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, int error) 95 { 96 struct inode *inode = d_inode(nfs_req_openctx(req)->dentry); 97 struct page *page = req->wb_page; 98 99 dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id, 100 (unsigned long long)NFS_FILEID(inode), req->wb_bytes, 101 (long long)req_offset(req)); 102 103 if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT) 104 SetPageError(page); 105 if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) { 106 struct address_space *mapping = page_file_mapping(page); 107 108 if (PageUptodate(page)) 109 nfs_readpage_to_fscache(inode, page, 0); 110 else if (!PageError(page) && !PagePrivate(page)) 111 generic_error_remove_page(mapping, page); 112 unlock_page(page); 113 } 114 nfs_release_request(req); 115 } 116 117 int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode, 118 struct page *page) 119 { 120 struct nfs_page *new; 121 unsigned int len; 122 struct nfs_pageio_descriptor pgio; 123 struct nfs_pgio_mirror *pgm; 124 125 len = nfs_page_length(page); 126 if (len == 0) 127 return nfs_return_empty_page(page); 128 new = nfs_create_request(ctx, page, 0, len); 129 if (IS_ERR(new)) { 130 unlock_page(page); 131 return PTR_ERR(new); 132 } 133 if (len < PAGE_SIZE) 134 zero_user_segment(page, len, PAGE_SIZE); 135 136 nfs_pageio_init_read(&pgio, inode, false, 137 &nfs_async_read_completion_ops); 138 if (!nfs_pageio_add_request(&pgio, new)) { 139 nfs_list_remove_request(new); 140 nfs_readpage_release(new, pgio.pg_error); 141 } 142 nfs_pageio_complete(&pgio); 143 144 /* It doesn't make sense to do mirrored reads! */ 145 WARN_ON_ONCE(pgio.pg_mirror_count != 1); 146 147 pgm = &pgio.pg_mirrors[0]; 148 NFS_I(inode)->read_io += pgm->pg_bytes_written; 149 150 return pgio.pg_error < 0 ? pgio.pg_error : 0; 151 } 152 153 static void nfs_page_group_set_uptodate(struct nfs_page *req) 154 { 155 if (nfs_page_group_sync_on_bit(req, PG_UPTODATE)) 156 SetPageUptodate(req->wb_page); 157 } 158 159 static void nfs_read_completion(struct nfs_pgio_header *hdr) 160 { 161 unsigned long bytes = 0; 162 int error; 163 164 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) 165 goto out; 166 while (!list_empty(&hdr->pages)) { 167 struct nfs_page *req = nfs_list_entry(hdr->pages.next); 168 struct page *page = req->wb_page; 169 unsigned long start = req->wb_pgbase; 170 unsigned long end = req->wb_pgbase + req->wb_bytes; 171 172 if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) { 173 /* note: regions of the page not covered by a 174 * request are zeroed in nfs_readpage_async / 175 * readpage_async_filler */ 176 if (bytes > hdr->good_bytes) { 177 /* nothing in this request was good, so zero 178 * the full extent of the request */ 179 zero_user_segment(page, start, end); 180 181 } else if (hdr->good_bytes - bytes < req->wb_bytes) { 182 /* part of this request has good bytes, but 183 * not all. zero the bad bytes */ 184 start += hdr->good_bytes - bytes; 185 WARN_ON(start < req->wb_pgbase); 186 zero_user_segment(page, start, end); 187 } 188 } 189 error = 0; 190 bytes += req->wb_bytes; 191 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) { 192 if (bytes <= hdr->good_bytes) 193 nfs_page_group_set_uptodate(req); 194 else { 195 error = hdr->error; 196 xchg(&nfs_req_openctx(req)->error, error); 197 } 198 } else 199 nfs_page_group_set_uptodate(req); 200 nfs_list_remove_request(req); 201 nfs_readpage_release(req, error); 202 } 203 out: 204 hdr->release(hdr); 205 } 206 207 static void nfs_initiate_read(struct nfs_pgio_header *hdr, 208 struct rpc_message *msg, 209 const struct nfs_rpc_ops *rpc_ops, 210 struct rpc_task_setup *task_setup_data, int how) 211 { 212 struct inode *inode = hdr->inode; 213 int swap_flags = IS_SWAPFILE(inode) ? NFS_RPC_SWAPFLAGS : 0; 214 215 task_setup_data->flags |= swap_flags; 216 rpc_ops->read_setup(hdr, msg); 217 trace_nfs_initiate_read(hdr); 218 } 219 220 static void 221 nfs_async_read_error(struct list_head *head, int error) 222 { 223 struct nfs_page *req; 224 225 while (!list_empty(head)) { 226 req = nfs_list_entry(head->next); 227 nfs_list_remove_request(req); 228 nfs_readpage_release(req, error); 229 } 230 } 231 232 static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = { 233 .error_cleanup = nfs_async_read_error, 234 .completion = nfs_read_completion, 235 }; 236 237 /* 238 * This is the callback from RPC telling us whether a reply was 239 * received or some error occurred (timeout or socket shutdown). 240 */ 241 static int nfs_readpage_done(struct rpc_task *task, 242 struct nfs_pgio_header *hdr, 243 struct inode *inode) 244 { 245 int status = NFS_PROTO(inode)->read_done(task, hdr); 246 if (status != 0) 247 return status; 248 249 nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count); 250 trace_nfs_readpage_done(task, hdr); 251 252 if (task->tk_status == -ESTALE) { 253 nfs_set_inode_stale(inode); 254 nfs_mark_for_revalidate(inode); 255 } 256 return 0; 257 } 258 259 static void nfs_readpage_retry(struct rpc_task *task, 260 struct nfs_pgio_header *hdr) 261 { 262 struct nfs_pgio_args *argp = &hdr->args; 263 struct nfs_pgio_res *resp = &hdr->res; 264 265 /* This is a short read! */ 266 nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD); 267 /* Has the server at least made some progress? */ 268 if (resp->count == 0) { 269 nfs_set_pgio_error(hdr, -EIO, argp->offset); 270 return; 271 } 272 273 /* For non rpc-based layout drivers, retry-through-MDS */ 274 if (!task->tk_ops) { 275 hdr->pnfs_error = -EAGAIN; 276 return; 277 } 278 279 /* Yes, so retry the read at the end of the hdr */ 280 hdr->mds_offset += resp->count; 281 argp->offset += resp->count; 282 argp->pgbase += resp->count; 283 argp->count -= resp->count; 284 resp->count = 0; 285 resp->eof = 0; 286 rpc_restart_call_prepare(task); 287 } 288 289 static void nfs_readpage_result(struct rpc_task *task, 290 struct nfs_pgio_header *hdr) 291 { 292 if (hdr->res.eof) { 293 loff_t pos = hdr->args.offset + hdr->res.count; 294 unsigned int new = pos - hdr->io_start; 295 296 if (hdr->good_bytes > new) { 297 hdr->good_bytes = new; 298 set_bit(NFS_IOHDR_EOF, &hdr->flags); 299 clear_bit(NFS_IOHDR_ERROR, &hdr->flags); 300 } 301 } else if (hdr->res.count < hdr->args.count) 302 nfs_readpage_retry(task, hdr); 303 } 304 305 /* 306 * Read a page over NFS. 307 * We read the page synchronously in the following case: 308 * - The error flag is set for this page. This happens only when a 309 * previous async read operation failed. 310 */ 311 int nfs_readpage(struct file *file, struct page *page) 312 { 313 struct nfs_open_context *ctx; 314 struct inode *inode = page_file_mapping(page)->host; 315 int error; 316 317 dprintk("NFS: nfs_readpage (%p %ld@%lu)\n", 318 page, PAGE_SIZE, page_index(page)); 319 nfs_inc_stats(inode, NFSIOS_VFSREADPAGE); 320 nfs_add_stats(inode, NFSIOS_READPAGES, 1); 321 322 /* 323 * Try to flush any pending writes to the file.. 324 * 325 * NOTE! Because we own the page lock, there cannot 326 * be any new pending writes generated at this point 327 * for this page (other pages can be written to). 328 */ 329 error = nfs_wb_page(inode, page); 330 if (error) 331 goto out_unlock; 332 if (PageUptodate(page)) 333 goto out_unlock; 334 335 error = -ESTALE; 336 if (NFS_STALE(inode)) 337 goto out_unlock; 338 339 if (file == NULL) { 340 error = -EBADF; 341 ctx = nfs_find_open_context(inode, NULL, FMODE_READ); 342 if (ctx == NULL) 343 goto out_unlock; 344 } else 345 ctx = get_nfs_open_context(nfs_file_open_context(file)); 346 347 if (!IS_SYNC(inode)) { 348 error = nfs_readpage_from_fscache(ctx, inode, page); 349 if (error == 0) 350 goto out; 351 } 352 353 xchg(&ctx->error, 0); 354 error = nfs_readpage_async(ctx, inode, page); 355 if (!error) { 356 error = wait_on_page_locked_killable(page); 357 if (!PageUptodate(page) && !error) 358 error = xchg(&ctx->error, 0); 359 } 360 out: 361 put_nfs_open_context(ctx); 362 return error; 363 out_unlock: 364 unlock_page(page); 365 return error; 366 } 367 368 struct nfs_readdesc { 369 struct nfs_pageio_descriptor *pgio; 370 struct nfs_open_context *ctx; 371 }; 372 373 static int 374 readpage_async_filler(void *data, struct page *page) 375 { 376 struct nfs_readdesc *desc = (struct nfs_readdesc *)data; 377 struct nfs_page *new; 378 unsigned int len; 379 int error; 380 381 len = nfs_page_length(page); 382 if (len == 0) 383 return nfs_return_empty_page(page); 384 385 new = nfs_create_request(desc->ctx, page, 0, len); 386 if (IS_ERR(new)) 387 goto out_error; 388 389 if (len < PAGE_SIZE) 390 zero_user_segment(page, len, PAGE_SIZE); 391 if (!nfs_pageio_add_request(desc->pgio, new)) { 392 nfs_list_remove_request(new); 393 error = desc->pgio->pg_error; 394 nfs_readpage_release(new, error); 395 goto out; 396 } 397 return 0; 398 out_error: 399 error = PTR_ERR(new); 400 unlock_page(page); 401 out: 402 return error; 403 } 404 405 int nfs_readpages(struct file *filp, struct address_space *mapping, 406 struct list_head *pages, unsigned nr_pages) 407 { 408 struct nfs_pageio_descriptor pgio; 409 struct nfs_pgio_mirror *pgm; 410 struct nfs_readdesc desc = { 411 .pgio = &pgio, 412 }; 413 struct inode *inode = mapping->host; 414 unsigned long npages; 415 int ret = -ESTALE; 416 417 dprintk("NFS: nfs_readpages (%s/%Lu %d)\n", 418 inode->i_sb->s_id, 419 (unsigned long long)NFS_FILEID(inode), 420 nr_pages); 421 nfs_inc_stats(inode, NFSIOS_VFSREADPAGES); 422 423 if (NFS_STALE(inode)) 424 goto out; 425 426 if (filp == NULL) { 427 desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ); 428 if (desc.ctx == NULL) 429 return -EBADF; 430 } else 431 desc.ctx = get_nfs_open_context(nfs_file_open_context(filp)); 432 433 /* attempt to read as many of the pages as possible from the cache 434 * - this returns -ENOBUFS immediately if the cookie is negative 435 */ 436 ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping, 437 pages, &nr_pages); 438 if (ret == 0) 439 goto read_complete; /* all pages were read */ 440 441 nfs_pageio_init_read(&pgio, inode, false, 442 &nfs_async_read_completion_ops); 443 444 ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc); 445 nfs_pageio_complete(&pgio); 446 447 /* It doesn't make sense to do mirrored reads! */ 448 WARN_ON_ONCE(pgio.pg_mirror_count != 1); 449 450 pgm = &pgio.pg_mirrors[0]; 451 NFS_I(inode)->read_io += pgm->pg_bytes_written; 452 npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >> 453 PAGE_SHIFT; 454 nfs_add_stats(inode, NFSIOS_READPAGES, npages); 455 read_complete: 456 put_nfs_open_context(desc.ctx); 457 out: 458 return ret; 459 } 460 461 int __init nfs_init_readpagecache(void) 462 { 463 nfs_rdata_cachep = kmem_cache_create("nfs_read_data", 464 sizeof(struct nfs_pgio_header), 465 0, SLAB_HWCACHE_ALIGN, 466 NULL); 467 if (nfs_rdata_cachep == NULL) 468 return -ENOMEM; 469 470 return 0; 471 } 472 473 void nfs_destroy_readpagecache(void) 474 { 475 kmem_cache_destroy(nfs_rdata_cachep); 476 } 477 478 static const struct nfs_rw_ops nfs_rw_read_ops = { 479 .rw_alloc_header = nfs_readhdr_alloc, 480 .rw_free_header = nfs_readhdr_free, 481 .rw_done = nfs_readpage_done, 482 .rw_result = nfs_readpage_result, 483 .rw_initiate = nfs_initiate_read, 484 }; 485