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