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 static 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 inode *inode = d_inode(nfs_req_openctx(req)->dentry); 114 struct page *page = req->wb_page; 115 116 dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id, 117 (unsigned long long)NFS_FILEID(inode), req->wb_bytes, 118 (long long)req_offset(req)); 119 120 if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT) 121 SetPageError(page); 122 if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) { 123 if (PageUptodate(page)) 124 nfs_fscache_write_page(inode, page); 125 unlock_page(page); 126 } 127 nfs_release_request(req); 128 } 129 130 struct nfs_readdesc { 131 struct nfs_pageio_descriptor pgio; 132 struct nfs_open_context *ctx; 133 }; 134 135 static void nfs_page_group_set_uptodate(struct nfs_page *req) 136 { 137 if (nfs_page_group_sync_on_bit(req, PG_UPTODATE)) 138 SetPageUptodate(req->wb_page); 139 } 140 141 static void nfs_read_completion(struct nfs_pgio_header *hdr) 142 { 143 unsigned long bytes = 0; 144 int error; 145 146 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) 147 goto out; 148 while (!list_empty(&hdr->pages)) { 149 struct nfs_page *req = nfs_list_entry(hdr->pages.next); 150 struct page *page = req->wb_page; 151 unsigned long start = req->wb_pgbase; 152 unsigned long end = req->wb_pgbase + req->wb_bytes; 153 154 if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) { 155 /* note: regions of the page not covered by a 156 * request are zeroed in readpage_async_filler */ 157 if (bytes > hdr->good_bytes) { 158 /* nothing in this request was good, so zero 159 * the full extent of the request */ 160 zero_user_segment(page, 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 zero_user_segment(page, 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 out: 185 hdr->release(hdr); 186 } 187 188 static void nfs_initiate_read(struct nfs_pgio_header *hdr, 189 struct rpc_message *msg, 190 const struct nfs_rpc_ops *rpc_ops, 191 struct rpc_task_setup *task_setup_data, int how) 192 { 193 rpc_ops->read_setup(hdr, msg); 194 trace_nfs_initiate_read(hdr); 195 } 196 197 static void 198 nfs_async_read_error(struct list_head *head, int error) 199 { 200 struct nfs_page *req; 201 202 while (!list_empty(head)) { 203 req = nfs_list_entry(head->next); 204 nfs_list_remove_request(req); 205 nfs_readpage_release(req, error); 206 } 207 } 208 209 static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = { 210 .error_cleanup = nfs_async_read_error, 211 .completion = nfs_read_completion, 212 }; 213 214 /* 215 * This is the callback from RPC telling us whether a reply was 216 * received or some error occurred (timeout or socket shutdown). 217 */ 218 static int nfs_readpage_done(struct rpc_task *task, 219 struct nfs_pgio_header *hdr, 220 struct inode *inode) 221 { 222 int status = NFS_PROTO(inode)->read_done(task, hdr); 223 if (status != 0) 224 return status; 225 226 nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count); 227 trace_nfs_readpage_done(task, hdr); 228 229 if (task->tk_status == -ESTALE) { 230 nfs_set_inode_stale(inode); 231 nfs_mark_for_revalidate(inode); 232 } 233 return 0; 234 } 235 236 static void nfs_readpage_retry(struct rpc_task *task, 237 struct nfs_pgio_header *hdr) 238 { 239 struct nfs_pgio_args *argp = &hdr->args; 240 struct nfs_pgio_res *resp = &hdr->res; 241 242 /* This is a short read! */ 243 nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD); 244 trace_nfs_readpage_short(task, hdr); 245 246 /* Has the server at least made some progress? */ 247 if (resp->count == 0) { 248 nfs_set_pgio_error(hdr, -EIO, argp->offset); 249 return; 250 } 251 252 /* For non rpc-based layout drivers, retry-through-MDS */ 253 if (!task->tk_ops) { 254 hdr->pnfs_error = -EAGAIN; 255 return; 256 } 257 258 /* Yes, so retry the read at the end of the hdr */ 259 hdr->mds_offset += resp->count; 260 argp->offset += resp->count; 261 argp->pgbase += resp->count; 262 argp->count -= resp->count; 263 resp->count = 0; 264 resp->eof = 0; 265 rpc_restart_call_prepare(task); 266 } 267 268 static void nfs_readpage_result(struct rpc_task *task, 269 struct nfs_pgio_header *hdr) 270 { 271 if (hdr->res.eof) { 272 loff_t pos = hdr->args.offset + hdr->res.count; 273 unsigned int new = pos - hdr->io_start; 274 275 if (hdr->good_bytes > new) { 276 hdr->good_bytes = new; 277 set_bit(NFS_IOHDR_EOF, &hdr->flags); 278 clear_bit(NFS_IOHDR_ERROR, &hdr->flags); 279 } 280 } else if (hdr->res.count < hdr->args.count) 281 nfs_readpage_retry(task, hdr); 282 } 283 284 static int 285 readpage_async_filler(struct nfs_readdesc *desc, struct page *page) 286 { 287 struct inode *inode = page_file_mapping(page)->host; 288 unsigned int rsize = NFS_SERVER(inode)->rsize; 289 struct nfs_page *new; 290 unsigned int len, aligned_len; 291 int error; 292 293 len = nfs_page_length(page); 294 if (len == 0) 295 return nfs_return_empty_page(page); 296 297 aligned_len = min_t(unsigned int, ALIGN(len, rsize), PAGE_SIZE); 298 299 if (!IS_SYNC(page->mapping->host)) { 300 error = nfs_fscache_read_page(page->mapping->host, page); 301 if (error == 0) 302 goto out_unlock; 303 } 304 305 new = nfs_create_request(desc->ctx, page, 0, aligned_len); 306 if (IS_ERR(new)) 307 goto out_error; 308 309 if (len < PAGE_SIZE) 310 zero_user_segment(page, len, PAGE_SIZE); 311 if (!nfs_pageio_add_request(&desc->pgio, new)) { 312 nfs_list_remove_request(new); 313 error = desc->pgio.pg_error; 314 nfs_readpage_release(new, error); 315 goto out; 316 } 317 return 0; 318 out_error: 319 error = PTR_ERR(new); 320 out_unlock: 321 unlock_page(page); 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 page *page = &folio->page; 335 struct nfs_readdesc desc; 336 struct inode *inode = page_file_mapping(page)->host; 337 int ret; 338 339 trace_nfs_aop_readpage(inode, page); 340 nfs_inc_stats(inode, NFSIOS_VFSREADPAGE); 341 342 /* 343 * Try to flush any pending writes to the file.. 344 * 345 * NOTE! Because we own the page lock, there cannot 346 * be any new pending writes generated at this point 347 * for this page (other pages can be written to). 348 */ 349 ret = nfs_wb_page(inode, page); 350 if (ret) 351 goto out_unlock; 352 if (PageUptodate(page)) 353 goto out_unlock; 354 355 ret = -ESTALE; 356 if (NFS_STALE(inode)) 357 goto out_unlock; 358 359 if (file == NULL) { 360 ret = -EBADF; 361 desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ); 362 if (desc.ctx == NULL) 363 goto out_unlock; 364 } else 365 desc.ctx = get_nfs_open_context(nfs_file_open_context(file)); 366 367 xchg(&desc.ctx->error, 0); 368 nfs_pageio_init_read(&desc.pgio, inode, false, 369 &nfs_async_read_completion_ops); 370 371 ret = readpage_async_filler(&desc, page); 372 if (ret) 373 goto out; 374 375 nfs_pageio_complete_read(&desc.pgio); 376 ret = desc.pgio.pg_error < 0 ? desc.pgio.pg_error : 0; 377 if (!ret) { 378 ret = wait_on_page_locked_killable(page); 379 if (!PageUptodate(page) && !ret) 380 ret = xchg(&desc.ctx->error, 0); 381 } 382 out: 383 put_nfs_open_context(desc.ctx); 384 trace_nfs_aop_readpage_done(inode, page, ret); 385 return ret; 386 out_unlock: 387 unlock_page(page); 388 trace_nfs_aop_readpage_done(inode, page, ret); 389 return ret; 390 } 391 392 void nfs_readahead(struct readahead_control *ractl) 393 { 394 unsigned int nr_pages = readahead_count(ractl); 395 struct file *file = ractl->file; 396 struct nfs_readdesc desc; 397 struct inode *inode = ractl->mapping->host; 398 struct page *page; 399 int ret; 400 401 trace_nfs_aop_readahead(inode, readahead_pos(ractl), nr_pages); 402 nfs_inc_stats(inode, NFSIOS_VFSREADPAGES); 403 404 ret = -ESTALE; 405 if (NFS_STALE(inode)) 406 goto out; 407 408 if (file == NULL) { 409 ret = -EBADF; 410 desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ); 411 if (desc.ctx == NULL) 412 goto out; 413 } else 414 desc.ctx = get_nfs_open_context(nfs_file_open_context(file)); 415 416 nfs_pageio_init_read(&desc.pgio, inode, false, 417 &nfs_async_read_completion_ops); 418 419 while ((page = readahead_page(ractl)) != NULL) { 420 ret = readpage_async_filler(&desc, page); 421 put_page(page); 422 if (ret) 423 break; 424 } 425 426 nfs_pageio_complete_read(&desc.pgio); 427 428 put_nfs_open_context(desc.ctx); 429 out: 430 trace_nfs_aop_readahead_done(inode, nr_pages, ret); 431 } 432 433 int __init nfs_init_readpagecache(void) 434 { 435 nfs_rdata_cachep = kmem_cache_create("nfs_read_data", 436 sizeof(struct nfs_pgio_header), 437 0, SLAB_HWCACHE_ALIGN, 438 NULL); 439 if (nfs_rdata_cachep == NULL) 440 return -ENOMEM; 441 442 return 0; 443 } 444 445 void nfs_destroy_readpagecache(void) 446 { 447 kmem_cache_destroy(nfs_rdata_cachep); 448 } 449 450 static const struct nfs_rw_ops nfs_rw_read_ops = { 451 .rw_alloc_header = nfs_readhdr_alloc, 452 .rw_free_header = nfs_readhdr_free, 453 .rw_done = nfs_readpage_done, 454 .rw_result = nfs_readpage_result, 455 .rw_initiate = nfs_initiate_read, 456 }; 457