| 1 | /* |
| 2 | * linux/fs/nfs/read.c |
| 3 | * |
| 4 | * Block I/O for NFS |
| 5 | * |
| 6 | * Partial copy of Linus' read cache modifications to fs/nfs/file.c |
| 7 | * modified for async RPC by okir@monad.swb.de |
| 8 | */ |
| 9 | |
| 10 | #include <linux/time.h> |
| 11 | #include <linux/kernel.h> |
| 12 | #include <linux/errno.h> |
| 13 | #include <linux/fcntl.h> |
| 14 | #include <linux/stat.h> |
| 15 | #include <linux/mm.h> |
| 16 | #include <linux/slab.h> |
| 17 | #include <linux/pagemap.h> |
| 18 | #include <linux/sunrpc/clnt.h> |
| 19 | #include <linux/nfs_fs.h> |
| 20 | #include <linux/nfs_page.h> |
| 21 | #include <linux/module.h> |
| 22 | |
| 23 | #include "nfs4_fs.h" |
| 24 | #include "internal.h" |
| 25 | #include "iostat.h" |
| 26 | #include "fscache.h" |
| 27 | |
| 28 | #define NFSDBG_FACILITY NFSDBG_PAGECACHE |
| 29 | |
| 30 | static const struct nfs_pageio_ops nfs_pageio_read_ops; |
| 31 | static const struct rpc_call_ops nfs_read_common_ops; |
| 32 | static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops; |
| 33 | |
| 34 | static struct kmem_cache *nfs_rdata_cachep; |
| 35 | |
| 36 | struct nfs_read_header *nfs_readhdr_alloc(void) |
| 37 | { |
| 38 | struct nfs_read_header *rhdr; |
| 39 | |
| 40 | rhdr = kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL); |
| 41 | if (rhdr) { |
| 42 | struct nfs_pgio_header *hdr = &rhdr->header; |
| 43 | |
| 44 | INIT_LIST_HEAD(&hdr->pages); |
| 45 | INIT_LIST_HEAD(&hdr->rpc_list); |
| 46 | spin_lock_init(&hdr->lock); |
| 47 | atomic_set(&hdr->refcnt, 0); |
| 48 | } |
| 49 | return rhdr; |
| 50 | } |
| 51 | EXPORT_SYMBOL_GPL(nfs_readhdr_alloc); |
| 52 | |
| 53 | static struct nfs_read_data *nfs_readdata_alloc(struct nfs_pgio_header *hdr, |
| 54 | unsigned int pagecount) |
| 55 | { |
| 56 | struct nfs_read_data *data, *prealloc; |
| 57 | |
| 58 | prealloc = &container_of(hdr, struct nfs_read_header, header)->rpc_data; |
| 59 | if (prealloc->header == NULL) |
| 60 | data = prealloc; |
| 61 | else |
| 62 | data = kzalloc(sizeof(*data), GFP_KERNEL); |
| 63 | if (!data) |
| 64 | goto out; |
| 65 | |
| 66 | if (nfs_pgarray_set(&data->pages, pagecount)) { |
| 67 | data->header = hdr; |
| 68 | atomic_inc(&hdr->refcnt); |
| 69 | } else { |
| 70 | if (data != prealloc) |
| 71 | kfree(data); |
| 72 | data = NULL; |
| 73 | } |
| 74 | out: |
| 75 | return data; |
| 76 | } |
| 77 | |
| 78 | void nfs_readhdr_free(struct nfs_pgio_header *hdr) |
| 79 | { |
| 80 | struct nfs_read_header *rhdr = container_of(hdr, struct nfs_read_header, header); |
| 81 | |
| 82 | kmem_cache_free(nfs_rdata_cachep, rhdr); |
| 83 | } |
| 84 | EXPORT_SYMBOL_GPL(nfs_readhdr_free); |
| 85 | |
| 86 | void nfs_readdata_release(struct nfs_read_data *rdata) |
| 87 | { |
| 88 | struct nfs_pgio_header *hdr = rdata->header; |
| 89 | struct nfs_read_header *read_header = container_of(hdr, struct nfs_read_header, header); |
| 90 | |
| 91 | put_nfs_open_context(rdata->args.context); |
| 92 | if (rdata->pages.pagevec != rdata->pages.page_array) |
| 93 | kfree(rdata->pages.pagevec); |
| 94 | if (rdata == &read_header->rpc_data) { |
| 95 | rdata->header = NULL; |
| 96 | rdata = NULL; |
| 97 | } |
| 98 | if (atomic_dec_and_test(&hdr->refcnt)) |
| 99 | hdr->completion_ops->completion(hdr); |
| 100 | /* Note: we only free the rpc_task after callbacks are done. |
| 101 | * See the comment in rpc_free_task() for why |
| 102 | */ |
| 103 | kfree(rdata); |
| 104 | } |
| 105 | EXPORT_SYMBOL_GPL(nfs_readdata_release); |
| 106 | |
| 107 | static |
| 108 | int nfs_return_empty_page(struct page *page) |
| 109 | { |
| 110 | zero_user(page, 0, PAGE_CACHE_SIZE); |
| 111 | SetPageUptodate(page); |
| 112 | unlock_page(page); |
| 113 | return 0; |
| 114 | } |
| 115 | |
| 116 | void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio, |
| 117 | struct inode *inode, |
| 118 | const struct nfs_pgio_completion_ops *compl_ops) |
| 119 | { |
| 120 | nfs_pageio_init(pgio, inode, &nfs_pageio_read_ops, compl_ops, |
| 121 | NFS_SERVER(inode)->rsize, 0); |
| 122 | } |
| 123 | EXPORT_SYMBOL_GPL(nfs_pageio_init_read); |
| 124 | |
| 125 | void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio) |
| 126 | { |
| 127 | pgio->pg_ops = &nfs_pageio_read_ops; |
| 128 | pgio->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize; |
| 129 | } |
| 130 | EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds); |
| 131 | |
| 132 | int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode, |
| 133 | struct page *page) |
| 134 | { |
| 135 | struct nfs_page *new; |
| 136 | unsigned int len; |
| 137 | struct nfs_pageio_descriptor pgio; |
| 138 | |
| 139 | len = nfs_page_length(page); |
| 140 | if (len == 0) |
| 141 | return nfs_return_empty_page(page); |
| 142 | new = nfs_create_request(ctx, inode, page, 0, len); |
| 143 | if (IS_ERR(new)) { |
| 144 | unlock_page(page); |
| 145 | return PTR_ERR(new); |
| 146 | } |
| 147 | if (len < PAGE_CACHE_SIZE) |
| 148 | zero_user_segment(page, len, PAGE_CACHE_SIZE); |
| 149 | |
| 150 | NFS_PROTO(inode)->read_pageio_init(&pgio, inode, &nfs_async_read_completion_ops); |
| 151 | nfs_pageio_add_request(&pgio, new); |
| 152 | nfs_pageio_complete(&pgio); |
| 153 | NFS_I(inode)->read_io += pgio.pg_bytes_written; |
| 154 | return 0; |
| 155 | } |
| 156 | |
| 157 | static void nfs_readpage_release(struct nfs_page *req) |
| 158 | { |
| 159 | struct inode *d_inode = req->wb_context->dentry->d_inode; |
| 160 | |
| 161 | if (PageUptodate(req->wb_page)) |
| 162 | nfs_readpage_to_fscache(d_inode, req->wb_page, 0); |
| 163 | |
| 164 | unlock_page(req->wb_page); |
| 165 | |
| 166 | dprintk("NFS: read done (%s/%Ld %d@%Ld)\n", |
| 167 | req->wb_context->dentry->d_inode->i_sb->s_id, |
| 168 | (long long)NFS_FILEID(req->wb_context->dentry->d_inode), |
| 169 | req->wb_bytes, |
| 170 | (long long)req_offset(req)); |
| 171 | nfs_release_request(req); |
| 172 | } |
| 173 | |
| 174 | /* Note io was page aligned */ |
| 175 | static void nfs_read_completion(struct nfs_pgio_header *hdr) |
| 176 | { |
| 177 | unsigned long bytes = 0; |
| 178 | |
| 179 | if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) |
| 180 | goto out; |
| 181 | while (!list_empty(&hdr->pages)) { |
| 182 | struct nfs_page *req = nfs_list_entry(hdr->pages.next); |
| 183 | struct page *page = req->wb_page; |
| 184 | |
| 185 | if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) { |
| 186 | if (bytes > hdr->good_bytes) |
| 187 | zero_user(page, 0, PAGE_SIZE); |
| 188 | else if (hdr->good_bytes - bytes < PAGE_SIZE) |
| 189 | zero_user_segment(page, |
| 190 | hdr->good_bytes & ~PAGE_MASK, |
| 191 | PAGE_SIZE); |
| 192 | } |
| 193 | bytes += req->wb_bytes; |
| 194 | if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) { |
| 195 | if (bytes <= hdr->good_bytes) |
| 196 | SetPageUptodate(page); |
| 197 | } else |
| 198 | SetPageUptodate(page); |
| 199 | nfs_list_remove_request(req); |
| 200 | nfs_readpage_release(req); |
| 201 | } |
| 202 | out: |
| 203 | hdr->release(hdr); |
| 204 | } |
| 205 | |
| 206 | int nfs_initiate_read(struct rpc_clnt *clnt, |
| 207 | struct nfs_read_data *data, |
| 208 | const struct rpc_call_ops *call_ops, int flags) |
| 209 | { |
| 210 | struct inode *inode = data->header->inode; |
| 211 | int swap_flags = IS_SWAPFILE(inode) ? NFS_RPC_SWAPFLAGS : 0; |
| 212 | struct rpc_task *task; |
| 213 | struct rpc_message msg = { |
| 214 | .rpc_argp = &data->args, |
| 215 | .rpc_resp = &data->res, |
| 216 | .rpc_cred = data->header->cred, |
| 217 | }; |
| 218 | struct rpc_task_setup task_setup_data = { |
| 219 | .task = &data->task, |
| 220 | .rpc_client = clnt, |
| 221 | .rpc_message = &msg, |
| 222 | .callback_ops = call_ops, |
| 223 | .callback_data = data, |
| 224 | .workqueue = nfsiod_workqueue, |
| 225 | .flags = RPC_TASK_ASYNC | swap_flags | flags, |
| 226 | }; |
| 227 | |
| 228 | /* Set up the initial task struct. */ |
| 229 | NFS_PROTO(inode)->read_setup(data, &msg); |
| 230 | |
| 231 | dprintk("NFS: %5u initiated read call (req %s/%lld, %u bytes @ " |
| 232 | "offset %llu)\n", |
| 233 | data->task.tk_pid, |
| 234 | inode->i_sb->s_id, |
| 235 | (long long)NFS_FILEID(inode), |
| 236 | data->args.count, |
| 237 | (unsigned long long)data->args.offset); |
| 238 | |
| 239 | task = rpc_run_task(&task_setup_data); |
| 240 | if (IS_ERR(task)) |
| 241 | return PTR_ERR(task); |
| 242 | rpc_put_task(task); |
| 243 | return 0; |
| 244 | } |
| 245 | EXPORT_SYMBOL_GPL(nfs_initiate_read); |
| 246 | |
| 247 | /* |
| 248 | * Set up the NFS read request struct |
| 249 | */ |
| 250 | static void nfs_read_rpcsetup(struct nfs_read_data *data, |
| 251 | unsigned int count, unsigned int offset) |
| 252 | { |
| 253 | struct nfs_page *req = data->header->req; |
| 254 | |
| 255 | data->args.fh = NFS_FH(data->header->inode); |
| 256 | data->args.offset = req_offset(req) + offset; |
| 257 | data->args.pgbase = req->wb_pgbase + offset; |
| 258 | data->args.pages = data->pages.pagevec; |
| 259 | data->args.count = count; |
| 260 | data->args.context = get_nfs_open_context(req->wb_context); |
| 261 | data->args.lock_context = req->wb_lock_context; |
| 262 | |
| 263 | data->res.fattr = &data->fattr; |
| 264 | data->res.count = count; |
| 265 | data->res.eof = 0; |
| 266 | nfs_fattr_init(&data->fattr); |
| 267 | } |
| 268 | |
| 269 | static int nfs_do_read(struct nfs_read_data *data, |
| 270 | const struct rpc_call_ops *call_ops) |
| 271 | { |
| 272 | struct inode *inode = data->header->inode; |
| 273 | |
| 274 | return nfs_initiate_read(NFS_CLIENT(inode), data, call_ops, 0); |
| 275 | } |
| 276 | |
| 277 | static int |
| 278 | nfs_do_multiple_reads(struct list_head *head, |
| 279 | const struct rpc_call_ops *call_ops) |
| 280 | { |
| 281 | struct nfs_read_data *data; |
| 282 | int ret = 0; |
| 283 | |
| 284 | while (!list_empty(head)) { |
| 285 | int ret2; |
| 286 | |
| 287 | data = list_first_entry(head, struct nfs_read_data, list); |
| 288 | list_del_init(&data->list); |
| 289 | |
| 290 | ret2 = nfs_do_read(data, call_ops); |
| 291 | if (ret == 0) |
| 292 | ret = ret2; |
| 293 | } |
| 294 | return ret; |
| 295 | } |
| 296 | |
| 297 | static void |
| 298 | nfs_async_read_error(struct list_head *head) |
| 299 | { |
| 300 | struct nfs_page *req; |
| 301 | |
| 302 | while (!list_empty(head)) { |
| 303 | req = nfs_list_entry(head->next); |
| 304 | nfs_list_remove_request(req); |
| 305 | nfs_readpage_release(req); |
| 306 | } |
| 307 | } |
| 308 | |
| 309 | static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = { |
| 310 | .error_cleanup = nfs_async_read_error, |
| 311 | .completion = nfs_read_completion, |
| 312 | }; |
| 313 | |
| 314 | static void nfs_pagein_error(struct nfs_pageio_descriptor *desc, |
| 315 | struct nfs_pgio_header *hdr) |
| 316 | { |
| 317 | set_bit(NFS_IOHDR_REDO, &hdr->flags); |
| 318 | while (!list_empty(&hdr->rpc_list)) { |
| 319 | struct nfs_read_data *data = list_first_entry(&hdr->rpc_list, |
| 320 | struct nfs_read_data, list); |
| 321 | list_del(&data->list); |
| 322 | nfs_readdata_release(data); |
| 323 | } |
| 324 | desc->pg_completion_ops->error_cleanup(&desc->pg_list); |
| 325 | } |
| 326 | |
| 327 | /* |
| 328 | * Generate multiple requests to fill a single page. |
| 329 | * |
| 330 | * We optimize to reduce the number of read operations on the wire. If we |
| 331 | * detect that we're reading a page, or an area of a page, that is past the |
| 332 | * end of file, we do not generate NFS read operations but just clear the |
| 333 | * parts of the page that would have come back zero from the server anyway. |
| 334 | * |
| 335 | * We rely on the cached value of i_size to make this determination; another |
| 336 | * client can fill pages on the server past our cached end-of-file, but we |
| 337 | * won't see the new data until our attribute cache is updated. This is more |
| 338 | * or less conventional NFS client behavior. |
| 339 | */ |
| 340 | static int nfs_pagein_multi(struct nfs_pageio_descriptor *desc, |
| 341 | struct nfs_pgio_header *hdr) |
| 342 | { |
| 343 | struct nfs_page *req = hdr->req; |
| 344 | struct page *page = req->wb_page; |
| 345 | struct nfs_read_data *data; |
| 346 | size_t rsize = desc->pg_bsize, nbytes; |
| 347 | unsigned int offset; |
| 348 | |
| 349 | offset = 0; |
| 350 | nbytes = desc->pg_count; |
| 351 | do { |
| 352 | size_t len = min(nbytes,rsize); |
| 353 | |
| 354 | data = nfs_readdata_alloc(hdr, 1); |
| 355 | if (!data) { |
| 356 | nfs_pagein_error(desc, hdr); |
| 357 | return -ENOMEM; |
| 358 | } |
| 359 | data->pages.pagevec[0] = page; |
| 360 | nfs_read_rpcsetup(data, len, offset); |
| 361 | list_add(&data->list, &hdr->rpc_list); |
| 362 | nbytes -= len; |
| 363 | offset += len; |
| 364 | } while (nbytes != 0); |
| 365 | |
| 366 | nfs_list_remove_request(req); |
| 367 | nfs_list_add_request(req, &hdr->pages); |
| 368 | desc->pg_rpc_callops = &nfs_read_common_ops; |
| 369 | return 0; |
| 370 | } |
| 371 | |
| 372 | static int nfs_pagein_one(struct nfs_pageio_descriptor *desc, |
| 373 | struct nfs_pgio_header *hdr) |
| 374 | { |
| 375 | struct nfs_page *req; |
| 376 | struct page **pages; |
| 377 | struct nfs_read_data *data; |
| 378 | struct list_head *head = &desc->pg_list; |
| 379 | |
| 380 | data = nfs_readdata_alloc(hdr, nfs_page_array_len(desc->pg_base, |
| 381 | desc->pg_count)); |
| 382 | if (!data) { |
| 383 | nfs_pagein_error(desc, hdr); |
| 384 | return -ENOMEM; |
| 385 | } |
| 386 | |
| 387 | pages = data->pages.pagevec; |
| 388 | while (!list_empty(head)) { |
| 389 | req = nfs_list_entry(head->next); |
| 390 | nfs_list_remove_request(req); |
| 391 | nfs_list_add_request(req, &hdr->pages); |
| 392 | *pages++ = req->wb_page; |
| 393 | } |
| 394 | |
| 395 | nfs_read_rpcsetup(data, desc->pg_count, 0); |
| 396 | list_add(&data->list, &hdr->rpc_list); |
| 397 | desc->pg_rpc_callops = &nfs_read_common_ops; |
| 398 | return 0; |
| 399 | } |
| 400 | |
| 401 | int nfs_generic_pagein(struct nfs_pageio_descriptor *desc, |
| 402 | struct nfs_pgio_header *hdr) |
| 403 | { |
| 404 | if (desc->pg_bsize < PAGE_CACHE_SIZE) |
| 405 | return nfs_pagein_multi(desc, hdr); |
| 406 | return nfs_pagein_one(desc, hdr); |
| 407 | } |
| 408 | EXPORT_SYMBOL_GPL(nfs_generic_pagein); |
| 409 | |
| 410 | static int nfs_generic_pg_readpages(struct nfs_pageio_descriptor *desc) |
| 411 | { |
| 412 | struct nfs_read_header *rhdr; |
| 413 | struct nfs_pgio_header *hdr; |
| 414 | int ret; |
| 415 | |
| 416 | rhdr = nfs_readhdr_alloc(); |
| 417 | if (!rhdr) { |
| 418 | desc->pg_completion_ops->error_cleanup(&desc->pg_list); |
| 419 | return -ENOMEM; |
| 420 | } |
| 421 | hdr = &rhdr->header; |
| 422 | nfs_pgheader_init(desc, hdr, nfs_readhdr_free); |
| 423 | atomic_inc(&hdr->refcnt); |
| 424 | ret = nfs_generic_pagein(desc, hdr); |
| 425 | if (ret == 0) |
| 426 | ret = nfs_do_multiple_reads(&hdr->rpc_list, |
| 427 | desc->pg_rpc_callops); |
| 428 | if (atomic_dec_and_test(&hdr->refcnt)) |
| 429 | hdr->completion_ops->completion(hdr); |
| 430 | return ret; |
| 431 | } |
| 432 | |
| 433 | static const struct nfs_pageio_ops nfs_pageio_read_ops = { |
| 434 | .pg_test = nfs_generic_pg_test, |
| 435 | .pg_doio = nfs_generic_pg_readpages, |
| 436 | }; |
| 437 | |
| 438 | /* |
| 439 | * This is the callback from RPC telling us whether a reply was |
| 440 | * received or some error occurred (timeout or socket shutdown). |
| 441 | */ |
| 442 | int nfs_readpage_result(struct rpc_task *task, struct nfs_read_data *data) |
| 443 | { |
| 444 | struct inode *inode = data->header->inode; |
| 445 | int status; |
| 446 | |
| 447 | dprintk("NFS: %s: %5u, (status %d)\n", __func__, task->tk_pid, |
| 448 | task->tk_status); |
| 449 | |
| 450 | status = NFS_PROTO(inode)->read_done(task, data); |
| 451 | if (status != 0) |
| 452 | return status; |
| 453 | |
| 454 | nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, data->res.count); |
| 455 | |
| 456 | if (task->tk_status == -ESTALE) { |
| 457 | set_bit(NFS_INO_STALE, &NFS_I(inode)->flags); |
| 458 | nfs_mark_for_revalidate(inode); |
| 459 | } |
| 460 | return 0; |
| 461 | } |
| 462 | |
| 463 | static void nfs_readpage_retry(struct rpc_task *task, struct nfs_read_data *data) |
| 464 | { |
| 465 | struct nfs_readargs *argp = &data->args; |
| 466 | struct nfs_readres *resp = &data->res; |
| 467 | |
| 468 | /* This is a short read! */ |
| 469 | nfs_inc_stats(data->header->inode, NFSIOS_SHORTREAD); |
| 470 | /* Has the server at least made some progress? */ |
| 471 | if (resp->count == 0) { |
| 472 | nfs_set_pgio_error(data->header, -EIO, argp->offset); |
| 473 | return; |
| 474 | } |
| 475 | /* Yes, so retry the read at the end of the data */ |
| 476 | data->mds_offset += resp->count; |
| 477 | argp->offset += resp->count; |
| 478 | argp->pgbase += resp->count; |
| 479 | argp->count -= resp->count; |
| 480 | rpc_restart_call_prepare(task); |
| 481 | } |
| 482 | |
| 483 | static void nfs_readpage_result_common(struct rpc_task *task, void *calldata) |
| 484 | { |
| 485 | struct nfs_read_data *data = calldata; |
| 486 | struct nfs_pgio_header *hdr = data->header; |
| 487 | |
| 488 | /* Note the only returns of nfs_readpage_result are 0 and -EAGAIN */ |
| 489 | if (nfs_readpage_result(task, data) != 0) |
| 490 | return; |
| 491 | if (task->tk_status < 0) |
| 492 | nfs_set_pgio_error(hdr, task->tk_status, data->args.offset); |
| 493 | else if (data->res.eof) { |
| 494 | loff_t bound; |
| 495 | |
| 496 | bound = data->args.offset + data->res.count; |
| 497 | spin_lock(&hdr->lock); |
| 498 | if (bound < hdr->io_start + hdr->good_bytes) { |
| 499 | set_bit(NFS_IOHDR_EOF, &hdr->flags); |
| 500 | clear_bit(NFS_IOHDR_ERROR, &hdr->flags); |
| 501 | hdr->good_bytes = bound - hdr->io_start; |
| 502 | } |
| 503 | spin_unlock(&hdr->lock); |
| 504 | } else if (data->res.count != data->args.count) |
| 505 | nfs_readpage_retry(task, data); |
| 506 | } |
| 507 | |
| 508 | static void nfs_readpage_release_common(void *calldata) |
| 509 | { |
| 510 | nfs_readdata_release(calldata); |
| 511 | } |
| 512 | |
| 513 | void nfs_read_prepare(struct rpc_task *task, void *calldata) |
| 514 | { |
| 515 | struct nfs_read_data *data = calldata; |
| 516 | NFS_PROTO(data->header->inode)->read_rpc_prepare(task, data); |
| 517 | } |
| 518 | |
| 519 | static const struct rpc_call_ops nfs_read_common_ops = { |
| 520 | .rpc_call_prepare = nfs_read_prepare, |
| 521 | .rpc_call_done = nfs_readpage_result_common, |
| 522 | .rpc_release = nfs_readpage_release_common, |
| 523 | }; |
| 524 | |
| 525 | /* |
| 526 | * Read a page over NFS. |
| 527 | * We read the page synchronously in the following case: |
| 528 | * - The error flag is set for this page. This happens only when a |
| 529 | * previous async read operation failed. |
| 530 | */ |
| 531 | int nfs_readpage(struct file *file, struct page *page) |
| 532 | { |
| 533 | struct nfs_open_context *ctx; |
| 534 | struct inode *inode = page_file_mapping(page)->host; |
| 535 | int error; |
| 536 | |
| 537 | dprintk("NFS: nfs_readpage (%p %ld@%lu)\n", |
| 538 | page, PAGE_CACHE_SIZE, page_file_index(page)); |
| 539 | nfs_inc_stats(inode, NFSIOS_VFSREADPAGE); |
| 540 | nfs_add_stats(inode, NFSIOS_READPAGES, 1); |
| 541 | |
| 542 | /* |
| 543 | * Try to flush any pending writes to the file.. |
| 544 | * |
| 545 | * NOTE! Because we own the page lock, there cannot |
| 546 | * be any new pending writes generated at this point |
| 547 | * for this page (other pages can be written to). |
| 548 | */ |
| 549 | error = nfs_wb_page(inode, page); |
| 550 | if (error) |
| 551 | goto out_unlock; |
| 552 | if (PageUptodate(page)) |
| 553 | goto out_unlock; |
| 554 | |
| 555 | error = -ESTALE; |
| 556 | if (NFS_STALE(inode)) |
| 557 | goto out_unlock; |
| 558 | |
| 559 | if (file == NULL) { |
| 560 | error = -EBADF; |
| 561 | ctx = nfs_find_open_context(inode, NULL, FMODE_READ); |
| 562 | if (ctx == NULL) |
| 563 | goto out_unlock; |
| 564 | } else |
| 565 | ctx = get_nfs_open_context(nfs_file_open_context(file)); |
| 566 | |
| 567 | if (!IS_SYNC(inode)) { |
| 568 | error = nfs_readpage_from_fscache(ctx, inode, page); |
| 569 | if (error == 0) |
| 570 | goto out; |
| 571 | } |
| 572 | |
| 573 | error = nfs_readpage_async(ctx, inode, page); |
| 574 | |
| 575 | out: |
| 576 | put_nfs_open_context(ctx); |
| 577 | return error; |
| 578 | out_unlock: |
| 579 | unlock_page(page); |
| 580 | return error; |
| 581 | } |
| 582 | |
| 583 | struct nfs_readdesc { |
| 584 | struct nfs_pageio_descriptor *pgio; |
| 585 | struct nfs_open_context *ctx; |
| 586 | }; |
| 587 | |
| 588 | static int |
| 589 | readpage_async_filler(void *data, struct page *page) |
| 590 | { |
| 591 | struct nfs_readdesc *desc = (struct nfs_readdesc *)data; |
| 592 | struct inode *inode = page_file_mapping(page)->host; |
| 593 | struct nfs_page *new; |
| 594 | unsigned int len; |
| 595 | int error; |
| 596 | |
| 597 | len = nfs_page_length(page); |
| 598 | if (len == 0) |
| 599 | return nfs_return_empty_page(page); |
| 600 | |
| 601 | new = nfs_create_request(desc->ctx, inode, page, 0, len); |
| 602 | if (IS_ERR(new)) |
| 603 | goto out_error; |
| 604 | |
| 605 | if (len < PAGE_CACHE_SIZE) |
| 606 | zero_user_segment(page, len, PAGE_CACHE_SIZE); |
| 607 | if (!nfs_pageio_add_request(desc->pgio, new)) { |
| 608 | error = desc->pgio->pg_error; |
| 609 | goto out_unlock; |
| 610 | } |
| 611 | return 0; |
| 612 | out_error: |
| 613 | error = PTR_ERR(new); |
| 614 | out_unlock: |
| 615 | unlock_page(page); |
| 616 | return error; |
| 617 | } |
| 618 | |
| 619 | int nfs_readpages(struct file *filp, struct address_space *mapping, |
| 620 | struct list_head *pages, unsigned nr_pages) |
| 621 | { |
| 622 | struct nfs_pageio_descriptor pgio; |
| 623 | struct nfs_readdesc desc = { |
| 624 | .pgio = &pgio, |
| 625 | }; |
| 626 | struct inode *inode = mapping->host; |
| 627 | unsigned long npages; |
| 628 | int ret = -ESTALE; |
| 629 | |
| 630 | dprintk("NFS: nfs_readpages (%s/%Ld %d)\n", |
| 631 | inode->i_sb->s_id, |
| 632 | (long long)NFS_FILEID(inode), |
| 633 | nr_pages); |
| 634 | nfs_inc_stats(inode, NFSIOS_VFSREADPAGES); |
| 635 | |
| 636 | if (NFS_STALE(inode)) |
| 637 | goto out; |
| 638 | |
| 639 | if (filp == NULL) { |
| 640 | desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ); |
| 641 | if (desc.ctx == NULL) |
| 642 | return -EBADF; |
| 643 | } else |
| 644 | desc.ctx = get_nfs_open_context(nfs_file_open_context(filp)); |
| 645 | |
| 646 | /* attempt to read as many of the pages as possible from the cache |
| 647 | * - this returns -ENOBUFS immediately if the cookie is negative |
| 648 | */ |
| 649 | ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping, |
| 650 | pages, &nr_pages); |
| 651 | if (ret == 0) |
| 652 | goto read_complete; /* all pages were read */ |
| 653 | |
| 654 | NFS_PROTO(inode)->read_pageio_init(&pgio, inode, &nfs_async_read_completion_ops); |
| 655 | |
| 656 | ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc); |
| 657 | |
| 658 | nfs_pageio_complete(&pgio); |
| 659 | NFS_I(inode)->read_io += pgio.pg_bytes_written; |
| 660 | npages = (pgio.pg_bytes_written + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
| 661 | nfs_add_stats(inode, NFSIOS_READPAGES, npages); |
| 662 | read_complete: |
| 663 | put_nfs_open_context(desc.ctx); |
| 664 | out: |
| 665 | return ret; |
| 666 | } |
| 667 | |
| 668 | int __init nfs_init_readpagecache(void) |
| 669 | { |
| 670 | nfs_rdata_cachep = kmem_cache_create("nfs_read_data", |
| 671 | sizeof(struct nfs_read_header), |
| 672 | 0, SLAB_HWCACHE_ALIGN, |
| 673 | NULL); |
| 674 | if (nfs_rdata_cachep == NULL) |
| 675 | return -ENOMEM; |
| 676 | |
| 677 | return 0; |
| 678 | } |
| 679 | |
| 680 | void nfs_destroy_readpagecache(void) |
| 681 | { |
| 682 | kmem_cache_destroy(nfs_rdata_cachep); |
| 683 | } |