR(new)) { 297 error = PTR_ERR(new); 298 goto out; 299 } 300 301 if (len < fsize) 302 folio_zero_segment(folio, len, fsize); 303 if (!nfs_pageio_add_request(pgio, new)) { 304 nfs_list_remove_request(new); 305 error = pgio->pg_error; 306 nfs_readpage_release(new, error); 307 goto out; 308 } 309 return 0; 310 out: 311 return error; 312 } 313 314 /* 315 * Read a page over NFS. 316 * We read the page synchronously in the following case: 317 * - The error flag is set for this page. This happens only when a 318 * previous async read operation failed. 319 */ 320 int nfs_read_folio(struct file *file, struct folio *folio) 321 { 322 struct inode *inode = file_inode(file); 323 struct nfs_pageio_descriptor pgio; 324 struct nfs_open_context *ctx; 325 int ret; 326 327 trace_nfs_aop_readpage(inode, folio); 328 nfs_inc_stats(inode, NFSIOS_VFSREADPAGE); 329 task_io_account_read(folio_size(folio)); 330 331 /* 332 * Try to flush any pending writes to the file.. 333 * 334 * NOTE! Because we own the folio lock, there cannot 335 * be any new pending writes generated at this point 336 * for this folio (other folios can be written to). 337 */ 338 ret = nfs_wb_folio(inode, folio); 339 if (ret) 340 goto out_unlock; 341 if (folio_test_uptodate(folio)) 342 goto out_unlock; 343 344 ret = -ESTALE; 345 if (NFS_STALE(inode)) 346 goto out_unlock; 347 348 ret = nfs_netfs_read_folio(file, folio); 349 if (!ret) 350 goto out; 351 352 ctx = get_nfs_open_context(nfs_file_open_context(file)); 353 354 xchg(&ctx->error, 0); 355 nfs_pageio_init_read(&pgio, inode, false, 356 &nfs_async_read_completion_ops); 357 358 ret = nfs_read_add_folio(&pgio, ctx, folio); 359 if (ret) 360 goto out_put; 361 362 nfs_pageio_complete_read(&pgio); 363 ret = pgio.pg_error < 0 ? pgio.pg_error : 0; 364 if (!ret) { 365 ret = folio_wait_locked_killable(folio); 366 if (!folio_test_uptodate(folio) && !ret) 367 ret = xchg(&ctx->error, 0); 368 } 369 out_put: 370 put_nfs_open_context(ctx); 371 out: 372 trace_nfs_aop_readpage_done(inode, folio, ret); 373 return ret; 374 out_unlock: 375 folio_unlock(folio); 376 goto out; 377 } 378 379 void nfs_readahead(struct readahead_control *ractl) 380 { 381 struct nfs_pageio_descriptor pgio; 382 struct nfs_open_context *ctx; 383 unsigned int nr_pages = readahead_count(ractl); 384 struct file *file = ractl->file; 385 struct inode *inode = ractl->mapping->host; 386 struct folio *folio; 387 int ret; 388 389 trace_nfs_aop_readahead(inode, readahead_pos(ractl), nr_pages); 390 nfs_inc_stats(inode, NFSIOS_VFSREADPAGES); 391 task_io_account_read(readahead_length(ractl)); 392 393 ret = -ESTALE; 394 if (NFS_STALE(inode)) 395 goto out; 396 397 ret = nfs_netfs_readahead(ractl); 398 if (!ret) 399 goto out; 400 401 if (file == NULL) { 402 ret = -EBADF; 403 ctx = nfs_find_open_context(inode, NULL, FMODE_READ); 404 if (ctx == NULL) 405 goto out; 406 } else 407 ctx = get_nfs_open_context(nfs_file_open_context(file)); 408 409 nfs_pageio_init_read(&pgio, inode, false, 410 &nfs_async_read_completion_ops); 411 412 while ((folio = readahead_folio(ractl)) != NULL) { 413 ret = nfs_read_add_folio(&pgio, ctx, folio); 414 if (ret) 415 break; 416 } 417 418 nfs_pageio_complete_read(&pgio); 419 420 put_nfs_open_context(ctx); 421 out: 422 trace_nfs_aop_readahead_done(inode, nr_pages, ret); 423 } 424 425 int __init nfs_init_readpagecache(void) 426 { 427 nfs_rdata_cachep = kmem_cache_create("nfs_read_data", 428 sizeof(struct nfs_pgio_header), 429 0, SLAB_HWCACHE_ALIGN, 430 NULL); 431 if (nfs_rdata_cachep == NULL) 432 return -ENOMEM; 433 434 return 0; 435 } 436 437 void nfs_destroy_readpagecache(void) 438 { 439 kmem_cache_destroy(nfs_rdata_cachep); 440 } 441 442 static const struct nfs_rw_ops nfs_rw_read_ops = { 443 .rw_alloc_header = nfs_readhdr_alloc, 444 .rw_free_header = nfs_readhdr_free, 445 .rw_done = nfs_readpage_done, 446 .rw_result = nfs_readpage_result, 447 .rw_initiate = nfs_initiate_read, 448 }; 449